Fast, sensitive and reliable multi-residue method for routine determination of 34 pesticides from various chemical groups in water samples by using dispersive liquid–liquid microextraction coupled with gas chromatography–mass spectrometry

Abstract

A simple and efficient dispersive liquid-liquid microextraction technique (DLLME) was developed by using a mixture of two solvents: 40 μL of tetrachlorethylene (extraction solvent) and 1.0 mL of methanol (disperser solvent), which was rapidly injected with a syringe into 10 mL of water sample. Some important parameters affecting the extraction efficiency, such as type and volume of solvents, water sample volume, extraction time, temperature, pH adjustment and salt addition effect were investigated. Simultaneous determination of 34 commonly used pesticides was performed by using gas chromatography coupled with mass spectrometry (GC-MS). The procedure has been validated in order to obtain the highest efficiency at the lowest concentration levels of analytes to fulfill the requirements of regulations on maximum residue limits. Under the optimum conditions, the linearity range was within 0.0096-100 μg L −1 . The limits of detection (LODs) of the developed DLLME-GC-MS methodology for all investigated pesticides were in the range of 0.0032 (endrin)-0.0174 (diazinon) μg L −1 and limits of quantification (LOQs) from 0.0096 to 0.052 μg L −1 . At lower concentration of 1 μg L −1 for each pesticide, recoveries ranged between 84% (tebufenpyrad) and 108% (deltamethrin) with relative standard deviations (RSDs) (n = 7) from 1.1% (metconazole) to 11% (parathion-mehtyl). This methodology was successfully applied to check contamination of environmental samples. The procedure has proved to be selective, sensitive and precise for the simultaneous determination of various pesticides. The optimized analytical method is very simple and rapid (less than 5 min).

An Overview of Determination of Milk Fat: Development, Quality Control Measures, and Application

“…Efficient routine analysis of milk fat is an important part of dairy production (Zhu et al, 2015). Nowadays, the aim is to develop fast and cost effective analytical methods that enable the identification of components with various physico-chemical properties in a single analytical run (Tankiewicz and Biziuk, 2018). Next, routine analyses are joined with routine implementation of performance-related tests for milk payment purposes under the Czech Republic conditions (Hanuš et al, 1998).…”

Analytical Methodology for Trace Determination of Propoxur and Fenitrothion Pesticide Residues by Decanoic Acid Modified Magnetic Nanoparticles

“…The accuracy and applicability of the proposed method were tested with recovery tests by using various environmental water samples. Samples were prepared by using the methods in literature [37,38]. Briefly, natural samples from river, lake, and pond collected in Sivas, Turkey (Kızılırmak River, Tödürge Lake and 4 Eylül pond) were selected for analysis.…”

Assessment of a Fully Optimized DPX-Based Procedure for the Multiclass Determination of Pesticides in Drinking Water Using High-Performance Liquid Chromatography with Diode Array Detection

“…The Brazilian government has set tolerance levels for pesticides in drinking water using maximum concentration levels (MCLs), which are in the range of parts-per-billion (µg L -1 ). 4 Due to the low levels of the permitted concentrations, the use of analytical instruments with high selectivity and detectability, such as gas chromatography-mass spectrometry (GC-MS), 5 liquid chromatography-tandem mass spectrometry (LC-MS/ MS), 6 ultra-high-performance liquid chromatographytandem mass spectrometry (UHPLC-MS/MS), 7 is often necessary to determine these compounds. However, instrumentation based on MS detectors is expensive and is not available in some laboratories.…”