RESUMEN
In vivo solid-phase microextraction (in vivo SPME) is an emerging fascinating sample pretreatment technique, but its quantitative correction method is different from the traditional correction methods, which has become a bottleneck limiting its development. At present, the sampling-rate calibration and equilibrium calibration are mainly used, however, their characteristics and applicability are not clear. In this study, the sampling-rate calibration and equilibrium calibration were evaluated in the case of the determination of neonicotinoids in bananas by in vivo SPME. The factors that affect the sampling rate (Rs), such as the matrix states, sampling durations, and individual differences were studied, and they all had impacts on Rs. Conversely, the equilibrium distribution coefficient (Kfs) remained constant after extraction equilibrium and the individual differences were smaller. The highest accuracy and precision were achieved by equilibrium calibration, and the relative recoveries were in the range of 83.2 %-104.3 % with the relative standard deviations below 8.1 % compared to a standard QuEChERS-based method. The lower limits of quantification for 4 neonicotinoids in bananas were below 5 ng g-1, lower than the standard method and the maximum residue levels in China and the European Union. This work clarifies the characteristics, rules and performance of the sampling-rate calibration and equilibrium calibration, which is of crucial importance for the development and application of in vivo SPME. The developed method is convenient, sensitive, and accurate for the determination of pesticide residues, which is of great significance to guide the safe use of pesticides in the field and prevent products with excessive pesticide residues from entering the market.
Asunto(s)
Musa , Neonicotinoides , Microextracción en Fase Sólida , Microextracción en Fase Sólida/métodos , Calibración , Neonicotinoides/análisis , Musa/química , Límite de Detección , Residuos de Plaguicidas/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Reproducibilidad de los Resultados , Insecticidas/análisis , Contaminación de Alimentos/análisisRESUMEN
A hyphenated liquid electrode glow discharge (LEGD)-dielectric barrier discharge (DBD) molecular emission spectrometer was constructed and used as a novel liquid chromatography (LC) detector for dithiocarbamates (DTC) determination. The LEGD was used as an acidolysis reactor for the in-situ transformation of DTCs into CS2 with high efficiencies of 74.11-97.98%. The DBD was used to excite CS2 gas to generate a specific molecular emission at 257.94 nm. The linear correlation coefficient of the method was > 0.99 from 1 to 200 µg mL-1. The detection limits ranged from 0.1 to 0.3 µg mL-1 with 76-119% recovery and relative standard deviations of 0.2-8.5%. Moreover, the hyphenated microplasma spectrometer achieved low power consumption, low temperature, immediate acidolysis, and high transformational efficiency, and can detect each DTC when combined with LC.
Asunto(s)
Espectrofotometría Atómica , Espectrofotometría Atómica/métodos , Electrodos , Cromatografía LiquidaRESUMEN
A sensitive and effective method, using gas chromatography (GC) and an electron capture detector (ECD), for the simultaneous quantitative determination of bifenthrin, chlorothalonil, cyfluthrin, cypermethrin, difenoconazole, fenvalerate, procymidone and pyridaben residues in cowpea was developed and validated. The method involved extracting with acetonitrile, purification with a graphitized carbon black/amino solid phase extraction cartridge, and then determining by GC-ECD. Recovery studies were carried out at three spiked levels (0.01, 0.1 and 0.5 mg/kg). The average recoveries at the three spiked levels ranged from 76.6 to 107.0% with relative standard deviations in the range of 1.2-5.6% for all analytes. The quantification limit was 0.01 mg/kg for each pesticide and was less than or equal to the relevant MRLs set by China, the Codex Alimentarius or the European Union. The developed analyzing method was convenient, time and cost saving, environment-friendly and readily available than the traditional methods.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Residuos de Plaguicidas/análisis , Vigna/química , Límite de Detección , Modelos Lineales , Reproducibilidad de los Resultados , Extracción en Fase SólidaRESUMEN
Residues of 14 pesticides were determined in 150 cowpea samples collected in five southern Chinese provinces in 2013 and 2014.70% samples were detected one or more residues. 61.3% samples were illegal mainly because of detection of unauthorized pesticides. 14.0% samples contained more than three pesticides. Deterministic and probabilistic methods were used to assess the chronic and acute risk of pesticides in cowpea to eight subgroups of people. Deterministic assessment showed that the estimated short-term intakes (ESTIs) of carbofuran were 1199.4%-2621.9% of the acute reference doses (ARfD) while the rates were 985.9%-4114.7% using probabilistic assessment. Probabilistic assessment showed 4.2%-7.8% subjects may suffer from unacceptable acute risk from carbofuran contaminated cowpeas from the five provinces (especially children). But undue concern is not necessary, because all the estimations are based on conservative assumption.
