A liquid chromatography mass spectrometry-based method to measure organophosphorous insecticide, herbicide and non-organophosphorous pesticide in grape and apple samples

The LC-MS/MS with Quick, Easy, Cheap, Effective, Rugged and safe method was used for analysis of eighteen pesticides in fruit samples. This method was found to be accurate (≥99%), as it possessed limits of detection in the 0.002-0.087 ranges respectively. The coefficients of variations (≥0.9999) were less than 2% at the low ng g⁻¹ concentration. Mean recoveries ranged between 97 and 101%, and % RSD were below 5%. The imidacloprid mean concentrations of red grapes (125.124 ng g⁻¹) and green grapes (702.030 ng g⁻¹) differed significantly (p < 0.05) between the grapes. Similarly, the fenitrothion mean concentration of red grapes (143.66 ng g⁻¹) and green grapes (51.554 ng g⁻¹) differed significantly (p < 0.001) between the fruits. The average concentration of quinalphos was 4.317 and 1.389 ng g⁻¹ differed significantly (p < 0.01) between the grapes. In apples imidacloprid, quinalphos, triazophos, ethion and acephate were also present. This study may be helpful in developing a regional exposure database and in the facilitation of health risk assessment due to pesticide exposure.     

Determination of methenamine residues in edible animal tissues by HPLC-MS/MS using a modified QuEChERS method: Validation and pilot survey in actual samples

A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was developed for the determination of methenamine in edible animal tissues by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Samples were extracted with acetonitrile, and cleaned with anhydrous sodium sulfate and primary secondary amine (PSA) sorbent. An isotope dilution mass spectrometry technique was applied to compensate for matrix effect. The separation was performed on a HILIC column, and the mobile phase composed of acetonitrile-0.1% of formic acid and 5.0 mmol/L of ammonium acetate in water. The method showed a linear relationship in the range of 1.0–20.0 μg/L for methenamine, and the determination coefficients (R²) ranged from 0.9939 to 0.9995. The limit of detection (LOD) and quantification (LOQ) for methenamine in animal tissues sample was 1.5 μg/kg and 5.0 μg/kg, respectively. The average recoveries were 86.7–109.5% at spiked levels of 5.0, 25.0, 100.0 μg/kg. The intra-day precision ranged from 2.6 to 7.0%, and the inter-day precision ranged from 4.9 to 11.3%. The validated method was successfully applied to determination of methenamine in swinish muscle, kidney and liver.