Determination of formaldehyde in bovine milk using a high sensitivity HPLC-UV method

A method of high performance liquid chromatography with UV detection (HPLC-UV) was implemented and validated for formaldehyde determination in bovine milk. A formaldehyde derivatization reaction with 2,4-dinitrophenylhydrazine, at pH 4.0, enabled its detection in milk at 360 nm. The clean up treatment of milk samples by liquid-liquid extraction with low temperature partitioning (LLE-LTP) was thoroughly optimized. The linearity of the method was shown by analytical curves ranging from 10.0 to 400.0 μg L− 1 in aqueous solutions and milk samples that were characterized by R2 > 0.99. The limit of quantification of 20.0 μg L− 1 demonstrated the high sensitivity of the method to determinate formaldehyde residues in milk. Extracts of milk samples fortified with formaldehyde at three concentration levels, led to a mean overall recovery of 102.2 ± 1.3% (n = 9), which satisfies the performance criteria established by the Codex Alimentarius for analytical methods suitable for determination of food residues. The accuracy was evaluated by comparison with a well-established procedure using the Student t-test. Comparable results were obtained at a 95% confidence level, demonstrating the usefulness and effectiveness of the proposed method.