Article pubs.acs.org/JAFC
Determination of Polymer Additives−Antioxidants and Ultraviolet (UV) Absorbers by High-Performance Liquid Chromatography Coupled with UV Photodiode Array Detection in Food Simulants Yali Gao, Yanxiang Gu, and Yun Wei* State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing 100029, China ABSTRACT: An analytical method for the quantitative determination of migration levels of polymer additives such as antioxidants and UV absorbers in food packages by high-performance liquid chromatography coupled with UV−vis photodiode array detection has been developed. The pretreatment step involved solid-phase extraction with silica C18 cartridges. The analytical method showed good linearity, presenting regression coefficients (R 2) ≥0.9990 for all compounds. This optimized method was also validated with respect to precision, reproducibility, stability, and accuracy. The limits of detection and quantification were between 0.09 and 1.72 μg mL−1 and between 0.20 and 5.64 μg mL−1 for 12 analytes, respectively. Recoveries were in the range of 67.48 and 108.55%, with relative standard deviations between 2.76 and 9.81%. Migration levels of antioxidants and UV absorbers were determined. Butylated hydroxyanisole, 2,6-di-tert-butyl-4-methylphenol (BHT), 2,4-di-tertbutylphenol, Cyanox 2246, Irganox 1035, Tinuvin 326, Tinuvin 328, Irganox 1010, and Irganox 1330 were detected; BHT and Cyanox 2246 were at higher levels than the specific migration levels in some food simulants. KEYWORDS: antioxidants, UV absorbers, food package, migration
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Irganox 1076, Irganox 1010, and Irgafos 1681,4,5,9,10 were studied, and UV absorbers are rarely addressed in research studies. The compounds Irganox 1035, Cyanox 2246, Tinuvin 326, Tinuvin 328, and Chimassorb 81 are often used as material additives, but there are no SML for Tinuvin 326 and Tinuvin 328 now. The aim of this study is to develop an analytical method with suitable detection limits, good repeatability, and accuracy for the determination of antioxidants and UV absorbers at the concentration range required by the legislation. The method involved solid-phase extraction (SPE) with a silica C18 cartridge in a pretreatment step, which has been increasingly used for extracting and concentrating different target compounds from liquid samples,11 and then HPLC-DAD was used to determine the migration levels of the usual commercial antioxidants and UV absorbers used in the food packages.
INTRODUCTION Plastic, as drink or food packaging, 1 is a commonly used material for food storage and protection, which usually is in contact with food. Nowadays, there is increasing interest regarding health and safety aspects associated with the use of polymer additives in food packages. Among a wide variety of polymer additives present in plastic, antioxidants and UV absorbers2,3 are particularly important because they delay the oxidation reaction of the polymer4−6 and can migrate into the food and contaminate it. Therefore, the quantification and specific migration levels (SML) of these additives are very important for the quality control of food. Under exposure to UV light, polymers may undergo degradation through oxidation mechanism. Antioxidants and UV absorbers are added to polymers to slow such oxidation processes. These compounds and their degradation products would migrate from plastics into foodstuffs during processing or storage. Therefore, legislation 7,8 imposes SML upon individual substances with the potential to migrate from plastics into foodstuffs according to their individual toxicity. Determination of the additives such as antioxidants and UV absorbers as result of migration from different food packaging films into food simulants is allowed by legislation:8 simulant A (distilled water), simulant B (3% acetic acid), simulant C (10% ethanol), and simulant D (oil) guarantee food safety. Antioxidants and UV absorbers in food packages are widely used in plastic packages. In this paper, the following compounds were studied: butylated hydroxyanisole (BHA), 2,6-di-tert-butyl-4-methylphenol (BHT), Cyanox 2246, Chimassorb 81, Irganox 1035, Irganox 1010, Irganox 1330, Irganox 1076, Irgafos 168 and its degradation product 2,4-ditert-butylphenol (DBP), Tinuvin 326, and Tinuvin 328. There are many studies regarding the migration of antioxidants from plastic packages. However, only a few antioxidants such as © 2011 American Chemical Society
