Simultaneous spectrophotometric determination of palladium(II) and gold(III) with methiomeprazine hydrochloride: analysis of alloys and minerals

Abstract

Methiomeprazine hydrochloride (MMH) is proposed as a reagent for the simultaneous spectrophotometric determination of palladium(II) and gold(III). The reagent instantaneously forms an orange-red 1:1 complex with palladium(II) and a blue species with gold(III) in hydrochloric acid-sodium acetate buffer. The palladium-MMH complex has an absorption maximum at 480 nm with a molar absorptivity of 3.6 × 10³ l mol^–1 cm^–1. The blue species has an absorption maximum at 630 nm with a molar absorptivity of 1.3 × 10⁴ l mol^–1 cm^–1. Beer's law is obeyed for the range 0.4–21 p.p.m. of palladium(II) and 0.2–10 p.p.m. of gold(III). Molar excesses of 4-fold and 35-fold of the reagent are required for palladium(II) and gold(III), respectively. The concentration of two metals in an unknown mixture can be simultaneously determined in the range of 0.5–15 p.p.m. of palladium(II) and 1–10 p.p.m. of gold(III) using the following equations: [Pd]× 10⁴= 3.023A₄₈₀– 0.840 3A₆₃₀[Au]× 10⁴= 0.8177A₆₃₀– 0.195 9A₄₈₀ The method has been used successfully for the determination of palladium and gold in alloys and minerals.