Cross validation of multiple methods for measuring pyrethroid and pyrethrum insecticide metabolites in human urine
The objective of our study was to compare three vastly different analytical methods for measuring urinary metabolites of pyrethroid and pyrethrum insecticides to determine whether they could produce comparable data and to determine if similar analytical characteristics of the methods could be obtained by a secondary laboratory. This study was conducted as a part of a series of validation studies undertaken by the German Research Foundation's Committee on the Standardization of Analytical Methods for Occupational and Environmental Medicine. We compared methods using different sample preparation methods (liquid-liquid extraction and solid-phase extraction with and without chemical derivatization) and different analytical detection methods (gas chromatography-mass spectrometry (single quadrupole), gas chromatography-high resolution mass spectrometry (magnetic sector) in both electron impact ionization and negative chemical ionization modes, and high-performance liquid chromatography-tandem mass spectrometry (triple quadrupole) with electrospray ionization). Our cross validation proved that similar analytical characteristics could be obtained with any combination of sample preparation/analytical detection method and that all methods produced comparable analytical results on unknown urine samples.