Feasibility of micro-extraction and subsequent HPLC analysis for evaluating the extractable formaldehyde content of medium-density fiber board

The perforator method is a widely accepted standard method for evaluating formaldehyde contents in medium-density fiber board (MDF) and particle board in most countries in the world. However, the test consumes considerable amounts of toluene, which belongs to a category of poisonous organic solutions. This study was conducted to determine the formaldehyde content of MDF accurately by high-performance liquid chromatography (HPLC), a method that uses significantly less amounts of organic solvents for extraction than other methods. Five extraction solvents, namely, ethyl acetate, acetonitrile, methyl alcohol, dichloromethane, and petroleum ether, were used in the experiment. 2,4-Dinitrophenylhydrazine (DNPH) derivatization and HPLC analysis coupled with UV detection were conducted. Optimum micro-extraction was obtained by using acetonitrile, especially formaldehyde contents below 6 mg/100 g. Three parallel tests demonstrated good average recoveries ranging from 95.4 to 97.9 % and low relative standard deviations ranging from 1.1 to 2.9 %, which is indicative of very high accuracy. A 0.02 mg/100 g limit of detection was also obtained. The formaldehyde–DNPH derivatives remained stable for at least 48 h under ambient conditions, which indicates the applicability of the proposed method in the laboratory.