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Showing 2 results for Liquid Chromatography Tandem Mass Spectrometry
M Elmi, S Eskandari, M Amirahmadi,
Volume 18, Issue 1 (3-2023)
Abstract
Background and Objectives: Dithiocarbamates are groups of fungicides used to control pests of agricultural products. Analysis of these pesticides with liquid and gas chromatography instruments is associated with various problems due to the presence of metal groups in the structure of these compounds. Therefore, one of the ways for analysis the pesticides is to check the level of decomposition metabolites of ethylene thiourea and propylene thiourea. The purpose of this study was to establish and validate a method for the analysis of ethylene thiourea and propylene thiourea in grains using liquid chromatography tandem mass spectrometry.
Materials and Methods: Preparation was based on the optimized QuPP-OP method with methanolic extraction in presence of ethylenediaminetetraacetic acid solution without purification steps. To overcome the matrix effect, calibration curve was drawn using analysis of spike samples.
Results: Results showed that the method was linear in the range of 10–400 ng/g and assessment results were accurate and precise. The average recovery proportions and CV% for repeatability were 96.42, 12.1, 97.40 and 13.86% for propylene thiourea and ethylenethiourea, respectively. The LOD and LOQ of the method for the two compounds were 3.3, and 10 ng/g, respectively.
Conclusion: Results showed that the presented assessment method included necessary validity of the analysis of ethylene thiourea and propylene thiourea in cereals.
M Elmi, R Pakzad, M Amirahmadi,
Volume 19, Issue 3 (10-2024)
Abstract
Background and Objectives: Macrocyclic lactones include two groups of common pesticides with a wide anti-parasitic spectrum, which are used to control immature nematodes and arthropods. Due to the potential adverse effects of the residues of these compounds in agricultural products, the aim of this study was to provide a reliable method for the simultaneous analysis of the pesticides in bell peppers as representative of high water content commodity groups using liquid chromatography tandem mass spectrometry.
Materials & Methods: Sample preparation was based on EN 15662 method with minor modifications using acetonitrile extraction in a buffer solution and PSA and GCB adsorbents. To overcome the matrix effect, calibration curves were plotted based on the matrix match approach in presence of the internal standard. Validation of the method included linearity, accuracy and precision studies, as well as calculation of the limits of detection and quantitation.
Results: Results showed that the method was linear in the range of 10–150 ng ml-1 with a correlation coefficient greater than 0.995. In addition, extraction recovery was 75.6–128% and precision of method based on RSD% was 2.8–22.8%. Detection limit of the method (except for Avermectin B1b and Moxidectin) was 3 ng g-1 and the limit of quantification (except for the two pesticides) was 10 ng g-1.
Conclusion: Results showed that the present method included the necessary validity for analyzing the addressed pesticides of macrocyclic lactones.
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