Determination of Polymer Additives-Antioxidants, Ultraviolet Stabilizers, Plasticizers and Photoinitiators in Plastic Food Package by Accelerated Solvent Extraction Coupled with High-Performance Liqui

19 Aug.,2022

 

Plastic Antioxidants

Antioxidants

Abstract

An analytical method for the quantitative determination of 4 antioxidants, 9 ultraviolet (UV) stabilizers, 12 phthalate plasticizers and 2 photoinitiators in plastic food package using accelerated solvent extraction (ASE) coupled with high-performance liquid chromatography-photodiode array detector (HPLC-PDA) has been developed. Parameters affecting the efficiency in the process such as extraction and chromatographic conditions were studied in order to determine operating conditions. The analytical method of ASE-HPLC showed good linearity with good correlation coefficients (R ≥ 0.9833). The limits of detection and quantification were between 0.03 and 0.30 µg mL−1 and between 0.10 and 1.00 µg mL−1 for 27 analytes. Average spiked recoveries for most analytes in samples were >70.4% at 10, 20 and 40 µg g−1 spiked levels, except UV-9 and Irganox 1010 (58.6 and 64.0% spiked at 10 µg g−1, respectively), the relative standard deviations were in the range from 0.4 to 15.4%. The methodology has been proposed for the analysis of 27 polymer additives in plastic food package.

Introduction

Plastic polymer is a commonly used material for food storage and protection because of several advantages including low production cost, good resistance, protect of the content, and reduced environmental impact. But during its manufacturing process, additives such as antioxidants, ultraviolet (UV) stabilizers, plasticizers, thermal stabilizers, lubricants, photoinitiators, antistatic agents, and others are required in polymer films in order to improve and preserve polymer properties (1).When the plastic package is in contact with food, there will be a concern about the health of consumers because the additives may migrate into the food during the process or storage (2, 3). In the present study, many scientific researches have been demonstrated that migration of additives from polymer films into food or food simulants has indeed happened (4–8). Reports about toxicological study and genotoxicity of polymer additives have also been published. So, the determination of additives content in polymers is an important component of the safety assessment of food packaging materials, the quantification and specific migration levels (SMLs) of these additives are also very important for the quality control of food.

Among a wide variety of polymer additives present in plastic, antioxidants, UV stabilizers, plasticizers and photoinitiators are widely used. Antioxidants are both natural and synthetic compounds able to scavenge free radical and to inhibit oxidation process. UV stabilizers can absorb most of the UV-light and reduce the UV-light absorption of polymer matrix. In addition, phthalate acid esters (PAEs) as the most common plasticizers are principally used to increase the flexibility of polymers. Nowadays, plastic makes an important contribution to our society. Polymer additives-antioxidants, UV stabilizers, phthalate plasticizers and photoinitiators have been focused on increasingly, especially, in food safety. The development of analytical methods for these additives analysis is an ongoing task of utmost importance.

Until now, many researchers have investigated the occurrence of antioxidants, UV stabilizers, phthalate plasticizers and photoinitiators in food (9–12), food simulants (13–17) or plastic materials (18–21). Several pretreatment techniques such as soxhlet extraction (22), liquid–liquid extraction (23), ultrasound-assisted extraction (24, 25), microwave-assisted extraction (26), supercritical fluid extraction (27), assisted solvent extraction (ASE) (28), solid-phase extraction (29, 30) and solid-phase micro-extraction (31, 32) followed by high-performance liquid chromatography (HPLC) (33, 34), ultra performance liquid chromatography (UPLC) (35), gas chromatography (GC) (36, 37), gas chromatography coupled to mass spectrometry (GC–MS) (38) or tandem MS (GC–MS-MS) and high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) (39, 40) or tandem MS (10, 41) have been used for the determination of polymer additives. To our knowledge, most studies only focused on the determination of one or two kinds of additives, the number of detection substances was also limited. There is no universal method for the simultaneous determination of antioxidants, UV stabilizers, phthalate plasticizers and photoinitiators in food packaging.

The aim of this study was to develop and validate a sensitive method with low detected limits, good repeatability and accuracy for the simultaneous determination of antioxidants, UV stabilizers, phthalate plasticizers and photoinitiators used in polymers to deal with the increasing demands on food packaging material safety.

Experimental

Chemicals and reagents

The sources and some information of studied chemicals are presented in Table I. Methanol (HPLC grade) and acetonitrile (HPLC grade) were purchased from Merck (Darmstadt, Germany), acetonitrile (A.R. grade) which was used for extraction solvent and methylbenzene (A.R. grade) were purchased from Tianjin Damao Chemical Reagent Factory (Tianjin, China), high-purity deionized water (resistivity 18.2 MΩ cm−1) was obtained using a ultrapure water system (Eped, Nanjing, China).

Table I

Standards type

Abbreviation

Chemical name

Molecular weight

CAS no.

SMLa (µg g−1)

Source

Antioxidant BHA Butylated hydroxyanisole 180.25 25013-16-5 30.0 Dr. Ehrenstorfer GmbH (Augsburg, Germany) BHT 2,6-Di-tert-butyl-4-methylphenol 220.36 128-37-0 3.0 Fluka Cheme GmbH, Buchs Sigma-Aldrich (Augsburg, Germany) Irganox 1010 Pentaerythritol(tetrakis)3,5-di-tert-butyl-4-hydroxycinnamate 1,177.67 6683-19-8 – AccuStandard, Inc. (New Haven, USA) Irganox 1076 Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate 530.88 2082-79-3 6.0 Pure Chemical Analysis Co., Ltd. (Boenew, Belgium) UV stabilizer UV-0 2,4-Di-hydroxy benzophenone 214.22 131-56-6 6.0 AccuStandard, Inc. (New Haven, USA) UV-9 2-Hydroxy-4-methoxybenzophenone 228.25 131-57-7 6.0 UV-234 2-(2h-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol 447.58 70321-86-7 1.5 UV-326 (2′-Hydroxy-3′-tert-5′-methylphenl)-5-chloroben zotriazole 315.80 3896-11-5 30.0 UV-327 2-(2′-Hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzotriazole 357.89 3864-99-1 30.0 UV-531 2-Hydroxy-4-n-octoxy-benzophenone 326.44 1843-05-6 6.0 UV-P 2-(2′-Hydroxy-5′-methylphenyl) 225.25 2440-22-4 30.0 Sigma-Aldrich (Steinheim, Germany) UV-24 2,2′-Di-hydroxy-4- methoxybenzophenone 224.25 131-53-3 6.0 UV-1577 o-Toluidine 425.52 147315-50-2 0.05 Toronto Research Chemicals, Inc. (North York, Canada) Photoinitiator UV-184 1-Hydroxycyclohexylphenylketone 204.26 947-19-3 – Sigma-Aldrich (Steinheim, Germany) UV-651 2,2-Dimethoxy-2-phenylaceto phenone 256.30 24650-42-8 – Fluka Cheme GmbH, Buchs Sigma-Aldrich (Augsburg, Germany) Phthalate plasticizer DEHP Di-(2-ethylhexyl) phthalate 390.56 117-81-7 1.5 Sinapharm Chemical Reagent Co., Ltd. (Shanghai, China) DMP Dimethyl phthalate 194.18 131-11-3 3.0 DEP Diethyl phthalate 222.23 84-66-2 – DNOP Di-n-octylphthalate 390.62 117-84-0 – DPhP Diphenyl phthalate 318.32 84-62-8 – DPP Dipentyl phthalate 306.40 131-18-0 – DCHP Dicyclohexyl phthalate 330.46 84-61-7 – Dr. Ehrenstorfer GmbH (Augsburg, Germany) DMEP Dimethoxyethyl phthalate 282.29 117-82-8 – Aladdin Chemistry Co., Ltd. (Shanghai, China) BBP Butyl benzyl phthalate 312.36 85-68-7 30.0 DNP Dinonyl phthalate 418.61 84-76-4 – DIBP Diisobutyl phthalate 278.34 84-69-5 – DHXP Dihexyl phthalate 334.46 84-75-3 – Standards type

Abbreviation

Chemical name

Molecular weight

CAS no.

SMLa (µg g−1)

Source

Antioxidant BHA Butylated hydroxyanisole 180.25 25013-16-5 30.0 Dr. Ehrenstorfer GmbH (Augsburg, Germany) BHT 2,6-Di-tert-butyl-4-methylphenol 220.36 128-37-0 3.0 Fluka Cheme GmbH, Buchs Sigma-Aldrich (Augsburg, Germany) Irganox 1010 Pentaerythritol(tetrakis)3,5-di-tert-butyl-4-hydroxycinnamate 1,177.67 6683-19-8 – AccuStandard, Inc. (New Haven, USA) Irganox 1076 Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate 530.88 2082-79-3 6.0 Pure Chemical Analysis Co., Ltd. (Boenew, Belgium) UV stabilizer UV-0 2,4-Di-hydroxy benzophenone 214.22 131-56-6 6.0 AccuStandard, Inc. (New Haven, USA) UV-9 2-Hydroxy-4-methoxybenzophenone 228.25 131-57-7 6.0 UV-234 2-(2h-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol 447.58 70321-86-7 1.5 UV-326 (2′-Hydroxy-3′-tert-5′-methylphenl)-5-chloroben zotriazole 315.80 3896-11-5 30.0 UV-327 2-(2′-Hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzotriazole 357.89 3864-99-1 30.0 UV-531 2-Hydroxy-4-n-octoxy-benzophenone 326.44 1843-05-6 6.0 UV-P 2-(2′-Hydroxy-5′-methylphenyl) 225.25 2440-22-4 30.0 Sigma-Aldrich (Steinheim, Germany) UV-24 2,2′-Di-hydroxy-4- methoxybenzophenone 224.25 131-53-3 6.0 UV-1577 o-Toluidine 425.52 147315-50-2 0.05 Toronto Research Chemicals, Inc. (North York, Canada) Photoinitiator UV-184 1-Hydroxycyclohexylphenylketone 204.26 947-19-3 – Sigma-Aldrich (Steinheim, Germany) UV-651 2,2-Dimethoxy-2-phenylaceto phenone 256.30 24650-42-8 – Fluka Cheme GmbH, Buchs Sigma-Aldrich (Augsburg, Germany) Phthalate plasticizer DEHP Di-(2-ethylhexyl) phthalate 390.56 117-81-7 1.5 Sinapharm Chemical Reagent Co., Ltd. (Shanghai, China) DMP Dimethyl phthalate 194.18 131-11-3 3.0 DEP Diethyl phthalate 222.23 84-66-2 – DNOP Di-n-octylphthalate 390.62 117-84-0 – DPhP Diphenyl phthalate 318.32 84-62-8 – DPP Dipentyl phthalate 306.40 131-18-0 – DCHP Dicyclohexyl phthalate 330.46 84-61-7 – Dr. Ehrenstorfer GmbH (Augsburg, Germany) DMEP Dimethoxyethyl phthalate 282.29 117-82-8 – Aladdin Chemistry Co., Ltd. (Shanghai, China) BBP Butyl benzyl phthalate 312.36 85-68-7 30.0 DNP Dinonyl phthalate 418.61 84-76-4 – DIBP Diisobutyl phthalate 278.34 84-69-5 – DHXP Dihexyl phthalate 334.46 84-75-3 –  Open in new tab

Table I

Standards type

Abbreviation

Chemical name

Molecular weight

CAS no.

SMLa (µg g−1)

Source

Antioxidant BHA Butylated hydroxyanisole 180.25 25013-16-5 30.0 Dr. Ehrenstorfer GmbH (Augsburg, Germany) BHT 2,6-Di-tert-butyl-4-methylphenol 220.36 128-37-0 3.0 Fluka Cheme GmbH, Buchs Sigma-Aldrich (Augsburg, Germany) Irganox 1010 Pentaerythritol(tetrakis)3,5-di-tert-butyl-4-hydroxycinnamate 1,177.67 6683-19-8 – AccuStandard, Inc. (New Haven, USA) Irganox 1076 Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate 530.88 2082-79-3 6.0 Pure Chemical Analysis Co., Ltd. (Boenew, Belgium) UV stabilizer UV-0 2,4-Di-hydroxy benzophenone 214.22 131-56-6 6.0 AccuStandard, Inc. (New Haven, USA) UV-9 2-Hydroxy-4-methoxybenzophenone 228.25 131-57-7 6.0 UV-234 2-(2h-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol 447.58 70321-86-7 1.5 UV-326 (2′-Hydroxy-3′-tert-5′-methylphenl)-5-chloroben zotriazole 315.80 3896-11-5 30.0 UV-327 2-(2′-Hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzotriazole 357.89 3864-99-1 30.0 UV-531 2-Hydroxy-4-n-octoxy-benzophenone 326.44 1843-05-6 6.0 UV-P 2-(2′-Hydroxy-5′-methylphenyl) 225.25 2440-22-4 30.0 Sigma-Aldrich (Steinheim, Germany) UV-24 2,2′-Di-hydroxy-4- methoxybenzophenone 224.25 131-53-3 6.0 UV-1577 o-Toluidine 425.52 147315-50-2 0.05 Toronto Research Chemicals, Inc. (North York, Canada) Photoinitiator UV-184 1-Hydroxycyclohexylphenylketone 204.26 947-19-3 – Sigma-Aldrich (Steinheim, Germany) UV-651 2,2-Dimethoxy-2-phenylaceto phenone 256.30 24650-42-8 – Fluka Cheme GmbH, Buchs Sigma-Aldrich (Augsburg, Germany) Phthalate plasticizer DEHP Di-(2-ethylhexyl) phthalate 390.56 117-81-7 1.5 Sinapharm Chemical Reagent Co., Ltd. (Shanghai, China) DMP Dimethyl phthalate 194.18 131-11-3 3.0 DEP Diethyl phthalate 222.23 84-66-2 – DNOP Di-n-octylphthalate 390.62 117-84-0 – DPhP Diphenyl phthalate 318.32 84-62-8 – DPP Dipentyl phthalate 306.40 131-18-0 – DCHP Dicyclohexyl phthalate 330.46 84-61-7 – Dr. Ehrenstorfer GmbH (Augsburg, Germany) DMEP Dimethoxyethyl phthalate 282.29 117-82-8 – Aladdin Chemistry Co., Ltd. (Shanghai, China) BBP Butyl benzyl phthalate 312.36 85-68-7 30.0 DNP Dinonyl phthalate 418.61 84-76-4 – DIBP Diisobutyl phthalate 278.34 84-69-5 – DHXP Dihexyl phthalate 334.46 84-75-3 – Standards type

Abbreviation

Chemical name

Molecular weight

CAS no.

