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In this study, we established a rapid and sensitive HPLC-MS/MS method for quantitative determination of tembotrione and its metabolite AE 1417268 (M5) in corn, corn oil, beef, pork, chicken, and eggs. Both analytes eluted from a C18 column within 6 min. The electrospray ionisation–positive mode was used for tembotrione, whereas the negative mode was used for M5. Acetonitrile was the extractant for all samples, and the addition of 2 g NaCl to each homogenised sample facilitated the extraction of the analytes into acetonitrile. The extracted analytes were further purified by the addition of 50 mg of C18 sorbent (25 mg GCB was also added to corn samples) for subsequent HPLC-MS/MS analysis. Satisfactory calibration-curve linearities (R2 ≥ 0.997) were obtained for the two analytes at concentrations of 1–500 μg/L. Mean recoveries in different matrices ranged from 73.7% to 110.4%, whereas intra-day and inter-day relative standard deviations were <15% for all concentrations of spiked analytes. The limit of quantification was 2 μg/kg for each analyte in all matrices. In food samples obtained from markets, residual tembotrione and M5 were all below the limits of quantification. These results confirm that the method is suitable for the routine monitoring of residual tembotrione and M5 in a variety of food matrices. [ABSTRACT FROM AUTHOR]

A rapid and sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method, in conjunction with multiwalled carbon nanotube purification, was developed to determine the mefentrifluconazole levels in grapes, cucumbers, tomatoes, peppers, wheat, maize, eggs, milk, pork, chicken, and fish. After purification, tandem mass spectrometry of mefentrifluconazole required <3.0 min. Matrix-matched external standard curves were used to quantify the residual mefentrifluconazole. The method meets the requirements of the European Union Document SANTE/11813/2017. Quantification was linear between 5 and 500 μg/kg (R2 ≥ 0.9988), and both the intra- and interday relative standard deviations were ≤13.7%. Analyte recovery ranged from 81.5% to 107.6%. The limit of mefentrifluconazole quantification was 5 μg/kg for all matrices. The method successfully detected and quantified mefentrifluconazole that had been applied to cucumbers and tomatoes grown in a test field. These results imply that the proposed method is effective and reliable for detecting mefentrifluconazole residues in plant- and animal-derived foods. [ABSTRACT FROM AUTHOR]

We have developed a rapid, multi-compound analytical method for measuring residues of the pesticides thiamethoxam and its metabolite, clothianidin; fipronil and its three metabolites, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl; and pyraclostrobin in unprocessed foods (rice, corn, cucumbers, tomatoes, apples, and bananas) by ultra-performance liquid chromatography coupled to tandem mass spectrometry. Acetonitrile was used as the extraction solvent, and an octadecylsilane-dispersive SPE was used to clean up the analytes, which were then separated through a UPLC HSS T3 column connected to a tandem mass spectrometer via an electrospray ionisation source. The linearity of this method for the target analytes was excellent (R2 ≥0.990) in the concentration range of 5–1000 μg kg–1. The average recoveries of the seven compounds at concentrations of 10, 100, and 1000 μg kg–1from six spiked matrix samples ranged from 73.6 to 110.6%, all with RSD values of ≤19.7%. The limit of quantification was 10 μg kg–1. The method validated the effectiveness of the method for routine monitoring the residue of these pesticides and their metabolites in foods. [ABSTRACT FROM PUBLISHER]

The effects of spraying and root irrigation on the uptake and transport of the fungicide difenoconazole under hydroponic and soil cultivation were investigated. Rice was used as the crop for a short-term exposure experiment. A modified QuEChERS pre-treatment combined with ultra-high-performance liquid chromatography–tandem mass spectrometry was used to extract and detect difenoconazole from rice plants, water and soil. The recoveries of difenoconazole were in the range of 72.8–110.5%, with a relative standard deviation of 2.4–19.5% for all the samples when spiked with 0.01, 0.1 and 1 mg kg−1 of difenoconazole, respectively. The limit of quantitation (LOQ) of this method was 0.01 mg kg−1. The exposure results showed that difenoconazole could be absorbed by rice plants and transmitted to different parts of rice plants in all the treatments. In the hydroponic experiment, difenoconazole was mainly distributed in the roots of rice regardless of whether irrigation or spraying was used. For rice cultivated in soil, difenoconazole mainly accumulated in leaves after the root irrigation treatment, whereas after the spraying treatment, the rice roots were the main site of accumulation of difenoconazole. This experiment extends our knowledge of the influence of the cultivation system and application mode on the translocation of difenoconazole in rice plants. [ABSTRACT FROM AUTHOR]

