Over the years, moringa pods are known for nutritional and health benefits. The cultivation of this crop receives frequent pesticide applications. In absence of risk assessment data, MRLs of pesticides in this crop are considered at the default level (0.01 mg/kg). However, there exists scarcely any validated method for pesticide residue analysis in this matrix.
This study was undertaken to develop, and validate a multiresidue method for simultaneous analysis of multi-class pesticides in moringa pods by gas chromatography-tandem mass spectrometry, and liquid chromatography-tandem mass spectrometry.
The homogenized sample (10 g) was extracted with acetonitrile (10 mL). The extract was cleaned by dispersive solid phase extraction using a combination of 50 mg primary secondary amine, 5 mg graphitized carbon black, and 25 mg C
sorbents, and was directly analyzed by LC-MS/MS. Another portion of the extract was reconstituted in ethyl acetate before GC-MS/MS analysis. The method was validated as per the SANTE/12682/2019 guidelines using GC-MS/MS (180 pesticides), and LC-MS/MS instruments (203 pesticides).
The method provided satisfactory analysis of the targeted pesticides with good calibration linearity (r2>0.99), high precision (RSD<20%), and accuracy (recoveries, 70-120%). The reconstitution of the acetonitrile extract in ethyl acetate significantly reduced the matrix effects on GC-MS/MS analysis. The use of matrix-matched standards could correct all recoveries.
The method offered a large-scale analysis of multi-class pesticides with high accuracy, and precision at 10 ng/g, and higher levels. The method performance complied with the regulatory requirements, and thus, can be implemented in routine testing purposes.
The study reports a validated method for large-scale multiresidue analysis of pesticides in moringa matrix for the first time. The method provided a high throughput analysis of multi-class pesticides with satisfactory selectivity, sensitivity, accuracy, and precision.