Global regulations require a large number of pesticide residue studies to provide risk assessment and residue monitoring data in varieties of matrices and locations. Robust high-throughput analytical methods are foundational to cost-effective residue analysis. An analytical platform including an automated liquid handler and Geno/Grinder® was integrated in our lab to develop a practical 96-well plate based high-throughput analytical platform. This work demonstrates how we simplify a complex residue quantitative method, for an innovative new fungicide, to a practical and fit-for-purpose high-throughput method on this platform. The residue method needs to quantify the parent fungicide and its four metabolites of interest in various crop matrices at a LOQ= 0.01 mg/kg. The original sample preparation method included labor intensive sample extraction using a probe-based homogenizer, followed by time-consuming sample clean-up requiring three separate solid phase extractions to recover five analytes. A fit-for-purpose method is developed to increase efficiency at each of these steps. 1) Replacing the probe-based homogenizer with a Geno/Grinder® for extraction reduced both sample size and manual operation time approximately five-fold. 2) Utilization of a sub-2µm particle LC column and higher flow rates improved peak resolution and sensitivity. 3) The increased sensitivity allowed use of a diluted extract, i.e., lower matrix load on column, which resulted in lower ion suppression. This enabled use of an efficient “dilute-and-shoot” analytical workflow for multiple matrices and processed fractions. Currently, this high throughput method has been successfully employed in on-going field residue studies in crop matrices including muskmelon, summer squash, grape and lettuce. Analytical figures of merit, including recovery and linearity were comparable between the two methods. Simplifying the method to a high-throughput method not only increased sample throughput efficiency, but also improved scalability, lab safety, and data quality, and reduced environmental impact. Our team is now applying this high throughput platform to more crop protection active ingredients to build up our high throughput residue analysis capabilities.

Development of a fit-for-purpose residue quantitative analytical method with high-throughput capabilities

ACS Fall 2021

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