Asunto(s)
Monitoreo del Ambiente , Contaminación de Alimentos/análisis , Residuos de Plaguicidas/análisis , Vigna/química , Adolescente , Adulto , Niño , Preescolar , China , Femenino , Humanos , Masculino , Persona de Mediana Edad , Residuos de Plaguicidas/efectos adversos , Medición de Riesgo , Vigna/efectos adversos , Adulto JovenRESUMEN
The acute toxicity and genotoxicity of carbendazim, two impurities (3-amino-2-hydroxyphenazine and 2,3-diaminophenazine) and one metabolite (2-aminobenzimidazole) to Eisenia foetida were assessed using artificial soil test and comet assay respectively. Acute toxicity results showed carbendazim was moderately toxic to the earthworms with 14 day-LC50 of 8.6 mg/kg dry soil while 3-amino-2-hydroxyphenazine, 2,3-diaminophenazine, and 2-aminobenzimidazole were of low toxicity with 14 day-LC50 values of 19.0, 14.9, and 27.7 mg/kg dry soil respectively (nominal concentration). The olive tail moment and percentage of DNA in the tail were used as genotoxicity indices, and carbendazim could significantly induce DNA damage to the earthworm coelomocytes with obviously positive dose- and duration-response relationships while the other three substances showed similar (p = 0.05) genotoxicity results to the negative controls in all of the tests.
Asunto(s)
Bencimidazoles/toxicidad , Carbamatos/toxicidad , Oligoquetos/efectos de los fármacos , Fenazinas/toxicidad , Animales , Ensayo Cometa , Daño del ADNRESUMEN
The dissipation and residues of an eco-friendly bio-pesticide, spinosad, in cowpea under field conditions were studied using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MSMS) after Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction. The method exhibited good linearity with respect to spinosyn A and spinosyn D in solvent or blank cowpea matrix with correlation coefficients>0.99. Additionally, matrix effects were not significant in the range 0.987-1.014, and the average recoveries at three concentration levels were 75.1-91.1 and 79.4-90.5% for spinosyn A and spinosyn D, respectively. The intra- and inter-day relative standard deviations were 2.5-9.3 and 7.8-9.8% for spinosyn A, respectively, and 4.1-7.9 and 6.6-8.3% for spinosyn D, respectively. The limits of detection (LODs) and limits of quantification (LOQs) were 0.005 and 0.01 mg kg(-1), respectively, for spinosyn A, and 0.002 and 0.005 mg kg(-1), respectively, for spinosyn D. The dissipation of spinosad (sum of spinosyn A and spinosyn D) fitted well to first-order kinetics with half-lives of 0.9-1.5 days. The highest residue (HR) at pre-harvest interval (PHI) of 12 h was 0.321 mg kg(-1). Compared with the maximum residue limit (MRL) set by Codex, a PHI of at least 24 h was recommended. The estimated daily chronic intake of spinosad from cowpea was less than 0.14% of the acceptable daily intake (ADI). Therefore, the risk of consuming cowpea sprayed with spinosad under recommended field conditions was considered acceptable for the Chinese population.
Asunto(s)
Monitoreo del Ambiente , Macrólidos/análisis , Residuos de Plaguicidas/análisis , Cromatografía Liquida , Combinación de Medicamentos , Semivida , Cinética , Límite de Detección , Medición de Riesgo , Espectrometría de Masas en TándemRESUMEN
Thermal processing can concentrate residues or convert residues to more toxic metabolites in food. Chinese traditional cooking pays more attention to thermal processing and more vegetables were eaten after thermal processing. In this study, the effect of Chinese traditional cooking (washing, blanching, stir-frying, frying and combined operations) on eight pesticides residues (pyridaben, procymidone, chlorothalonil, difenoconazole, α-cypermethrin, bifenthrin, S-fenvalerate and λ-cyhalothrin) in cowpea which was one of the most important legume crops in China was examined. Result showed washing and blanching could reduce residues with low Kow while stir-frying and frying were more effective to residues with high Kow; stir-frying and frying could concentrate residues with low Kow; the residue levels in oil increased following increasing frying time and frequency especially the residues with high Kow; one metabolite studied in this paper was not detected. Blanching (5 min) followed by stir-frying (3 min) was the most effective combined operation.
Asunto(s)
Residuos de Plaguicidas/análisis , Verduras/química , China , CulinariaRESUMEN
Residues of a fungicide suspension (12 % difenoconazole, 18 % azoxystrobin) in bananas and soil were studied under tropical and subtropical monsoon climates, in Hainan and Yunnan provinces, respectively. The half-lives in bananas were shorter in Hainan (difenoconazole: 8.4-10.7 days; azoxystrobin: 7.8-8.4 days) than Yunnan (difenoconazole: 11.3-13.0 days; azoxystrobin: 10.4-11.6 days), possibly because of the higher temperatures and solar radiation levels in Hainan. The half-lives in soil were shorter in Yunnan (difenoconazole: 15.5-16.7; azoxystrobin: 11.9-13.9 days) than Hainan (difenoconazole: 23.1-23.2 days; azoxystrobin: 16.0-16.1 days), possibly because the organic carbon content was higher and rainfall lower in Yunnan than Hainan. Their physico-chemical properties suggest difenoconazole and azoxystrobin should be stable in bananas and soil, but both decreased to safe concentrations by the minimum harvest time after spraying the mixture at the recommended dosage and 1.5 times that dosage, through physical, chemical, and biological processes.