Validation and application of a QuEChERS-based method for estimation of the half-lives of cyromazine and acetamiprid in cowpeas and soil by LC-ESI-MS/MS
A rapid and sensitive method for the simultaneous determination of cyromazine and acetamiprid in cowpeas by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was developed. The cleanup performance by primary secondary amine (PSA), C18 and graphitised carbon black (GCB) was carried out to optimise the sample preparation step. The analytical method showed satisfactory specificity, selectivity, linearity (R2 > 0.99) and recoveries (85.8–109.0%), relative standard deviation (intra-day RSD) between 2.7% and 14%, precision (92.0–104.2%), the inter-day precision RSD between 0.49% and 9.6%. The limits of detection (LODs) for cyromazine and acetamiprid were 0.0009 mg/kg and 0.0001 mg/kg, respectively, in soil and cowpeas, and the limits of quantification (LOQs) for each was 0.001 mg/kg. The retention times of cyromazine and acetamiprid were 1.54 min and 2.37 min, respectively. The half-lives of cyromazine in cowpeas and soil were 3.13 − 11.18 d, and the half-lives of acetamiprid were 2.1–11.95 d, which indicates that they are low-persistence insecticides with the possibility of evaporating into the air. The matrix effect was compensated for by using the standard addition method. This LC-ESI (+)-MS/MS method with short run time, high sensitivity, and low matrix effects may help laboratories handle routine pesticide residue analysis in different food samples.
