Improvement of performance of anti-cancer (dacarbazine) drug sensor utilizing tetraphenylborate anion

A sensor for dacarbazine, an anticancer drug denoted DAC, is presented. A dacarbazine-modified carbon paste electrode was fabricated and improved by incorporation of sodium tetraphenylborate as an additive. Dacarbazine–phosphotungstate, a salt of dacarbazine abbreviated DAC-PT, was used in a carbon paste electrode as an ion-pair. Incorporation of sodium tetraphenylborate abbreviated STPB as an additive distinctly improved the slope from 43.7±0.3 to 55.6±0.3 mV per decade of DAC‏ ion. The present electrode exhibits linearly over a wide concentration range from 1.80 × 10^-6 to 1.0 × 10^-2 M with a notably small detection limit of 8.9 × 10^-7 M in a significantly fast response time (~ 5 s). These measurements are independent of the pH of the test solution in the pH range 3.2 to 9.5. The present sensor has distinct selectivity toward the drug ion over other common inorganic ions, sugars, amino acids, and drugs. This sensor was satisfactorily used as an indicator in potentiometric titrations and determination of dacarbazine in pharmaceutical preparations and urine samples.