Determination of formaldehyde in fruit juice based on magnetic strong cation-exchange resin modified with 2,4-dinitrophenylhydrazine

A method was developed using magnetic strong cation-exchange resin modified with 2,4-dinitrophenylhydrazine (DNPH) for the determination of formaldehyde (HCHO) in fruit juice samples. The procedures of extraction and derivatization were carried out in a single step by stirring the resins and diluted fruit juice with water. When the procedures were completed, the resins adsorbing the HCHO–DNPH derivative were easily separated from the sample matrix by an adscititious magnet. The HCHO–DNPH derivative eluted from the resins was directly determined by high-performance liquid chromatography with UV detector at 360 nm. The limit of detection of the proposed method in fruit juice obtained is 6.0 ng mL−1. In this work, the volume of fruit juice was 5 mL and the amount of MSCX resins was 100 mg, and the resins can be reused 10 times. The relative standard deviations of intra-day and inter-day ranging from 3.9% to 6.1% and from 4.2% to 7.0% are obtained, respectively. The recovery of HCHO in the analysis of spiked fruit juice samples is in the range of 85.7–100.4%.