Miniaturized liquid extraction cartridge with a functional porous polytetrafluoroethylene membrane for the determination of formaldehyde in gaseous samples

A new miniaturized liquid extraction cartridge equipped with a functional porous polytetrafluoroethylene membrane was developed for the determination of formaldehyde in gaseous samples. The functional polytetrafluoroethylene membrane allows gas to pass through while repelling both water-based and organic-based liquids. A derivatization reagent for formaldehyde, 2,4-dinitrophenylhydrazine, was placed in the cartridge and gaseous samples are collected through the cartridge at 20 ml/min for 30 min. Formaldehyde in the gaseous sample is captured as the corresponding 2,4-dinitrophenylhydrazine hydrazone, and an aliquot of the sample collection solution can be directly subjected to high-performance liquid chromatographic analysis. The limit of quantification for the developed method was 5 ng/L formaldehyde in gas with a sampling volume of 600 ml. Proof-of-concept for formaldehyde determination in an aqueous sample was demonstrated using the developed cartridge in a purge-and-trap extraction setup.