HPLC Determination of Formaldehyde in Aquatic Products by Pre-derivatization with unsym.-Dimethyl Hydrazine

unsym.-Dimethyl hydrazine was used as derivatizing agent in the pre-derivatization of formaldehyde in the HPLC determination.The derivatization product,unsym-dimethyl hydrazone which showed strong UV-absorption with absorption maximum at 237 nm,was formed quantitatively in a neutral solution after reacting for 10 min,and it was determined directly by HPLC,without the necessity of pre-concentration.Linear relationship between the absorbance and concentration of unsym-dimethyl hydrazone (expressed in terms of formaldehyde) was found in the range of 0.12-1 200 mg·L-1.Detection limit (3S/N) of the method was found to be 0.5 μg·g-1.Precision was tested in the analysis of 3 samples of aquatic products,giving values of RSD′s (n=5) less than 6%.Test for recovery was made by adding standard formaldehyde to 3 different kinds of aquatic product samples,and the results obtained were in the range from 88.0%-110.0%.