Analyzing HAAs and ketoacids without diazomethane

摘要

Currently available methods for analyzing haloacetic acids (HAAs) and ketoacids in water generally require the use of diazomethane for sample derivatization. This article proposes methods based on a less toxic, alternative methylating agent. The reagent in both cases is acidic methanol. Side-by-side comparison of the proposed method for HAA analysis and method 6251B showed no significant difference. These two methods were also found to give similar method detection limits and spike recoveries. The new O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBHA)-acidic methanol derivatization analytical method for two ketoacids—glyoxylic acid and pyruvic acid—was found to be comparable to the method using PFBHA-diazomethane. Additional study is needed to improve methylation efficiency for ketomalonic acid. Work is also needed to further test the proposed HAA method with monochloroacetic acid and brominated haloacetic acids.