Study on the determination of pesticide residues in crops by ion-trap GC/MS/MS

Ion-trap GC/MS/MS was evaluated for the multi-residue determination of pesticides in agricultural products. Matrices were extracted from samples (spinach, carrot, onion and brown rice) with acetone and submitted to gel permeation chromatography, followed by a clean-up step through a graphite carbon cartridge. Thirty-five pesticides were added to either matrix, and analyzed by GC/MS/MS. Detection limits of pesticides by GC/MS/MS was almost the same as those by GC/MS (SIM). Coefficients of variation of peak area in 5 measurements of each pesticide at 0.1 microgram/mL or 0.05 microgram/mL with or without matrices were mostly acceptable, though those of 20 pesticides out of 35 were higher than 10% at a concentration of 0.02 microgram/mL. It was indicated that matrix artifacts, which interfere with GC/MS-Scan analysis, could be eliminated in some cases by using GC/MS/MS.     

Determination of low-level pesticide residues in agricultural products by ion-trap GC/MS/MS

The objective of this study was to elucidate the utility of ion-trap GC/MS/MS for the analysis of pesticides in extracted matrices from various agricultural products. Identification and quantitative analysis of pesticides in matrices were performed by quadrupole GC/MS and ion-trap GC/MS/MS. Chlorpyrifos was added to the matrix of spinach, soybean in the pod or corn, and aldrin, dieldrin, endrin, alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, p,p'-DDD, p,p'-DDE, o,p'-DDT and p,p'-DDT were added to each matrix of green tea, black tea or oolong tea. Although most of the pesticides in the matrix could not be determined by quadrupole GC/MS-Scan analysis at 0.1 microgram/mL, every pesticide was identified from the mass spectrum using ion-trap GC/MS/MS at the same concentration. The quantitation limit of every pesticide in each matrix by ion-trap GC/MS/MS analysis was higher than that by GC/MS-SIM analysis. The calibration curves obtained by GC/MS/MS were linear in the range of 0.01-0.25 microgram/mL of each pesticide. The recoveries of each pesticide from four kinds of samples spiked at the levels of 0.01 ppm to 0.02 ppm in extracts were 61.2-138.3% with SD values in the range from 1.2 to 15.4%. This study revealed that ion-trap GC/MS/MS was useful for the identification and quantitative analysis of low-level pesticides residues in matrices of agricultural products.     

气相色谱法测定皮革中的戊二醛含量

采用气相色谱法测定皮革中的戊二醛含量,研究萃取条件、测试条件对检测结果的影响,优化检测条件和仪器分析条件,研究检测方法的枪出限、回收率等.实验结果表明:戊二醛的回收率在82％以上.GC/MS方法检出限为4.0 mg/kg,GC-FID方法检出限为25 mg/kg,GC/MS法的检出限远远低于GC-FID.     

Improved test for the migration of antimony and germanium from polyethylene terephthalate

A simple and rapid test has been developed to quantitatively measure the migration of antimony (Sb) and germanium (Ge) from polyethylene terephthalate (PET) products. The PET product was soaked in 4% acetic acid (2 mL/cm2) for 30 min at 60 degrees C and 95 degrees C. The test solution was analyzed by ICP-MS. Recoveries of spiked Sb (0.025 microg/mL) and Ge (0.05 microg/mL) were 101% and 100%, respectively, with relative standard deviations (RSDs) of 2.3% and 1.7%. In ten successive analyses, Sb and Ge in the 4% acetic acid solution were analyzed with RSDs of 1.7% and 2.2%. Sb and Ge were not subject to interference from other elements simultaneously present in the 4% acetic acid solution. This method is simple, rapid and safe, requiring no pretreatment or use of the hazardous solvent carbon tetrachloride. Therefore, this test is a useful method to analyze Sb and Ge migration from PET products.     

