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Zhong G.-X.,Hubei Research and Designing Institute of Mechanical Electronic Engineering | Huang Q.-H.,Hubei Research and Designing Institute of Building Material | Yan G.-H.,Hubei Research and Designing Institute of Mechanical Electronic Engineering
Yejin Fenxi/Metallurgical Analysis | Year: 2011

The content of aluminum in aluminum-manganese alloy was directly determined by fluoride replacement complexometric titration without pre-separation of iron and manganese. The samples were dissolved in hydrochloric acid and H 2O 2. Excessive EDTA solution was added in the presence of copper ion to complex with metals ions such as iron, manganese and copper. The solution was boiled to make aluminum completely form complex. The excessive EDTA was back-titrated with lead standard solution using PAN as indicator. Fluoride was added to demask Al-EDTA complex, and equivalent EDTA to aluminum was released. Then, it was titrated with standard lead solution to calculate the mass fraction of aluminum. The optimal analytical conditions were tested and obtained. This method was applied to determine aluminum in aluminum-manganese alloy, and the relative standard deviation (RSD) was smaller than 0.2%. The results were consistent with those obtained by classic alkali separation EDTA titration method. This method was used to determine the aluminum-manganese alloy sample containing 15%-30% aluminum in mass fraction.


Zhong G.-X.,Hubei Research and Designing Institute of Mechanical Electronic Engineering | Huang Q.-H.,Hubei Research and Designing Institute of Building Material | Gao L.,Jianghan University
Yejin Fenxi/Metallurgical Analysis | Year: 2012

The color reaction of chromogenic reagent chlorophosphonazo III and strontium was investigated. The experiments showed that in H 3PO 4 solution at pH 2.9, strontium reacted with chlorophosphonazo III to form a blue complex which exhibited an maximum absorption wavelength at 660 nm with apparent molar absorptivity of 2.67×10 4 L·mol -1·cm -1. Under the optimum experimental conditions, Beer's law was obeyed in the range of 0.04-1.6 mg/L for strontium, and the detection limit was 0.04 μg/mL. After iron was masked by EDTA-Mn solution, this method was used for the determination of strontium in strontium-bearing ferrosilicon samples. The results were in accordance with those obtained by atomic absorption spectrometry, the relative standard deviations (n=5) were 1.5%-2.2%, and the recoveries were 98%-102%.


Zhong G.-X.,Hubei Research and Designing Institute of Mechanical Electronic Engineering | Huang Q.-H.,Hubei Research and Designing Institute of Building Material
Yejin Fenxi/Metallurgical Analysis | Year: 2010

The color reaction between dibromo-p-nitro-chlorophosphonazo and iron could occur in 0.072 mol/L hydrochloric acid medium, forming a complex (2:1) which had maximum absorption at 610 nm. Beer's law was obeyed for iron in the range of 0.14-0.80 μg/mL. The apparent molar absorptivity of the complex was 1.63× 10 4 L·mol -1·cm -1. The proposed method was applied to the determination of iron in standard silicon iron sample, and the results were consistent with the certified values, giving RSD (n=6) of 1.4%-2.1%.


Zhong G.-X.,Hubei Research and Designing Institute of Mechanical Electronic Engineering | Huang Q.-H.,Hubei Research and Designing Institute of Building Material | Yang H.-Y.,Hubei Research and Designing Institute of Mechanical Electronic Engineering
Yejin Fenxi/Metallurgical Analysis | Year: 2010

The coloring reaction between chlorophosphonazo III and calcium was studied, and a determination method of calcium in silicon iron by spectrophotometry was established. The optimal reaction conditions were investigated and obtained. The results showed that in NH 3 · H 2O-NH 4Cl buffer solution at pH 10.0, the calcium(II) could form green complex with chlorophosphonazo III. The complex had maximum absorption at 672 nm, and the absorbency was in direct proportion to the concentration of calcium. Beer's law was obeyed for calcium in the range of 0.072-1.00 μg/mL. The detection limit of method was 0.022 μg/mL. After triethanolamine and ο-phenanthroline for masking aluminum, manganese and iron was added, the proposed method was applied to the determination of calcium in common silicon iron standard samples. The results were consistent with the certified values, and the relative standard deviation (RSD) was about 2.0%.

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