SMLa (µg g−1)

Source

Antioxidant BHA Butylated hydroxyanisole 180.25 25013-16-5 30.0 Dr. Ehrenstorfer GmbH (Augsburg, Germany) BHT 2,6-Di-tert-butyl-4-methylphenol 220.36 128-37-0 3.0 Fluka Cheme GmbH, Buchs Sigma-Aldrich (Augsburg, Germany) Irganox 1010 Pentaerythritol(tetrakis)3,5-di-tert-butyl-4-hydroxycinnamate 1,177.67 6683-19-8 – AccuStandard, Inc. (New Haven, USA) Irganox 1076 Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate 530.88 2082-79-3 6.0 Pure Chemical Analysis Co., Ltd. (Boenew, Belgium) UV stabilizer UV-0 2,4-Di-hydroxy benzophenone 214.22 131-56-6 6.0 AccuStandard, Inc. (New Haven, USA) UV-9 2-Hydroxy-4-methoxybenzophenone 228.25 131-57-7 6.0 UV-234 2-(2h-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol 447.58 70321-86-7 1.5 UV-326 (2′-Hydroxy-3′-tert-5′-methylphenl)-5-chloroben zotriazole 315.80 3896-11-5 30.0 UV-327 2-(2′-Hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzotriazole 357.89 3864-99-1 30.0 UV-531 2-Hydroxy-4-n-octoxy-benzophenone 326.44 1843-05-6 6.0 UV-P 2-(2′-Hydroxy-5′-methylphenyl) 225.25 2440-22-4 30.0 Sigma-Aldrich (Steinheim, Germany) UV-24 2,2′-Di-hydroxy-4- methoxybenzophenone 224.25 131-53-3 6.0 UV-1577 o-Toluidine 425.52 147315-50-2 0.05 Toronto Research Chemicals, Inc. (North York, Canada) Photoinitiator UV-184 1-Hydroxycyclohexylphenylketone 204.26 947-19-3 – Sigma-Aldrich (Steinheim, Germany) UV-651 2,2-Dimethoxy-2-phenylaceto phenone 256.30 24650-42-8 – Fluka Cheme GmbH, Buchs Sigma-Aldrich (Augsburg, Germany) Phthalate plasticizer DEHP Di-(2-ethylhexyl) phthalate 390.56 117-81-7 1.5 Sinapharm Chemical Reagent Co., Ltd. (Shanghai, China) DMP Dimethyl phthalate 194.18 131-11-3 3.0 DEP Diethyl phthalate 222.23 84-66-2 – DNOP Di-n-octylphthalate 390.62 117-84-0 – DPhP Diphenyl phthalate 318.32 84-62-8 – DPP Dipentyl phthalate 306.40 131-18-0 – DCHP Dicyclohexyl phthalate 330.46 84-61-7 – Dr. Ehrenstorfer GmbH (Augsburg, Germany) DMEP Dimethoxyethyl phthalate 282.29 117-82-8 – Aladdin Chemistry Co., Ltd. (Shanghai, China) BBP Butyl benzyl phthalate 312.36 85-68-7 30.0 DNP Dinonyl phthalate 418.61 84-76-4 – DIBP Diisobutyl phthalate 278.34 84-69-5 – DHXP Dihexyl phthalate 334.46 84-75-3 –  Open in new tab

For the omnipresence of phthalates, special care was taken to avoid the contact of solvents and reagents with plastic materials. Glass materials were used in place of plastic materials to reduce the background contamination. Prior to analysis, all glasswares were washed with water and soap, then rinsed with tap water and ultrapure water. Finally, glassware was stored in a clean environment.

Instrumentation

The HPLC system was a Waters 2695 (Waters, Milford, MA, USA) equipped with a gradient pump, an automatic injector and a model 2996 UV photodiode array (Waters). Accelerated solvent extraction (ASE350) (Dionex Corporation, Sunnyvale, CA, USA) and LABUY-10LHT ultrasonic system (Hangzhou Labuy Instrument Co., Ltd., Hangzhou, China) were used for the sample extraction. TurboVap®II evaporation system (Caliper Life Sciences Inc., Hopkinton, USA) was also used for sample concentration.

Samples

In order to verify the accuracy and precision of the proposed method, a blank polyethylene (PE) film sample was supplied by Guangzhou Jin Fangyuan Machinery and Equipment Manufacturing Co., Ltd. (Guangzhou, China). Nine kinds of commercial plastic films used for food packaging were selected in order to demonstrate the applicability of the method for the analysis of real matrix samples. These samples were supplied by Shenzhen Border Inspection and Quarantine Bureau. They were numbered from Sample 1 to Sample 9. The information of these samples is presented in Table II.

Table II

Sample

Type of materiala

Thickness ± SD (mm) (n = 6)

Density ± SD (g cm−3) (n = 6)

Remark

Food packaged

Blank PE 0.057 ± 0.007 0.89 ± 0.04 Unprinted, unshaped – 1 PP 0.090 ± 0.003 0.90 ± 0.01 Printed, unshaped tofu 2 PE 0.059 ± 0.001 0.89 ± 0.01 Printed, unshaped Almond crisp 3 BOPP/CPP 0.070 ± 0.004 0.84 ± 0.01 Printed, shaped Bean stick 4 PE 0.059 ± 0.002 0.86 ± 0.02 Printed, shaped Mushroom & pock shao mai 5 PP 0.113 ± 0.012 0.83 ± 0.09 Printed, shaped Cuttlefish flavor fish ball 6 OPP 0.042 ± 0.001 0.79 ± 0.01 Unprinted, unshaped Pickle 7 PE 0.079 ± 0.002 0.89 ± 0.02 Unprinted, shaped Pepper 8 OPP/CPP 0.087 ± 0.001 0.93 ± 0.02 Printed, shaped Shrimp noodle 9 OPP/CPP 0.085 ± 0.003 0.96 ± 0.03 Printed, shaped Cake Sample

Type of materiala

Thickness ± SD (mm) (n = 6)

Density ± SD (g cm−3) (n = 6)

Remark

Food packaged

Blank PE 0.057 ± 0.007 0.89 ± 0.04 Unprinted, unshaped – 1 PP 0.090 ± 0.003 0.90 ± 0.01 Printed, unshaped tofu 2 PE 0.059 ± 0.001 0.89 ± 0.01 Printed, unshaped Almond crisp 3 BOPP/CPP 0.070 ± 0.004 0.84 ± 0.01 Printed, shaped Bean stick 4 PE 0.059 ± 0.002 0.86 ± 0.02 Printed, shaped Mushroom & pock shao mai 5 PP 0.113 ± 0.012 0.83 ± 0.09 Printed, shaped Cuttlefish flavor fish ball 6 OPP 0.042 ± 0.001 0.79 ± 0.01 Unprinted, unshaped Pickle 7 PE 0.079 ± 0.002 0.89 ± 0.02 Unprinted, shaped Pepper 8 OPP/CPP 0.087 ± 0.001 0.93 ± 0.02 Printed, shaped Shrimp noodle 9 OPP/CPP 0.085 ± 0.003 0.96 ± 0.03 Printed, shaped Cake  Open in new tab

Table II

Sample

Type of materiala

Thickness ± SD (mm) (n = 6)

Density ± SD (g cm−3) (n = 6)

Remark

Food packaged

Blank PE 0.057 ± 0.007 0.89 ± 0.04 Unprinted, unshaped – 1 PP 0.090 ± 0.003 0.90 ± 0.01 Printed, unshaped tofu 2 PE 0.059 ± 0.001 0.89 ± 0.01 Printed, unshaped Almond crisp 3 BOPP/CPP 0.070 ± 0.004 0.84 ± 0.01 Printed, shaped Bean stick 4 PE 0.059 ± 0.002 0.86 ± 0.02 Printed, shaped Mushroom & pock shao mai 5 PP 0.113 ± 0.012 0.83 ± 0.09 Printed, shaped Cuttlefish flavor fish ball 6 OPP 0.042 ± 0.001 0.79 ± 0.01 Unprinted, unshaped Pickle 7 PE 0.079 ± 0.002 0.89 ± 0.02 Unprinted, shaped Pepper 8 OPP/CPP 0.087 ± 0.001 0.93 ± 0.02 Printed, shaped Shrimp noodle 9 OPP/CPP 0.085 ± 0.003 0.96 ± 0.03 Printed, shaped Cake Sample

Type of materiala

Thickness ± SD (mm) (n = 6)

Density ± SD (g cm−3) (n = 6)

Remark

Food packaged

Blank PE 0.057 ± 0.007 0.89 ± 0.04 Unprinted, unshaped – 1 PP 0.090 ± 0.003 0.90 ± 0.01 Printed, unshaped tofu 2 PE 0.059 ± 0.001 0.89 ± 0.01 Printed, unshaped Almond crisp 3 BOPP/CPP 0.070 ± 0.004 0.84 ± 0.01 Printed, shaped Bean stick 4 PE 0.059 ± 0.002 0.86 ± 0.02 Printed, shaped Mushroom & pock shao mai 5 PP 0.113 ± 0.012 0.83 ± 0.09 Printed, shaped Cuttlefish flavor fish ball 6 OPP 0.042 ± 0.001 0.79 ± 0.01 Unprinted, unshaped Pickle 7 PE 0.079 ± 0.002 0.89 ± 0.02 Unprinted, shaped Pepper 8 OPP/CPP 0.087 ± 0.001 0.93 ± 0.02 Printed, shaped Shrimp noodle 9 OPP/CPP 0.085 ± 0.003 0.96 ± 0.03 Printed, shaped Cake  Open in new tab

Preparation of standard solution

For butylated hydroxyanisole (BHA), 2,6-di-tert-butyl-4-methylphenol (BHT), 2,4-di-hydroxy benzophenone (UV-0),2-hydroxy-4-methoxy-benzophenone(UV-9), 1-hydroxycyclohexylphenylketone (UV-184), 2,2-dimethoxy-2-phenylaceto phenone (UV-651), 2-(2′-hydroxy-3′,5′ -di-tert-butylphenyl)-5-chlorobenzotriazole (UV-327), di-(2-ethylhexyl) phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), butyl benzyl phthalate (BBP), di-n-octylphthalate (DNOP), dinonyl phthalate (DNP), diphenyl phthalate (DPhP), dihexyl phthalate (DHXP), dicyclohexyl phthalate (DCHP), diisobutyl phthalate (DIBP), dipentyl phthalate (DPP) and dimethoxyethyl phthalate (DMEP), individual stock standard solution of each additive chemical (1,000 µg mL−1) was prepared with analytical accuracy dissolving 10 mg of standard substance in 10 mL of methanol. Due to the limited solubility of pentaerythritol(tetrakis)3,5-di-tert-butyl-4-hydroxycinnamate (Irganox 1010), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076), 2-(2′-hydroxy-5′-methylphenyl) (UV-P), 2,2′-di-hydroxy-4-methoxybenzophenone (UV-24), 2-(2h-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (UV-234), (2′-hydroxy-3′-tert-5′-methylphenl)-5-chloroben zotriazole (UV-326), 2-hydroxy-4-n-octoxy-benzophenone (UV-531) and o-toluidine (UV-1577) in methanol, 10 mg of these polymer additives were initially dissolved in methylbenzene, then diluted to 10 mL volume with methanol to obtain the stock standard solutions (1,000 µg mL−1). A mixed working standard solution at a concentration of 20 µg mL−1 of each compound was prepared from individual standard solutions (1,000 µg mL−1) by appropriate dilution with acetonitrile. Calibration standard solutions of the compounds (0.05, 0.1, 0.2, 0.5, 1.0, 2.0, 5.0 and 10.0 µg mL−1) were also prepared by serial dilution in acetonitrile. All solutions were stored in brown glass stopper bottles at 4°C.

Sample preparation

Accelerated solvent extraction

Each sample was rinsed using ultrapure water, rubbed with absorbent cotton and dried before use, then cut into small pieces of ∼0.5 × 0.5 cm and extracted with acetonitrile by ASE. 0.5 g of polymer sample was mixed with 4.0 g diatomite to fill a thimble. The polymer–diatomite mix was transferred to 22 mL ASE extraction cell, and the cell was closed with a cell cap. The cell was thereafter put in the accelerated solvent extractor (ASE 350), programmed as follows: oven temperature: 100°C, pressure: 1,500 psi, heat time: 5 min, static time: 5 min, flush volume: 50%, purge time: 60 s, static cycle twice. The extracts were collected and evaporated to dryness under 45°C with a TurboVap®II evaporation system. The concentration was made up with acetonitrile to an accurate volume of 2.0 mL and filtered with 0.22 µm nylon membrane filter for further HPLC analysis.

Ultrasonic extraction

With the ultrasonic system, ∼0.5 g of sample was extracted with 15 mL of acetonitrile at 40°C for 30 min. This step was then repeated once. The resultant extracts were collected and evaporated to dryness under 45°C with a TurboVap®II evaporation system. After that, the following operations were similar to the ASE section described previously.