1,4-hydroxycarbonyl products of the OH radical initiated reactions of C5-C8 n-alkanes in the presence of NO

Alkanes account for approximately 50% of nonmethane organic compounds present in urban atmospheres. Previous studies have shown that hydroxycarbonyls are important products ofthe OH radical initiated reactions of > or = C5 n-alkanes, but isomer-specific identifications and quantifications of these products have not been carried out. In this work, we have used solid-phase microextraction fibers precoated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine for on-fiber derivatization of carbonyl-containing compounds with subsequent analyses by combined gas chromatography-mass spectrometry (GC-MS) and GC with flame ionization detection (GC-FID). GC-MS analyses showed the presence of the oximes of 5-hydroxy-2-pentanone and 4-hydroxypentanal from the n-pentane reaction; 5-hydroxy-2-hexanone, 6-hydroxy-3-hexanone, and 4-hydroxyhexanal from the n-hexane reaction; 5-hydroxy-2-heptanone, 6-hydroxy-3-heptanone, 1-hydroxy-4-heptanone, and 4-hydroxyheptanal from the n-heptane reaction; and 5-hydroxy-2-octanone, 6-hydroxy-3-octanone, 7-hydroxy-4-octanone, and 4-hydroxyoctanal from the n-octane reaction. The formation yields of these 1,4-hydroxycarbonyls were determined from GC-FID analyses. By use of the yields of 1,4-hydroxycarbonyls formed from n-hexane, n-heptane, and n-octane at 50% relative humidity (and those from n-pentane at both 5 and 50% relative humidity), then formation of 1,4-hydroxycarbonyls accounts for 54% of the reaction products from n-pentane, 57% from n-hexane, 51% from n-heptane, and 53% from n-octane. Combined with previously measured yields of carbonyls, alkyl nitrates, and hydroxyalkyl nitrates, we can now accountfor approximately 74-118% of the products formed from the n-pentane through n-octane reactions.     

Identification of chemical detected in kiwi fruit during analysis for residual pesticide

An unknown peak was detected in a GC chromatogram of many kiwi fruit extracts during analysis for pesticide residues. It was identified by GC/MS as diphenyl 2-ethylhexyl phosphate (DPEHP), used as a plasticizer and flame retardant. The concentration of DPEHP was investigated in 15 samples of kiwi fruit, and it was detected at between 0.02 and 0.14 microgram/g in 10 of the samples. It might be due to migration of DPEHP into the fruit from the printed portion of the polyethylene terephthalate (PET) package.     

Testing the influence of various conditions on the migration of epoxidised soybean oil from polyvinylchloride gaskets

Epoxidised soybean oil (ESBO) is widely used as a plasticiser and stabiliser mainly in food contact materials on the base of polyvinylchloride (PVC), especially in the gaskets of jar lids. PVC gaskets containing 10–37% of ESBO were prepared by the baking of PVC plastisols at various process temperatures (180–240°C) in the laboratory. ESBO migration into olive oil and 3% acetic acid was studied at various temperatures (4°C, 25°C, 40°C and 60°C) during a storage time up to 12 months. ESBO released into food simulants was transmethylated, derivatised and analysed by gas chromatography-mass spectrometry (GC/MS). The effect of food processing, i.e. pasteurisation (80°C and 100°C) and sterilisation (125°C) on ESBO migration was also evaluated. The results were critically assessed with respect to the test conditions of specific migration in accordance with the current European Union legislation (Regulation (EU) No. 10/2011). The levels of ESBO migration found confirmed that the test conditions (i.e. 40°C or 60°C, 10 days) representing contact in the worst foreseeable use scenario seem to be insufficient for the simulation of ESBO migration during long-term storage and thus do not provide satisfactory objective results.     

Determination of polyadipates migrating from lid gaskets of glass jars. Hydrolysis to adipic acid and measurement by LC–MS/MS

Polyadipate plasticizers can be present in the polyvinylchloride (PVC) gaskets used to seal the lids of glass jars. As the gaskets can come into direct contact with the foodstuffs inside the jar, the potential exists for polyadipate migration into the food. The procedure and performance characteristics of a test method for the analysis of polyadipates in food simulants (3% aqueous acetic acid and 10% aqueous ethanol) and the volatile test media used in substitute fat tests (isooctane and 95% aqueous ethanol) are described. The PVC gaskets were exposed to the food simulants or their substitutes under standard test conditions. Studies were initially carried out using direct measurement of the polyadipate oligomers by liquid chromatography with time-of-flight mass spectrometric detection (LC-TOF-MS) but this was not practical due to the number of peaks detected. Instead, the migrating polyadipates were hydrolysed to adipic acid and measured by liquid chromatography with tandem mass spectrometric detection (LC–MS/MS). The amount of polyadipate that this measurement of adipic acid represents was then calculated. Method performance was assessed by analysis of gaskets from two types of jar lids by single-laboratory validation. Linearity, sensitivity, repeatability, intermediate reproducibility and recovery were determined to be suitable for checking compliance with the 30 mg/kg specific migration limits for polyesters of 1,2-propane diol and/or 1,3- and/or 1,4-butanediol and/or polypropylene-glycol with adipic acid, which may be end-capped with acetic acid or fatty acids C₁₂–C₁₈ or n-octanol and/or n-decanol. The method was found to be much quicker than previous methods involving extraction, clean-up, hydrolysis, esterification, derivatisation and GC measurement, consequently saving time and money.     

