Separation and determination of carnitine and acyl-carnitines by capillary electrophoresis with indirect UV detection Original Research Article

A new capillary zone electrophoretic (CZE) method has been developed for the simultaneous determination of carnitine, acetyl-carnitine, hexanoyl-carnitine, octanoyl-carnitine, decanoyl-carnitine and lauroyl-carnitine with indirect photometric detection. Two selected buffers were evaluated and optimized; the first one used copper sulfate and methanol, and the second used quinine as the principal constituent. Different chemical variables were evaluated and optimized in order to setup the most appropriate system for separating the acyl-carnitines. The robustness test showed that the quantitative responses (areas and heights) were affected mainly by pH and quinine concentration, while the migration times were influenced by quinine concentration, pH, voltage and temperature. The present method achieved times of separation of 20 min for six carnitine compounds with complete resolution of all compounds. The detection limits of the method were between 0.2 and 2.5 μg ml−1 using electrokinetic injection and reproducibility (RSD%) was between 2.1 and 7.7%. The proposed method was applied to determine carnitines in synthetic samples; the recoveries of the compounds were between 95 to 110% in different samples and the errors were lower than 10% in all cases.