Compare 3 different QuEChERS pre-processing methods
Pesticide is used more during the growth and storage of crops, and the widespread use of pesticides can cause residues in crop products to enter the human body through the food chain, thereby endangering human health. As food safety issues become more prominent, governments and related agencies have developed residue limits for a variety of pesticides on different crops. Among them, the International Tobacco Scientific Research Collaborating Center (CORES-TA) formulated the Guiding Limits (GRLs) for pesticide residues in tobacco in 2003, a total of 99 pesticides; and then revised and expanded in 2008, now contains 118 Kind of pesticide. The increase of pesticide types and the strictness of the limit indicators have proposed five series of standards for the analysis and detection of various pesticide residues in tobacco. The first three are multi-pesticide residue analysis methods, which contain about 160 pesticides. The detection means used mainly include gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The pretreatment method is mostly based on the QuEChERS method, which is characterized by infiltration of the pulverized tobacco sample, extraction with acetonitrile, addition of a salting-out package, centrifugation, and adsorption with N-propyl ethylenediamine (PSA). The agent is purified. Since 2003, QuEChERS and its improved methods have been widely used in the analysis of a variety of pesticide residues in substrates such as vegetables, fruits, grains, tea and tobacco.
In the previous work, we established a solvent conversion method based on the QuEChERS method, combined with GC-MS/MS technology to analyze 132 pesticide residues in tobacco. The recovery rate of most targets is between 70% and 120%. And using this method to detect the tobacco blind samples of CORESTA’s 2012 joint experiment, the results are in good agreement with the results obtained by the existing standard methods, compared with the statistical results of the CORESTA organization for multi-party laboratories, z-score value All meet the requirements.
In 2008, Lee et al. compared liquid-liquid extraction (LLE, different from n-hexane LLE in the text), pressurized liquid extraction (PLE) and QuEChERS three pretreatment methods to detect 49 pesticides in tobacco by GC-MS/MS. The advantages and disadvantages of the time are mainly to examine the matrix effect, recovery rate, precision and limit of quantification. The QuEChERS method is simple and fast, and the recovery rate is good.
Gas chromatography-tandem mass spectrometry (GC-MS/MS) was used as the detection method to improve the solvent based on the QuEChERS method. Three different pretreatment methods were compared in solvent conversion, extract dilution and n-hexane liquid extraction. The applicability of the analysis of hundreds of different types of pesticide residues has certain reference significance for further deepening the analysis of harmful substances in tobacco.