Evaluation of test procedures for the quantification of urinary (2-methoxyethoxy) acetic acid.
Toxicologist 2005 Mar; 84(Suppl 1):40
(2-Methoxyethoxy)acetic acid (MEAA) is a metabolite and biomarker for exposure to 2-(2-methoxyethoxy)ethanol [diethylene glycol monomethyl ether, DEGME, or DiEGME], a glycol ether which is of concern because of general toxicity. Glycol ethers have been frequently reported to damage the hemopoietic system, the male reproductive system and have demonstrated fetal/embryonic developmental toxicity. Specifically of interest to this laboratory is the use of 2-(2-methoxyethoxy)ethanol as an anti-icing additive to the military jet fuel JP-8. 2-(2- Methoxyethoxy)ethanol is readily absorbed through the skin and of concern for human dermal exposure. Test procedures to quantify the level of MEAA in human urine were developed and compared. Gas chromatography using a mass selective detector and a 50-m X 0.20-mm (id) dimethylpolysiloxane capillary column were used in each procedure studied. Two derivatization procedures were used in this evaluation. First, MEAA was extracted from fortified urine with ethyl acetate. Esterification of MEAA to the corresponding ethyl ester was one approach, and derivatization of MEAA to the corresponding t-butyldimethyl silane derivative was the second approach for gas chromatographic anaylsis. Recovery studies using 2, 5, 10 and 20 ug/ml MEAA fortified human urine samples demonstrated good accuracy and precision for both procedures. Recoveries using the ethyl ester procedure varied between 95-105% with precision [measured as percent relative standard deviation (%RSD)] as high as 14.3%, and recoveries using the silylation reagent were between 94-99% with precision (%RSD) as high as 7.3%. The t-butyldimethyl silane derivative procedure was less labor intensive and demonstrated better precision. The diethyl ester derivative procedure had better chromatographic performance from the more extensive sample cleanup.
Acetic-acids; Metabolites; Biomarkers; Exposure-levels; Glycols; Toxins; Toxic-effects; Ethers; Reproductive-system-disorders; Ethanols; Skin-exposure; Urinalysis; Gas-chromatography; Teratogenesis; Teratogens; Analytical-chemistry; Analytical-methods; Analytical-processes
Research Tools and Approaches: Exposure Assessment Methods
The Toxicologist. Society of Toxicology 44th Annual Meeting and ToxExpo, March 6-10, 2005, New Orleans, Louisiana