Determination of dabrafenib and trametinib in serum by dispersive solid phase extraction with multi-walled carbon nanotubes and capillary electrophoresis coupled to ultraviolet/visible detection

Abstract

Dispersive solid phase extraction (DSPE) prior to capillary electrophoresis with ultraviolet and visible detection was used for the first time for the determination of dabrafenib (DB) and trametinib (TT), the main drugs used for the treatment of metastatic melanoma, in serum. Six different magnetic and non-magnetic nanomaterials were evaluated as DSPE sorbents for the extraction and preconcentration of the analytes. The best results were obtained with 4 mg of pristine multi-walled carbon nanotubes in phosphate buffer (pH 12.5; 10 mM). The electrophoretic separation was carried out in a fused silica capillary (30 cm × 75 µm i.d.) at 22 °C in a voltage ramp (8–12 kV) with a background electrolyte consisting of borate buffer (pH 9.2; 25 mM), 37 mM sodium dodecylsulfate, 22% (v/v) acetonitrile and 3% (v/v) methanol.The preconcentration factor achieved was 4, and the limits of detection were 0.012 and 0.008 mg L−1 for DB and TT in serum, respectively. Linearity was observed up to 5 mg/L and precision (n = 7) was below 3% in migration time and 7.8% in peak areas. The present method was applied to six patients under treatment with DB and TT for metastatic melanoma. It requires a less sophisticated instrumentation and lower volume of harmful organic solvents than the methods reported up to present.