AUTOMATED SOLID-PHASE EXTRACTION AND COUPLED-COLUMN REVERSED-PHASE LIQUID-CHROMATOGRAPHY FOR THE TRACE-LEVEL DETERMINATION OF LOW-MOLECULAR-MASS CARBONYL-COMPOUNDS IN AIR

This study reports the development of a coupled-column RPLC method for the trace level determination of several volatile aldehydes in ambient air. Carbonyls in air are sampled using a ozone scrubber and SPE C-18 cartridges which are pretreated with 2,4-dinitrophenylhydrazone. The method is used for the separation of 13 different aldehydes and ketones. All analytes are separated without high blanks or ozone interferences. The analytical detection limits for the most important compounds formaldehyde, acetaldehyde, 2-propenal (acroleine), 2-butenal (crotonaldehyde) and benzaldehyde, range from 50 to 150 ng/m(3) (ppt) or 0.5-1.0 pmol/l, with relative standard deviations of 6%. The sampled air volume was 200 1. Due to the high sensitivity of the method, high purity solvents must be used. The analytical method as described below, has high recoveries for all analytes (> 90%) and is fully automated. This procedure has been applied in a pilot study with 60 air samples.