Papers by Author: Lu Chen

Abstract: A new method for the determination of manganese in food grade FeSO₄•7H₂O samples by flame atomic absorption spectrometry (FAAS) after solid phase extraction was developed. The research showed that when coexistent amount of iron was greater than or equal to 100 times of manganese, the relative error of direct determination of manganese by FAAS was greater than or equal to +5%. Firstly, Fe²⁺ was oxidized to Fe³⁺ by HNO₃. Fe³⁺ was masked by EDTA. Mn²⁺ ions were then adsorbed by strong acid cation exchange fiber (SACEF) in pH 1.5 sample solution for 10 minutes and eluted by 2.5 mol/L HNO₃ for 15 minutes. Iron and manganese can be effectively separated by this method. Under the optimum conditions, the adsorption capacity of SACEF to Mn²⁺ ions was attained to be 9.27 mg•g^-1. The detection limit of the method was 0.032 μg•mL^-1. The proposed method was used for determination of manganese in three batches of FeSO₄•7H₂O samples. The contents of manganese were 325 μg/g, 823 μg/g, 772 μg/g respectively. The recoveries were in the range of 96.1%~103 % and RSDs (n=5) were less than 3.0%.

Abstract: The reasearch shows that when the mass ratio of copper to iron is equal or greater than 100, the influence of copper on the determination of trace iron can not be ignored. To eliminate the interference, the polypropylene radical strong base anion ion exchange fiber was taken as the solid phase extraction solvent. Extraction and separation of trace iron (Ⅲ) from solution copper (Ⅱ) by the extraction solvent was studied. The extraction conditions including of adsorption and elution were optimized. The strong base anion ion exchange fiber was put into the analysis solution with the medium of 6mol/L HCl. After adsorption 1h by vibration on the oscillator, adsorptive iron(Ⅲ) was eluted with the 1mol/L HCl. The concentration of iron (Ⅲ) in the eluate solution was mesured by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that the residual Cu (Ⅱ) in the eluate solution did not affected the accurate determination of iron. The iron in metal copper, copper oxide and copper nitrate were separated and determinated, and the RSDs(n=3) were between 2.3% and 4.2%, the recoveries were between 96% and 103%, the detection limit of the method was 0.011μg/mL.