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MATERIALS AND METHODS
Solutions and Reagents. The antioxidants included BHA, Chimassorb 81, Irganox 1010, Irganox 1330, Irganox 1076, and Irgafos 168 and its degradation product DBP together with UV absorbers Tinuvin 326 and Tinuvin 328 were from Sigma-Aldrich (Steinheim, Germany), BHT was from Alfa Aesar (Karlsruhe, Germany), and Irganox 1035 and Cyanox 2246 were from TCI (Shanghai, China). Individual stock standard solutions of each antioxidant and UV absorber (1 mg mL−1) were prepared in acetonitrile4,12,13 for BHA, DBP, BHT, Irganox 1010, Irganox 1035, Chimassorb 81, and Cyanox 2246, in a mixture of acetonitrile/ tetrahydrofuran (1:1, v/v) for Irganox 1330, Irganox 1076, Irgafos 168, Received: Revised: Accepted: Published: 12982
August 13, 2011 November 9, 2011 November 21, 2011 December 5, 2011 dx.doi.org/10.1021/jf203257b | J. Agric.Food Chem. 2011, 59, 12982−12989
Journal of Agricultural and Food Chemistry
Article
Table 1. Antioxidants and UV Absorbers BHA DBP BHT Cyanox 2246 Chimassorb 81 Irganox 1035 Tinuvin 326 Tinuvin 328 Irganox 1010 Irganox 1330 Irganox 1076 Irgafos 168 a
SMLa (mg kg−1)7,15
chemical name
CAS Registry No.
Mw
butylated hydroxyanisole 2,4-di-tert-butylphenol 2,6-di-tert-butyl-4-methylphenol 2,2′-methylenebis(4-methyl-6-tert-butylphenol) 2-hydroxy-4-(octyloxy)benzophenone 2,2′-thiodiethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] 2-tert--butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol pentaerythritol (tetrakis)3,5-di-tert-butyl-4-hydroxycinnamate 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate tris(2, 4-di-tert-butylphenyl)phosphite
25013-16-5 96-76-4 128-37-0 119-47-1 1843-05-6 41484-35-9 3896-11-5 25793-55-1 6683-19-8 1709-70-2 2082-79-3 31570-04-4
180.25 206.32 220.36 340.50 326 642.93 316.81 351.5 1177.67 775.22 530.88 646.94
30
source Sigma Sigma Alfa Aesar TCI Sigma TCI Sigma Sigma Sigma Sigma Sigma Sigma
3 1.5 2.4
6.0
SML, specific migration levels.
Tinuvin 326, and Tinuvin 328 (Table 1). Low molecular weight compounds (molecular weight < 400) included BHA, DBP, BHT, Cyanox 2246, Chimassorb 81, Tinuvin 326, and Tinuvin 328; middle molecular weight compounds (400 < molecular weight < 800), Irganox 1035, Irganox 1076, Irganox 1330, and Irgafos 168; and high molecular weight (molecular weight > 1000) compounds, Irganox 1010. Mixed stock standard solutions containing all of the compounds were prepared from individual standard solution (1 mg mL−1) by dilution with acetonitrile/tetrahydrofuran (THF) (1:1, v/v). Acetonitrile of HPLC grade was supplied by Dikma (Lake Forest, IL), THF of HPLC gradient grade was supplied by J. T. Baker (Deventer, The Netherlands), and water was supplied by Wahaha Pure Water (Zhejiang, China). Soybean oil used as fatty food simulant was bought from a local supermarket. SPE Procedure. The used silica C18 cartridges (500 mg) were purchased from Supelco (Bellefonte, PA). At pretreatment step, the samples of simulant (A, B, or C) spiked with the antioxidants and UV absorbers were modified by adding acetic acid and ethanol to a concentration of 3% (v/v) acetic acid and 10% (v/v) ethanol for all samples.12,14,15 Before extraction, silica C18 cartridges were conditioned first with 5 mL of acetonitrile and then with 5 mL of distilled water. The spiked samples were percolated at a flow rate of approximately 1.0 mL min−1. Elution of the retained antioxidants and UV