Residual chemicals in silicone rubber products for food contact use]

The residues of additives and other chemicals in 23 kinds of silicone rubber products for food contact use, including nipples, packing and spatulas, were investigated by GC/MS. The packing and spatulas contained 80-480 micrograms/g of BHT, 60-5,830 micrograms/g of di(2-ethylhexyl) phthalate (DEHP), and 60-80 micrograms/g of dibutyl phthalate, while the nipples contained no additives. All of the samples contained 15 to 20 peaks of polydimethylcyclosiloxanes. Dodecamethylcyclohexasiloxane (D6) to tetratriacomethylcycloheptadecasiloxane (D17) were confirmed, and other larger siloxanes up to pentacontamethylcyclopentacosasiloxane (D25) were estimated. A rough estimate of the total cyclosiloxane content was 3,310-14,690 micrograms/g. They might be mainly unreacted materials or by-products, and some of them might be additives. Based on the migration test, no chemicals were released into 20% ethanol at 60 degrees C for 30 min, though DEHP and the polydimethylcyclosiloxanes were released into n-heptane at 25 degrees C for 60 min.     

Identification of organic contaminants in disposable aluminium foil containers

A series of disposable aluminium foil containers designed for cooking and packaging foods and available on the Italian market were investigated. Using different analytical techniques (near infrared (NIR), High Resolution Gas Chromatography (HRGC), gas chromatography/mass spectrometry (GC/MS)), organic substances used as lubricants in the manufacturing of the containers were detected on the aluminium layer in contact with the food. These contaminants were not mineral hydrocarbon fractions used for the shaping of can lids and bodies, but had an organic structure identifiable as esters derived by synthesis between fatty acids C8 and C10 with glycerine, and between C16 and C18 with butyl alcohol. Mixtures of higher esters were also identified as contaminants. Twelve samples were analysed, and the total amount of contaminant substances was found to range from 900 to 1200 µg dm^-2. It is recommended, for safety and compliance with European Community (EC) Regulation No. 1935/2004 (27 October 2004), that the use of aluminium foil containers be subject to appropriate regulation concerning substances adopted for technological purposes.     

Determination and Confirmation of Chloramphenicol Residues in Swine Muscle and Liver

ABSTRACT: Average high-performance liquid chromatography (HPLC) recoveries of chloramphenicol (CAP) in swine muscle and liver ranged from 91.3 to 94.2% and 93.1 to 103.7%, respectively, with coefficients of variation ranging from 1.4 to 4.3% and 1.1 to 11.2% for each tissue sample. The method described was repeatable and reproducible in swine muscle and liver, with a limit of quantification of 15 ng/mL and a limit of detection estimated at 5 ng/mL. The limit of identification of CAP was 25 ng/mL, 5ng/mL, and 20 ng/mL for HPLC/PDA, GC/MS selected ion monitoring (SIM), and LC/MS analysis, respectively.     

Determination of lipoic acid in meat of commercial quality.

For the quantitative determination of lipoic acid in meat a sensitive GC/MS method in the chemical ionisation mode with methane as reactant gas has been developed. Firstly, the cleavage of protein-bound lipoic acid from the epsilon-amino group of lysine residues was optimized by hydrolysing the synthesized model compound epsilon-lipoyllysine with several organic and inorganic acids and proteolytic enzymes. The concentrations of lipoyllysine and lipoic acid during this test hydrolysis were monitored by HPLC. Optimum hydrolytic conditions were heating at 120 degrees C in 2 mol H2SO4 for seven hours. After tissue hydrolysis, the lipoic acid in the hydrolysate was separated by a diethylether/sodium bicarbonate/diethylether extraction and then derivatised for GC with MBDSTFA. The highest amounts of lipoic acid in meat of commercial quality were detected in liver, heart and kidney whereas in muscle tissues its content was lower.     

