Analysis of pesticides in cherimoya and gulupa minor tropical fruits using AOAC 2007.1 and ammonium formate QuEChERS versions: A comparative study

Abstract

In this work, 48 representative pesticides of different chemical families were analysed in cherimoya (Annona cherimola) and gulupa (Passiflora pinnatistipula), two minor tropical fruits cultivated in Colombia. For this purpose, a comparative study between the AOAC 2007.1 QuEChERS method and its modification replacing the acetic acid/acetate buffer by ammonium formate was developed. Besides, the addition of graphitized carbon black (GCB) was also studied during the dispersive solid-phase extraction clean up to eliminate pigments. Gas chromatography tandem mass spectrometry analysis was performed. Triphenyl phosphate as quality control of the injection and atrazine-d5 as surrogate internal standard were used. Among both methods, the ammonium formate version with GCB addition provided the cleanest extracts (lowest amounts of co-extractive material) as well as consistent recovery values in the 70–120% range with relative standard deviation values below 20% for a higher number of analytes (spiked levels of 10, 100, and 400 μg/kg). Matrix-matched calibration was carried out obtaining determination coefficients above 0.9901. Matrix effects were also studied, finding soft matrix effects for most pesticides in both matrices. The analysis of 10 samples of each type revealed the presence of propoxur in two gulupa samples and propyzamide in one cherimoya sample, but below the lowest calibration level of the method (set at 5 µg/kg).