Modification of Multiresidue QuEChERS Protocol to Minimize Matrix Effect and Improve Recoveries for Determination of Pesticide Residues in Dried Herbs Followed by GC-MS/MS

Abstract

An accurate, rapid, and reliable multiresidue QuEChERS method based on gas chromatography coupled with tandem mass spectrometry was developed for the determination of 235 pesticides in challenging, dry, complex herb matrices (Centaurea cyanus L., Matricaria chamomilla L., Thymus vulgaris L.). Sample mass and the type of cleanup sorbent used to estimate the procedure's effectiveness were optimized. Purification steps with ChloroFiltr, ENVI-Carb, GCB, octadecyl, PSA, and Z-Sep as cleanup sorbents and a step without purification were compared. To minimize the matrix effect and obtain acceptable recoveries for pesticides, 2 g of herb sample and 10 mL acetonitrile, followed by d-SPE cleanup step with a combination of 150 mg PSA/ 45 mg ENVI-Carb/900 mg MgSO 4 , and additionally 50 μL of 5% formic acid and some droplets of dodecane, were needed. Matrix effects for the vast majority of pesticides were reduced (> 20%), showing suppression or enhancement. Most recoveries were in the range of 70-120% (RSD < 18%), reaching the quantification limit of 0.001 to 0.002 mg kg −1 . There was excellent linearity within the range from 0.001 to 2.00 μg mL −1 , and a correlation coefficient higher than 0.999 was obtained. Expanded measurement uncertainty was estimated to be between 4 and 43%. Finally, the developed method was successfully employed to identify and quantify pesticide residues in the analysis of 46 real herb samples.

Evaluation of the impact of chlorophyll removal techniques on polyphenols in rosemary and thyme by‐products

“…An additional important step for the applicability of plant extracts for preservation purposes is their standardization, as it is important for the active compounds of interest to exist at known and reproducible levels. However, dried herbs constitute an analytical challenge owing to their high content of in matrix co‐extractives such as chlorophyll (Rutkowska, Łozowicka, & Kaczyński, ; Žiaková, Brandšteterová, & Blahová, ) as these compounds may interfere in the liquid chromatography‐mass spectrometry analysis of the targeted analytes (Rutkowska et al, ; Žiaková et al, ) and influence their quantification.…”

The difference in dissipation of clomazone and metazachlor in soil under field and laboratory conditions and their uptake by plants

“…To a large extent, these methods are based on traditional approaches: soxhlet extraction [14][15][16] , solid phase extraction 17,18 , pressurised liquid extraction 19,20 , matrix solid-phase dispersion 21,22 , solid-phase microextraction 23,24 , or dispersive liquid-liquid microextraction 25 . Currently, the QuEChERS procedure 26 is one of the most commonly used analytical methods for the determination of pesticides residues, and frequently this procedure is modified in terms of amounts and types of reagents, as well as available equipment [27][28][29][30] .…”

Determination, residue analysis, risk assessment and processing factors of tebufenozide in okra fruits under field conditions

“…Method validation is used to determine whether the established method is suitable for residual analysis of the target compound . The efficacy of the method was evaluated by the following parameters: linearity, determination coefficient ( R 2 ), matrix effect (ME), LOD, LOQ, accuracy and precision . The linear range of the method was assessed by using the standard solutions and matrix‐matched standard solutions at six concentrations for tebufenozide.…”

“…Intra‐day precision ( n = 5) was determined by comparing the standard deviation of the recovery percentage for spiked samples run on the same day. Inter‐day precision ( n = 15) was measured by analysing spiked samples from three different days …”