铝塑复合食品包装中的铝向食品模拟物的迁移研究

建立了基于电感耦合等离子体质谱法（ICP-MS）,铝塑复合食品包装中的铝向食品模拟物迁移量的测定方法。采用两种食品模拟物（3%（w/v）乙酸、水）,利用迁移机使食品模拟物与铝塑食品包装材料单面接触,在温度27±2、45、70℃下进行迁移实验,采用电感耦合等离子体质谱仪对食品模拟物中的铝元素进行测定,得出迁移规律。随着迁移时间的延长,铝的最大迁移量都在增加;在实验温度区间,随着温度的升高,铝的迁移量也随之增加至迁移平衡。本方法适合用于铝塑复合食品包装中的铝向3%（w/v）乙酸溶液和蒸馏水两种食品模拟物迁移后的检测。      

Residual chemicals in natural rubber products for food contact use

The residues of additives and other chemicals were investigated by GC/MS in natural rubber products for food contact, which included nipples, packing, gloves and a net for ham. The packings and gloves contained 980-6,570 micrograms/g of vulcanization accelerators, such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate (EZ), zinc di-n-buthyldithiocarbamate (BZ) and 2-mercaptobenzothiazole. Some samples contained BHT, Irganox 1076 and Yoshinox 2246R as antioxidants; dibutyl phthalate and di(2-ethylhexyl) phthalate as plasticizers; and palmitic acid, stearic acid, palmitamide, stearamide and hydrocarbons as lubricants. Two unknown peaks were identified as stigmasterol and beta-sitosterol, and others were estimated to be fucosterol, oryzanol and alpha-sitosterol. These sterols are widely distributed in plants, so their origin was presumed to be the rubber plants. The sterols were detected at a level of 340-2,940 micrograms/g in all natural rubber samples. A migration test was carried out for some samples. No chemicals were released into water, 4% acetic acid or 20% ethanol at 60 degrees C for 30 min, though BHT, Yoshinox 2246R, EZ, BZ and sterols were released into n-heptane at 25 degrees C for 60 min.     

气质联用法测定空心胶囊中的邻苯二甲酸酯

采用改进的液-液萃取提取方法:样品在室温下超纯水中浸泡膨胀软化后在50℃水浴直至溶解;加乙醚萃取,于蒸发皿中将乙醚萃取层水浴蒸干;残渣用正己烷转移并定容至1.00mL,微孔膜过滤,结合气相色谱-质谱(GC-MS)联用分析技术,检测空心胶囊中邻苯二甲酸酯类化合物的含量。该方法线性相关系数>0.997,检出限为0.50 mg/L~5.88 mg/L之间;在0.5 mg/L和4.0 mg/L添加水平时样品加标回收率为72.52%~106.37%,RSD(n=6)为2.25%~8.8%。并运用该方法对市售的空心胶囊进行了检测,结果表明,在25批空心胶囊样品中,有4批空心胶囊检测含有邻苯二甲酸二异丁酯(DIBP)和邻苯二甲酸二丁酯(DBP),它们的含量范围分别是1.40 mg/kg~2.63 mg/kg和1.24 mg/kg~1.62 mg/kg;1批空心胶囊中检出含有DIBP,含量是1.85 mg/kg。该方法灵敏度高,操作简便、准确,效率高,适用于快速测定空心胶囊中邻苯二甲酸酯类物质的含量。     

食品接触用硅橡胶中3种环硅氧烷的测定及迁移规律

采用溶剂提取-气相质谱联用法(Solvent extraction-gas chromatography/mass spectrometry,solvent extraction-GC/MS)测定食品接触用硅橡胶中八甲基环四硅氧烷(Octamethylcyclotetrasiloxane,D4)、十甲基环五硅氧烷(Decamethylcyclopentasiloxane,D5)和十二甲基环六硅氧烷(Dodecamethylcyclohexasiloxane,D6)等3种环硅氧烷的含量,并研究硅橡胶烤盘中D4~D6向油性食品模拟物中的迁移规律。采用衰减全反射-傅里叶变换红外光谱(Attenuated total reflectance-Fourier transform infrared spectroscopy,ATR-FTIR)分析方法确定硅橡胶的材质,以优化的提取溶剂正己烷和超声提取时间30 min,通过GC/MS检测3种不同用途的9个硅橡胶品牌产品中D4~D6的含量。以其中一种硅橡胶烤盘进行单面迁移试验。结果表明:D4~D6在0.5~20.0 μg/mL质量浓度范围内线性良好,决定系数R²大于0.9961,且D4~D6的检出限均小于为11.2 ng/mL,定量限均小于37.2 ng/mL。通过加标验证,D4~D6的平均回收率为85.20%~98.12%,相对偏差RSD为2.17%~4.27%(n=6)。硅橡胶奶嘴和高压锅密封圈中D4~D6含量较少,而硅橡胶烤盘中含量最多,其D4~D6的均值分别为175.08、824.12和901.17 mg/kg。通过迁移试验,发现硅橡胶烤盘在60 ℃油性食品模拟物95%乙醇中达到迁移平衡时,D4~D6的迁移率分别为71.36%、57.03%和49.31%。这表明D4~D6会迁移到油性食品中,且分子量较小的D4更易迁出,其安全性不可忽视。     

