Rapid determination of meldonium in urine samples by capillary electrophoresis with capacitively coupled contactless conductivity detection.

Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) was employed for fast determination of meldonium (MEL) in urine samples. Background electrolyte consisting of 2M acetic acid (pH 2.3) was used for separation of MEL from cationic compounds present in urine samples and the overall analysis time was less than 4min per sample. Direct injection of urine samples was possible after 1:9 dilution with deionized water. This simple sample pretreatment was sufficient to eliminate possible matrix effects on CE performance and allowed for precise and sensitive determination of free MEL in urine. Excellent linearity (r2≥0.9998) was obtained for two concentration ranges, 0.02-4μgmL-1 and 2-200μgmL-1, by simply changing injection time from 10 to 2s without the need for additional dilution of urine samples. Limit of detection was 0.015μgmL-1 and average recoveries from urine samples spiked at 0.02-123.5μgmL-1 MEL ranged from 97.6-99.9%. Repeatability of migration times and peak areas was better than 0.35% and 4.2% for intraday and 0.95% and 4.7% for interday measurements, respectively. The above reported data proved good applicability of the CE-C4D method to determination of various MEL concentrations in urine samples and good long-term performance of the analytical system. The method might be particularly useful in analyses of large batches of samples for initial testing of MEL-positive vs. MEL-negative urine samples.