Preparation and characterization of a codeine responsive electrode

The behaviour of codeine reineckate and codeine tetraphenylborate membrane electrodes has been observed with a respective Nernstian response of 58 and 56 mV/decade for 9.3 x 10(-5)-1.3 x 10(-3) M codeine sulfate solutions. The working pH ranges were 5-8 and 4-8, respectively. The selectivity towards sugars, amines, amino acids, cations, and some pharmaceutical compounds was found to be satisfactory. The isothermal temperature coefficient was 0.0014 V/degrees C. The electrodes were applied successfully for the determination of codeine in some pharmaceutical dosage forms with a relative standard deviation range of 0.16-0.30% and an average recovery of 98.6 +/- 0.6%.