Extraction, Preconcentration, and Quantification of Low Levels of Free Formaldehyde from Some Beverage Matrices by Combination of Ultrasound-Assisted-Cloud Point Extraction with Spectrophotometry

In the present study, due to use of formaldehyde (FA) as a food additive as well as its endogenous and natural occurrence in aquatic products, a new preconcentration method for the quantification of free formaldehyde (FA) in beverages was developed before analysis by spectrophotometry at 538 nm. The method is based on spontaneously Cannizzaro disproportionation of FA with Variamine blue (VBH2) in the presence of ionic surfactant, sodium dodecylsulfate (SDS) as both sensitivity enhancer and counter ion at pH 7.0, and then extraction of the formed ion-pairing complex into the nonionic surfactant, polyethylene glycol tert-octylphenyl ether (Triton X-114). The effect of analytical variables was evaluated in detail, and the optimal working conditions were established. There was a rectilinear relationship in the range of 2-400 mu g L-1 with changing sensitivity. The limits of detection and quantification of the method with a sensitivity enhancement of 65 after preconcentration were 0.53 and 1.76 mu g L-1, respectively. The accuracy was validated by using two spiked quality control samples in linear working range and by comparing the results obtained from the samples with those of independent method, which is known as a slight modified acetylacetone method. It has been observed that the results obtained by both methods are statistically compatible with a t value ranging from 0.09 to 0.65 (t (critical) 2.31). The intra-day and inter-day precisions as a result of stabilization of mixed micellar system were lower than 4.9% (as RSD%, n 5), and the recoveries were quantitatively higher than 95% for the two quality control samples spiked with 10, 25, and 50 mu g L-1 with satisfactory results. The method was successfully applied to the quantification of low levels of free FA in selected beverage matrices.