Quantitative Endogenous Formate Analysis in Plasma Using Headspace Gas Chromatography Without a Headspace Analyzer

• Published in: Journal of analytical toxicology 2007-07, Vol.31 (6), p.342-346
• Main Authors: Sokoro, AbdulRazaq, Lehotay, Denis, Eichhorst, Jeff, Treble, Ronald
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Chemical and industrial products toxicology. Toxic occupational diseases; Chromatography, Gas - methods; Female; Flame Ionization; Formates - blood; Humans; Medical sciences; Pregnancy; Solvents; Swine; Toxicology; Various organic compounds
• ISSN: 0146-4760; 1945-2403
• DOI: 10.1093/jat/31.6.342

The objective was to develop a simple routine method for quantitative measurement of endogenous formic acid in plasma and whole blood using headspace gas chromatography-flame ionization detection. (GC-FID). Two-hundred microliters of sample was placed in a 1-mL glass vial. Fifty microliters of aqueous ethanol (10%) was added as an internal standard and a derivatizing agent. Ethylformate formation was enhanced by addition of 200 µL concentrated sulfuric acid as a catalyst. The vials were then sealed immediately and placed in a water bath for 15 min at 60°C. One milliliter of this headspace gas was siphoned using a gas-tight syringe and injected into a GC-FID fitted with a capillary column. Ethanol eluted at approximately 3.0 min, and ethylformate eluted around 4.7 min. The limit of quantitation for ethylformate was 0.026 mmol/L, and the limit of detection was 0.020 mmol/L. Imprecisions for spiked plasma samples at 0.25 and 1 mmol/L were 10% and 9%, respectively, and recoveries were at 100% and 108%, respectively. A simple, reliable, and highly specific headspace analysis method for quantifying endogenous formate without the use of a headspace analyzer was developed. This method enables the routine clinical analysis of formate in plasma and whole blood samples.