Abstract
A simple method based on miniaturized dispersive liquid–liquid extraction is reported for extraction and preconcentration of formaldehyde in water samples. Eight milliliters of an aqueous sample containing 2,4-dinitrophenylhydrazine were added to a 10.0 mL volumetic flask containing 1.0 mL of methanol–butyl acetate (2: 1) mixture. After phase separation the analyte was determined by HPLC-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 × 10–4–10 µg/mL (r = 0.996), and the limit of detection was 5 × 10–5 µg/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%.
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