High-performance liquid chromatography-photodiode array detector analysis

The signal acquired from the detector was recorded by a personal computer and the chromatographic analyses of chemicals were performed using an Empower2 software (Waters, Milford, MA, USA). Separations were achieved using an X BridgeTm C18 column (250 × 4.6 mm, 5 µm) from Waters. Chromatographic separation was carried out using a gradient elution with acetonitrile as eluent A, and water as eluent B. The mobile phase gradient program is given in Table III. The column temperature was maintained at 30°C. The injection volume was 10 µL. The wavelength in the PDA detector was set at 276 nm. Each compound was identified by comparison of its retention time with corresponding peak in the standard solution and its UV spectrum. Quantification was carried out using a calibration plot of external standard.

Table III

Time (min)

Acetonitrile (%)

Water (%)

Flow (mL min−1)

0 25 75 1.0 35 50 50 1.0 45 70 30 1.0 55 85 15 1.0 62 90 10 1.0 72 97 3 1.0 74 100 0 1.0 75 100 0 1.2 95 100 0 1.2 98 70 30 1.0 100 25 75 1.0 Time (min)

Acetonitrile (%)

Water (%)

Flow (mL min−1)

0 25 75 1.0 35 50 50 1.0 45 70 30 1.0 55 85 15 1.0 62 90 10 1.0 72 97 3 1.0 74 100 0 1.0 75 100 0 1.2 95 100 0 1.2 98 70 30 1.0 100 25 75 1.0  Open in new tab

Table III

Time (min)

Acetonitrile (%)

Water (%)

Flow (mL min−1)

0 25 75 1.0 35 50 50 1.0 45 70 30 1.0 55 85 15 1.0 62 90 10 1.0 72 97 3 1.0 74 100 0 1.0 75 100 0 1.2 95 100 0 1.2 98 70 30 1.0 100 25 75 1.0 Time (min)

Acetonitrile (%)

Water (%)

Flow (mL min−1)

0 25 75 1.0 35 50 50 1.0 45 70 30 1.0 55 85 15 1.0 62 90 10 1.0 72 97 3 1.0 74 100 0 1.0 75 100 0 1.2 95 100 0 1.2 98 70 30 1.0 100 25 75 1.0  Open in new tab

Statistical analysis

Analysis of variance was carried out using Statistical Product and Service Solutions (SPSS) 16.0 (IBM SPSS Inc., New York, NY, USA) statistical software to compare the recoveries of the different extraction methods, temperatures and static cycles.

Results

Validation of the HPLC method

The presented method was validated for linearity, limits of detection (LOD), limits of quantitation (LOQ), accuracy, repeatability and inter/intra-assay deviation under the optimum conditions.

Linearity of HPLC for the determination of chemicals

To obtain the calibration curves for the analytes, mixed working solutions range from 0.05, 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 and 20.0 µg mL−1 were investigated, and each working solution was injected in triplicate with an injection volume of 10 µL. The quantification was based on the external calibration graph obtained by plotting the individual peak areas against the concentration of the calibration standards. The chemicals responses are found to be linear over the concentration range explored with good correlation coefficients (Table IV). Analysis time was 100 min.

Table IV

Compound

Retention time ± SD (min)

Slope ± SD

Intercept ± SD

Linearity range (µg mL−1)

Correlation coefficient/R

Purity angle

Purity threshold

LODI, LODM (µg mL−1, µg g−1)

LOQI, LOQM (µg mL−1, µg g−1)

BHA 33.86 ± 0.02 5,758 ± 52 1,310 ± 21 0.5–20.0 0.9944 0.874 1.120 0.15, 2.20 0.50, 7.25 BHT 55.58 ± 0.01 5,347 ± 34 2,358 ± 69 0.5–20.0 0.9942 0.712 1.081 0.15, 2.00 0.50, 6.60 Irganox 1010 80.33 ± 0.01 2,146 ± 45 501 ± 58 1.0–20.0 0.9912 1.233 1.819 0.30, 5.00 1.00, 17.00 Irganox 1076 97.10 ± 0.07 1,839 ± 48 528 ± 71 1.0–20.0 0.9961 5.155 8.229 0.30, 9.00 1.00, 30.00 UV-0 25.33 ± 0.05 24,696 ± 263 −425 ± 23 0.2–20.0 0.9979 0.713 0.772 0.05, 0.50 0.15, 1.60 UV-9 41.10 ± 0.03 26,217 ± 412 −9,875 ± 550 0.5–20.0 0.9982 0.613 0.639 0.10, 0.40 0.30, 1.40 UV-P 48.66 ± 0.04 16,572 ± 309 429 ± 17 0.2–20.0 0.9968 0.343 0.463 0.06, 0.50 0.20, 1.60 UV-24 30.84 ± 0.04 28,677 ± 226 −13,179 ± 403 0.5–20.0 0.9971 0.257 0.771 0.10, 0.50 0.30, 1.60 UV-234 69.59 ± 0.05 5,875 ± 22 2,276 ± 198 0.5–20.0 0.9931 0.582 0.671 0.20, 1.30 0.60, 4.20 UV-326 69.19 ± 0.01 5,266 ± 54 1,403 ± 25 0.5–20.0 0.9923 0.591 0.601 0.20, 1.60 0.60, 5.30 UV-327 74.88 ± 0.01 6,581 ± 170 1,290 ± 95 0.5–20.0 0.9963 0.550 0.662 0.20, 1.10 0.60, 3.70 UV-531 65.03 ± 0.02 21,414 ± 229 −4702 ± 63 0.5–20.0 0.9982 0.509 0.582 0.10, 0.40 0.30, 1.40 UV-1577 58.92 ± 0.02 961 ± 14 5,445 ± 23 1.0–20.0 0.9865 7.415 12.288 0.30, 5.40 1.00, 18.00 UV-184 29.38 ± 0.04 3,160 ± 30 799 ± 18 0.5–20.0 0.9914 0.457 0.696 0.10, 3.20 0.30, 10.50 UV-651 38.06 ± 0.02 7,369 ± 48 409 ± 116 0.5–20.0 0.9938 0.487 0.696 0.20, 1.40 0.60, 4.70 DEHP 70.86 ± 0.04 1,771 ± 9 837 ± 59 1.0–20.0 0.9928 0.849 1.183 0.30, 3.70 1.00, 12.30 DMP 15.61 ± 0.02 4,062 ± 129 −452 ± 32 1.0–20.0 0.9959 0.623 0.728 0.30, 2.30 1.00, 7.70 DEP 28.63 ± 0.03 3,158 ± 139 −488 ± 29 1.0–20.0 0.9876 0.621 0.910 0.30, 2.70 1.00, 9.00 BBP 49.36 ± 0.01 2,397 ± 61 790 ± 95 1.0–20.0 0.9914 0.552 0.764 0.30, 2.30 1.00, 7.70 DNOP 72.59 ± 0.02 1,667 ± 56 130 ± 71 1.0–20.0 0.9893 0.883 1.304 0.30, 4.10 1.00, 13.50 DNP 76.76 ± 0.01 58,370 ± 348 1,604 ± 123 0.1–20.0 0.9979 0.425 0.959 0.03, 0.10 0.10, 0.35 DPhP 47.07 ± 0.01 4,455 ± 64 1,502 ± 40 0.5–20.0 0.9953 0.350 0.578 0.20, 1.30 0.60, 4.30 DHXP 61.28 ± 0.02 2,012 ± 22 108 ± 6 1.0–20.0 0.9895 0.629 0.982 0.30, 3.10 1.00, 10.30 DCHP 56.49 ± 0.01 2,214 ± 25 852 ± 24 0.5–20.0 0.9927 0.624 0.966 0.20, 2.80 0.60, 9.40 DIBP 49.95 ± 0.01 2,693 ± 48 582 ± 75 0.5–20.0 0.9867 0.504 0.807 0.20, 2.10 0.60, 7.00 DPP 56.05 ± 0.01 2,331 ± 22 463 ± 17 0.5–20.0 0.9833 0.566 0.835 0.20, 2.60 0.60, 8.70 DMEP 16.10 ± 0.03 2,774 ± 136 −120 ± 13 1.0–20.0 0.9971 0.929 1.066 0.30, 3.10 1.00, 10.20 Compound

Retention time ± SD (min)

Slope ± SD

Intercept ± SD

Linearity range (µg mL−1)

Correlation coefficient/R

Purity angle

Purity threshold

LODI, LODM (µg mL−1, µg g−1)

LOQI, LOQM (µg mL−1, µg g−1)

BHA 33.86 ± 0.02 5,758 ± 52 1,310 ± 21 0.5–20.0 0.9944 0.874 1.120 0.15, 2.20 0.50, 7.25 BHT 55.58 ± 0.01 5,347 ± 34 2,358 ± 69 0.5–20.0 0.9942 0.712 1.081 0.15, 2.00 0.50, 6.60 Irganox 1010 80.33 ± 0.01 2,146 ± 45 501 ± 58 1.0–20.0 0.9912 1.233 1.819 0.30, 5.00 1.00, 17.00 Irganox 1076 97.10 ± 0.07 1,839 ± 48 528 ± 71 1.0–20.0 0.9961 5.155 8.229 0.30, 9.00 1.00, 30.00 UV-0 25.33 ± 0.05 24,696 ± 263 −425 ± 23 0.2–20.0 0.9979 0.713 0.772 0.05, 0.50 0.15, 1.60 UV-9 41.10 ± 0.03 26,217 ± 412 −9,875 ± 550 0.5–20.0 0.9982 0.613 0.639 0.10, 0.40 0.30, 1.40 UV-P 48.66 ± 0.04 16,572 ± 309 429 ± 17 0.2–20.0 0.9968 0.343 0.463 0.06, 0.50 0.20, 1.60 UV-24 30.84 ± 0.04 28,677 ± 226 −13,179 ± 403 0.5–20.0 0.9971 0.257 0.771 0.10, 0.50 0.30, 1.60 UV-234 69.59 ± 0.05 5,875 ± 22 2,276 ± 198 0.5–20.0 0.9931 0.582 0.671 0.20, 1.30 0.60, 4.20 UV-326 69.19 ± 0.01 5,266 ± 54 1,403 ± 25 0.5–20.0 0.9923 0.591 0.601 0.20, 1.60 0.60, 5.30 UV-327 74.88 ± 0.01 6,581 ± 170 1,290 ± 95 0.5–20.0 0.9963 0.550 0.662 0.20, 1.10 0.60, 3.70 UV-531 65.03 ± 0.02 21,414 ± 229 −4702 ± 63 0.5–20.0 0.9982 0.509 0.582 0.10, 0.40 0.30, 1.40 UV-1577 58.92 ± 0.02 961 ± 14 5,445 ± 23 1.0–20.0 0.9865 7.415 12.288 0.30, 5.40 1.00, 18.00 UV-184 29.38 ± 0.04 3,160 ± 30 799 ± 18 0.5–20.0 0.9914 0.457 0.696 0.10, 3.20 0.30, 10.50 UV-651 38.06 ± 0.02 7,369 ± 48 409 ± 116 0.5–20.0 0.9938 0.487 0.696 0.20, 1.40 0.60, 4.70 DEHP 70.86 ± 0.04 1,771 ± 9 837 ± 59 1.0–20.0 0.9928 0.849 1.183 0.30, 3.70 1.00, 12.30 DMP 15.61 ± 0.02 4,062 ± 129 −452 ± 32 1.0–20.0 0.9959 0.623 0.728 0.30, 2.30 1.00, 7.70 DEP 28.63 ± 0.03 3,158 ± 139 −488 ± 29 1.0–20.0 0.9876 0.621 0.910 0.30, 2.70 1.00, 9.00 BBP 49.36 ± 0.01 2,397 ± 61 790 ± 95 1.0–20.0 0.9914 0.552 0.764 0.30, 2.30 1.00, 7.70 DNOP 72.59 ± 0.02 1,667 ± 56 130 ± 71 1.0–20.0 0.9893 0.883 1.304 0.30, 4.10 1.00, 13.50 DNP 76.76 ± 0.01 58,370 ± 348 1,604 ± 123 0.1–20.0 0.9979 0.425 0.959 0.03, 0.10 0.10, 0.35 DPhP 47.07 ± 0.01 4,455 ± 64 1,502 ± 40 0.5–20.0 0.9953 0.350 0.578 0.20, 1.30 0.60, 4.30 DHXP 61.28 ± 0.02 2,012 ± 22 108 ± 6 1.0–20.0 0.9895 0.629 0.982 0.30, 3.10 1.00, 10.30 DCHP 56.49 ± 0.01 2,214 ± 25 852 ± 24 0.5–20.0 0.9927 0.624 0.966 0.20, 2.80 0.60, 9.40 DIBP 49.95 ± 0.01 2,693 ± 48 582 ± 75 0.5–20.0 0.9867 0.504 0.807 0.20, 2.10 0.60, 7.00 DPP 56.05 ± 0.01 2,331 ± 22 463 ± 17 0.5–20.0 0.9833 0.566 0.835 0.20, 2.60 0.60, 8.70 DMEP 16.10 ± 0.03 2,774 ± 136 −120 ± 13 1.0–20.0 0.9971 0.929 1.066 0.30, 3.10 1.00, 10.20  Open in new tab

Table IV

Compound

Retention time ± SD (min)

Slope ± SD

Intercept ± SD

Linearity range (µg mL−1)

Correlation coefficient/R

Purity angle

Purity threshold

LODI, LODM (µg mL−1, µg g−1)

LOQI, LOQM (µg mL−1, µg g−1)

