Objective To establish a novel method for the determination of betaine in serum by high performance liquid chromatography with UV detection.Methods Pre-column derivatization of serum was performed directly in acetonitrile without extraction with p-bromophenacyl bromide and 18-crown-6 ether as catalyst.The p-bromophenacyl ester derivatives were then separated by Supelcosil LC-SCX, using an was 0.8 ml/min and the effluent was monitored at 259 nm. Betaine was used for preparation of standard curve and quantification with external standards.Results The linearity of this method was 6.25-200.00 μmol/L,the regression was 0.999 8.The detection limit was 3.0 μmol/L.The within-day imprecision was 1.88%-3.79% ( average 3.24% ), the between-day imprecision was 3.14%-6.76% ( average 4.39% ), the recovery rates were 95.89%-102.86% (average 99.16% ).Conclusion This method is sensitive, rapid, accurate and suitable for the research and routine clinical practice.

Atrioventricular Block ; Heart Septal Defects, Ventricular ; Humans