Spectrophotometric determination of magnesium in the presence of polyvinyl alcohol

Article type: Research Article

Authors: Tang, Yan-Ru^{; *}

Affiliations: College of Chemistry, Changchun Normal University, Changchun, Jilin Province, China

Correspondence: [*] Corresponding author: Yan-Ru Tang, College of Chemistry, Changchun Normal University, Changchun 130032, Jilin Province, China. E-mail: [email protected].

Abstract: The optimum conditions of complex color reaction between Mg2+ and arsenazo-III (ASA-III) in the presence of polyvinyl alcohol were studied. In the medium of pH 10.0 ammonia-ammonium chloride, Mg2+ and ASA-III form a 1:2 purple complex and the maximum absorption peak is at 574 nm. At this wavelength, the absorbance (A) is linearly related with the concentration of Mg2+ over the range of 0.1–2.5 μg/mL and its equation: A = 0.4969 C (μg/mL)+0.0634, with a regression coefficient of 0.9993. The apparent molar absorption coefficient of method is 1.35×104 L·mol–1·cm–1 and its detection limit is 76 ng/mL. Appropriate amount of polyvinyl alcohol can make sensitivity of the determination of magnesium increase 10.1%. The method was used to determine magnesium in potato and salt samples. The recovery of the standard addition was 99.6%–100.5%. The relative standard deviation was less than 5% for thirteen replicate determinations. The reliability of this method has been certified by parallel determination against atomic absorption spectrometric method.

Keywords: Magnesium, spectrophotometry, arsenazo-III, polyvinylalcohol, potato, sodium chloride

DOI: 10.3233/MGC-170638

Journal: Main Group Chemistry, vol. 17, no. 3, pp. 191-196, 2018