DETERMINATION OF NOVACAINE, SOVCAINE, AND TRIMECAINE USING ION-SELECTIVE ELECTRODES

Novocaine, Sovcaine and Trimecaine, which find application as active local anesthetics [1], are manufactured in the form of powders and ampules (from 1.0 to 10.0 ml in volume) with a medicinal preparation content of 0.25 to 1.00%. The Control and Analysis Service has recommended that these compounds be assayed by using a titrimetric method based on an oxidation-reduction reaction (sodium nitrite titrant) or by acid-base titration in nonaqueous systems [2]. These latter techniques have the disadvantage of low sensitivity and selectivity, and the subjective elements involved in identifying the indicator color change, which leads to errors in fixing the indicator signal. Highly sensitive preextraction-photometry methods can also be employed, but the length and complexity of analysis, coupled with the toxicity and expense of the reagents required, limit their use for series analyses. In their current work the authors set out to develop a technique for determining these preparations by direct potentiometric means, using ion-selective electrodes (ISE); these comprised a polyvinyl chloride membrane containing dibutylphathalate and an electrode-active substance, in this case 12-molybdophosphate salt with the cation of the nitrogen-containing medicinal substance under analysis.