Stopped-flow determination of procaine hydrochloride in pharmaceutical preparations

A stopped-flow photometric method for the quantitative determination of procaine hydrochloride is proposed. It is based on the measurement of the rate of formation of a coloured product between procaine and sodium 1,2-naphthoquinone-4-sulphonate. The conversion of an equilibrium method to a kinetic method by the stopped-flow technique results in an improved detection limit and linear range, and in considerably increased sample throughput. A simple modular stopped-flow system has been used for this purpose. The results obtained on application of this method to the determination of procaine in various pharmaceutical preparations, show the suitability of the stopped-flow technique for routine pharmaceutical analyses.