Abstract
Formaldehyde and formic acid were simultaneously determined by isotachophoresis after derivatizing the former to hydroxymethane sulfonate with sodium hydrogen sulphite. The recommended procedure is as follows. The sample solution containing less than 30 mg of formaldehyde and 100 mg of formic acid was neutralized to pH 7 with dilute sulfuric acid. Sodium hydrogen sulphite was added in five-fold molar excess of formaldehyde, and the mixture was diluted to 100 ml with degassed water. The leading and terminating electrolyte solutions were {10-2 M hydrogen chloride+ L-histidine} (pH 6.0) and 10-2 M hexanoic acid (pH 3.4), respectively. The calibration curves were linear for 00.3 μg formaldehyde and for 01.0 μg formic acid. The detection limit was 0.05μg for formaldehyde and 0.1 μg for formic acid. The method was applied to the determination of formaldehyde and formic acid in non-electrolytic copper plating solutions. The results were in good agreement with those by spectrophotometric and ion chromatographic method.