BHA 33.86 ± 0.02 5,758 ± 52 1,310 ± 21 0.5–20.0 0.9944 0.874 1.120 0.15, 2.20 0.50, 7.25 BHT 55.58 ± 0.01 5,347 ± 34 2,358 ± 69 0.5–20.0 0.9942 0.712 1.081 0.15, 2.00 0.50, 6.60 Irganox 1010 80.33 ± 0.01 2,146 ± 45 501 ± 58 1.0–20.0 0.9912 1.233 1.819 0.30, 5.00 1.00, 17.00 Irganox 1076 97.10 ± 0.07 1,839 ± 48 528 ± 71 1.0–20.0 0.9961 5.155 8.229 0.30, 9.00 1.00, 30.00 UV-0 25.33 ± 0.05 24,696 ± 263 −425 ± 23 0.2–20.0 0.9979 0.713 0.772 0.05, 0.50 0.15, 1.60 UV-9 41.10 ± 0.03 26,217 ± 412 −9,875 ± 550 0.5–20.0 0.9982 0.613 0.639 0.10, 0.40 0.30, 1.40 UV-P 48.66 ± 0.04 16,572 ± 309 429 ± 17 0.2–20.0 0.9968 0.343 0.463 0.06, 0.50 0.20, 1.60 UV-24 30.84 ± 0.04 28,677 ± 226 −13,179 ± 403 0.5–20.0 0.9971 0.257 0.771 0.10, 0.50 0.30, 1.60 UV-234 69.59 ± 0.05 5,875 ± 22 2,276 ± 198 0.5–20.0 0.9931 0.582 0.671 0.20, 1.30 0.60, 4.20 UV-326 69.19 ± 0.01 5,266 ± 54 1,403 ± 25 0.5–20.0 0.9923 0.591 0.601 0.20, 1.60 0.60, 5.30 UV-327 74.88 ± 0.01 6,581 ± 170 1,290 ± 95 0.5–20.0 0.9963 0.550 0.662 0.20, 1.10 0.60, 3.70 UV-531 65.03 ± 0.02 21,414 ± 229 −4702 ± 63 0.5–20.0 0.9982 0.509 0.582 0.10, 0.40 0.30, 1.40 UV-1577 58.92 ± 0.02 961 ± 14 5,445 ± 23 1.0–20.0 0.9865 7.415 12.288 0.30, 5.40 1.00, 18.00 UV-184 29.38 ± 0.04 3,160 ± 30 799 ± 18 0.5–20.0 0.9914 0.457 0.696 0.10, 3.20 0.30, 10.50 UV-651 38.06 ± 0.02 7,369 ± 48 409 ± 116 0.5–20.0 0.9938 0.487 0.696 0.20, 1.40 0.60, 4.70 DEHP 70.86 ± 0.04 1,771 ± 9 837 ± 59 1.0–20.0 0.9928 0.849 1.183 0.30, 3.70 1.00, 12.30 DMP 15.61 ± 0.02 4,062 ± 129 −452 ± 32 1.0–20.0 0.9959 0.623 0.728 0.30, 2.30 1.00, 7.70 DEP 28.63 ± 0.03 3,158 ± 139 −488 ± 29 1.0–20.0 0.9876 0.621 0.910 0.30, 2.70 1.00, 9.00 BBP 49.36 ± 0.01 2,397 ± 61 790 ± 95 1.0–20.0 0.9914 0.552 0.764 0.30, 2.30 1.00, 7.70 DNOP 72.59 ± 0.02 1,667 ± 56 130 ± 71 1.0–20.0 0.9893 0.883 1.304 0.30, 4.10 1.00, 13.50 DNP 76.76 ± 0.01 58,370 ± 348 1,604 ± 123 0.1–20.0 0.9979 0.425 0.959 0.03, 0.10 0.10, 0.35 DPhP 47.07 ± 0.01 4,455 ± 64 1,502 ± 40 0.5–20.0 0.9953 0.350 0.578 0.20, 1.30 0.60, 4.30 DHXP 61.28 ± 0.02 2,012 ± 22 108 ± 6 1.0–20.0 0.9895 0.629 0.982 0.30, 3.10 1.00, 10.30 DCHP 56.49 ± 0.01 2,214 ± 25 852 ± 24 0.5–20.0 0.9927 0.624 0.966 0.20, 2.80 0.60, 9.40 DIBP 49.95 ± 0.01 2,693 ± 48 582 ± 75 0.5–20.0 0.9867 0.504 0.807 0.20, 2.10 0.60, 7.00 DPP 56.05 ± 0.01 2,331 ± 22 463 ± 17 0.5–20.0 0.9833 0.566 0.835 0.20, 2.60 0.60, 8.70 DMEP 16.10 ± 0.03 2,774 ± 136 −120 ± 13 1.0–20.0 0.9971 0.929 1.066 0.30, 3.10 1.00, 10.20 Compound

Retention time ± SD (min)

Slope ± SD

Intercept ± SD

Linearity range (µg mL−1)

Correlation coefficient/R

Purity angle

Purity threshold

LODI, LODM (µg mL−1, µg g−1)

LOQI, LOQM (µg mL−1, µg g−1)

BHA 33.86 ± 0.02 5,758 ± 52 1,310 ± 21 0.5–20.0 0.9944 0.874 1.120 0.15, 2.20 0.50, 7.25 BHT 55.58 ± 0.01 5,347 ± 34 2,358 ± 69 0.5–20.0 0.9942 0.712 1.081 0.15, 2.00 0.50, 6.60 Irganox 1010 80.33 ± 0.01 2,146 ± 45 501 ± 58 1.0–20.0 0.9912 1.233 1.819 0.30, 5.00 1.00, 17.00 Irganox 1076 97.10 ± 0.07 1,839 ± 48 528 ± 71 1.0–20.0 0.9961 5.155 8.229 0.30, 9.00 1.00, 30.00 UV-0 25.33 ± 0.05 24,696 ± 263 −425 ± 23 0.2–20.0 0.9979 0.713 0.772 0.05, 0.50 0.15, 1.60 UV-9 41.10 ± 0.03 26,217 ± 412 −9,875 ± 550 0.5–20.0 0.9982 0.613 0.639 0.10, 0.40 0.30, 1.40 UV-P 48.66 ± 0.04 16,572 ± 309 429 ± 17 0.2–20.0 0.9968 0.343 0.463 0.06, 0.50 0.20, 1.60 UV-24 30.84 ± 0.04 28,677 ± 226 −13,179 ± 403 0.5–20.0 0.9971 0.257 0.771 0.10, 0.50 0.30, 1.60 UV-234 69.59 ± 0.05 5,875 ± 22 2,276 ± 198 0.5–20.0 0.9931 0.582 0.671 0.20, 1.30 0.60, 4.20 UV-326 69.19 ± 0.01 5,266 ± 54 1,403 ± 25 0.5–20.0 0.9923 0.591 0.601 0.20, 1.60 0.60, 5.30 UV-327 74.88 ± 0.01 6,581 ± 170 1,290 ± 95 0.5–20.0 0.9963 0.550 0.662 0.20, 1.10 0.60, 3.70 UV-531 65.03 ± 0.02 21,414 ± 229 −4702 ± 63 0.5–20.0 0.9982 0.509 0.582 0.10, 0.40 0.30, 1.40 UV-1577 58.92 ± 0.02 961 ± 14 5,445 ± 23 1.0–20.0 0.9865 7.415 12.288 0.30, 5.40 1.00, 18.00 UV-184 29.38 ± 0.04 3,160 ± 30 799 ± 18 0.5–20.0 0.9914 0.457 0.696 0.10, 3.20 0.30, 10.50 UV-651 38.06 ± 0.02 7,369 ± 48 409 ± 116 0.5–20.0 0.9938 0.487 0.696 0.20, 1.40 0.60, 4.70 DEHP 70.86 ± 0.04 1,771 ± 9 837 ± 59 1.0–20.0 0.9928 0.849 1.183 0.30, 3.70 1.00, 12.30 DMP 15.61 ± 0.02 4,062 ± 129 −452 ± 32 1.0–20.0 0.9959 0.623 0.728 0.30, 2.30 1.00, 7.70 DEP 28.63 ± 0.03 3,158 ± 139 −488 ± 29 1.0–20.0 0.9876 0.621 0.910 0.30, 2.70 1.00, 9.00 BBP 49.36 ± 0.01 2,397 ± 61 790 ± 95 1.0–20.0 0.9914 0.552 0.764 0.30, 2.30 1.00, 7.70 DNOP 72.59 ± 0.02 1,667 ± 56 130 ± 71 1.0–20.0 0.9893 0.883 1.304 0.30, 4.10 1.00, 13.50 DNP 76.76 ± 0.01 58,370 ± 348 1,604 ± 123 0.1–20.0 0.9979 0.425 0.959 0.03, 0.10 0.10, 0.35 DPhP 47.07 ± 0.01 4,455 ± 64 1,502 ± 40 0.5–20.0 0.9953 0.350 0.578 0.20, 1.30 0.60, 4.30 DHXP 61.28 ± 0.02 2,012 ± 22 108 ± 6 1.0–20.0 0.9895 0.629 0.982 0.30, 3.10 1.00, 10.30 DCHP 56.49 ± 0.01 2,214 ± 25 852 ± 24 0.5–20.0 0.9927 0.624 0.966 0.20, 2.80 0.60, 9.40 DIBP 49.95 ± 0.01 2,693 ± 48 582 ± 75 0.5–20.0 0.9867 0.504 0.807 0.20, 2.10 0.60, 7.00 DPP 56.05 ± 0.01 2,331 ± 22 463 ± 17 0.5–20.0 0.9833 0.566 0.835 0.20, 2.60 0.60, 8.70 DMEP 16.10 ± 0.03 2,774 ± 136 −120 ± 13 1.0–20.0 0.9971 0.929 1.066 0.30, 3.10 1.00, 10.20  Open in new tab

Limits of detection and limits of quantitation

The LOD and LOQ of the instrument were typically set at the signal-to-noise ratio (S/N) of 3 and 10 times the average of the baseline in pure solution. The LOD and LOQ of the method were estimated based on the analysis of spiked blank plastic film samples at S/N of 3 and 10 times the average of the baseline. In this study, serially diluted standard mixture solutions were injected or spiked from high concentration to low concentration until the response of chemicals was 3 and 10 times the average of the baseline noise, respectively. The LODs and LOQs of the analytes are presented in Table IV.

Accuracy and repeatability of the method

In order to check the accuracy of the developed method, a recovery study was performed at three different concentration levels. Each analytical sequence was composed of procedural blanks, solvent blanks, calibration standards, reference blank samples spiked with 27 chemicals. Six replicate experiments were carried out for each spiked concentration level. The experiment was performed for 1.0 g blank sample spiked with 10, 20 and 40 µg g−1 of each chemical. The extraction procedure was followed as described in the ASE section. The recovery of the compounds was calculated as the ratio between the experimentally observed concentration and the theoretical concentration. The achieved recoveries of 27 different analytes are between 58.6% for UV-9 (spiked at 10 µg g−1) and 97.7% for DMEP (spiked at 20 µg g−1) (Table V). The repeatability, expressed as the relative standard deviation (RSD), is also listed in Table V. The RSDs were <10% for all compounds except four, and no RSD was >16%. The results demonstrated that the proposed sample preparation is reliable.

Table V

Compound

Fortified concentration

Compound

Fortified concentration

10 (µg g−1)

20 (µg g−1)

40 (µg g−1)

10 (µg g−1)

20 (µg g−1)

40 (µg g−1)

BHA 71.1 (7.2) 70.5 (5.6) 73.6 (2.5) DEHP 91.0 (4.8) 97.6 (2.4) 96.2 (3.8) BHT 71.7 (2.7) 74.5 (3.9) 78.2 (2.8) DMP 70.4 (6.4) 87.3 (7.1) 93.3 (2.3) Irganox 1010 64.0 (10.1) 80.1 (3.4) 72.2 (6.2) DEP 78.3 (4.5) 88.9 (6.9) 76.8 (3.8) Irganox 1076 71.1 (2.3) 74.6 (2.7) 76.7 (2.6) BBP 70.7 (5.8) 83.0 (6.5) 86.5 (0.9) UV-0 79.5 (3.7) 87.5 (1.8) 88.3 (2.0) DNOP 91.6 (7.4) 92.3 (4.0) 93.0 (1.7) UV-9 58.6 (15.4) 73.2 (3.9) 87.9 (4.0) DNP 89.7 (3.0) 91.4 (5.5) 93.4 (2.1) UV-P 79.7 (2.2) 85.9 (1.4) 90.3 (2.4) DPhP 88.1 (0.6) 90.5 (4.7) 89.1 (2.1) UV-24 71.1 (4.9) 70.8 (2.2) 81.2 (2.2) DHXP 77.4 (4.9) 91.0 (5.0) 92.8 (1.1) UV-234 86.8 (2.4) 94.7 (3.8) 91.4 (2.7) DCHP 82.7 (12.3) 89.7 (3.1) 87.0 (1.2) UV-326 82.1 (5.2) 90.7 (4.7) 87.3 (2.7) DIBP 93.4 (2.6) 85.8 (0.4) 83.8 (1.3) UV-327 83.7 (2.1) 93.6 (3.1) 86.5 (2.4) DPP 82.7 (12.1) 97.5 (5.7) 89.8 (2.0) UV-531 75.4 (1.6) 82.9 (2.8) 90.9 (2.4) DMEP 74.1 (3.6) 97.7 (8.8) 95.0 (7.5) UV-1577 83.3 (6.6) 73.4 (6.0) 87.5 (3.2)     UV-184 70.5 (3.3) 86.0 (4.5) 79.5 (5.7)     UV-651 82.5 (3.0) 95.0 (2.2) 87.9 (4.0)     Compound

