Residue dynamic of pyrimorph on tomatoes, cucumbers and soil under greenhouse trails

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.

Simultaneous determination of pesticides from soils: a comparison between QuEChERS extraction and Dutch mini-Luke extraction methods

The expanding nature of the agricultural sector has fuelled the intensification of plant protection products usage, including pesticides. These pesticides may persist in soils, necessitating their accurate determination in a variety of soil types. However, due to their complex nature, the effective extraction of pesticide residues from soil matrices can present challenges to pesticide detection and quantification. This research compared two well-known extraction methods, QuEChERS and Dutch mini-Luke, by assessing their specificity, sensitivity, accuracy, precision and reproducibility in extracting seven distinct pesticides with a range of chemico-physical characteristics from Irish soils. The HPLC-UV conditions were optimised to separate the seven pesticides, and it was shown that both extraction methods successfully extracted neonicotinoids with recovery values ranging between 85 and 115%. Fluroxypyr and prothioconazole could not be efficiently extracted using QuEChERS, however, the recovery values of both the analytes ranged between 59 and 117% using Dutch mini-Luke. Furthermore, with the exception of prothioconazole using Dutch mini-Luke, both extraction methods resulted in reproducibility and precision values below or equal to 20%. Lastly, Dutch mini-Luke is noted to have a lower matrix effect than QuEChERS, except for prothioconazole. The comparison results showed that Dutch mini-Luke resulted in superior method sensitivity, better recovery, and lower matrix effect towards most investigated analytes and was the only extraction technique that successfully extracted all pesticides analysed in soil matrices.

Method Development and Determination of Chlorinated Polycyclic Aromatic Hydrocarbons in Different Matrices

The aim of this study was to develop an analytical method, which separates selected chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) from fat, and fat-free or vegetable matrices. The method contains extraction-, cleanup-, and quantification steps. Integration of automated analysis actions, as in extraction and cleanup, should enhance the reproducibility, precision, and efficiency of the method. This was confirmed by validation of the overall analytical process. In the end, as a performance check, the developed method was applied on different matrices, e.g., tea, rice, grilled pork, and eel and predator eggs, as a non-food example. An inter-laboratory check was initiated as replacement for the lack of proficiency tests. Due to the high level of automation, both personnel and time effort are very low. In addition, the method is very robust with regard to the variability of the solvent selection and the loss of analytes by evaporation to dryness. It could be demonstrated that the developed method is applicable to different matrices with reproducible and precise results. This applies also to low-fat food and feed.

Improved analysis of propamocarb and cymoxanil for the investigation of residue behavior in two vegetables with different cultivation conditions

BACKGROUND

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was developed for the simultaneous determination of highly water-soluble propamocarb and hydrophobic cymoxanil in potato tuber and tomato fruit. Residue behaviors of the fungicides in open field or greenhouse were investigated for the safety evaluation of these two pesticides, and the effects of cultivation conditions, fungicide exposure and fruit size of tomato on residue level are discussed.

RESULTS

Vegetable samples were extracted with ammonia-acetonitrile, further purified with multiwall carbon nanotubes and analyzed using high-performance liquid chromatography tandem mass spectrometry. The method was validated with fortified samples at different concentration levels (0.05-2.0 mg kg^-1 ). Average recoveries ranged from 84 to 111% with relative standard deviations between 0.3 and 5.5%. Limits of quantification (LOQs) were set at the lowest spiking level of 0.05 mg kg^-1 . In tomato and cherry tomato, initial residue level of cymoxanil was below LOQ at recommended good agricultural practices. Propamocarb residues were affected by the cultivation conditions, with highest levels of 0.52 and 0.72 mg kg^-1 in open field and greenhouse, respectively. In addition, residues of propamocarb in cherry tomatoes were found to be present at 1.25 mg kg^-1 .

CONCLUSIONS

The field trial results showed that propamocarb and cymoxanil residues in potato tubers were below LOQ due to the tubers not being exposed to sprayed pesticides. The unexpected high residue levels in cherry tomato seem to indicate that cherry tomato with small size presents certain accumulative effects of propamocarb. © 2020 Society of Chemical Industry.

