Quantification of organophosphate insecticides and herbicides in vegetable samples using the “Quick Easy Cheap Effective Rugged and Safe” (QuEChERS) method and a high-performance liquid chromatography-electrospray ionisation-mass spectrometry (LC-MS/MS) technique

A Quick Easy Cheap Effective Rugged and Safe (QuEchERS) extraction was developed and followed by selective analysis using a liquid chromatography-mass spectrometry method for the quantification of eighteen pesticides in vegetable samples. This method was accurate (?99.5%), and it exhibited limits of detection and quantification values in the 0.006-0.091 and 0.020-0.314 μg kg⁻¹ ranges, respectively. Furthermore, the coefficients of variations (?0.9999) were less than 1% at the low μg kg⁻¹ end of the method. Mean recoveries ranged between 94% and 102%, and relative standard deviations were below 10%. Based on these results, the methodology was proven to be highly efficient, robust, and suitable for monitoring the maximum residue limits (MRL) compliance of a wide range of commodity/pesticide combination. This method was successfully applied to the analysis of vegetable samples that were collected from different government farmers’ markets and street shops in urban areas. The presence of target pesticides was found in the range of 0.016 and 50.85 μg kg⁻¹.     

QuEChERS-超高压液相色谱-串联质谱法同时测定水产品中的6种丁香酚类麻醉剂

建立了同时测定水产品中的丁香酚、异丁香酚、甲基丁香酚、甲基异丁香酚、乙酸丁香酚酯、乙酰基异丁香酚残留量的超高压液相色谱-串联质谱法。样品用乙腈提取,经50 mg乙二胺-N-丙基硅烷、100 mg C₁₈、150 mg Mg SO₄净化,采用Kinetex C₁₈(2.1 mm×100 mm,2.6μm)色谱柱分离,以甲醇-水作为流动相进行梯度洗脱,电喷雾离子源正负快速切换,多反应监测模式检测,内标法定量。丁香酚和异丁香酚的线性范围为2～100 ng/m L,其他4种丁香酚类药物的线性范围为1～100 ng/m L,线性相关系数均不低于0.999。丁香酚类药物检出限(信噪比为3)为0.5～1.5μg/kg,定量限为2.0～5.0μg/kg。6种丁香酚类麻醉剂的方法回收率为67.0%～106.4%,相对标准偏差为1.2%～15.7%。该方法能实现对水产品中丁香酚类麻醉剂的准确、快速检测,测定结果可靠。     

Applications of sample preparation techniques in the analysis of pesticides and PCBs in food

Pesticides and polychlorinated biphenyls (PCBs) are found in various parts of the environment in quite small concentrations, but they accumulate and thus become a threat to human health and life. A review is focused on the application of some popular techniques for sample preparation in analysis of these compounds in food. Even with the emergence of advanced techniques of final analysis, complex matrices, such as food, require extensive sample extraction and purification. Traditional sample preparation techniques are time consuming and require large amount of solvents, which are expensive, generate considerable waste, contaminate the sample and can enrich it for analytes. There have been many sample preparation techniques proposed to meet the requirements connected with the multiplicity of food. Optimal sample preparation can reduce analysis time, sources of error, enhance sensitivity and enable unequivocal identification and quantification. Sample extraction and purification techniques are discussed and their most recent applications in food analysis are provided. This review pointed out that sample preparation is the critical step.     

Evaluation of an analytical methodology using QuEChERS and GC-SQ/MS for the investigation of the level of pesticide residues in Brazilian melons

A multiresidue method based on the sample preparation by modified QuEChERS and detection by gas chromatography coupled to single quadruple mass spectrometers (GC-SQ/MS) was used for the analysis of 35 multiclass pesticides in melons (Cucumis melo inodorus) produced in Ceara-Brazil. The rates of recovery for pesticides studied were satisfactory (except for the etridiazole), ranging from 85% to 117% with a relative standard deviation (RSD) of less than 15%, at concentrations between 0.05 and 0.20 mg kg⁻¹. The limit of quantification (LOQ) for most compounds was below the MRLs established in Brazil. The combined relative uncertainty (Uc) and expanded uncertainty (Ue) was determined using repeatability, recovery and calibration curves data for each pesticide. Analysis of commercial melons samples revealed the presence of pesticides bifenthrin and imazalil at levels below the MRLs established by ANVISA, EU and USEPA.     

Optimisation of octadecyl (C18) sorbent amount in QuEChERS analytical method for the accurate organophosphorus pesticide residues determination in low-fatty baby foods with response surface methodology

Three low-fatty baby food matrices were fortified with 0.01–0.2 mg/kg of phorate, diazinon, chlorpyrifos and methidathion. A “quick, easy, cheap, effective, rugged and safe” – like method (QuEChERS) was used. Quantities of octadecyl (C₁₈) sorbent differed with fortification level and matrix fat, based on central composite experimental design. Quantification was performed by Nitrogen–Phosphorus Detector gas chromatography, using matrix-matched standards. The highest (p < 0.05) recoveries were observed for methidathion, the lowest fortification levels for a specific C₁₈ amount and the lowest C₁₈ amounts. In meals containing vegetables (1.9% fat) and lamb (3.0% fat), 180–210 mg C₁₈ gave recoveries from 67.0% to 105.0% and absence of co-extracts. Yogurt dessert (4.5% fat) required 200–230 mg C₁₈ for similar results. Recoveries could also be predicted with <20% error by a polynomial model. The results suggest that modified QuEChERS could be effectively used in the low-fatty baby meals residue analysis.