Integrated Retention/Spectrophotometric Detection Method for the Determination of Formaldehyde

An integrated-sensor method for the determination of formaldehyde based on retention of the reaction product of the analyte with p-rosaniline and sulfite in a flow-cell packed with Dowex 1-X-8 anion exchange resin was developed. The method has a good selectivity with a detection limit of 0.3 μg ml−1 (1 ml sample) or 75 ng ml−1 (2 ml sample), and a linear range between 1–30 μg ml−1. The relative standard deviations (n = 11) were 2.8 and 1.3% for 2 and 20 μg ml−1 formaldehyde, respectively. Depending on the working conditions, the sampling frenquency ranged between 10 and 18 h−1. The method was applied to the determination of formaldehyde in well water.