Quantitative Assessment of Destruxins from Strawberry and Maize in the Lower ppb Range: Combination of a QuEChERS-based Extraction Protocol with a Fast and Selective UHPLC-QTOF-MS Assay

A fast and selective UHPLC-QTOF-MS method was developed to monitor the presence of secreted destruxins in two model food plants for the application of this fungal biocontrol agent, namely strawberry and maize. The liquid-chromatography-mass spectrometric assay for destruxin trace analysis is combined with a novel QuEChER-based extraction protocol. The whole assay was optimized for the application in these crops and it allows quantitative analysis of the major M. brunneum metabolites destruxin A, 1, destruxin B, 2, and destruxin E, 3, down to the ppb range. In strawberry limits of quantitation (LOQs) were found to be less than 2.0 ppb for all analytes, in maize LOQs were found to be less than 3.2 ppb for destruxin A, and destruxin B. Destruxin E showed a distinctive loss of recovery in maize and was excluded from further quantitative analysis in this crop. For both crops assay linearities ranged from the LOQs to 100 ppb, inter-assay repeatabilities (RSD) were found to be better than 16.4% and accuracies ranged from 83.5-105.3% (assessed at four spiking levels between 5 ppb and 75 ppb).

Website: http://www.arjonline.org/agricultural-sciences/american-research-journal-of-agriculture/