APPLICATION OF LOW DENSITY MINIATURIZED DISPERSrVE LIQUID-LIQUID EXTRACTION METHOD FOR DETERMINATION OF FORMALDEHYDE IN AQUEOUS SAMPLES (WATER, FRUIT JUICE AND STREPTOCOCCUS VACCINE) BY HPLC-UV

摘要

A simple method based on miniaturized dispersive liquid-liquid extraction is reported for extraction and pre-concentration of formaldehyde in water samples. Eight milliliters of an aqueous sample containing 2,4-dini-trophenylhydrazine were added to a10.0 mL volumetic flask containing 1.0 mL of methanol—butyl acetate (2:1) mixture. After phase separation the analyte was determined by H PLC-UV. No clean-up or evaporation were required after extraction. Several factors influencing the extraction efficiency, such as the type and volume of organic solvent, type and volume of co-solvent, pH of the sample solution, ionic strength, and extraction time were evaluated and optimized. Under optimal experimental conditions, good linearity was obtained in the range of 1.5 x 10~4-10 pg/mL(r= 0.996), and the limit of detection was 5 x 10"5 ug/mL. The method produced 20-fold enrichment of the formaldehyde. The average recovery of spiked formaldehyde in real samples was in the range of 90-110% with RSD in the range of 3—8%.