DEVELOPMENT OF A METHOD TO IDENTIFY KETO ACIDS IN OZONATED FULVIC-ACID SOLUTIONS

A gas chromatographic-mass spectrometric method, combining an 4,5,6-pe ntafluorobenzyl)hydroxylamine-diazomethane double derivatization, was developed to identify major keto acids in ozonated fulvic acid solutio ns. Three keto acids, glyoxylic, pyruvic, and ketomalonic acid, four a ldehydes and two analytical artifacts were identified. The detailed ma ss spectra, obtained in both electron impact and positive chemical ion ization modes, and their fragment assignments are presented. Owing to the similarity of their electron impact mass spectra, electron impact mass spectra along with positive chemical ionization mass spectra are needed to identify these keto acids reliably. The effects of the forma tion of keto acids on water quality are also discussed.