Fortified concentration

Compound

Fortified concentration

10 (µg g−1)

20 (µg g−1)

40 (µg g−1)

10 (µg g−1)

20 (µg g−1)

40 (µg g−1)

BHA 71.1 (7.2) 70.5 (5.6) 73.6 (2.5) DEHP 91.0 (4.8) 97.6 (2.4) 96.2 (3.8) BHT 71.7 (2.7) 74.5 (3.9) 78.2 (2.8) DMP 70.4 (6.4) 87.3 (7.1) 93.3 (2.3) Irganox 1010 64.0 (10.1) 80.1 (3.4) 72.2 (6.2) DEP 78.3 (4.5) 88.9 (6.9) 76.8 (3.8) Irganox 1076 71.1 (2.3) 74.6 (2.7) 76.7 (2.6) BBP 70.7 (5.8) 83.0 (6.5) 86.5 (0.9) UV-0 79.5 (3.7) 87.5 (1.8) 88.3 (2.0) DNOP 91.6 (7.4) 92.3 (4.0) 93.0 (1.7) UV-9 58.6 (15.4) 73.2 (3.9) 87.9 (4.0) DNP 89.7 (3.0) 91.4 (5.5) 93.4 (2.1) UV-P 79.7 (2.2) 85.9 (1.4) 90.3 (2.4) DPhP 88.1 (0.6) 90.5 (4.7) 89.1 (2.1) UV-24 71.1 (4.9) 70.8 (2.2) 81.2 (2.2) DHXP 77.4 (4.9) 91.0 (5.0) 92.8 (1.1) UV-234 86.8 (2.4) 94.7 (3.8) 91.4 (2.7) DCHP 82.7 (12.3) 89.7 (3.1) 87.0 (1.2) UV-326 82.1 (5.2) 90.7 (4.7) 87.3 (2.7) DIBP 93.4 (2.6) 85.8 (0.4) 83.8 (1.3) UV-327 83.7 (2.1) 93.6 (3.1) 86.5 (2.4) DPP 82.7 (12.1) 97.5 (5.7) 89.8 (2.0) UV-531 75.4 (1.6) 82.9 (2.8) 90.9 (2.4) DMEP 74.1 (3.6) 97.7 (8.8) 95.0 (7.5) UV-1577 83.3 (6.6) 73.4 (6.0) 87.5 (3.2)     UV-184 70.5 (3.3) 86.0 (4.5) 79.5 (5.7)     UV-651 82.5 (3.0) 95.0 (2.2) 87.9 (4.0)      Open in new tab

Table V

Compound

Fortified concentration

Compound

Fortified concentration

10 (µg g−1)

20 (µg g−1)

40 (µg g−1)

10 (µg g−1)

20 (µg g−1)

40 (µg g−1)

BHA 71.1 (7.2) 70.5 (5.6) 73.6 (2.5) DEHP 91.0 (4.8) 97.6 (2.4) 96.2 (3.8) BHT 71.7 (2.7) 74.5 (3.9) 78.2 (2.8) DMP 70.4 (6.4) 87.3 (7.1) 93.3 (2.3) Irganox 1010 64.0 (10.1) 80.1 (3.4) 72.2 (6.2) DEP 78.3 (4.5) 88.9 (6.9) 76.8 (3.8) Irganox 1076 71.1 (2.3) 74.6 (2.7) 76.7 (2.6) BBP 70.7 (5.8) 83.0 (6.5) 86.5 (0.9) UV-0 79.5 (3.7) 87.5 (1.8) 88.3 (2.0) DNOP 91.6 (7.4) 92.3 (4.0) 93.0 (1.7) UV-9 58.6 (15.4) 73.2 (3.9) 87.9 (4.0) DNP 89.7 (3.0) 91.4 (5.5) 93.4 (2.1) UV-P 79.7 (2.2) 85.9 (1.4) 90.3 (2.4) DPhP 88.1 (0.6) 90.5 (4.7) 89.1 (2.1) UV-24 71.1 (4.9) 70.8 (2.2) 81.2 (2.2) DHXP 77.4 (4.9) 91.0 (5.0) 92.8 (1.1) UV-234 86.8 (2.4) 94.7 (3.8) 91.4 (2.7) DCHP 82.7 (12.3) 89.7 (3.1) 87.0 (1.2) UV-326 82.1 (5.2) 90.7 (4.7) 87.3 (2.7) DIBP 93.4 (2.6) 85.8 (0.4) 83.8 (1.3) UV-327 83.7 (2.1) 93.6 (3.1) 86.5 (2.4) DPP 82.7 (12.1) 97.5 (5.7) 89.8 (2.0) UV-531 75.4 (1.6) 82.9 (2.8) 90.9 (2.4) DMEP 74.1 (3.6) 97.7 (8.8) 95.0 (7.5) UV-1577 83.3 (6.6) 73.4 (6.0) 87.5 (3.2)     UV-184 70.5 (3.3) 86.0 (4.5) 79.5 (5.7)     UV-651 82.5 (3.0) 95.0 (2.2) 87.9 (4.0)     Compound

Fortified concentration

Compound

Fortified concentration

10 (µg g−1)

20 (µg g−1)

40 (µg g−1)

10 (µg g−1)

20 (µg g−1)

40 (µg g−1)

BHA 71.1 (7.2) 70.5 (5.6) 73.6 (2.5) DEHP 91.0 (4.8) 97.6 (2.4) 96.2 (3.8) BHT 71.7 (2.7) 74.5 (3.9) 78.2 (2.8) DMP 70.4 (6.4) 87.3 (7.1) 93.3 (2.3) Irganox 1010 64.0 (10.1) 80.1 (3.4) 72.2 (6.2) DEP 78.3 (4.5) 88.9 (6.9) 76.8 (3.8) Irganox 1076 71.1 (2.3) 74.6 (2.7) 76.7 (2.6) BBP 70.7 (5.8) 83.0 (6.5) 86.5 (0.9) UV-0 79.5 (3.7) 87.5 (1.8) 88.3 (2.0) DNOP 91.6 (7.4) 92.3 (4.0) 93.0 (1.7) UV-9 58.6 (15.4) 73.2 (3.9) 87.9 (4.0) DNP 89.7 (3.0) 91.4 (5.5) 93.4 (2.1) UV-P 79.7 (2.2) 85.9 (1.4) 90.3 (2.4) DPhP 88.1 (0.6) 90.5 (4.7) 89.1 (2.1) UV-24 71.1 (4.9) 70.8 (2.2) 81.2 (2.2) DHXP 77.4 (4.9) 91.0 (5.0) 92.8 (1.1) UV-234 86.8 (2.4) 94.7 (3.8) 91.4 (2.7) DCHP 82.7 (12.3) 89.7 (3.1) 87.0 (1.2) UV-326 82.1 (5.2) 90.7 (4.7) 87.3 (2.7) DIBP 93.4 (2.6) 85.8 (0.4) 83.8 (1.3) UV-327 83.7 (2.1) 93.6 (3.1) 86.5 (2.4) DPP 82.7 (12.1) 97.5 (5.7) 89.8 (2.0) UV-531 75.4 (1.6) 82.9 (2.8) 90.9 (2.4) DMEP 74.1 (3.6) 97.7 (8.8) 95.0 (7.5) UV-1577 83.3 (6.6) 73.4 (6.0) 87.5 (3.2)     UV-184 70.5 (3.3) 86.0 (4.5) 79.5 (5.7)     UV-651 82.5 (3.0) 95.0 (2.2) 87.9 (4.0)      Open in new tab

Stability of the studied chemicals

It has been observed that insufficient stability of the calibration standard in solution may give rise to significant deviation in the outcome of the result of analysis. Intra- and interday variations were chosen to determine the stability of the chemicals. Intraday stability was validated with three different concentration levels of mixed standard solutions under the optimized conditions three times within 1 day. Interday stability was validated with the mixed standard solutions used above once a day for 6 days. Intra- and interday stabilities for the 27 analytes were expressed as the RSD of individual peak areas, the results is listed in Table VI. As in the case of stability, good results were obtained for almost all of the tests (RSD < 12%). The lowest value of intraday stability was obtained for DNP, spiked at 2 µg mL−1 (0.1%), whereas the highest value of intraday stability was obtained for DEP, spiked at 10 µg mL−1 (9.9%). Meanwhile, the lowest value of interday stability was obtained for DNP, spiked at 10 µg mL−1 (1.0%), whereas the highest value of interday stability was obtained for Irganox 1076, spiked at 2 µg mL−1 (11.9%).

Table VI

Compound

RSD of concn (%)

2 µg mL−1

10 µg mL−1

20 µg mL−1

Intraday (n = 3)

Interday (n = 6)

Intraday (n = 3)

Interday (n = 6)

Intraday (n = 3)

Interday (n = 6)

BHA 3.7 8.7 0.2 3.3 1.6 2.5 BHT 3.5 9.5 1.8 3.1 1.0 1.9 Irganox 1010 9.0 8.7 2.2 4.0 1.2 3.1 Irganox 1076 3.7 11.9 5.7 5.2 9.1 8.2 UV-0 5.4 3.9 1.8 1.4 1.2 1.3 UV-9 4.0 5.3 1.5 1.9 1.2 2.1 UV-P 0.1 8.9 1.1 2.7 1.6 2.4 UV-24 2.2 9.2 1.6 2.0 1.0 1.1 UV-234 7.3 7.7 0.6 3.4 0.6 1.5 UV-326 3.7 3.3 1.4 2.9 1.0 2.9 UV-327 0.4 11.0 2.5 2.7 2.2 2.0 UV-531 0.5 3.5 1.4 1.3 1.2 1.2 UV-1577 7.8 6.0 7.4 7.2 7.4 8.5 UV-184 6.3 9.9 3.3 3.7 1.1 3.5 UV-651 5.2 7.3 2.6 1.8 0.4 1.3 DEHP 5.6 10.0 2.2 7.5 3.7 5.3 DMP 3.6 5.7 4.6 4.9 3.0 4.0 DEP 1.6 4.9 9.9 6.2 4.2 3.3 BBP 3.0 7.3 1.5 5.9 5.5 4.9 DNOP 2.3 2.0 2.7 4.3 4.1 3.6 DNP 0.1 1.1 0.5 1.0 0.5 1.4 DPhP 4.7 5.9 0.7 3.0 0.8 2.7 DHXP 2.2 5.5 6.9 7.2 1.9 4.7 DCHP 5.3 7.3 2.7 3.8 1.2 1.1 DIBP 2.2 10.2 1.4 4.6 2.5 2.3 DPP 2.4 8.3 1.9 4.2 1.2 1.1 DMEP 8.2 6.9 5.5 6.3 4.1 4.0 Compound

RSD of concn (%)

2 µg mL−1

10 µg mL−1

20 µg mL−1

Intraday (n = 3)

Interday (n = 6)

Intraday (n = 3)

Interday (n = 6)

Intraday (n = 3)

Interday (n = 6)

BHA 3.7 8.7 0.2 3.3 1.6 2.5 BHT 3.5 9.5 1.8 3.1 1.0 1.9 Irganox 1010 9.0 8.7 2.2 4.0 1.2 3.1 Irganox 1076 3.7 11.9 5.7 5.2 9.1 8.2 UV-0 5.4 3.9 1.8 1.4 1.2 1.3 UV-9 4.0 5.3 1.5 1.9 1.2 2.1 UV-P 0.1 8.9 1.1 2.7 1.6 2.4 UV-24 2.2 9.2 1.6 2.0 1.0 1.1 UV-234 7.3 7.7 0.6 3.4 0.6 1.5 UV-326 3.7 3.3 1.4 2.9 1.0 2.9 UV-327 0.4 11.0 2.5 2.7 2.2 2.0 UV-531 0.5 3.5 1.4 1.3 1.2 1.2 UV-1577 7.8 6.0 7.4 7.2 7.4 8.5 UV-184 6.3 9.9 3.3 3.7 1.1 3.5 UV-651 5.2 7.3 2.6 1.8 0.4 1.3 DEHP 5.6 10.0 2.2 7.5 3.7 5.3 DMP 3.6 5.7 4.6 4.9 3.0 4.0 DEP 1.6 4.9 9.9 6.2 4.2 3.3 BBP 3.0 7.3 1.5 5.9 5.5 4.9 DNOP 2.3 2.0 2.7 4.3 4.1 3.6 DNP 0.1 1.1 0.5 1.0 0.5 1.4 DPhP 4.7 5.9 0.7 3.0 0.8 2.7 DHXP 2.2 5.5 6.9 7.2 1.9 4.7 DCHP 5.3 7.3 2.7 3.8 1.2 1.1 DIBP 2.2 10.2 1.4 4.6 2.5 2.3 DPP 2.4 8.3 1.9 4.2 1.2 1.1 DMEP 8.2 6.9 5.5 6.3 4.1 4.0  Open in new tab

Table VI

Compound

RSD of concn (%)

2 µg mL−1

10 µg mL−1

20 µg mL−1

Intraday (n = 3)

Interday (n = 6)

Intraday (n = 3)

Interday (n = 6)

Intraday (n = 3)

Interday (n = 6)

