Separation and determination of carnitine and acyl-carnitines by capillaryelectrophoresis with indirect UV detection

A new capillary zone electrophoretic (CZE) method has been developed for th e simultaneous determination of carnitine, acetyl-carnitine, hexanoyl-carni tine, octanoyl-carnitine, decanoyl-carnitine and lauroyl-carnitine with ind irect photometric detection. Two selected buffers were evaluated and optimi zed; the first one used copper sulfate and methanol, and the second used qu inine as the principal constituent. Different chemical variables were evalu ated and optimized in order to setup the most appropriate system for separa ting the acyl-carnitines. The robustness test showed that the quantitative responses (areas and heights) were affected mainly by pH and quinine concen tration, while the migration times were influenced by quinine concentration , pH, voltage and temperature. The present method achieved times of separat ion of 20 min for six carnitine compounds with complete resolution of all c ompounds. The detection Limits of the method were between 0.2 and 2.5 mu g ml(-1) using electrokinetic injection and reproducibility (RSD%) was betwee n 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. (C) 1 999 Elsevier Science B.V. All rights reserved.