Use of palladium(II) chloride as colour-forming reagent in determination of pralidoxime chloride in water and tablets.

Pralidoxime chloride (PAM-2Cl) has been determined spectrophotometrically in Britton-Robinson buffer solution at pH = 6.45; the method is based on measurement of the absorbance of the Pd(II)-pralidoxime complex at 327 nm. Studies of the composition of the complex by Job's continuous variation method, the molar ratio method and Bent-French's method yielded a Pd(II):pralidoxime ratio of 1:1. The conditional stability constant (K') of the complex at the optimum pH of 6.45 and an ionic strength (mu) of 0.3 M was found to be 10(5.2). The molar absorptivity was 1.05 x 10(4) 1 mol(-1) cm(-1). Beer's law was obeyed at concentrations up to 60 microM. The detection limit was 0.55 microg ml(-1). The relative standard deviation (N = 10) was 0.28-1.03%. The method was accurate and sensitive for the analysis of PAM-2Cl in water and tablets.