Analysis of Low Concentration Aldehyde and Ketone Compounds in Automotive Exhaust Gas by New Collection Reagent.

Acidified 2,4-dinitrophenylhydrazine (DNPH) solution, or DNPH-impregnated cartridges are commonly used for the collection of automotive exhaust carbonyl compounds. There are some DNPH-carbonyl compounds in not in use DNPH cartridges and DNPH solution. Furthermore, concentrations of automotive exhaust carbonyl compounds are decreasing according to improvement of the purification technology for automotive exhaust. Automotive exhaust carbonyl compounds become to be difficult to be analyzed with DNPH collection method, because of these two reasons. It is thought that reliable analysis of acrolein in automotive exhaust is very difficult because concentration of DNPH-acrolein in extracted solution is not stable. Furthermore, it is found out that DNPH-acrolein in DNPH-cartridge is disappeared for short time storage in this research.

Recently, O-(4-cyano-2-ethoxybenzyl)hydroxylamine (CNET) has been developed for the purpose of carbonyl compounds collection reagent with low concentration of contaminations of DNPH-carbonyl compounds. We applied this reagent for collection of automotive exhaust carbonyl compounds. CNET cartridge is compared with some kinds of DNPH cartridges and DNPH solution for collecting many kinds of automotive exhaust. In this result, concentration levels of contaminative CNET-carbonyl compounds in a not in use CNET cartridges are lower than DNPH cartridge on the market. Furthermore CNET-acrolein concentration is not decreased so fast in the CNET cartridge at room temperature and CNET-acrolein concentration is not decreased at 278K for several hours. When carbonyl compounds concentrations are high, correlations of CNET collection and DNPH collection are good. In the case of low concentrations, CNET is superior to DNPH as collection reagent of carbonyl compounds. For the purpose of automotive exhaust acrolein collection, CNET is better than DNPH.