A QuEChERS extraction followed by GC/MS/MS and GC-μECD/NPD for 216 pesticide and metabolites determination in soil simultaneously were developed and compared. Volume of water, volume and polarity of solvent, and cleanup sorbents (C18, GCB, PSA) were optimized. The QuEChERS with and without purification step were applied to estimate effectiveness of the method. The recovery and matrix effect (ME) were critical parameters within each tested procedure. The optimal method without cleanup was validated. Accuracy (expressed as recovery), precision (expressed as RSD), linearity, LOQ, and uncertainty were determined. The recoveries at the three spiking levels using matrix-matched standards ranged between 65 and 116% with RSD ≤17 and 60–112% with RSD ≤18% for MS/MS and μEC/NP, respectively. The LOQ ranged from 0.005–0.01 mg/kg for MS/MS to 0.05 mg/kg for μEC/NP. The ME for most of pesticides resulted in enhancement of the signal and depended on the analyte and detection system: MS/MS showed ME from −25 to 74%, while μEC/NP from −45 to 96%. A principal component analysis was performed to explain the relationships between physicochemical parameters and ME of 216 pesticides. The QuEChERS protocol without the cleanup step is a promising option to make the method less expensive and faster. This methodology was applied in routine analysis of 263 soil samples in which p,p’ DDT was the most frequently detected (23.5% of samples) and pendimethalin with the highest concentration (1.63 mg/kg).

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 MgSO₄, 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.

In this study two analytical methods, one based on matrix solid phase dispersion (MSPD) and the other on liquid–solid extraction (LSE), coupled with gas chromatography, were evaluated and used to determine the presence of 163 pesticides (6 acaricides, 62 fungicides, 18 herbicides and 77 insecticides) in various herbs. Both methods were optimized considering different parameters (sample to sorbent mass ratio, extracting solvent, sorbents for clean-up step, etc.). The results of these validated sample preparation procedures were compared. Under optimum conditions, the mean recoveries obtained were in the range of 70–119 % for MSPD for most pesticides and 70–118 % for LSE, but with several exceptions. Precision values, expressed as relative standard deviation (RSD), were ≤16 % for MSPD and <18 % for LSE. Correlation coefficients were higher than 0.99254 for both methods. LODs (limits of detection) and LOQs (limits of quantification) for MSPD were within the ranges of 0.003–0.03 and 0.005–0.04 mg/kg, respectively. The data demonstrate that the MSPD method was successfully used for the analysis of 163 pesticides in the following herbs: chamomile (Matricaria chamomilla L.), linden (Tilia), lungwort (Pulmonaria L.), melissa (Melissa L.), peppermint (Mentha piperita L.) and thyme (Thymus vulgaris L.). This paper indicates the potential of MSPD for qualitative and quantitative analysis of pesticide residues. This method was therefore validated at three spiking levels (the first ranging from 0.005 to 0.05 mg/kg, the second from 0.05 to 0.5 mg/kg and the third from 0.25 to 2.5 mg/kg) and applied to real samples (n = 15). MSPD proves to be a simple, fast and very useful multiresidue method and can be recommended for routine pesticide monitoring studies in various herbs.