Simultaneous determination of bovine alpha-lactalbumin and beta-lactoglobulin in infant formulae by ultra-high-performance liquid chromatography-mass spectrometry.

A reliable ultra-high-performance liquid chromatography-mass spectrometry method for simultaneous determination of bovine alpha-lactalbumin (alpha-La) and beta-lactoglobulin (beta-Lg) was developed. Compared to the previous methods, the developed approach with mass spectrometer operated in selected area monitoring mode offered increased speed and enhanced lower detection limit. A linear gradient mobile phase, consisting of (A) water containing 0.1% trifluoroacetic acid (TFA) and (B) acetonitrile containing 0.1% TFA, and an Acquity UPLC BEH300 C18 column (150mmx2.1mm, 1.7microm) were employed to obtain the best resolution of the target analytes. The accurate quantitation was achieved by employing human alpha-lactalbumin as the internal standard. The established method was extensively validated by determining the linearity (R(2)>or=0.9991), sensitivity (limit of quantitation, 0.15-0.19microgmL(-1)), recovery (94.0-98.7%), precision (relative standard deviation<or=11.1%) and repeatability (relative standard deviation<or=5.7%). It was shown to be a suitable method for simultaneous determination of the major whey proteins in biological samples. Current validated method was successfully applied to the nutrient investigation of infant formulae.