Analysis of aldehydes in cloud- and fogwater samples by HPLC with a postcolumn reaction detector

Abstract

High-performance liquid chromatography (HPLC) coupled with a segmented-flow analyzer was used for the analysis of aldehydes. The aldehydes, which were separated on a reversed-phase C_(18) column, were derivatized with 3-methyl-2-benzothiazolinonhe ydrazone (MBTH) and detected at 640 nm. MBTH reacts readily with all aliphatic aldehydes to form MBTH derivatives with high molar absorptivities. Aldehydes below 1 µM can be easily detected by this method. Because aldehydes and other solutes are separated by HPLC before derivatization, free aldehydes are detected without interference. Aldehydes in cloud- and fogwater samples were analyzed. Form-aldehyde, acetaldehyde, glyoxal, and methylglyoxal concentrations were determined. Results obtained with the MBTH method were consistent with those obtained with the 2,4-dinitrophenylhydrazine (DNPH) method. The MBTH method allows for the rapid determination of the concentration of free aldehydes; the DNPH method will yield similar results, although the procedure is more cumbersome and time consuming.

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