“…Most methods were developed based on reaction of formaldehyde with various reagents to form colored derivatives for spectrophotometric detection. In recent years, chromatographic methods including GC [6,7] and HPLC [9][10][11] have been the most frequently reported one for the determination of formaldehyde. The most commonly used sample preparation procedure for chromatographic determination of formaldehyde is based on its reaction with 2,4-dinitrophenylhydrazine (DNPH) to form the corresponding hydrazone (DNPHo), which is extracted by liquid-liquid extraction [12], solid-phase extraction [11] or solid-phase microextraction [7,8].…”