Spectrofluorimetric determinations of chromium, selenium and manganese in their mixtures and their application to environmental and biological samples

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "dejavu="" sans";mso-hansi-theme-font:minor-latin;mso-bidi-font-family:mangal;="" mso-bidi-theme-font:minor-bidi;color:#00000a;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Highly sensitive and selective fluorimetric methods have been developed for sequential determination of ultratrace amounts of toxic metals, Cr, Se, Mn present in mixtures and in biological samples. These are based on a novel oxidative action of Cr(VI), Se(IV) and Mn(Vll) on nonfluorescent 2-(α-pyridyl) thioquinaldinamide, PTQA, in different acidic media, Le., 0.9-0.54 M H₂SO₄ (for Cr), 0.05-0.15 M H₂SO₄ (for Se) and 0.033-0.833 M H₃PO₄ (for Mn) to produce intensely fluorescent oxidized product of the reagent, having excitation and emission wavelength maximum at 360 and 500 nm respectively. Sequential determination of Cr, Se and Mn in their mixtures at different mass ratios has been achieved with high accuracies. The method has been applied to the environmental analysis of biological materials, e.g., aquatic fish samples after destruction of organic matter with HNO₃HCIO₄-H₂SO₄. The standard deviation for analysis is ±0.003 for Cr; ±0.004 for Se and ±0.0014 for Mn in mixture while their corresponding values are ±0.3, ±0.3 and ±0.5 in fish samples. The methods are simple, rapid and highly reproducible and do not require any cleanup or enrichment step.</span>