Quantification of plasma lactate concentrations using capillary electrophoresis with contactless conductivity detection.

The quantification of plasma lactate and evaluation of the lactate threshold by CE with capacitively coupled contactless conductivity is demonstrated. The only sample preparation needed was deproteinization with a ACN/methanol mixture. A solution of 10 mmol/L 2-morpholinoethanesulfonic acid monohydrate, 10 mmol/L DL-histidine, 70 μmol/L hexadecyltrimethylammonium bromide, pH 6.0 was found suitable as running buffer. Linearity was achieved for the concentration range of 10-1000 μmol/L with a correlation coefficient of 0.9994. The limit of detection (3 S/N) was determined as 3.2 μmol/L. Intra- and inter-day variabilities were less than 7% RSD. The suitability of the method could be demonstrated by analyzing various clinical samples, where the results correlated satisfactorily with those of an established enzymatic method.