Determination of Formaldehyde and Methanol Contents in Aqueous Environmental Samples by Reaction-Based Headspace Gas Chromatography

The study develops a headspace gas chromatography (HS-GC) method for the simultaneous determination of formaldehyde and methanol in aqueous environmental samples, such as surface water, groundwater, and industrial wastewater. The method is based on the quantitative conversion of formaldehyde to methanol via its reaction with sodium borohydride in a concentrated potassium carbonate medium. The contents of both analytes are determined by measuring the methanol concentration in the sample before and after the borohydride reduction. Introducing a known amount of isopropanol as an internal standard and using its signal for calibration significantly reduces the measurement uncertainty associated with the two separate HS-GC analyses. Results demonstrate that the present method offers good accuracy (recovery ranging from 94–103%). The limit of quantification (LOQ) is 0.835 mmol/kg. This method is straightforward, reliable, and suitable for high-throughput monitoring of these common water pollutants, making it a valuable tool for environmental quality control and pollution assessment.