A Rapid and Direct Sensitive Spectrophotometric Method for the Determination of Molybdenum(VI) using Gallacetophenone Phenylhydrazone with Application to Alloy Steel Samples

Abstract

A rapid, sensitive and fairly selective spectrophotometric method has been developed for the determination of molybdenum(VI) using gallacetophenone phenylhydrazone (GPPH) as an analytical reagent. The GPPH forms an orange red species of molybdenum(VI) at a pH range of 3.0-4.0 and the complex is soluble in 20% ethanol. The Mo(VI)-GPPH complex shows maximum absorbance at 375 nm with molar absorptivity and Sandellʼs sensitivity being 1.539x10⁴ L/mol cm and 1.5x10^-3 μg cm^-2 respectively. The system obeys Beerʼs law in the range of 1.0-6.0 μg/mL. The repeatability of the method was checked by finding the relative standard deviation. The composition of the Mo(VI)-GPPH complex is established as 1:2 by slope analysis method. The instability constant of the complex calculated from Edmond and Birnbaumʼs method is 6.785x10^-8 at room temperature. The interfering effect of various cations and anions has also been studied. The method has been applied for the determination of Mo(VI) in alloy steel samples.