Determination of Picomolar Concentrations of Carbonyl Compounds in Natural Waters, Including Seawater, by Liquid Chromatography

Abstract

Low molecular weight carbonyl compounds in natural waters were determined at picomolar to nanomolar levels by derivatization with 2, 4-dinitrophenylhydrazine followed by liquid chromatography. The uniqueness of the method is attributed to the extremely low blanks obtained and the minimal sample preparation involved. The detection limit for direct injection of derivatized natural water samples is 0.5 nM for aldehydes and 5 nM for ketones with a precision of ~7% RSD at the 30 nM level for aldehydes. The detection limit can be further lowered by using off-line cartridge enrichment in which derivatized natural water is passed through a C18 extraction cartridge. Recoveries for the enrichment method were 95–105% for a sample volume of 20 mL and for concentrations of carbonyl compounds in the 1–30 nM range. A field procedure for storage of derivatized sample extracts for extended periods is also presented. Applications of enrichment and sample storage techniques to marine and estuarine waters are presented. © 1990, American Chemical Society. All rights reserved.