absorbers was carried out (without vacuum) with acetonitrile and THF. Both solvents were passed sequentially and collected together. Fatty Food Simulant Samples. An amount of 2 mL of oil was diluted with acetonitrile and THF to a volume of 10 mL before the quantification of antioxidants and UV absorbers by HPLC. Food Simulants. The selected food packages were polymeric packages used to pack different kinds of food and acquired in the supermarket (Table 2). Migration tests were performed with a single side contact. Each sample, approximately 1 dm2, was put in 165 mL of simulant.12 The conditions of the migration tests were 10 days at 40 °C using the following food stimulants: distilled water (simulant A), 3% acetic acid (simulant B), 10% ethanol (simulant C), and oil (simulant D).8 An amount of 100 mL of aqueous food simulant sample (A, B, or C) was modified by adding acetic acid and/or ethanol to a concentration of 3% (v/v) acetic acid and 10% (v/v) of ethanol for all samples. 12 The methods mentioned above were used to activate the SPE. Elution of the retained antioxidants and UV absorbers was carried out with 8 mL of acetonitrile and 2 mL of THF. Both solvents were passed sequentially and collected together. The eluent was concentrated by rotary evaporator, and then 1 mL of acetonitrile/THF (1:1, v/v) was used to dissolve the eluent before the quantification of antioxidants and UV absorbers by HPLC. HPLC-DAD Analysis. The chromatographic experiments were carried out on a Shimadzu LC-20A system including two LC-20A solvent delivery units an SPD-M20A UV−vis photodiode array detector (DAD), a model 7725 injection valve with a 20 μL loop, an SCL-20A system controller, and a Class-VP-LC workstation (Shimadzu, Kyoto,
Table 2. Studied Commercial Food Packages and Corresponding Stimulants no.
food packaged
food simulant
ref 8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
yogurt moon cake beverage mineral water biscuit beverage beverage yogurt yogurt granulated sugar beverage bacon biscuit biscuit beverage honey peanut oil yogurt milk beverage beverage ethanol ethanol soybean milk preservative film vinegar egg
B D B A D A A B B A B D D D B A D B A A A C C A A B A
07, milk products 02, biscuits, cakes 01, beverage 01, beverage 02, biscuits, cakes 01, beverage 01, beverage 07, milk products 07, milk products 03, chocolate, sugar 01, beverage 06, animal products and eggs 02, biscuits, cakes 02, biscuits, cakes 01, beverage 03, chocolate, sugar 05, fats and oils 07, milk products 07, milk products 01, beverage 01, beverage 01, beverage 01, beverage 01, beverage 04 fruit, vegetables 08, miscellaneous products 06, animal products and eggs
Japan). The 12 analytes were completely separated using a column 150 mm × 4.6 mm packed with Zorbax Eclipse XDB C18, 5 μm particle size (Agilent, Santa Clara, CA), maintained at 30 °C. The detection wavelength was 276 nm. The quantification was based on at least a five-point external calibration graph obtained by plotting the individual peak areas against the concentration of the calibration standards.16,17 The conditions of chromatographic method were as follows: the gradient was run from 55% acetonitrile to 85% acetonitrile in 4 min, to 100% acetonitrile within the next 21 min, and kept at this level for another 75 min.
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RESULTS AND DISCUSSION Calibration Curves, Limits of Detection (LOD), and Limits of Quantification (LOQ). The HPLC chromatogram obtained under the above conditions is shown in Figure 1.
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1035. Acetonitrile and THF were modified between 2 and 10 mL to select the best elution volume using the methods mentioned before. Equal volumes of acetonitrile and THF were employed in each assay. Two milliliters of acetonitrile and 2 mL of THF were used in the first assay and 10 mL of acetonitrile and 10 mL of THF in the last assay;12 recoveries are presented in Figure 2.
