title: Catalytic spectrophotometric determination of trace aluminium with indigo carmine.
abstract: A new catalytic spectrophotometric method is described for the determination of trace amounts of Al(III). The methods based on catalytic action of Al(III) on the oxidation of indigo carmine (IC) by ammonium persulfate in hexamethylene tetramine-hydrochloric acid ((CH2)6N4-HCl) buffer medium (pH 5.4) and in the presence of surfactant-TritonX-100. The effects of some factors on the reaction speed were investigated. Aluminium concentration is linear for 0-1.2x10(-7) g/ml in this method. The detection limit of the proposed method is 1.96x10(-8) g/ml. Most of the foreign ions except for Cu(II), Fe(III) do not interfere with the determination, and the interference of Cu(II) and Fe(III) in this method can be removed by extraction with sodium diethyldithiocarbamate-carbon tetrachloride (DDTC-CCl4). This system is a quasi-zero-order reaction for Al(III), but it is a quasi-first-order reaction for IC. The apparent rate constant is 2.62x10(-5) s-1 and the apparent activation energy is 6.60 kJ/mol in the system. The proposed method was applied to the determination of trace aluminium(III) in real samples with satisfactory results.
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, PR China. zhenghl@cta.cq.cn
authors.forename: Huai-Li
authors.initials: HL
authors.lastname: Zheng
authors.forename: Wen-Qiang
authors.initials: WQ
authors.lastname: Xiong
authors.forename: Ying-Kun
authors.initials: YK
authors.lastname: Gong
authors.forename: De-Jun
authors.initials: DJ
authors.lastname: Peng
authors.forename: Ling-Chun
authors.initials: LC
authors.lastname: Li
mesh_terms: D000535:Aluminum / Q000032:analysis*; D002138:Calibration; D002384:Catalysis; D006801:Humans; D007202:Indicators and Reagents / Q000737:chemistry; D007203:Indigo Carmine / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014131:Trace Elements / Q000032:analysis*
chemical_list: D007202:Indicators and Reagents; D016877:Oxidants; D013501:Surface-Active Agents; D014131:Trace Elements; D000535:Aluminum; D007203:Indigo Carmine