ADAPTATION OF METHOD OF ANALYSIS OF METHEMOGLOBIN AS A BIOMARKER OF EFFECT OF EXPOSURE TO THE PESTICIDE DIFLUBENZURON

Abstract

This work aimed to adapt the analysis of methemoglobin recommended by Evelyn - Malloy (visible spectrophotometry), in order to facilitate its application in the field, or to analysis in laboratory, of existing sites of diflubenzuron application. The parameters changed included: rotation speed; time between the collection of biological sample and analysis, and storage temperature of the samples; and the volume of reagents. The comparison of the rotation speed (rpm) of the reference methodology with the rpm of a clinical centrifuge did not reveal a statistically significant difference in the levels of methemoglobin. The time between the collection of biological sample and analysis was extended for a period of up to 48 hours for both conservation by refrigeration and ambient temperature, producing no statistically significant difference when compared to the standard duration of 2 hours. Regarding the reagents, the reference methodology already uses the volume necessary to ensure complete reaction, whereas a wider range from the recommended volume to a 5-fold reduction in comparison to the reference methodology could be used. It was concluded that the proposed changes to the methodology for adapting the analysis are applicable to studies of field / workplace exposure and ensure the reliability of results. The adapted methodology was inter-laboratory validated and the parameters changed can be selected according to the requirements of the laboratory at which the methemoglobin is to be measured.