Determination of Trace Amounts of Highly Hydrophilic Compounds in Water by Direct Derivatization and Gas Chromatography - Mass Spectrometry

A new procedure has been developed to derivatize a large set of highly hydrophilic substances ((poly) hydroxy and/or (poly)carboxylic acids, glycols and dihydroxybenzenes) directly in water. The key element of the method is the derivatizing agent used, n-hexyl chloroformate, which proved to be much more effective than other alkyl and aryl chloroformates. Detection limits in the low g/L range were found for most of the compounds studied, using positive ion chemical ionization mass spectrometry as the detection technique. Calibration curves exhibited a good linearity over 2–3 orders of magnitude, so that quantitative determinations were possible. Among the experimental parameters tested, it was found crucial to introduce the chloroformate slowly and under sonication. The whole derivatization procedure takes only 2–3 min from sample collection to injection into the gas chromatograph.