Critical evaluation of the Br-MMC fluorescent labeling technique for the determination of organic acids in precipitation

Methylmethoxycoumarin-labeled organic acids can be detected with great sensitivity and alow, therefore, the measurement of very small acid concentrations: For the analysis of organic acids in a complex aqueous matrix such as rain or snowmelt water, the method is not fully satisfactory. The use of tetrabutylammonium hydroxide as a phase transfer agent makes the derivatization procedure very easy but inreases the amount of by-products. The high blank levels for the C1 and C2 fatty acids cannot be fully controlled and introduce, therefore, an additional error. Another disadvantage lies in the fact that the tree lowest dicarboxylic acids cannot be measured because the esterification does not go to completion.