On-site Analysis of Trace Amounts of Formaldehyde in Ambient Air Using Batchwise Collection/Concentration Method and Portable Flow Injection System

Abstract

A simple and rapid method for the determination of formaldehyde (HCHO) in air was developed by using a portable flow injection analysis (FIA) system installed with a detector consisting of a light emitting diode (LED) as a light source, and a flow cell and with a heating system. The method was used for on-site measurement by coupling with a simple batchwise absorption collection method. HCHO in air was collected quantitatively on-site in a 50-ml syringe (volume: 7 1.92k0.43 ml) containing 3 ml of purified water as an absorbing solution, which was subsequently introduced into the carrier stream of the FIA system. The amounts of HCHO in the absorbing solution were measured at 450 nm after reaction with a mixed reagent of acetylacetone and ammonium acetate at pH 6.0 or with a fluoral P solution of 0.4 M phosphate buffer (pH 6.0). A calibration graph with standard HCHO aqueous solutions could be adopted for the determination of formaldehyde in air. The relative standard deviation (RSD) was 0.63% for lx10-~ M (n = 12) and with the limit of detection (LOD) was 2.7x10-' M (0.8 ppb) in aqueous solution (SN =3), which corresponds to 35 pptv of HCHO in air. The proposed method was successfhlly applied to air samples