The potential of different techniques for volatile compounds analysis coupled with PCA for the detection of the adulteration of olive oil with hazelnut oil

This paper investigates the effectiveness of three rapid methods of volatile compounds analysis with subsequent principal component analysis (PCA) treatment of data for differentiation between virgin olive oil samples adulterated with hazelnut oil. Tested methods included comparison of chromatograms of volatiles obtained using SPME-fast GC-FID, volatiles analysis by electronic nose based on MOS sensors (HS-Enose), and by direct coupling of SPME to MS (SPME-MS). Volatile compounds were analyzed also by SPME-GC/MS technique. Data obtained as a result of SPME-GC/MS was subjected to PCA. SPME-GC–MS analysis with subsequent PCA yielded good results, however being time consuming. The three methods of analysis of volatiles, with subsequent PCA treatment of data, allowed detection of olive oil adulteration with different contents of hazelnut oil ranging from 5 to 50% (v/v).     

Analysis of imazalil and its major metabolite in citrus fruits by GC-FTD

A simplified simultaneous analytical method of imazalil (IZ) and its major metabolite, alpha-(2,4-dichlorophenyl)-1H-imidazole-1-ethanol (IZM), in citrus fruits was developed, and commodities samples were investigated. A homogenate of citrus fruits was extracted with ethyl acetate under basic conditions. The crude extract was partitioned between 0.025 mol/L of sulfuric acid and ethyl acetate. The analytes were extracted from the aqueous fraction under basic conditions with ethyl acetate. The extract solution was purified with an ENVI-Carb cartridge, and then analyzed by GC-FTD and GC/MS. Recoveries of IZ and IZM added to grapefruit at the level of 0.05 microgram/g were 90.0 and 108.7%, and those in the case of lemon were 100.4 and 93.0%, respectively. The detection limits were 0.01 microgram/g in samples. By this method, IZ and IZM were analyzed in 46 citrus fruits on the market and were detected simultaneously in some samples.     

Improved method for determining bisphenol A in polycarbonate products without using dichloromethane

An improved method for determination of bisphenol A (BPA), phenol (PH), p-tert-butylphenol (PTBP) and diphenylcarbonate (DPC) in polycarbonate products was developed without using the hazardous solvent dichloromethane. Polycarbonate samples were ground to powder or cut into small pieces, and 0.5 g was soaked in 5 mL of acetonitrile for 24 hours at 40 degrees C. The test solution was then filtered and subjected to HPLC analysis. The proposed method was evaluated by comparison of the results with those of the standard method for 14 polycarbonate products. Extraction ratios (average values obtained by the present method/average values obtained by the standard method) of BPA, PH, PTBP and DPC were 0.89-1.19, 0.89-1.14, 0.94-1.30 and 1.08-1.11, respectively. While 120 mL/sample of organic solvent is required in the standard method, only 5 mL/sample of acetonitrile was used in our new method.     

Determination of captafol,cyhexatin, 1-naphthylacetic acid and quintozene in apple,Japanese pear and melon by simultaneous extraction

A simple and rapid method is described for the determination of the non-registered pesticides, captafol, quintozene (PCNB), cyhexatin and 1-naphthylacetic acid (NAA), in fruits. These pesticides were extracted with acidified acetone, then captafol and PCNB were purified with a Florisil mini column and analyzed by GC-ECD. Cyhexatin was ethylated with ethylmagnesium bromide, and the ethyl derivative was analyzed by GC-FPD (Sn filter). NAA was purified with liquid-liquid extraction and determined by HPLC equipped with a fluorescence detector. These analytes were identified with GC/MS or LC/MS. The minimum identified concentration of the pesticides was below 0.2 ng per injection, which corresponds to a detection limit of below 0.02 microgram/g in the original samples. Recoveries of the pesticides spiked at 0.1 microgram/g into apple, Japanese pear and melon were greater than 61%.