Abstract: A derivative solution extraction was applied to determine free formaldehyde in mushrooms by high performance liquid chromatography. The formaldehyde in mushrooms directly reacted with 2,4-dinitrophenylhydrazine in acetonitrile-phosphate buffer (pH 5) (1:1, v/v) solution, and then determined by high performance liquid chromatography. The formaldehyde formation by enzyme reaction in mushrooms was inhibited in acetonitrile-phosphate buffer (pH 5) (1:1, v/v) solution, and therefore only free formaldehyde was extracted. To improve the detecting efficiency, 2,4-dinitrophenylhydrazine was dissolved in the solution and free formaldehyde was directly derived during extracting process. The recoveries were 89.2%, 91.7% and 90.4% at the spiking levels of 5.0, 10.0 and 20.0 mg/kg of formaldehyde in mushrooms, respectively, and the relative standard deviations (n=6) were less than 5.0%. The limit of quantification of the formaldehyde in mushrooms was 5.0 mg/kg. The method has been applied to the determination of formaldehyde in real samples and the results showed that the content of formaldehyde was significantly lower than that obtained by the traditional methods. The method has the advantages of simple operation, good accuracy, and meets the requirement of the determination of naturally-occurring formaldehyde in mushrooms.

Key words: derivative solution extraction, free formaldehyde, mushrooms, high performance liquid chromatography (HPLC)