BHA 3.7 8.7 0.2 3.3 1.6 2.5 BHT 3.5 9.5 1.8 3.1 1.0 1.9 Irganox 1010 9.0 8.7 2.2 4.0 1.2 3.1 Irganox 1076 3.7 11.9 5.7 5.2 9.1 8.2 UV-0 5.4 3.9 1.8 1.4 1.2 1.3 UV-9 4.0 5.3 1.5 1.9 1.2 2.1 UV-P 0.1 8.9 1.1 2.7 1.6 2.4 UV-24 2.2 9.2 1.6 2.0 1.0 1.1 UV-234 7.3 7.7 0.6 3.4 0.6 1.5 UV-326 3.7 3.3 1.4 2.9 1.0 2.9 UV-327 0.4 11.0 2.5 2.7 2.2 2.0 UV-531 0.5 3.5 1.4 1.3 1.2 1.2 UV-1577 7.8 6.0 7.4 7.2 7.4 8.5 UV-184 6.3 9.9 3.3 3.7 1.1 3.5 UV-651 5.2 7.3 2.6 1.8 0.4 1.3 DEHP 5.6 10.0 2.2 7.5 3.7 5.3 DMP 3.6 5.7 4.6 4.9 3.0 4.0 DEP 1.6 4.9 9.9 6.2 4.2 3.3 BBP 3.0 7.3 1.5 5.9 5.5 4.9 DNOP 2.3 2.0 2.7 4.3 4.1 3.6 DNP 0.1 1.1 0.5 1.0 0.5 1.4 DPhP 4.7 5.9 0.7 3.0 0.8 2.7 DHXP 2.2 5.5 6.9 7.2 1.9 4.7 DCHP 5.3 7.3 2.7 3.8 1.2 1.1 DIBP 2.2 10.2 1.4 4.6 2.5 2.3 DPP 2.4 8.3 1.9 4.2 1.2 1.1 DMEP 8.2 6.9 5.5 6.3 4.1 4.0 Compound

RSD of concn (%)

2 µg mL−1

10 µg mL−1

20 µg mL−1

Intraday (n = 3)

Interday (n = 6)

Intraday (n = 3)

Interday (n = 6)

Intraday (n = 3)

Interday (n = 6)

BHA 3.7 8.7 0.2 3.3 1.6 2.5 BHT 3.5 9.5 1.8 3.1 1.0 1.9 Irganox 1010 9.0 8.7 2.2 4.0 1.2 3.1 Irganox 1076 3.7 11.9 5.7 5.2 9.1 8.2 UV-0 5.4 3.9 1.8 1.4 1.2 1.3 UV-9 4.0 5.3 1.5 1.9 1.2 2.1 UV-P 0.1 8.9 1.1 2.7 1.6 2.4 UV-24 2.2 9.2 1.6 2.0 1.0 1.1 UV-234 7.3 7.7 0.6 3.4 0.6 1.5 UV-326 3.7 3.3 1.4 2.9 1.0 2.9 UV-327 0.4 11.0 2.5 2.7 2.2 2.0 UV-531 0.5 3.5 1.4 1.3 1.2 1.2 UV-1577 7.8 6.0 7.4 7.2 7.4 8.5 UV-184 6.3 9.9 3.3 3.7 1.1 3.5 UV-651 5.2 7.3 2.6 1.8 0.4 1.3 DEHP 5.6 10.0 2.2 7.5 3.7 5.3 DMP 3.6 5.7 4.6 4.9 3.0 4.0 DEP 1.6 4.9 9.9 6.2 4.2 3.3 BBP 3.0 7.3 1.5 5.9 5.5 4.9 DNOP 2.3 2.0 2.7 4.3 4.1 3.6 DNP 0.1 1.1 0.5 1.0 0.5 1.4 DPhP 4.7 5.9 0.7 3.0 0.8 2.7 DHXP 2.2 5.5 6.9 7.2 1.9 4.7 DCHP 5.3 7.3 2.7 3.8 1.2 1.1 DIBP 2.2 10.2 1.4 4.6 2.5 2.3 DPP 2.4 8.3 1.9 4.2 1.2 1.1 DMEP 8.2 6.9 5.5 6.3 4.1 4.0  Open in new tab

Purity angle test

The test was carried out using peak purity judgment, which is part of the Waters HPLC-PDA system for handling chromatographic data. The principle of peak purity judgment is to obtain purity threshold and purity angle of individual peaks. A component with a peak purity threshold higher than its purity angle would be considered most likely to be a pure substance, no co-eluting component and the separation would be acceptable. The purity threshold and purity angle values in the chromatogram of all the studied chemicals are mentioned in Table IV, which illustrates that the peaks obtained high purity.

Analytical applications

Nine commercial plastic films used for food packaging were prepared and determined using the obtained ASE-HPLC analytical method. The quantitative values of the analyses in different real samples are shown in Table VII. It can be seen that most of samples determined contained one or two phthalate plasticizer (mainly DEP and DIBP). Samples 1, 2 and 8 contained DEP, its content was 11.40 ± 0.22, 16.61 ± 2.15 and 13.90 ± 1.40 µg g−1, respectively. DIBP was frequently found in Samples 1–5 and the content ranged from 25.04 ± 1.49 to 62.51 ± 2.85 µg g−1. Antioxidants, UV stabilizers and photoinitiators were not detected in all the samples. A typical chromatogram of Sample 2 is shown in Figure 2(b).

Table VII

Compound

Content ± SD (µg g−1)

Sample 1 (PP)

Sample 2 (PE)

Sample 3 (BOPP/CPP)

Sample 4 (PE)

Sample 5 (PP)

Sample 6 (OPP)

Sample 7 (PE)

Sample 8 (OPP/CPP)

Sample 9 (OPP/CPP)

BHA nd (not detected) nd nd nd nd nd nd nd nd BHT nd nd nd nd nd nd nd nd nd Irganox 1010 nd nd nd nd nd nd nd nd nd Irganox 1076 nd nd nd nd nd nd nd nd nd UV-0 nd nd nd nd nd nd nd nd nd UV-9 nd nd nd nd nd nd nd nd nd UV-P nd nd nd nd nd nd nd nd nd UV-24 nd nd nd nd nd nd nd nd nd UV-234 nd nd nd nd nd nd nd nd nd UV-326 nd nd nd nd nd nd nd nd nd UV-327 nd nd nd nd nd nd nd nd nd UV-531 nd nd nd nd nd nd nd nd nd UV-1577 nd nd nd nd nd nd nd nd nd UV-184 nd nd nd nd nd nd nd nd nd UV-651 nd nd nd nd nd nd nd nd nd DEHP nd nd nd nd nd nd nd nd nd DMP nd nd nd nd nd nd nd nd nd DEP 11.40 ± 0.22 16.61 ± 2.15 nd nd nd nd nd 13.90 ± 1.40 nd BBP nd nd nd nd nd nd nd nd nd DNOP nd nd nd nd nd nd nd nd nd DNP nd nd nd nd nd nd nd nd nd DPhP nd nd nd nd nd nd nd nd nd DHXP nd nd nd nd nd nd nd nd nd DCHP nd nd nd nd nd nd nd nd nd DIBP 49.54 ± 3.02 60.60 ± 2.44 62.51 ± 2.85 25.04 ± 1.49 25.36 ± 1.61 nd nd nd nd DPP nd nd nd nd nd nd nd nd nd DMEP nd nd nd nd nd nd nd nd nd Compound

Content ± SD (µg g−1)

Sample 1 (PP)

Sample 2 (PE)

Sample 3 (BOPP/CPP)

Sample 4 (PE)

Sample 5 (PP)

Sample 6 (OPP)

Sample 7 (PE)

Sample 8 (OPP/CPP)

Sample 9 (OPP/CPP)

BHA nd (not detected) nd nd nd nd nd nd nd nd BHT nd nd nd nd nd nd nd nd nd Irganox 1010 nd nd nd nd nd nd nd nd nd Irganox 1076 nd nd nd nd nd nd nd nd nd UV-0 nd nd nd nd nd nd nd nd nd UV-9 nd nd nd nd nd nd nd nd nd UV-P nd nd nd nd nd nd nd nd nd UV-24 nd nd nd nd nd nd nd nd nd UV-234 nd nd nd nd nd nd nd nd nd UV-326 nd nd nd nd nd nd nd nd nd UV-327 nd nd nd nd nd nd nd nd nd UV-531 nd nd nd nd nd nd nd nd nd UV-1577 nd nd nd nd nd nd nd nd nd UV-184 nd nd nd nd nd nd nd nd nd UV-651 nd nd nd nd nd nd nd nd nd DEHP nd nd nd nd nd nd nd nd nd DMP nd nd nd nd nd nd nd nd nd DEP 11.40 ± 0.22 16.61 ± 2.15 nd nd nd nd nd 13.90 ± 1.40 nd BBP nd nd nd nd nd nd nd nd nd DNOP nd nd nd nd nd nd nd nd nd DNP nd nd nd nd nd nd nd nd nd DPhP nd nd nd nd nd nd nd nd nd DHXP nd nd nd nd nd nd nd nd nd DCHP nd nd nd nd nd nd nd nd nd DIBP 49.54 ± 3.02 60.60 ± 2.44 62.51 ± 2.85 25.04 ± 1.49 25.36 ± 1.61 nd nd nd nd DPP nd nd nd nd nd nd nd nd nd DMEP nd nd nd nd nd nd nd nd nd  Open in new tab

Table VII

Compound

Content ± SD (µg g−1)

Sample 1 (PP)

Sample 2 (PE)

Sample 3 (BOPP/CPP)

Sample 4 (PE)

Sample 5 (PP)

Sample 6 (OPP)

Sample 7 (PE)

Sample 8 (OPP/CPP)

Sample 9 (OPP/CPP)

BHA nd (not detected) nd nd nd nd nd nd nd nd BHT nd nd nd nd nd nd nd nd nd Irganox 1010 nd nd nd nd nd nd nd nd nd Irganox 1076 nd nd nd nd nd nd nd nd nd UV-0 nd nd nd nd nd nd nd nd nd UV-9 nd nd nd nd nd nd nd nd nd UV-P nd nd nd nd nd nd nd nd nd UV-24 nd nd nd nd nd nd nd nd nd UV-234 nd nd nd nd nd nd nd nd nd UV-326 nd nd nd nd nd nd nd nd nd UV-327 nd nd nd nd nd nd nd nd nd UV-531 nd nd nd nd nd nd nd nd nd UV-1577 nd nd nd nd nd nd nd nd nd UV-184 nd nd nd nd nd nd nd nd nd UV-651 nd nd nd nd nd nd nd nd nd DEHP nd nd nd nd nd nd nd nd nd DMP nd nd nd nd nd nd nd nd nd DEP 11.40 ± 0.22 16.61 ± 2.15 nd nd nd nd nd 13.90 ± 1.40 nd BBP nd nd nd nd nd nd nd nd nd DNOP nd nd nd nd nd nd nd nd nd DNP nd nd nd nd nd nd nd nd nd DPhP nd nd nd nd nd nd nd nd nd DHXP nd nd nd nd nd nd nd nd nd DCHP nd nd nd nd nd nd nd nd nd DIBP 49.54 ± 3.02 60.60 ± 2.44 62.51 ± 2.85 25.04 ± 1.49 25.36 ± 1.61 nd nd nd nd DPP nd nd nd nd nd nd nd nd nd DMEP nd nd nd nd nd nd nd nd nd Compound

Content ± SD (µg g−1)

Sample 1 (PP)

Sample 2 (PE)

Sample 3 (BOPP/CPP)

Sample 4 (PE)

Sample 5 (PP)

Sample 6 (OPP)

Sample 7 (PE)

Sample 8 (OPP/CPP)

Sample 9 (OPP/CPP)

BHA nd (not detected) nd nd nd nd nd nd nd nd BHT nd nd nd nd nd nd nd nd nd Irganox 1010 nd nd nd nd nd nd nd nd nd Irganox 1076 nd nd nd nd nd nd nd nd nd UV-0 nd nd nd nd nd nd nd nd nd UV-9 nd nd nd nd nd nd nd nd nd UV-P nd nd nd nd nd nd nd nd nd UV-24 nd nd nd nd nd nd nd nd nd UV-234 nd nd nd nd nd nd nd nd nd UV-326 nd nd nd nd nd nd nd nd nd UV-327 nd nd nd nd nd nd nd nd nd UV-531 nd nd nd nd nd nd nd nd nd UV-1577 nd nd nd nd nd nd nd nd nd UV-184 nd nd nd nd nd nd nd nd nd UV-651 nd nd nd nd nd nd nd nd nd DEHP nd nd nd nd nd nd nd nd nd DMP nd nd nd nd nd nd nd nd nd DEP 11.40 ± 0.22 16.61 ± 2.15 nd nd nd nd nd 13.90 ± 1.40 nd BBP nd nd nd nd nd nd nd nd nd DNOP nd nd nd nd nd nd nd nd nd DNP nd nd nd nd nd nd nd nd nd DPhP nd nd nd nd nd nd nd nd nd DHXP nd nd nd nd nd nd nd nd nd DCHP nd nd nd nd nd nd nd nd nd DIBP 49.54 ± 3.02 60.60 ± 2.44 62.51 ± 2.85 25.04 ± 1.49 25.36 ± 1.61 nd nd nd nd DPP nd nd nd nd nd nd nd nd nd DMEP nd nd nd nd nd nd nd nd nd  Open in new tab

Discussion

Optimization of separation condition using HPLC

The chromatographic conditions were studied to obtain the best peak shape and an effective separation of all analytes with good stability of retention times. First, chromatographic conditions were built up referred to literature, the chromatographic condition was a mobile phase of acetonitrile as eluent A and water as eluent B (30, 34, 42). Initial experiments were (i) 40% A kept for 5 min, (ii) increase to 55% A during 5 min, (iii) 60% A kept for 15 min, (iv) increase to 70% A for 20 min, (v) increase to 100% A for 20 min, (vi) 100% A kept for 25 min, (vii) decrease to 70% A during 5 min and (viii) decrease to 40% A during 5 min. The total time was 100 min. However, the 27 chemicals did not show good resolution. Especially, the chromatographic peaks of DMP and DMEP are overlapped (Fig. 1). So experiments were performed by testing different gradient profiles in order to obtain a good response. From the results of the test series, it was found that a proportion of A started at 25% and increased slowly to 100% was the most effective for better resolution for the 27 chemicals, the optimum conditions reached are those described in Table III. A typical chromatogram of the selected 27 chemicals (20 µg mL−1 standard solution) obtained with this methodology is shown in Figure 2(a).