To evaluate the safety of orange consumption induced by mycotoxins, 'Newhall' navel oranges were artificially inoculated with P. expansum and A. tenuissima, followed by an evaluation of the distribution and migration patterns of corresponding mycotoxins (patulin [PAT], tentoxin [Ten], altenuene [ALT], alternariol monomethyl ether [AME], alternariol [AOH] and tenuazonic acid [TeA]) during orange storage and processing. The concentration of mycotoxins decreased as the increase of distance from the lesion, and mycotoxins could be detected throughout the orange when the lesion extended to 8 mm in diameter. AOH and AME pose the primary source of dietary risk with high concentrations and low thresholds of toxicological concern. Orange juice and pectin processing could remove 43.4–98.7% of mycotoxins, while tangerine peelprocessing might lead to significant enrichment of mycotoxins with the processing factors (PFs) of 2.8–3.5. The findings may offer scientific insights into mitigating the dietary risk of mycotoxin exposure from oranges and their derivatives. [ABSTRACT FROM AUTHOR]

A new analytical method using the quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure for simultaneous determination of afidopyropen and its metabolite M440I007 residues in tomato, watermelon, pepper, cucumber, pear, grape, cabbage and soil samples was developed using ultra-high performance liquid chromatography coupled with tandem mass spectrometry. The target compound was determined in less than 5.0 min using an electrospray ionisation source in positive mode (ESI+). The limit of quantification was 1 μg kg−1 in different matrices. Two sorbents primary secondary amine and graphitised carbon black were used in the QuEChERS procedure, and matrix-matched standards gave satisfactory recoveries and relative standard deviation (RSD) values in different matrices at three spiked levels (1, 10 and 500 μg kg−1). For afidopyropen, the recoveries ranged from 83% to 104% with an intra-day relative standard deviation (RSDr) of 1-8%, while they were from 80% to 103% with RSDr of 2-8% for M440I007. Reproducibility ranged between 1% and 19% for the three spiked levels. [ABSTRACT FROM AUTHOR]

The matrix effect in complex spices and herbs presents a great challenge to the simultaneous, rapid, quantitative analysis of multiple pesticides by mass spectrometry. The aim of this work was to develop and validate an effective UPLC–MS/MS multi-residue method for the analysis of pesticide residues to reduce matrix effects in four spices and one herb and infer which component caused the matrix effect in black pepper. In this paper, we highlight the importance of reducing matrix effects. SPE and dilution factors combined with d-SPE were two approaches to reduce matrix effects compared with d-SPE, and dilution (5-fold) combined with d-SPE was more effective than SPE in reducing matrix effects. With the validated d-SPE method combined with dilution (5-fold), 22 pesticides showed satisfactory recovery (77 to 114%) and RSDs (1.4%–19.1%) at three spiked concentrations in dried chilli pepper, star anise, mint, and cinnamon skin, but not in black pepper. Compared to the other three spices and one herb, black pepper appeared to have a stronger matrix effect. D-SPE method combined with dilution (5-fold) was not suitable for black pepper and required more efficient purification methods and higher dilution factors. With the validated SPE method combined with 10-fold dilution, 19 pesticides showed satisfactory recovery (71% to 113%) and RSDs (2.1%–18.2%) at three spiked concentrations in black pepper. We ascertained that piperine was the component contributing most to the matrix effect in black pepper. The method was used to monitor 15 market samples. [ABSTRACT FROM AUTHOR]