Simultaneous Determination of Multi-Class Pesticide Residues and PAHs in Plant Material and Soil Samples Using the Optimized QuEChERS Method and Tandem Mass Spectrometry Analysis

Validation of a modified QuEChERS method for the quantification of residues of currently used pesticides in Cuban agricultural soils, using gas chromatography tandem mass spectrometry

We present an analytical method to detect and quantify residues of currently used pesticides (CUPs), which include 31 active ingredients (ai) and seven transformation products (TPs) in tropical and agricultural soils of Cuba. Ten isotopically labeled analogous compounds served as internal standards (IL-IS). The novelty of this research is the inclusion of different tropical soils type scarcely studied for CUPs and TPs, based on the QuEChERS (quick, easy, cheap, effective, rugged and safe) method, followed by chromatography tandem mass spectrometry. All figures of merit proved to be satisfactory according to SANTE guidelines 2020 and 2021. Matrix effects (ME) calculated by the external standard method were significant (|ME| > 20% for almost all compounds; grand mean ± standard deviation (STD) 104 ± 108%) in all soils. The internal standard method compensated ME to non-significant levels (8 ± 50%), even for analytes with a non-structure identical IL-IS (STD, 13 ± 57%). Repeatability (relative standard deviation, RSDr) and reproducibility (RSDR) for skeletic regosol (SR) were 7.5 ± 2.8% and 11.7 ± 4.7%, respectively. Absolute (quantified for 11 analytes with structure identical IL-IS) and relative recovery from SR was 92 ± 13% (mean ± STD) and 90 ± 12%, respectively. Limits of quantification for SR ranged from 0.1 to 10 ng/g, except metalaxyl and oxyfluorfen (25 ng/g each). Linearity of matrix-matched (MM) calibration curves (5 to 100 ng/g) had an R2 of ≥ 0.99 for all soils and almost all analytes. The method was successfully applied to 30 real soil samples.

Degradation of a mixture of 13 polycyclic aromatic hydrocarbons by commercial effective microorganisms

The study focused on the contribution of effective microorganisms (EM) and their consortia, used in commercial biological preparations and formulations for soil revitalization, to the degradation of a mixture of 13 polycyclic aromatic hydrocarbons (PAHs) commonly found in the soil environment. PAHs, diverse forms of which are present in the environment, never occur individually but always as a part of a chemical mixture. Therefore, the research presented in this article, focusing on the EM impact on the mixture of PAHs, reflects the conditions most similar to natural ones. On Day 35 of the experiment, PAH levels decreased by 75.5-95.5%. The highest PAHs degradation efficiency was achieved for fluorene, with a preparation containing eight bacteria strains from the Bacillus genus: B. coagulans, B. amyloliquefaciens, B. laterosporus, B. licheniformis, B. mucilaginosus, B. megaterium, B. polymyxa, and B. pumilus. All tested preparations containing bacterial consortia and a preparation with the yeast S. cerevisiae intensified the PAHs degradation more effectively than formulations including only the yeast Yarrowia lipolytica or a mixture of Debaryomyces hansenii and Bacillus. The designed and proposed research will contribute to the development of biotechnological methods - bioremediation by microorganisms that are safe for the human and environment health.

Optimizing the QuEChERS method for efficient monitoring of fipronil, thiobencarb, and cartap residues in paddy soils with varying properties

This study aims to optimize the QuEChERS methodology for extracting three pesticides (fipronil, thiobencarb, and cartap) from two paddy soils with distinct characteristics. Various modifications were explored to enhance extraction efficiency, employing acetonitrile (MeCN) or ethyl acetate (EtOAc) for extraction and primary-secondary amine (PSA) and graphitized carbon black (GCB) for the clean-up. Assessment criteria included accuracy, precision, linearity, detection limits, uncertainty, and matrix effects. Results revealed that the clayey soil with lower organic carbon (OC) content (1.26%) and 100% moisture yielded the highest pesticide recoveries (113.72%, 115.73%, and 116.41% for FIP, THIO, and CART, respectively). In contrast, the silty clayey soil with higher OC content (2.91%) and 20% water content exhibited poor recoveries (< 60%). FIP and CART demonstrated better recoveries with MeCN, while THIO performed better with EtOAc under specific moisture conditions. Clean-up sorbents significantly reduced FIP and CART recoveries, with THIO recoveries less affected. Acidifying with HCl substantially improved CART recovery. EtOAc introduced a moderate to strong matrix effect for FIP and THIO, while MeCN in soils with 100% moisture resulted in a strong matrix effect for CART. The study highlighted the substantial impact of extraction conditions, pesticide properties, and soil conditions on the outcomes of the QuEChERS method. A comprehensive understanding of these interplays was deemed crucial for accurately quantifying pesticide residues in agricultural soils.