Figure 1.

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Chromatographic peaks of DMP and DMEP (a), UV-326 and UV-234 (b) in the initial and optimum separation conditions.

Figure 2.

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HPLC chromatogram of mixed standard solution at the concentration of 20 µg mL−1 (a) and chromatogram from a real PE sample which packaged almond crisp (Sample 2) (b) (1 DMP, 2 DMEP, 3 UV-0, 4 DEP, 5 UV-184, 6 UV-24, 7 BHA, 8 UV-651, 9 UV-9, 10 DPhP, 11 UV-P, 12 BBP, 13 DIBP, 14 BHT,15 DPP, 16 DCHP, 17 UV-1577, 18 DHXP, 19 UV-531, 20 UV-326, 21 UV-234, 22 DEHP, 23 DNOP, 24 UV-327, 25 DNP, 26 Irganox 1010, 27 Irganox 1076).

Optimization of extraction condition

According to literature, acetonitrile was chosen to extract polymer additives in plastic food package more efficiently (24). Furthermore, acetonitrile was used as eluent A throughout this study, so acetonitrile was chosen as extraction solvent.

ASE is one of the most recent sample preparation techniques. The parameters such as the pressure, heat time, static time, purge time and flush volume were set according to literature (43), 1,500 psi, 5 min, 5 min, 60 s and 50%, respectively. The investigation focused mainly on the two most influential parameters temperature and static cycle. The effect of extraction temperature (80, 100 and 120°C) and static cycle (1, 2 and 3 times) on the recoveries were investigated. The experiments were carried out by adding 1.0 mL mixed standard solution (10 µg mL−1) into 0.5 g blank sample on a spiked concentration level at 20 µg g−1, and the results are shown in Table VIII. Column 1 in Table VIII is the names of the analytes, columns 2–7 are the recoveries for all analytes based on ASE at different temperatures and static cycles, column 8 is the recoveries obtained by ultrasonic extraction method. LSD multiple comparison was used to compare the recoveries of different extraction temperatures and static cycles of ASE at a 95% confidence level.

Table VIII

Compound

ASE: extract temperaturea

ASE: static cycleb

Ultrasonic extraction

80°C

100°C

120°C

1

2

3

BHA 66.8 (4.4)a 71.8 (4.9)a,b 73.1 (3.2)b 50.7 (3.7)A 70.5 (1.4)B 74.4 (1.8)C 72.8 (1.7) BHT 71.3 (1.4)a 78.4 (2.9)b 75.6 (2.3)b 51.2 (1.9)A 74.6 (1.0)B 70.7 (1.7)C 75.6 (1.4) Irganox 1010 59.7 (2.0)a 74.4 (1.8)b 75.7 (1.0)b 42.4 (4.0)A 75.7 (1.6)B 78.4 (2.8)B 71.4 (2.7) Irganox 1076 62.6 (3.8)a 68.4 (5.5)a,b 70.3 (4.4)b 56.2 (3.5)A 77.2 (2.8)B 74.3 (3.6)B 79.2 (3.3) UV-0 78.7 (3.0)a 84.6 (2.6)b 82.1 (4.1)a,b 60.9 (6.7)A 86.8 (2.8)B 83.3 (3.3)B 88.2 (2.5) UV-9 60.8 (6.2)a 73.9 (2.6)b 75.3 (3.0)b 57.4 (3.2)A 76.2 (1.2)B 71.4 (5.2)B 75.5 (3.1) UV-P 65.0 (5.9)a 80.2 (6.7)b 88.6 (2.4)c 60.4 (2.9)A 83.2 (2.2)B 85.5 (2.6)B 85.5 (1.7) UV-24 59.3 (3.4)a 70.2 (4.0)b 72.2 (4.6)b 43.7 (2.7)A 69.4 (5.7)B 72.8 (3.4)B 71.7 (5.2) UV-234 79.9 (4.0)a 88.1 (2.3)b 92.5 (2.9)b 68.0 (2.1)A 90.7 (2.1)B 87.7 (2.4)B 96.3 (2.0) UV-326 81.8 (4.8)a 92.1 (2.2)b 87.5 (2.7)a,b 63.7 (2.0)A 96.1 (2.1)B 90.1 (2.2)C 94.5 (1.8) UV-327 79.6 (2.7)a 86.2 (2.9)b 90.7 (4.7)b 62.0 (3.7)A 89.5 (1.9)B 93.5 (2.1)C 95.5 (1.7) UV-531 76.8 (3.4)a 80.2 (4.8)a 81.9 (2.3)a 54.8 (3.8)A 82.4 (3.0)B 78.9 (4.4)B 80.8 (6.3) UV-1577 74.7 (1.6)a 76.7 (4.7)a 82.5 (2.2)b 58.5 (5.1)A 79.0 (4.6)B 83.1 (1.1)B 87.9 (1.6) UV-184 70.3 (3.0)a 85.8 (3.6)b 83.1 (3.5)b 56.9 (7.0)A 84.7 (2.6)B 89.5 (2.2)B 86.5 (1.1) UV-651 89.4 (1.4)a 90.8 (2.0)a,b 93.6 (2.0)b 65.8 (1.8)A 92.6 (4.2)B 95.3 (1.2)B 97.4 (2.0) DEHP 94.6 (0.8)a 96.8 (1.8)a 100.2 (1.9)b 70.5 (2.3)A 100.7 (2.9)B 97.9 (1.9)B 102.3 (1.1) DMP 74.7 (1.8)a 90.1 (1.6)b 92.2 (2.0)b 66.9 (2.0)A 94.7 (1.3)B 87.4 (3.0)C 93.9 (2.3) DEP 77.3 (2.4)a 81.6 (4.1)a 80.6 (2.4)a 55.4 (3.4)A 80.9 (1.7) 88.7 (2.5)C 83.2 (2.4) BBP 73.9 (1.3)a 85.6 (3.9)b 84.4 (1.3)b 61.3 (1.2)A 87.6 (2.3)B 83.5 (2.1)C 84.9 (4.2) DNOP 90.2 (3.8)a 91.7 (2.5)a 88.9 (1.6)a 67.5 (1.7)A 90.3 (1.0)B 93.2 (2.0)C 94.3 (5.6) DNP 86.7 (3.1)a 89.4 (2.1)a,b 91.7 (1.4)b 72.9 (3.3)A 91.4 (4.6)B 95.1 (1.0)B 93.8 (2.7) DPhP 79.4 (2.3)a 88.4 (3.3)b 93.1 (2.2)c 64.8 (3.8)A 91.5 (3.3)B 88.0 (2.2)B 92.4 (3.0) DHXP 85.0 (5.4)a 90.7 (5.2)a 91.1 (4.2)a 58.7 (5.0)A 93.6 (3.2)B 90.6 (1.3)B 92.4 (0.6) DCHP 80.6 (2.6)a 86.3 (4.6)a,b 88.6 (3.7)b 59.4 (3.6)A 87.3 (2.1)B 90.5 (1.9)B 91.6 (4.1) DIBP 75.7 (2.7)a 88.6 (3.4)b 85.2 (1.1)b 54.9 (6.9)A 89.7 (5.4)B 88.3 (2.2)B 85.6 (4.7) DPP 85.3 (2.3)a 95.4 (2.7)b 97.2 (1.5)b 67.6 (4.3)A 99.9 (2.3)B 97.7 (2.0)B 101.3 (4.2) DMEP 90.7 (2.3)a 92.3 (3.7)a 93.1 (3.3)a 63.9 (3.7)A 95.7 (2.2)B 98.4 (2.2)B 90.2 (2.2) Compound

ASE: extract temperaturea

ASE: static cycleb

Ultrasonic extraction

80°C

100°C

120°C

1

2

3

BHA 66.8 (4.4)a 71.8 (4.9)a,b 73.1 (3.2)b 50.7 (3.7)A 70.5 (1.4)B 74.4 (1.8)C 72.8 (1.7) BHT 71.3 (1.4)a 78.4 (2.9)b 75.6 (2.3)b 51.2 (1.9)A 74.6 (1.0)B 70.7 (1.7)C 75.6 (1.4) Irganox 1010 59.7 (2.0)a 74.4 (1.8)b 75.7 (1.0)b 42.4 (4.0)A 75.7 (1.6)B 78.4 (2.8)B 71.4 (2.7) Irganox 1076 62.6 (3.8)a 68.4 (5.5)a,b 70.3 (4.4)b 56.2 (3.5)A 77.2 (2.8)B 74.3 (3.6)B 79.2 (3.3) UV-0 78.7 (3.0)a 84.6 (2.6)b 82.1 (4.1)a,b 60.9 (6.7)A 86.8 (2.8)B 83.3 (3.3)B 88.2 (2.5) UV-9 60.8 (6.2)a 73.9 (2.6)b 75.3 (3.0)b 57.4 (3.2)A 76.2 (1.2)B 71.4 (5.2)B 75.5 (3.1) UV-P 65.0 (5.9)a 80.2 (6.7)b 88.6 (2.4)c 60.4 (2.9)A 83.2 (2.2)B 85.5 (2.6)B 85.5 (1.7) UV-24 59.3 (3.4)a 70.2 (4.0)b 72.2 (4.6)b 43.7 (2.7)A 69.4 (5.7)B 72.8 (3.4)B 71.7 (5.2) UV-234 79.9 (4.0)a 88.1 (2.3)b 92.5 (2.9)b 68.0 (2.1)A 90.7 (2.1)B 87.7 (2.4)B 96.3 (2.0) UV-326 81.8 (4.8)a 92.1 (2.2)b 87.5 (2.7)a,b 63.7 (2.0)A 96.1 (2.1)B 90.1 (2.2)C 94.5 (1.8) UV-327 79.6 (2.7)a 86.2 (2.9)b 90.7 (4.7)b 62.0 (3.7)A 89.5 (1.9)B 93.5 (2.1)C 95.5 (1.7) UV-531 76.8 (3.4)a 80.2 (4.8)a 81.9 (2.3)a 54.8 (3.8)A 82.4 (3.0)B 78.9 (4.4)B 80.8 (6.3) UV-1577 74.7 (1.6)a 76.7 (4.7)a 82.5 (2.2)b 58.5 (5.1)A 79.0 (4.6)B 83.1 (1.1)B 87.9 (1.6) UV-184 70.3 (3.0)a 85.8 (3.6)b 83.1 (3.5)b 56.9 (7.0)A 84.7 (2.6)B 89.5 (2.2)B 86.5 (1.1) UV-651 89.4 (1.4)a 90.8 (2.0)a,b 93.6 (2.0)b 65.8 (1.8)A 92.6 (4.2)B 95.3 (1.2)B 97.4 (2.0) DEHP 94.6 (0.8)a 96.8 (1.8)a 100.2 (1.9)b 70.5 (2.3)A 100.7 (2.9)B 97.9 (1.9)B 102.3 (1.1) DMP 74.7 (1.8)a 90.1 (1.6)b 92.2 (2.0)b 66.9 (2.0)A 94.7 (1.3)B 87.4 (3.0)C 93.9 (2.3) DEP 77.3 (2.4)a 81.6 (4.1)a 80.6 (2.4)a 55.4 (3.4)A 80.9 (1.7) 88.7 (2.5)C 83.2 (2.4) BBP 73.9 (1.3)a 85.6 (3.9)b 84.4 (1.3)b 61.3 (1.2)A 87.6 (2.3)B 83.5 (2.1)C 84.9 (4.2) DNOP 90.2 (3.8)a 91.7 (2.5)a 88.9 (1.6)a 67.5 (1.7)A 90.3 (1.0)B 93.2 (2.0)C 94.3 (5.6) DNP 86.7 (3.1)a 89.4 (2.1)a,b 91.7 (1.4)b 72.9 (3.3)A 91.4 (4.6)B 95.1 (1.0)B 93.8 (2.7) DPhP 79.4 (2.3)a 88.4 (3.3)b 93.1 (2.2)c 64.8 (3.8)A 91.5 (3.3)B 88.0 (2.2)B 92.4 (3.0) DHXP 85.0 (5.4)a 90.7 (5.2)a 91.1 (4.2)a 58.7 (5.0)A 93.6 (3.2)B 90.6 (1.3)B 92.4 (0.6) DCHP 80.6 (2.6)a 86.3 (4.6)a,b 88.6 (3.7)b 59.4 (3.6)A 87.3 (2.1)B 90.5 (1.9)B 91.6 (4.1) DIBP 75.7 (2.7)a 88.6 (3.4)b 85.2 (1.1)b 54.9 (6.9)A 89.7 (5.4)B 88.3 (2.2)B 85.6 (4.7) DPP 85.3 (2.3)a 95.4 (2.7)b 97.2 (1.5)b 67.6 (4.3)A 99.9 (2.3)B 97.7 (2.0)B 101.3 (4.2) DMEP 90.7 (2.3)a 92.3 (3.7)a 93.1 (3.3)a 63.9 (3.7)A 95.7 (2.2)B 98.4 (2.2)B 90.2 (2.2)  Open in new tab

