Abstract
A simple and precise analytical method is described for the determining the presence of formaldehyde (FA) in residential air by high-performance liquid chromatography (HPLC) after passive sampling.
FA in the air was collected for 24 hours using a commercial porous PTFE (polytetrafluoroethylene) tube packing silica gel impregnated with triethanolamine. After sampling, FA was extracted from the silica gel with 7ml of 0.5-M phosphoric acid. A 0.3ml of acetonitrile dissolved 2, 4-dinitrophenylhydrazine (DNPH) (20mg/ml) and 2.7ml of acetonitrile were added to the extract, and FA was allowed to convert to hydrazone derivative (FA-DNPH). The compound was quantified by reversed-phase HPLC. Silica gel taken out of a fresh sampler was similarly treated, and analyzed as a control.
The concentration of FA in the air could be determined linearly from 1 to about 200ppb(v/v). For all concentrations examined, the coefficient of variation on replicate assays of the whole preparation was less than 5%. Both the FA in used sampler and the FA-DNPH in prepared analytical solutions were stable for up to one month at 4°C in the dark. Present method was compared with colorimetric method using 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazole (AHMT) and HPLC method using DNPH-cartridge for quantifying FA in air.
