Determination of nano-molar levels of formaldehyde in drinking water using flow-injection system with immobilized formaldehyde dehydrogenase after off-line solid-phase extraction Original Research Article

Low levels of formaldehyde were determined by preconcentration with poly(allylamine) beads and analysis by flow-injection system with immobilized formaldehyde dehydrogenase. Formaldehyde dehydrogenase was immobilized on tresylate-poly(vinyl alcohol) beads and packed into a stainless-steel column (5 cm×4 mm). The column was incorporated in a flow-injection system with fluorimetic detection. The calibration graph was linear from 0.5 to 10 μM (15–300 μg l−1). The poly(allylamine) beads (0.5 g) were used to adsorb formaldehyde present at 20–400 nM (0.6–12 μg l−1) from drinking water (1 l). Formaldehyde was eluted with 1 M HCl (10 ml). The solution (50 μl) adjusted to pH 9 was injected into the flow-injection system. Concentration factor was 25-fold. Recovery of formaldehyde spiked into purified water was >96% with a relative standard deviation of ≤3.0%.