Figure 1. HPLC chromatogram of standard antioxidants and UV absorbers. Samples: 1, BHA; 2, DBP; 3, BHT; 4, Cyanox 2246; 5, Chimassorb 81; 6, Irganox 1035; 7, Tinuvin 326; 8, Tinuvin 328; 9, Irganox 1010; 10, Irganox 1330; 11, Irganox 1076; 12, Irgafos 168.
Each compound was identified by comparison of its retention time with the corresponding peak of the standard solution and its UV spectra. All calibration curves were constructed from peak areas of the reference standards against their concentrations. Good linearity was achieved for all of the compounds for the concentration ranges selected (regression coefficients (R 2) ≥ 0.9990 for all compounds). According to the concept of LOD,18−20 in practice, the noise and signal are measured manually on the chromatogram printout. LOD corresponds to the analyte amount for which the signal-to-noise ratio is equal to 3, and LOQ corresponds to the analyte amount for which the signal-to-noise ratio is equal to 10. Detailed information regarding the calibration curves, linear ranges, LOD, and LOQ was listed in Table 3. The lowest LOD and LOQ values were 0.09 μg mL−1 (DBP and Chimassorb 81) and 0.20 (Chimassorb 81) μg mL−1, respectively, whereas the highest LOD and LOQ values were 1.72 μg mL−1 (Irgafos 168) and 5.64 μg mL−1 (Irgafos 168) μg mL−1, respectively. Low molecular weight compounds attained lower LOD and LOQ, and middle molecular weight compounds attained higher LOD and LOQ. The ranges of the concentrations were not the same for all of the compounds because physical and chemical characteristics affect the analytical signal, so for some compounds higher concentrations had to be used to detect the compounds. Determination of Elution Volume. SPE with a silica C18 cartridge was used in the pretreatment step. A volume of 100 mL of water was spiked with the antioxidants and UV absorbers by adding acetic acid and ethanol to concentrations of 3% (v/v) acetic acid and 10% (v/v) ethanol; the concentrations of the compounds were 0.2 μg mL−1 for BHA and DBP, 0.3 μg mL−1 for Tinuvin 328, 0.4 μg mL−1 for BHT and Chimassorb 81, 0.5 μg mL−1 for Tinuvin 326, Irganox 1076, Irganox 1010, Irganox 1330, Irgafos 168, and Cyanox 2246, and 1 μg mL−1 for Irganox
Figure 2. Recoveries with acetonitrile and THF in the elution by SPE C18.
Using only 4 mL of acetonitrile followed by 4 mL of THF, UV absorbers and most of the antioxidants were completely eluted (88% for BHA, 105% for DBP, 99% for Cyanox 2246, 90% for Irganox 1035, 90% for Tinuvin 326, 92% for Tinuvin 328, 91% for Irganox 1010, 89% for Irganox 1330, and 87% for Irganox 1076), but the volume of 4 mL of acetonitrile followed by 4 mL of THF was not sufficient for the elution of Chimassorb 81 and Irgafos 168 (51% for Chimassorb 81 and 52% for Irgafos 168). When the volume increased to 8 mL of acetonitrile followed by 8 mL of THF, recoveries increased slightly (from 51 to 59% for Chimassorb 81 and from 53 to 65% for Irgafos 168). With a further increase to 10 mL of acetonitrile followed by 10 mL of THF, the recoveries of Chimassorb 81 and Irgafos 168 were similar to that using 8 mL of acetonitrile followed by 8 mL of THF; there was no significant difference for other compounds. As a result, 8 mL of acetonitrile followed by 8 mL of THF