A Miniaturized Sample Preparation Method for the Determination of Vitamins A and E in Food Products

A new analytical approach to the simultaneous identification and quantification of vitamins A and E in three representative matrices (Parmesan, spinach, and almonds) was developed. The analyses were based on high-performance liquid chromatography with UV-VIS/DAD detection. The procedure was optimized by a significant reduction in the weight of the tested products and quantities of reagents added during the saponification and extraction stages. A full method validation study was performed for retinol at two concentration levels (LOQ and 200 × LOQ), which showed satisfactory results, with recoveries ranging from 98.8 to 110.1%, and an average CV of 8.9%. Linearity was tested in the range of 1-500 µg/mL and showed the coefficient of determination R² = 0.999. The satisfactory recovery and precision parameters were achieved for α-tocopherol (LOQ and 500 × LOQ) in the range of 70.6-143.2%, with a mean CV equal to 6.5%. The observed linearity for this analyte in the concentration range of 1.06-532.0 µg/mL was R² = 0.999. The average extended uncertainties were estimated, using a top-down approach of 15.9% and 17.6% for vitamin E and A, respectively. Finally, the method was successfully applied to determine vitamins in 15 commercial samples.

Analysis of Residues in Environmental Samples

The state of the environment is very important for our lives and for that of future generations [...]

Effect of Three Commercial Formulations Containing Effective Microorganisms (EM) on Diflufenican and Flurochloridone Degradation in Soil

The aim of this study was to determine the influence of effective microorganisms (EM) present in biological formulations improving soil quality on degradation of two herbicides, diflufenican and flurochloridone. Three commercially available formulations containing EM were used: a formulation containing Bifidobacterium, Lactobacillus, Lactococcus, Streptococcus, Bacillus, and Rhodopseudomonas bacteria and the yeast Saccharomyces cerevisiae; a formulation containing Streptomyces, Pseudomonas, Bacillus, Rhodococcus, Cellulomonas, Arthrobacter, Paenibacillusa, and Pseudonocardia bacteria; and a formulation containing eight strains of Bacillus bacteria, B. megaterium, B. amyloliquefaciens, B. pumilus, B. licheniformis, B. coagulans, B. laterosporus, B. mucilaginosus, and B. polymyxa. It was demonstrated that those formulations influenced degradation of herbicides. All studied formulations containing EM reduced the diflufenican degradation level, from 35.5% to 38%, due to an increased acidity of the soil environment and increased durability of that substance at lower pH levels. In the case of flurochloridone, all studied EM formulations increased degradation of that active substance by 19.3% to 31.2% at the most. For control samples, equations describing kinetics of diflufenican and flurochloridone elimination were plotted, and a time of the half-life of these substances in laboratory conditions was calculated, amounting to 25.7 for diflufenican and 22.4 for flurochloridone.

Pesticide-Residue Analysis in Soils by the QuEChERS Method: A Review

Pesticides are among the most important contaminants worldwide due to their wide use, persistence, and toxicity. Their presence in soils is not only important from an environmental point of view, but also for food safety issues, since such residues can migrate from soils to food. However, soils are extremely complex matrices, which present a challenge to any analytical chemist, since the extraction of a wide range of compounds with diverse physicochemical properties, such as pesticides, at trace levels is not an easy task. In this context, the QuEChERS method (standing for quick, easy, cheap, effective, rugged, and safe) has become one of the most green and sustainable alternatives in this field due to its inherent advantages, such as fast sample preparation, the minimal use of hazardous reagents and solvents, simplicity, and low cost. This review is aimed at providing a critical revision of the most relevant modifications of the QuEChERS method (including the extraction and clean-up steps of the method) for pesticide-residue analysis in soils.