Determination of pesticides residues in quinoa (Chenopodium quinoa Willd) using QuEChERS and LC-MS/MS
The QuEChERS method was optimized and validated for the determination of 40 pesticides in 37 samples of quinoa from the harvest 2010-2011 in Puno - Peru. The method involves extraction with 1% acetic acid acetonitrile with CH3COONa anhydrous and MgSO4 followed by dispersive solid-phase extraction with PSA and C18. Analyses were performed with LC-MS/MS using C18 column 150 mm x 2.1 x 3.5 µm, water and acetonitrile 0.1% formic acid used as mobile phase. Spiked quinoa blank at 0.01 and 0.1 mg kg-1 was employed to evaluate recovery ranging from the 31.6 and 125.1% with RSD ≤ 23. The method showed linearity r2 ≥ 0.99 and limits of quantification ranged from 0.001 and 0.01 mg kg-1, and was not observed a matrix effects. No pesticides residues were observed in the analyzed samples.