was selected. The individual effect of acetonitrile and THF elution volume on the recovery of the analytes was studied by injecting their eluents separately to make sure the acetonitrile and THF must be utilized together. From the results, none of these solvents could achieve good recoveries of all analytes. The recovery of Irganox 1076 was only 69% under acetonitrile elution, and the recovery of BHA was 81% under THF elution. In Figure 3, the volume of acetonitrile was increased from 2 to 4 mL, and recoveries increased slightly for Tinuvin 326, Tinuvin 328, Irganox 1010, and Irganox 1330; when the volume of acetonitrile was
Table 3. Regression Data, LODs, and LOQs for 12 Compounds Analyzed by HPLC compd
regression (Y = aX + b)
R2
linear range (μg mL−1)
LOD (μg mL−1)
LOQ (μg mL−1)
BHA DBP BHT Cyanox 2246 Chimassorb 81 Irganox 1035 Tinuvin 326 Tinuvin 328 Irganox 1010 Irganox 1330 Irganox 1076 Irgafos 168
Y = 6.54X − 1.82 Y = 6.48X + 0.38 Y = 3.17X + 259.2 Y = 6.90X + 20.50 Y = 20.78X − 3.29 Y = 3.12X − 1.73 Y = 8.19X − 0.35 Y = 10.08X − 0.74 Y = 3.38X − 1.74 Y = 4.67X − 2.17 Y = 1.96X − 2.60 Y = 2.19X − 9.77
0.9995 0.9994 0.9995 0.9994 0.9990 0.9995 0.9991 0.9995 0.9993 0.9995 0.9996 0.9995
2−20 2−20 4−40 5−50 4−40 10−100 5−50 3−30 5−50 5−50 10−50 10−50
0.17 0.09 0.16 0.15 0.09 0.54 0.19 0.17 0.67 0.54 1.25 1.72
0.58 0.27 0.33 0.55 0.20 1.07 0.41 0.85 2.58 1.81 4.42 5.64
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the same amount of analytes. The chosen volumes took into consideration the concentration factor of analytes needed and the period required for the percolation of the whole volume
Figure 3. Recoveries with acetonitrile in the elution volume by SPE C18.
increased from 4 to 8 mL, there was no significant difference for most of the analytes except Irganox 1076 and Irgafos 168, which increased to 69 and 61%, respectively. When the volume of acetonitrile was increased from 8 to 10 mL, the recoveries of Irganox 1076 and Irgafos 168 were almost the same. Therefore, 8 mL of acetonitrile was selected. In Figure 4, when the volume
Figure 5. Recoveries for the breakthrough volume by SPE C18 from samples with 10% ethanol and 3% acetic acid spiked with antioxidants and UV absorbers.
on cartridge. The achieved results are shown in Figure 5. As seen in Figure 5, there was no apparent decrease in the recoveries with the food simulant volume between 25 and 100 mL, the high molecular weight compound and most of the low and middle molecular weight compounds obtained good recoveries (>87%), and the recoveries of Chimassorb 81 and Irgafos 168 were 69 and 73%, respectively. Recoveries decreased for all of the compounds except DBP in the 150 mL assay but increased in the 250 mL assay except BHA, Chimassorb 81, and Irgafos 168; there was no significant difference of recoveries between 100 and 250 mL. Consequently, 100 mL could be fixed as a suitable sample volume. Precision. The precision was determined for the food simulants spiked with antioxidants and UV absorbers at three different concentration levels of mixed standard solutions.11,17,21,22 The precision for the 12 analytes was described as relative standard deviations (RSD) (Table 4), n = 3.
Figure 4. Recoveries with THF in the elution volume by SPE C18.
