Modification and re-validation of the ethyl acetate-based multi-residue method for pesticides in produce

The ethyl acetate-based multi-residue method for determination of pesticide residues in produce has been modified for gas chromatographic (GC) analysis by implementation of dispersive solid-phase extraction (using primary–secondary amine and graphitized carbon black) and large-volume (20 μL) injection. The same extract, before clean-up and after a change of solvent, was also analyzed by liquid chromatography with tandem mass spectrometry (LC–MS–MS). All aspects related to sample preparation were re-assessed with regard to ease and speed of the analysis. The principle of the extraction procedure (solvent, salt) was not changed, to avoid the possibility invalidating data acquired over past decades. The modifications were made with techniques currently commonly applied in routine laboratories, GC–MS and LC–MS–MS, in mind. The modified method enables processing (from homogenization until final extracts for both GC and LC) of 30 samples per eight hours per person. Limits of quantification (LOQs) of 0.01 mg kg⁻¹ were achieved with both GC–MS (full-scan acquisition, 10 mg matrix equivalent injected) and LC–MS–MS (2 mg injected) for most of the pesticides. Validation data for 341 pesticides and degradation products are presented. A compilation of analytical quality-control data for pesticides routinely analyzed by GC–MS (135 compounds) and LC–MS–MS (136 compounds) in over 100 different matrices, obtained over a period of 15 months, are also presented and discussed. At the 0.05 mg kg⁻¹ level acceptable recoveries were obtained for 93% (GC–MS) and 92% (LC–MS–MS) of pesticide–matrix combinations.     

Analysis of heat-induced contaminants (acrylamide, chloropropanols and furan) in carbohydrate-rich food

Heat-induced food contaminants have attracted attention of both the scientific community and the public in recent years. The presence of substances considered possibly or probably carcinogenic to humans has triggered an extensive debate on the healthiness of even staple foods. In that respect, acrylamide, furan and chloropropanols are the main substances of concern. Their widespread occurrence in processed food, which concomitantly causes considerable exposure to humans, led either to the setting of maximum limits (for some chloropropanols) or at least the initiation of monitoring programmes in order to put risk assessment on a solid data basis. Acrylamide, furan and chloropropanols are small molecules with physicochemical properties that make their analysis challenging. Their amount in food ranges typically from below the limit of detection to hundreds of micrograms per kilo or even milligrams per kilo. However, a number of recently published scientific reports deal with the analysis of these substances in different kinds of food. The aim of this publication is to give an overview of analytical approaches for the determination of acrylamide, furan and chloropropanols in foodstuffs.     

在线净化液相色谱串联质谱法测定动物源食品中金刚烷胺的残留

建立了在线净化液相色谱串联质谱法测定动物源食品中金刚烷胺的残留。样品用甲醇-1%三氯乙酸或乙腈提取,提取液用阳离子交换在线净化柱(Cyclone MCX)净化,5%氨水-甲醇溶液将分析物洗脱转入至Capcell Pak MG C18分析柱,经色谱分离后,用串联质谱检测。方法的定量限(LOQ)牛奶为0.25μg/kg,动物组织和鸡蛋为0.5μg/kg,在0.1～20μg/L浓度范围内呈良好线性,线性相关系数大于0.9995。方法在3个水平的添加回收率为83.3%～93.6%,相对标准偏差在3.5%～5.9%之间。方法简单快速,回收率高,重现性好,适用于动物源食品中金刚烷胺残留的定量及确证分析。     

Certification of standard reference materials containing bitter orange

A suite of three dietary supplement standard reference materials (SRMs) containing bitter orange has been developed, and the levels of five alkaloids and caffeine have been measured by multiple analytical methods. Synephrine, octopamine, tyramine, N-methyltyramine, hordenine, total alkaloids, and caffeine were determined by as many as six analytical methods, with measurements performed at the National Institute of Standards and Technology and at two collaborating laboratories. The methods offer substantial independence, with two types of extractions, two separation methods, and four detection methods. Excellent agreement was obtained among the measurements, with data reproducibility for most methods and analytes better than 5% relative standard deviation. The bitter-orange-containing dietary supplement SRMs are intended primarily for use as measurement controls and for use in the development and validation of analytical methods. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Development and Application of an Immobilized Enzyme Electrode for the Determination of Sulfite in Foods and Feeds

Abstract

An enzyme electrode was developed using the enzyme sulfite oxidase (EC 1.8.3.1) immobilized onto pig intestine. All experimental parameters such as pH, temperature, buffer constituent concentration, etc., were thoroughly investigated and optimized when appropriate. Hydrogen peroxide was monitored amperometrically. The response to sulfite concentration was linear in the range of 5.2 × 10^?6 to 1.0×10^?3M. The proposed method was found to have a correlation coefficient of 0.952 when evaluated versus the standard titration method.     

超高效液相色谱-串联质谱法同时测定食品中碱性橙、碱性嫩黄O和碱性桃红T

本文建立了同时测定食品中碱性橙、碱性嫩黄O和碱性桃红的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法.样品经碱化甲醇提取、二氯甲烷萃取、浓缩、酸化甲醇溶解和甲醇饱和正己烷溶液萃取净化后进行测定.本方法检出限分别为碱性橙0.6 μg/kg、碱性嫩黄O 0.3 μg/kg、碱性桃红T 0.7 μg/kg.六种食品样品的回收率为72.1%～91.1%,相对标准偏差(RSD)为2.4%～9.1%(n=6),三种染料在0.01～0.5 μg/mL范围内呈良好的线性关系,线性回归系数r均大于0.9950.