Table VIII

Compound

ASE: extract temperaturea

ASE: static cycleb

Ultrasonic extraction

80°C

100°C

120°C

1

2

3

BHA 66.8 (4.4)a 71.8 (4.9)a,b 73.1 (3.2)b 50.7 (3.7)A 70.5 (1.4)B 74.4 (1.8)C 72.8 (1.7) BHT 71.3 (1.4)a 78.4 (2.9)b 75.6 (2.3)b 51.2 (1.9)A 74.6 (1.0)B 70.7 (1.7)C 75.6 (1.4) Irganox 1010 59.7 (2.0)a 74.4 (1.8)b 75.7 (1.0)b 42.4 (4.0)A 75.7 (1.6)B 78.4 (2.8)B 71.4 (2.7) Irganox 1076 62.6 (3.8)a 68.4 (5.5)a,b 70.3 (4.4)b 56.2 (3.5)A 77.2 (2.8)B 74.3 (3.6)B 79.2 (3.3) UV-0 78.7 (3.0)a 84.6 (2.6)b 82.1 (4.1)a,b 60.9 (6.7)A 86.8 (2.8)B 83.3 (3.3)B 88.2 (2.5) UV-9 60.8 (6.2)a 73.9 (2.6)b 75.3 (3.0)b 57.4 (3.2)A 76.2 (1.2)B 71.4 (5.2)B 75.5 (3.1) UV-P 65.0 (5.9)a 80.2 (6.7)b 88.6 (2.4)c 60.4 (2.9)A 83.2 (2.2)B 85.5 (2.6)B 85.5 (1.7) UV-24 59.3 (3.4)a 70.2 (4.0)b 72.2 (4.6)b 43.7 (2.7)A 69.4 (5.7)B 72.8 (3.4)B 71.7 (5.2) UV-234 79.9 (4.0)a 88.1 (2.3)b 92.5 (2.9)b 68.0 (2.1)A 90.7 (2.1)B 87.7 (2.4)B 96.3 (2.0) UV-326 81.8 (4.8)a 92.1 (2.2)b 87.5 (2.7)a,b 63.7 (2.0)A 96.1 (2.1)B 90.1 (2.2)C 94.5 (1.8) UV-327 79.6 (2.7)a 86.2 (2.9)b 90.7 (4.7)b 62.0 (3.7)A 89.5 (1.9)B 93.5 (2.1)C 95.5 (1.7) UV-531 76.8 (3.4)a 80.2 (4.8)a 81.9 (2.3)a 54.8 (3.8)A 82.4 (3.0)B 78.9 (4.4)B 80.8 (6.3) UV-1577 74.7 (1.6)a 76.7 (4.7)a 82.5 (2.2)b 58.5 (5.1)A 79.0 (4.6)B 83.1 (1.1)B 87.9 (1.6) UV-184 70.3 (3.0)a 85.8 (3.6)b 83.1 (3.5)b 56.9 (7.0)A 84.7 (2.6)B 89.5 (2.2)B 86.5 (1.1) UV-651 89.4 (1.4)a 90.8 (2.0)a,b 93.6 (2.0)b 65.8 (1.8)A 92.6 (4.2)B 95.3 (1.2)B 97.4 (2.0) DEHP 94.6 (0.8)a 96.8 (1.8)a 100.2 (1.9)b 70.5 (2.3)A 100.7 (2.9)B 97.9 (1.9)B 102.3 (1.1) DMP 74.7 (1.8)a 90.1 (1.6)b 92.2 (2.0)b 66.9 (2.0)A 94.7 (1.3)B 87.4 (3.0)C 93.9 (2.3) DEP 77.3 (2.4)a 81.6 (4.1)a 80.6 (2.4)a 55.4 (3.4)A 80.9 (1.7) 88.7 (2.5)C 83.2 (2.4) BBP 73.9 (1.3)a 85.6 (3.9)b 84.4 (1.3)b 61.3 (1.2)A 87.6 (2.3)B 83.5 (2.1)C 84.9 (4.2) DNOP 90.2 (3.8)a 91.7 (2.5)a 88.9 (1.6)a 67.5 (1.7)A 90.3 (1.0)B 93.2 (2.0)C 94.3 (5.6) DNP 86.7 (3.1)a 89.4 (2.1)a,b 91.7 (1.4)b 72.9 (3.3)A 91.4 (4.6)B 95.1 (1.0)B 93.8 (2.7) DPhP 79.4 (2.3)a 88.4 (3.3)b 93.1 (2.2)c 64.8 (3.8)A 91.5 (3.3)B 88.0 (2.2)B 92.4 (3.0) DHXP 85.0 (5.4)a 90.7 (5.2)a 91.1 (4.2)a 58.7 (5.0)A 93.6 (3.2)B 90.6 (1.3)B 92.4 (0.6) DCHP 80.6 (2.6)a 86.3 (4.6)a,b 88.6 (3.7)b 59.4 (3.6)A 87.3 (2.1)B 90.5 (1.9)B 91.6 (4.1) DIBP 75.7 (2.7)a 88.6 (3.4)b 85.2 (1.1)b 54.9 (6.9)A 89.7 (5.4)B 88.3 (2.2)B 85.6 (4.7) DPP 85.3 (2.3)a 95.4 (2.7)b 97.2 (1.5)b 67.6 (4.3)A 99.9 (2.3)B 97.7 (2.0)B 101.3 (4.2) DMEP 90.7 (2.3)a 92.3 (3.7)a 93.1 (3.3)a 63.9 (3.7)A 95.7 (2.2)B 98.4 (2.2)B 90.2 (2.2) Compound

ASE: extract temperaturea

ASE: static cycleb

Ultrasonic extraction

80°C

100°C

120°C

1

2

3

BHA 66.8 (4.4)a 71.8 (4.9)a,b 73.1 (3.2)b 50.7 (3.7)A 70.5 (1.4)B 74.4 (1.8)C 72.8 (1.7) BHT 71.3 (1.4)a 78.4 (2.9)b 75.6 (2.3)b 51.2 (1.9)A 74.6 (1.0)B 70.7 (1.7)C 75.6 (1.4) Irganox 1010 59.7 (2.0)a 74.4 (1.8)b 75.7 (1.0)b 42.4 (4.0)A 75.7 (1.6)B 78.4 (2.8)B 71.4 (2.7) Irganox 1076 62.6 (3.8)a 68.4 (5.5)a,b 70.3 (4.4)b 56.2 (3.5)A 77.2 (2.8)B 74.3 (3.6)B 79.2 (3.3) UV-0 78.7 (3.0)a 84.6 (2.6)b 82.1 (4.1)a,b 60.9 (6.7)A 86.8 (2.8)B 83.3 (3.3)B 88.2 (2.5) UV-9 60.8 (6.2)a 73.9 (2.6)b 75.3 (3.0)b 57.4 (3.2)A 76.2 (1.2)B 71.4 (5.2)B 75.5 (3.1) UV-P 65.0 (5.9)a 80.2 (6.7)b 88.6 (2.4)c 60.4 (2.9)A 83.2 (2.2)B 85.5 (2.6)B 85.5 (1.7) UV-24 59.3 (3.4)a 70.2 (4.0)b 72.2 (4.6)b 43.7 (2.7)A 69.4 (5.7)B 72.8 (3.4)B 71.7 (5.2) UV-234 79.9 (4.0)a 88.1 (2.3)b 92.5 (2.9)b 68.0 (2.1)A 90.7 (2.1)B 87.7 (2.4)B 96.3 (2.0) UV-326 81.8 (4.8)a 92.1 (2.2)b 87.5 (2.7)a,b 63.7 (2.0)A 96.1 (2.1)B 90.1 (2.2)C 94.5 (1.8) UV-327 79.6 (2.7)a 86.2 (2.9)b 90.7 (4.7)b 62.0 (3.7)A 89.5 (1.9)B 93.5 (2.1)C 95.5 (1.7) UV-531 76.8 (3.4)a 80.2 (4.8)a 81.9 (2.3)a 54.8 (3.8)A 82.4 (3.0)B 78.9 (4.4)B 80.8 (6.3) UV-1577 74.7 (1.6)a 76.7 (4.7)a 82.5 (2.2)b 58.5 (5.1)A 79.0 (4.6)B 83.1 (1.1)B 87.9 (1.6) UV-184 70.3 (3.0)a 85.8 (3.6)b 83.1 (3.5)b 56.9 (7.0)A 84.7 (2.6)B 89.5 (2.2)B 86.5 (1.1) UV-651 89.4 (1.4)a 90.8 (2.0)a,b 93.6 (2.0)b 65.8 (1.8)A 92.6 (4.2)B 95.3 (1.2)B 97.4 (2.0) DEHP 94.6 (0.8)a 96.8 (1.8)a 100.2 (1.9)b 70.5 (2.3)A 100.7 (2.9)B 97.9 (1.9)B 102.3 (1.1) DMP 74.7 (1.8)a 90.1 (1.6)b 92.2 (2.0)b 66.9 (2.0)A 94.7 (1.3)B 87.4 (3.0)C 93.9 (2.3) DEP 77.3 (2.4)a 81.6 (4.1)a 80.6 (2.4)a 55.4 (3.4)A 80.9 (1.7) 88.7 (2.5)C 83.2 (2.4) BBP 73.9 (1.3)a 85.6 (3.9)b 84.4 (1.3)b 61.3 (1.2)A 87.6 (2.3)B 83.5 (2.1)C 84.9 (4.2) DNOP 90.2 (3.8)a 91.7 (2.5)a 88.9 (1.6)a 67.5 (1.7)A 90.3 (1.0)B 93.2 (2.0)C 94.3 (5.6) DNP 86.7 (3.1)a 89.4 (2.1)a,b 91.7 (1.4)b 72.9 (3.3)A 91.4 (4.6)B 95.1 (1.0)B 93.8 (2.7) DPhP 79.4 (2.3)a 88.4 (3.3)b 93.1 (2.2)c 64.8 (3.8)A 91.5 (3.3)B 88.0 (2.2)B 92.4 (3.0) DHXP 85.0 (5.4)a 90.7 (5.2)a 91.1 (4.2)a 58.7 (5.0)A 93.6 (3.2)B 90.6 (1.3)B 92.4 (0.6) DCHP 80.6 (2.6)a 86.3 (4.6)a,b 88.6 (3.7)b 59.4 (3.6)A 87.3 (2.1)B 90.5 (1.9)B 91.6 (4.1) DIBP 75.7 (2.7)a 88.6 (3.4)b 85.2 (1.1)b 54.9 (6.9)A 89.7 (5.4)B 88.3 (2.2)B 85.6 (4.7) DPP 85.3 (2.3)a 95.4 (2.7)b 97.2 (1.5)b 67.6 (4.3)A 99.9 (2.3)B 97.7 (2.0)B 101.3 (4.2) DMEP 90.7 (2.3)a 92.3 (3.7)a 93.1 (3.3)a 63.9 (3.7)A 95.7 (2.2)B 98.4 (2.2)B 90.2 (2.2)  Open in new tab

The results of statistical analysis indicated that the recoveries increased significantly with increasing temperature from 80 to 100°C for most compounds. With elevated temperature, desorption of analyte from active sites in the matrix increased which resulted in improved extraction efficiencies. Additionally, the solvent has higher capacity to solubilize analytes at higher temperature while surface tension and solvent viscosity decrease, which will improve matrix penetration. However, no statistically difference was observed in the mean recoveries of the analytes between 100 and 120°C. High extraction temperature is harmful for the equipment, so the optimum extraction temperature was selected at 100°C.

As in other extraction techniques, static cycle is another parameter whose influence needs to be taken into account. The effect of static cycle from 1 to 3 times on recoveries was investigated at 100°C. We also compared the recoveries of different static cycles at a 95% confidence level by LSD multiple comparison. An increase in static cycle from 1 to 2 gave a considerable increase in the mean recoveries. The differences of mean recoveries were insignificant when the duration of extraction was increased from 2 to 3 times. For the best effect, saving solvent and decreasing pollution, the static cycle of ASE at 2 was selected.

Paired t-tests were performed on the recoveries of ASE and ultrasonic extraction for the 27 chemicals at a 99% confidence level. No significant differences about the recoveries of the two extraction methods (P = 0.013) were observed. The ASE method is automated and combined use of high pressures and temperatures provide a faster extraction process that decreases time and solvent consumption. The total process of the ASE method in this study only required 20 min, including washing.

Strengths and weaknesses

The research is the first time to develop a method for the simultaneous determination of antioxidants, UV stabilizers, phthalate plasticizers and photoinitiators used in polymers based on ASE and high-performance liquid chromatography-photodiode array detector (HPLC-PDA). Although HPLC system with a long column (250 mm) separated as many as 27 compounds, an analysis time of 100 min was required. Other analytical equipment, such as UPLC and HPLC-MS might be a solution for the determination of these compounds in a shorter analysis time, but the cost of UPLC and HPLC-MS is higher than HPLC.

Future research

In the next phase of the project, the analytical method obtained in this research will be widely used in the analysis of practical samples. Moreover, a second, more targeted, migration test will be set up. This extra campaign will focus on the migrate level of these chemicals from food package into food simulant or real food to estimate the dietary exposure.

Conclusions

In this paper, a suitable method for the extraction, detection and quantification of 27 polymer additives in plastic food packages has been developed. This method involved ASE with acetonitrile and subsequent determination by HPLC-PDA, good linearity, precision, repeatability, stability and accuracy. The LODs of the 27 compounds were between 0.03 and 0.30 µg mL−1, recoveries in the range of 58.6–97.7%, with RSDs between 0.4 and 15.4%. This method is not limited to the detection of one kind of additive, it supports the simultaneous determination of antioxidants, UV stabilizers, phthalate plasticizers and photoinitiators used in polymers. It is valuable in real application and can be applied in routine analysis, moreover, would contribute to counter increasingly serious food security environments more effectively.

Acknowledgements

The authors acknowledged the financial support of this research by Projects 21277061, 21077045 and 21277085 supported by the National Natural Science Foundation of China. We also acknowledged the support by Project 11613411 supported by the Fundamental Research Funds for the Central Universities.

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