Determination of formaldehyde in aquatic products by micellar electrokinetic capillary chromatography with 2,4-dinitrophenylhydrazine derivatization

Formaldehyde in aquatic products was determined by micellar electrokinetic capillary chromatography (MEKC) after derivatization with 2,4-dinitrophenylhydrazine. Separation was carried out at 25 °C and 25 kV, using a fused silica capillary (75 µ internal diameter; 50.5 cm effective length) and an ultraviolet detector set at 360 nm. The optimal background electrolyte was 20 mM sodium tetraborate and 20 mM sodium dodecyl sulfate at pH 9.0 with 3 s hydrodynamic injection at 30 mbar. Electrophoretic analysis took approximately 6.5 min. The correlation coefficient of the calibration curve was 0.999 over the concentration range 2.0–100.0 mg L-1 and the LOD and LOQ values were 0.57 and 1.89 µg mL-1, respectively. The recoveries were from 83.7% to 97.2% with steam distillation as the sample pretreatment method.