Enhanced separation of purine and pyrimidine bases using carboxylic multiwalled carbon nanotubes as additive in capillary zone electrophoresis.

This paper describes the enhanced separation of adenine (A), hypoxanthine (HX), 8-azaadenine (8-AA), thymine (T), cytosine (C), uracil (U) and guanine (G) by CZE dispersing carboxylic multiwalled carbon nanotubes (c-MWNTs) into the running buffer. The effect of important factors such as c-MWNT nanoparticle concentration, the acidity and concentration of running buffer, and separation voltage were investigated to acquire the optimum conditions. The seven purine and pyrimidine bases could be well separated within 16min in a 35cm effective length fused-silica capillary at a separation voltage of +8.0kV in a 23 mM tetraborate buffer (pH 9.2) containing 8.0 x 10 -5 g/mL c-MWNTs. Under the optimal conditions, the linear ranges were of 2-250 μg/mL for A (R 2 = 0.995), 3-200 μg/mL for U (R 2 = 0.990) and G (R 2 = 0.992), 3-250 μg/mL for T (R 2 = 0.998), 2-200 pg/mL for C (R 2 = 0.985) and 4-200 μg/mL for HX (R 2 = 0.988) and 8-AA (R 2 = 0.990). The detection limits were 0.9 μg/mL for A (S/N = 3), 2.4 μg/mL for U, 2.0 pg/mL for T, 1.5 μg/mL for C, 2.5 μg/mL for G and 3.0 μg/mL for HX and 8-AA. The proposed method was successfully applied for determining five purine and pyrimidine bases in yeast RNA.