A modified QuEChERS/GC–MS for simultaneous determination of 16 pesticide adjuvant residues in fruits and vegetables

Determination of hexachlorophene residue in fruits and vegetables by ultra-high performance liquid chromatography-tandem mass spectrometry

A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) -LC-MS/MS method was developed for the determination of hexachlorophene in fruits and vegetables. Samples were extracted by acetonitrile and then salted with an acetate buffer system. Extractants neutral alumina (Al-N), strong cation exchange silica gel bonded adsorbent (SCX) and graphitized carbon black (GCB) were used for sample purification. The method demonstrates excellent accuracy and reproducibility. Under optimized conditions, the correlation coefficients of hexachlorophene were higher than 0.995 in the range of 0.5-20 ng/mL. The limit of quantification (LOQ) was 2.0 μg/kg. The average recoveries, assessed at three spiked levels (2.0, 4.0, and 20.0μg/kg) across various matrices including cabbage, celery, tomato, eggplant, potato, radish, cowpea, chives, apple, peach, grape, citrus, bitter melon, banana and hami melon ranged from 72.0 to 100.5% with relative standard deviations from 3.2 to 9.8% (n = 6).

Dissipation, residue and dietary risk assessment of difenoconazole in Rosa roxburghii

Rosa roxburghii is a medicinal and edible plant, which is favored by consumers due to its rich vitamin C content. Residues and potential health risks of difenoconazole in the R. roxburghii ecosystem has aroused a concern considering its extensive use for controlling the powdery mildew of R. roxburghii. In this study, the residue of difenoconazole in R. roxburghii and soil was extracted by acetonitrile, purified by primary secondary amine and detected by liquid chromatography-tandem triple quadrupole mass spectrometry. The average recoveries in R. roxburghii and soil matrix varied from 82.59% to 99.63%, with relative standard deviations (RSD) of 1.14%-8.23%. The limit of quantification (LOQ) and detection (LOD) of difenoconazole in R. roxburghii and soil samples were 0.01 mg/kg. The dissipation of difenoconazole followed well the first-order kinetic, with a half-life of 3.99-5.57 d in R. roxburghii and 4.94-6.23 d in soil, respectively. And the terminal residues were <0.01-2.181 mg/kg and 0.014-2.406 mg/kg, respectively. The chronic and acute risk quotient values of difenoconazole were respectively 0.42% and 4.1%, which suggests that the risk was acceptable and safe to consumers. This study provides a reference for the safe and reasonable use of difenoconazole in R. roxburghii production.

Characterization of the composition of plant protection products in different formulation types employing suspect screening and unknown approaches

BACKGROUND

Plant protection products (PPPs) are used extensively in agriculture to control crops. These PPPs, which may be found in different types of formulations, are composed of a designated pesticide (active principle) and other inactive ingredients as co-formulants. They perform specific functions in the formulation, as solvents, preservatives or antifreeze agents, among others.

RESULTS

A research technique based on ultra-high-performance liquid chromatography (UHPLC) coupled to a Quadrupole-Orbitrap mass analyzer was successfully applied to characterize the composition of six different PPPs in terms of the presence of co-formulants and types of formulations: emulsifiable concentrate (EC), emulsion in water (EW), suspension concentrate and water-dispersible granule. These PPPs (FLINT MAX, MASSOCUR 12.5 EC, IMPACT EVO, TOPAS, LATINO and IMPALA STAR) had antifungal activity, containing one triazole compound as active principle (tebuconazole, penconazole, myclobutanil, flutriafol or fenbuconazole, respectively). Non-targeted approaches, applying suspect and unknown analysis, were carried out and ten compounds were identified as potential co-formulants. Six (glyceryl monostearate, 1-monopalmitin, dimethyl sulfoxide, N,N-dimethyldecanamide, hexaethylene glycol and 1,2-benzisothiazol-3(2H)-one) were confirmed by injecting analytical standards. Finally, these compounds were quantified in the PPPs.

CONCLUSION

The current study allowed for detecting co-formulants in a wide range of concentrations, between 0.04 (dimethyl sulfoxide) and 19.00 g L^-1 (glyceryl monostearate), highlighting the feasibility of the proposed analytical methodology. Moreover, notable differences among the types of formulations of PPPs were achieved, revealing that EC and EW were the formulations that contained the largest number of co-formulants (four out of six detected compounds). © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Rapid Determination of Mixed Pesticide Residues on Apple Surfaces by Surface-Enhanced Raman Spectroscopy

Chlorpyrifos (CPF) and 2,4-dichlorophenoxyacetic acid (2,4-D) are insecticides and herbicides which has been widely used on farms. However, CPF and 2,4-D residues on corps can bring high risks to human health. Accurate detection of pesticide residues is important for controlling health risks caused by CPF and 2,4-D. Therefore, we developed a fast, sensitive, economical, and lossless surface-enhanced Raman spectroscopy (SERS)-based method for pesticide detection. It can rapidly and simultaneously determine the CPF and 2,4-D mixed pesticide residues on an apple surface at a minimum of 0.001 mg L⁻¹ concentration, which is far below the pesticide residue standard in China and the EU. The limits of detection reach down to 1.28 × 10⁻⁹ mol L⁻¹ for CPF and 2.47 × 10⁻¹⁰ mol L⁻¹ for 2,4-D. The limits of quantification are 4.27 × 10⁻⁹ mol L⁻¹ and 8.23 × 10⁻¹⁰ mol L⁻¹ for CPF and 2,4-D. This method has a great potential for the accurate detection of pesticide residues, and may be applied to other fields of agricultural products and food industry.

Mutagenicity Assessment to Pesticide Adjuvants of Toluene, Chloroform, and Trichloroethylene by Ames Test

Pesticide adjuvants (PAs) denote the general term for auxiliaries in pesticide preparations except for the active components. Toluene, chloroform, and trichloroethylene are the three most commonly used PAs as organic solvents. The residues of the three chemicals in the process of production and application of pesticides may endanger the ecosystem. In the present study, the mutagenicity of toluene, chloroform, and trichloroethylene as well the mixture of the three chemicals was tested by the Salmonella typhimurium reverse mutation test (Ames test) with TA97, TA98, TA100, and TA102 strains in the system with and without rat liver microsomal preparations (S9). The four tester strains have been used for more than 40 years to detect mutagenic compounds in chemicals, cosmetics, and environmental samples. The mutagenicity was detected on tester strains in the separated experiment from the three chemicals. The addition of S9 decreased the mutation ratios of toluene to four strains, except for the TA100 strain, but increased the mutation ratios of chloroform to four strains except for the TA98 strain. Trichloroethylene caused positive mutagenicity to become negative on the TA102 strain. In the mixed experiment, positive effects were detected only on the TA102 strain in the absence of S9. The addition of S9 increased the mutagenicity except for the TA102 strain. The mixture of toluene, chloroform, and trichloroethylene showed antagonism in mutagenicity to tester strains, except for the TA102 strain without S9. However, the mixture showed a synergistic effect to tester strains after adding S9 except for the TA98 strain.