Anisaldehyde-4-phenyl-3-thiosemicarbazone as an analytical reagent for the extractive spectrophotometric determination of gold

Abstract

The synthesis, spectral characteristics and analytical applications of anisaldehyde-4-phenyl-3-thiosemicarbazone (APT) are described. A simple, rapid, selective and sensitive spectrophotometric method for the determination of microgram amounts of gold, alone or in the presence of associated metals, is developed, based on the colour reaction between the metal ion and anisaldehyde-4-phenyl-3-thiosemicarbazone. The yellow-brown complex (λ_max.= 365 nm) is extracted into ethyl acetate. Gold(III) reacts with the reagent in the ratio 1 : 1 (metal to ligand) over the pH range 4.0–7.0. Beer's law is obeyed over the concentration range 0.1–12.3 µg ml^–1 of gold. The molar absorptivity and Sandell's sensitivity of the method are 2.12 × 10⁴ l mol^–1 cm^–1 and 0.0092 µg cm^–2, respectively. The relative standard deviation for ten replicate determinations of 45 µg of gold(III) was 1.71%. The interference of various ions has been studied and conditions were developed for the determination of gold in some synthetic samples.