Determination of formaldehyde in bovine milk by micellar electrokinetic chromatography with diode array detection
Isaura Daniele Leite Faria, Marcos Martins Gouvêa, Annibal Duarte Pereira Netto, Flávia Ferreira de Carvalho Marques
Abstract
Formaldehyde has been illegally added to milk to reduce microbial activity and extend the shelf life of the product. In Brazil, the official method for formaldehyde detection in milk consists of a qualitative colorimetric analysis. This work aimed to develop a more sensitive method, based on Micellar Electrokinetic Chromatography with Diode Array Detection (MEKC-UV/DAD), to determine formaldehyde in bovine milk. Sample preparation consisted of formaldehyde derivatization with 2,4-dinitrophenylhydrazine followed by protein precipitation and extraction with acetonitrile. The method showed linearity in aqueous solutions and in milk in the range of 50.0–1000 μg/L (R2 > 0.99), LOQ of 50.0 μg/L, adequate precision (RSD <3.9%) and accuracy (average recovery: 94.2 ± 0.7%). Formaldehyde traces were found in two commercial milk samples. However, the concentration levels could not be considered adulteration because they were within the acceptable range of endogenous sources (0.1–0.3 mg/L). The usefulness and effectiveness of the developed method can contribute to increase food safety.