Determination of ultra-trace formaldehyde in air using ammonium sulfate as derivatization reagent and capillary electrophoresis coupled with on-line electrochemiluminescence detection

The reaction between formaldehyde and ammonium ion to produce hexamethylenetetramine is well known. The reaction conditions are very easily controlled in situ and the experiment operation is very simple. However, such derivatization reaction for trace formaldehyde determination using capillary electrophoresis (CE) electrochemiluminescence (ECL) has not been reported before. In this study, the application of ammoniun sulfate as derivatization reagent to in-situ determination of formaldehyde in air was reported. Based on ECL enhancement of tris(2,2′-bipyridyl)ruthenium(II) with hexamethylenetetramine, a novel approach for the determination of ultra-trace formaldehyde in air using CE coupled with on-line ECL of tris(2,2′-bipyridyl)ruthenium(II) has been developed. The parameters affecting separation and detection such as detection potential, concentration and pH of phosphate buffer, and electrokinetic voltage, were investigated. Under the optimal conditions, the linear concentration range of formaldehyde in air was from 0.48 μg/m3 to 96 mg/m3 (linear range covering 5 orders of magnitude). The limit of detection (3σ) was 0.15 μg/m3. The relative standard deviations of peak height and migration time for six consecutive injection of 1 ng/mL formaldehyde derivative were 0.9% and 0.8%, respectively. The recoveries of formaldehyde in air were between 99.3% and 101%.

► A novel method for determination of ultra-trace formaldehyde in air was developed.
► The whole experiment allowed real-time monitoring of formaldehyde in air.
► The linear range covering five orders of magnitude was not reported before.
► The limit of detection using this method was better than those previously reported.
► The simple and inexpensive equipment, good reproducibility and high sensitivity.