of THF was increased from 2 to 10 mL, there was a little difference for most of the analytes’ recovery between 2 and 8 mL (increased or decreased about 5%); the recoveries of most of the antioxidants and UV absorbers were >80%. Some compounds eluted better with THF than with acetonitrile, such as Chimassorb 81, which was not well recovered with acetonitrile (Figure 3) even when 8 or 10 mL of acetonitrile was used. Although the volume of 10 mL of THF achieved the best recoveries, when using 2 mL of THF, the recoveries of Irgafos 168 and Chimassorb 81 were 69 and 82%, respectively; there was no significant difference with 10 mL of THF. Therefore, 8 mL of acetonitrile followed by different volumes (2, 4, 6, 8, and 10 mL) of THF was used to select the volume of THF to decrease the THF amount; as a result, 8 mL of acetonitrile and 2 mL of THF were required to ensure a maximum elution of the 12 analytes. Determination of Breakthrough Volume. After the volume of eluent had been chosen, it was important to find the appropriate breakthrough volume. Breakthrough of the analyte occurs either when the analyte is no longer retained by the sorbent or when the capacity of the sorbent has been overloaded.21 The experiment was performed for samples with 10% ethanol and 3% acetic acid spiked with antioxidants and UV absorbers. The contents of the compounds were 0.02 mg for BHA and DBP, 0.03 mg for Tinuvin 328, 0.04 mg for BHT and Chimassorb 81, 0.05 mg for Tinuvin 326, Irganox 1076, Irganox 1010, Irganox 1330, Irgafos 168, and Cyanox 2246, and 0.1 mg for Irganox 1035. The sample volume was modified to determine the breakthrough volume of compounds from 25 to 250 mL, each containing
Table 4. Precision of 12 Compounds of the SPE-HPLCDAD Analytical Method (n = 3) compd
12985
concn RSD (μg mL−1) (%)
compd
concn (μg mL−1)
RSD (%)
BHA
24 32 40
1.82 2.7 3.12
Tinuvin 326
60 80 100
0.85 3.89 3.35
DBP
24 32 40
2.7 4.69 3.96
Tinuvin 328
36 48 60
1.23 3.83 2.64
BHT
48 64 80
0.43 0.53 1.9
Irganox 1010
60 80 100
0.94 3.55 4.78
Cyanox 2246
60 80 100
0.5 2.06 3.01
Irganox 1330
60 80 100
0.49 4.3 2.13
Chimassorb81
48 64 80
1.99 3.54 3.38
Irganox 1076
60 80 100
1.64 1.42 3.25
Irganox 1035
120 160 200
1.47 3.53 2.74
Irgafos 168
60 80 100
1.5 1.47 1.06
dx.doi.org/10.1021/jf203257b | J. Agric.Food Chem. 2011, 59, 12982−12989
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Table 5. Reproducibility and Intra- and Interday Stability of 12 Compounds of the SPE-HPLC-DAD Analytical Method reproducibility(n = 3) concn (μg mL−1)
RSD (%)
stability intraday(n = 5) concn (μg mL−1)
RSD (%)
stability interday(n = 3) concn (μg mL−1)
RSD (%)
BHA
24 32 40
5.29 1.39 0.97
24 32 40
5.84 6.05 5.61
24 32 40
5.41 6.24 5.41
DBP
24 32 40
4.21 2.84 8.16
24 32 40
6.22 5.72 4.77
24 32 40
5.82 6.37 5.74
BHT
48 64 80
2.34 2.08 5.54
48 64 80
8.69 4.76 4.92
48 64 80
8.22 4.92 5.5
60 80 100
2.13 4.27 6.45
60 80 100
4.43 4.91 5.15
60 80 100
4.17 6.05 5.72
48 64 80
1.01 2.33 5.24
48 64 80
4.47 5.66 4.97
48 64 80
4.22 6.21 5.52
Irganox 1035
120 160 200
4.88 1.95 1.73
120 160 200
3.4 5.37 5.05
120 160 200
3.11 5.73 5.61
Tinuvin 326
60 80 100
6.12 2.69 2.12
60 80 100
3.89 5.45 5.07
60 80 100
3.5 5.63 5.56
Tinuvin 328
36 48 60
5.98 3.17 2.28
36 48 60
4.4 5.68 5.05
36 48 60
4.12 6.07 5.59
Irganox 1010
60 80 100
7.01 2.24 0.7
60 80 100
3.82 5.11 5.26
60 80 100
3.61 5.92 5.62
Irganox 1330
60 80 100
6.83 3.78 3.34
60 80 100
4.61 5.19 4.46
60 80 100
4.22 5.84 6.15
Irganox 1076
60 80 100
7.45 5.92 0.8
60 80 100
7.63 6.3 6.55
