Improved Cleanup and Determination of Dialkyl Phosphates in the Urine of Children Exposed to Organophosphorus Insecticides

Analysis of dialkylphosphate urinary metabolites of organophosphorus insecticides has been used to estimate dose in nonoccupationally exposed populations, including children. Analytical methods must continue to be improved in order to accurately and reproducibly measure less than 10 ng/mL of these m...

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Bibliographic Details
Published in:Journal of analytical toxicology 1999-07, Vol.23 (4), p.230-236
Main Authors: Moate, T.F., Lu, C., Fenske, R.A., Hahne, R.M.A., Kalman, D.A.
Format: Article
Language:English
Subjects:
Alkylation
Biological and medical sciences
Child
Child, Preschool
dialkylphosphate
Environmental Exposure - analysis
Female
Humans
Infant
Infant, Newborn
Insecticides - adverse effects
Insecticides - analysis
Male
Medical sciences
Organophosphorus Compounds
Pesticides, fertilizers and other agrochemicals toxicology
Phosphates - metabolism
Phosphates - urine
Sensitivity and Specificity
Toxicology
Urinalysis - standards
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Summary:Analysis of dialkylphosphate urinary metabolites of organophosphorus insecticides has been used to estimate dose in nonoccupationally exposed populations, including children. Analytical methods must continue to be improved in order to accurately and reproducibly measure less than 10 ng/mL of these metabolites. Dialkyl phosphates are commonly determined as their pentafluorobenzyl bromide derivatives via gas chromatography (GC) with flame photometric detection. Presented here is an improved method for precleanup of urine using solid-phase extraction, followed by derivatization and GC analysis. The method includes the quantitative determination of the following dialkyl phosphate metabolites: dimethylphosphate, diethylphosphate, dimethylthiophosphate, diethylthiophosphate, and dimethyldithiophosphate. Additional cleanup of urine samples allows for increasing sample size and improving sensitivity while minimizing interferences and variability associated with derivatization. Sample aliquot size was 5 mL with limits of quantitation of 10 ng/mL of urine for dimethylphosphate and diethylphosphate and 2 ng/mL of urine for dimethylthiophosphate, diethylthiophosphate, and dimethyldithiophosphate. This level of method sensitivity allows for quantitative determination of trace dialkyl phosphates in approximately 75% of individuals in nonoccupationally exposed populations. This streamlined method increases sample throughput, provides a clean extract for analysis, and requires no custom glassware.
ISSN:0146-4760
1945-2403
DOI:10.1093/jat/23.4.230