Analysis of epsilon-N-2-furoylmethyl-L-lysine (furosine) in dried milk by capillary electrophoresis with controlled electroosmotic flow using N,N,N',N'-tetramethyl-1,3-butanediamine in the running electrolyte solution.

The electrophoresis of epsilon-N-2-furoylmethyl-L-lysine (furosine) was studied in an attempt to develop a method for the identification and quantitation of this compound in processed food. The effect of pH and composition of electrolyte solution on both the electrophoretic migration of furosine and the electroosmotic flow in a bare fused-silica capillary of 75 mu m internal diameter was investigated. We demonstrate that the addition, to the running electrolyte solution, of N,N,N',N'-tetramethyl-1,3-butanediamine (TMBD) at concentrations ranging from 20 to 80 mM improves peak efficiency and can be used to modulate the migration time of furosine by controlling the electroosmotic flow which is reversed from cathodic to anodic. In a sample of dried milk subjected to a long period of storage under controlled conditions, furosine could be efficiently and reproducibly separated and quantitated by employing as the running electrolyte 60 mM TMBD titrated to pH 2.5. Capillary electrophoresis is a promising technique for the rapid identification and quantitation of furosine in processed food.