60 80 100
7.35 5.78 6.85
Irgafos 168
60 80 100
5.29 1.39 0.97
60 80 100
7.35 6.45 6.03
60 80 100
7.81 5.92 6.25
compd
Cyanox 2246
Chimassorb 81
100 μg mL −1 (0.70%), whereas the highest value of reproducibility was obtained for DBP, spiked at 40 μg mL−1 (8.16%). Intra- and interday variations were chosen to determine the stability of the developed assay.17 Intraday stability was validated with three different concentration levels of mixed standard food simulants under the optimized conditions five times within 1 day. Interday precision was validated with the mixed standard solutions used above once a day for 3 days. Inter- and intraday stabilities for the 12 analytes were expressed as RSD (Table 5). As in the case of stability, good results were
Good results were obtained for almost all of the tests (RSD < 5%). The lowest value of RSD was obtained for BHT, spiked at 48 μg mL−1 (0.43%), whereas the highest value was obtained for Irgaonx 1010, spiked at 100 μg mL−1 (4.78%). Reproducibility and Stability. To test the reproducibility of the SPE-HPLC method, three different concentration levels of mixed standard food simulants were analyzed. Variations were expressed as RSD (Table 5). As in the case of reproducibility, good results were obtained for almost all of the tests (RSD < 10%). The lowest value of reproducibility was obtained for Irganox 1010, spiked at 12986
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Table 6. Accuracy of the SPE-HPLC-DAD Analytical Method (n = 3) concn (μg mL−1)
recovery (%)
RSD (%)
compd
concn (μg mL−1)
recovery (%)
RSD (%)
BHA
24 32 40
83.76 91.14 94.53
9.35 5.21 3.79
Tinuvin 326
60 80 100
83.72 92.12 92.45
9.03 5.21 4.82
DBP
24 32 40
88.04 98.51 98.09
6.69 3.88 3.35
Tinuvin 328
36 48 60
81.26 90.19 91.79
9.07 6.1 4.86
BHT
48 64 80
101.64 105.9 108.55
5.55 5.44 5.11
Irganox 1010
60 80 100
81.59 90.86 90.74
9.01 5.66 6.26
60 80 100
101.66 104.49 102.26
5.08 2.76 4.37
Irganox 1330
60 80 100
82.37 91.65 93.35
9.58 5.61 3.89
48 64 80
67.48 71.22 77.24
9.31 5.25 4.37
Irganox 1076
60 80 100
84.42 93.54 94.67
9.76 7.83 5.43
120 160 200
80.74 90.84 92.65
9.29 6.75 6.57
Irgafos 168
60 80 100
68.57 70.65 73.82
9.81 7.85 6.91
compd
Cyanox 2246
Chimassorb 81
Irganox 1035
Table 7. Contents (Micrograms per Gram) of 12 Compounds in Commercial Food Packages no.
BHA
DBP
BHT
Cyanox 2246
Chimassorb 81
Irganox 1035
Tinuvin 326
Tinuvin 328
Irganox 1010
Irganox 1330
Irganox 1076
Irgafox 168
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
nd nd nd nd nd a a nd nd a nd nd nd nd nd nd nd nd nd nd nd nd a nd nd nd nd
nd nd nd nd nd b nd a a a nd nd nd nd nd nd nd nd nd nd nd nd 14.43 nd nd nd nd
nd nd nd nd nd 63.66 195.48 114.18 113.82 706.3 23.46 nd nd a 53.09 27.8 nd nd nd 160.63 61.23 192.68 591.12 516.52 5562.3 625.14 505.65
nd nd nd nd nd nd nd nd nd 20.68 nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd
nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd
nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 2.03 nd nd nd nd nd nd nd nd nd
nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 1.51 nd nd nd nd nd nd nd nd nd
nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd 6.01 nd nd nd nd nd nd nd nd nd
nd 51.22 nd nd 330.44 nd nd nd nd nd nd 96.88 43.56 27.87 nd nd 20.28 nd nd nd nd nd nd nd nd nd nd
nd 7.59 nd nd 47.31 nd nd nd nd nd nd 14.09 6.29 3.96 nd nd 3.08 nd nd nd nd nd nd nd nd nd nd
nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd
nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd nd
a
