Determination of Lysinoalanine in Dairy Products by High Performance Liquid Chromatography (HPLC)

Jasim M. S. Al-Saadi


Reversed-phase high performance liquid chromatography was used for determination of lysinoalanine (LAL) in milk and milk products after derivatization with dansyl chloride. A new derivatization method was used which is easier and faster, and requires less reagent than other methods. The recovery of a LAL standard was 95–102%, the coefficients of variation for elution time reproducibility, peak area reproducibility and repeatability were 1.36, 0.82 and 2.4% respectively, while the minimum detectable amount of LAL was 0.2 ng for a LAL standard and 2 ng for a milk sample. The average lysinoalanine concentrations, determined using this new method, in raw and UHT milk were 9.4 and 87.1 ppm crude protein respectively, while the concentrations in infants formula, low-heat skim milk powder, medium-heat skim milk powder high-heat skim milk powder and sodium caseinate were 124.9, 49.4,179.9, 294.6 and 856.1 ppm crude protein respectively.

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