Polycyclic aromatic hydrocarbons in edible oils and fatty foods: Occurrence, formation, analysis, change and control

Numerous studies have demonstrated that dozens of polycyclic aromatic hydrocarbons (PAHs) are mutagenic, genotoxic and strongly carcinogenic. PAHs are found to be widely present in foods contaminated through multiple paths. Due to their lipophilic nature, these compounds easily accumulate in edible oils and fatty foods where they can range from no detection to over 2000μg/kg. Compared to precursor PAHs, researchers have seldom studied the presence of PAH derivatives, especially in food matrices. This chapter includes the physical and chemical characteristics of PAHs and their types, occurrence, sample pretreatment and instrumental determination methods, and their formation, change and control in edible oils and fatty foods. The occurrence and formation of PAH derivatives in foods are much less investigated compared to those of their precursor PAHs. Although the removal of matrix effects and accuracy remain difficult for current rapid determination methods, a prospective research direction of PAH analysis for large-scale screening is in demand. To date, physical absorption, chemical oxidation and biodegradation have been widely used in PAH removal techniques. Specific types of bacteria, fungi, and algae have also been used to degrade PAHs into harmless compounds. However, most of them can only degrade a range of LPAHs, such as naphthalene, anthracene and phenanthrene. Their ability to degrade HPAHs requires further study. Moreover, it is still a great challenge to maintain food nutrition and flavor during the PAH removal process using these methods.

Insecticide residues in head lettuce, cabbage, Chinese cabbage, and broccoli grown in fields

The residues of four insecticides belonging to different families were studied on head lettuce (Lactuca sativa L. var. capitata L.), cabbage (Brassica oleracea Linn. var. capitata DC.), Chinese cabbage (Brassica pekinensis Skeels), and broccoli (Brassica oleracea var. italica) after pesticide application. To reduce application variability, a tank mix of acetamiprid 20% SP, chlorpyrifos 22.5% EC, deltamethrin 2.4% SC, and methomyl 40% SP was applied at recommended and double doses. Initial deposits of all pesticides on head lettuce were higher than those of the other three crops. The residues of chlorpyrifos and deltamethrin were higher than the maximum residue limits (MRLs) at recommended preharvest intervals (PHIs) on head lettuce and Chinese broccoli treated with higher doses. The residues of methomyl on head lettuce also showed the same phenomenon.

Dissipation and residues of rimsulfuron in potato and soil under field conditions

The analytical method for the residue analysis of a sulfonylurea herbicide, rimsulfuron, and its dissipation in soil and potato plants under field conditions were studied. Rimsulfuron residues were determined by Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method and ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Mean recoveries ranged from 74.6 % to 106.2 % with relative standard deviations (RSDs) of 2.0 %-13.8 % at three different spiking levels for each different matrix. The limits of detection (LOD) of rimsulfuron were ranged from 0.3 to 1.4 μg/kg, while the limits of quantification (LOQ) ranged from 0.9 to 4.3 μg/kg in different matrixes. The dissipation dynamics of rimsulfuron in the field trials in Shandong and Zhejiang Province were investigated. The half-lives in potato seedlings were 4.1 days in Shandong and 4.3 days in Zhejiang, both with a dissipation rate of 90 % about 7 days after application. The half-lives in soil were 6.0 days in Shandong and 6.6 days in Zhejiang, and with a dissipation rate of 90 % over 28 days. The terminal residues in potato and soil were not detectable. The fact that all the terminal residues were below the maximum residue level (0.1 mg/kg) set by Japan and 0.05 mg/kg set by EU. Hence it was safe for the use of this pesticide and the results also could give a reference for maximum residue limits setting of rimsulfuron in potato in China.

Residues and dynamics of kasugamycin in chilli and soil

A simple and efficient method for determination of kasugamycin in chilli and soil was developed, and the fate of kasugamycin in chilli field ecosystem was also studied. Kasugamycin residues were extracted from sample, cleaned up by solid phase extraction and chromatographic column and then determined by ultra performance liquid chromatography with tandem mass spectrometry detection. The method got recoveries ranged from 77.82% to 83.35% with relative standard deviations of 2.20%-6.54%. As far as the accuracy and precision was concerned, the method met certain standard. The LODs of kasugamycin calculated as a sample concentration (S/N ratio of 3) was 2.50 μg kg(-1). The degradation of kasugamycin in chilli and soil was determined. The results showed that kasugamycin degradation in chilli plant and soil followed the first-order kinetics. The half-lives of kasugamycin in chilli and soil was 2.76-3.77 and 3.07-3.91 days, respectively. The final kasugamycin residues in chilli and soil were undetectable at levels of recommended and 1.5 times recommended dosage with an interval of 21 days.