Determination of carnitine in food and food supplements by capillary electrophoresis with contactless conductivity detection

A CE method with capacitively coupled contactless conductivity detection was developed and tested for the quantification of carnitine in different types of foodstuffs, namely fruit juices, milk, yogurt, cheese, red meat and chicken meat. Sample preparation was minimal as chemical or enzymatic conversion of the analyte is not necessary with the non-UV-absorbing compound when conductivity detection is employed. A 500 mmol/L acetic acid solution at pH 2.6 with 0.05% Tween-20, was used as the optimized running buffer. The analysis time was approximately 4 min. Linearity was achieved for the concentration range of 5-500 micromol/L with a correlation coefficient of 0.9996. The LOD (3 signal/noise) was determined as 2.6 micromol/L. Intra- and inter-day variabilities were less than 10% for both migration time and peak area, indicating a good precision of the method.