Determination of pseudoephedrine hydrochloride and dextromethorphan hydrobromide in cold tablet by micro-fluidic chip

A method was established for the determination of pseudoephedrine hydrochloride and dextromethorphan hydrobromide in Bufferin Cold Tablet by micro-fluidic chip with contactless conductivity detection. The electrophoretic parameters, such as the variety and concentration of buffer solution, separation voltage etc. were researched. Pseudoephedrine hydrochloride and dextromethorphan hydrobromide in the Bufferin Cold Tablet were separated in buffer of 20 mmol/L Tris + 20 mmol/L H3BO3 (pH 8.0) at 3.0 kV of constant voltage, and detected at frequency of 60 kHz and excitation voltage of 60 V(Vp-p). The linear concentrations of pseudoephedrine hydrochloride and dextromethorphan hydrobromide ranged from 20 mg/L to 1000 mg/L (r = 0.999) and from 10 mg/L to 1000 mg/L (r = 0.998), respectively, the limits of detection (LOD) reached 10 mg/L and 5.0 mg/L (S/N =3), respectively. The average recoveries were 99.3% (RSD = 1.4%, n =6) and 97.6% (RSD = 1.9%, n = 6), respectively. The method was rapid, effective, simple and sensitive; it could be used in the quality control of the product.