RESUMEN
A rapid, efficient, simple, and high-throughput method for the simultaneous determination of 108 pesticide residues in three traditional Chinese medicines (TCMs) was established, comprising an improved QuEChERS method in combination with HPLC-MS/MS based on mixed samples. A quantity of 10 mL of acetonitrile was used as extraction solvent, and 10 mg of amino-modified multi-walled carbon nanotubes (MWCNTs-NH2) and 150 mg of anhydrous magnesium sulfate (MgSO4) were selected as sorbents for dispersive solid phase extraction. The performance of the method was verified according to the analytical quality control standards of SANTE/11813/2017 guidelines. With good linearity (R2 > 0.9984) in the range of 2−200 µg/L for all pesticides in the selected matrices, and good accuracy, precision, and high sensitivity, the recoveries were in the range of 70−120% for more than 95% of the pesticides, with a relative standard deviation (RSD) of less than 16.82% for all. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.01−3.87 µg/kg and 0.07−12.90 µg/kg, respectively, for Fritillaria thunbergii Miq (F. thunbergii), Chrysanthemum Morifolium Ramat (C. morifolium), and Dendrobium officinale Kimura et Migo (D. officinale). The method was successfully applied to 60 batches of actual samples from different regions.
Asunto(s)
Nanotubos de Carbono , Residuos de Plaguicidas , Plaguicidas , Residuos de Plaguicidas/análisis , Cromatografía Líquida de Alta Presión , Espectrometría de Masas en Tándem/métodos , Nanotubos de Carbono/química , Extracción en Fase Sólida/métodos , ChinaRESUMEN
Tea polyphenols, chlorophyll and lutein generally cause strong matrix effects and challenge analysis of trace substances in tea. Seven frequently used adsorbents were chosen to test removal ability for tea polyphenols, chlorophyll and lutein based on the adsorption isotherm fitting. Results showed that MWCNTs-NH2 demonstrated the strongest removal ability, which may be ascribed to the π-π and electrostatic interaction. Then a method of MWCNTs-NH2 modified QuEChERS coupled with HPLC-MS/MS detection of 10 organophosphorus pesticide residues in tea was developed and validated. Unlike traditional QuEChERS, only one adsorbent (MWCNTs-NH2) was applied in this method to replace the combined effect of various adsorbents, which improved the easiness and generality of the method. The LOQs were 1.7-9.0 µg/kg. The average recovery rate ranged from 72% to 116% with RSDs less than 14%. This study provides a targeted strategy to develop analysis method for trace substances in a complicated matrix.
Asunto(s)
Organofosfatos/química , Residuos de Plaguicidas/química , Té/química , Adsorción , Cromatografía Líquida de Alta Presión , Organofosfatos/análisis , Residuos de Plaguicidas/análisis , Espectrometría de Masas en TándemRESUMEN
Carbon nanotubes (CNTs) inevitably enter domestic sewage and industrial wastewater with the continuous increase of their production and application field. The potential effect of CNTs on biological wastewater treatment processes has raised wide concerns due to their biotoxicity. In the present study, the performance, microbial community and enzymatic activity of sequencing batch reactors (SBRs) were evaluated under 148-day exposure of amino-functionalized multi-walled CNTs (MWCNTs-NH2) at 10 and 30â¯mg/L. The COD removal efficiency at 10 and 30â¯mg/L MWCNTs-NH2 gradually reduced from 91.03% and 90.43% on day to 89.11% and 86.70% on day 148, respectively. The NH4+-N removal efficiency at 10 and 30â¯mg/L MWCNTs-NH2 gradually reduced from 98.98% and 98.46% on day 1 to 96.65% and 63.39% on day 148, respectively. Compared to 0â¯mg/L MWCNTs-NH2, the oxygen-utilizing rate, ammonia-oxidizing rate, nitrite-oxidizing rate, nitrite-reducing rate and nitrate-reducing rate at 30â¯mg/L MWCNTs-NH2 were decreased by 52.35%, 60.58%, 55.12%, 56.56% and 57.42% on day 148, respectively. The microbial reactive oxygen species and lactate dehydrogenase release on day 148 was increased by 59.71% and 55.28% at 30â¯mg/L MWCNTs-NH2, respectively. The key microbial enzymatic activity related to nitrogen removal decreased with the increase of operation time under MWCNTs-NH2 stress. The relative abundances of Nitrosomonas, Nitrosospira, Nitrospira and some denitrifying bacteria at 10â¯mg/L MWCNTs-NH2 gradually reduced with an increment in operation time. The changes of nitrogen removal rate, microbial community and enzymatic activity of SBR were related to the time-cumulative nonlinear inhibition effect under long-term exposure.