Simultaneous determination of arsenate and phosphate by use of the kinetic wavelength-pair method

✍ Scribed by M. López Carreto; D. Sicilia; S. Rubio; D. Pérez-Bendito

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 758 KB
• Volume: 283
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(93)85260-q

✦ Synopsis

Ah&act

Application of the kinetic wavelength-pair method was extended to the fixed-time kinetic variant with the simultaneous determination of arsenate and phosphate based on the formation of a heteropoly acid with molybdate and subsequent reduction with ascorbic acid to molybdenum blue compounds with strongly overlapping spectra. Resolution of the mixture by using discrete wavelengths was impossible. Selectivity in the resolution was achieved by measuring the absorbance difference at the wavelength pair 820-740 nm and a fixed time of 100 s, where the contribution of phosphate was greatly decreased. Arsenate and phosphate were simultaneously determined in weight ratios between 5 : 1 and 0.3 : 1 at concentrations from 0.5 to 6 pg ml-', with relative standard deviations between 3% and 5% for arsenate and between 1.5% and 2.5% for phosphate. The theoretical basis adapted to first-order kinetic-based determinations was established.