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 (μ) of 0.3 M was found to be 10 5.2. The molar absorptivity was 1.05 × 10 4 1 mol −1 cm −1. Beer's law was obeyed at concentrations up to 60 μM. The detection limit was 0.55 μg 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.