Stabilization strategies for unstable pesticides in calibration reference materials

Laura E. Morales, Diana C. Sinuco, Diego A. Ahumada

Abstract

To achieve measuring methods harmonization, improve reliability, and quality of measurement results, the use of certified reference materials (CRM) are necessary. Due to the instability of some compounds, the offer of CRM of pesticides is low. The National Metrology Institute of Colombia, as reference materials producer, has evaluated strategies to determinate and improve the stability of ten multiclass selected pesticides in calibration solutions. For this purpose, to obtain an overview of the degradation behavior of pesticides, ten compounds with different physicochemical characteristics were chosen. Three mixtures were prepared, which contained one polychlorinated biphenyl (PCB) as control. Various strategies were applied for the stabilization of the pesticides (an additive, inert atmosphere, and their combinations). The stability assessment was performed using an isochronous design at extreme conditions to induce a faster degradation of the compounds. Three analytical methods using gas chromatography were developed and validated. After methods validation, the stability measures were realized under repeatability conditions. The results were evaluated using regression. The results demonstrated that the strategies used for stability increasing were adequate for all of the evaluated compounds. In this study, it was found that when a stability strategy is adopted, the uncertainty associated with the stability improve up to 15 times.

Keywords

Pesticide, Stability, Reference Materials, Uncertainty, Method validation

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IMEKO-TC10-2020-015.pdf

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IMEKO TC

TC10 - Measurement for Diagnostics, Optimization and Control

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