SPECIATION OF Fe(Ⅲ) AND Fe(Ⅱ) IN WATER SAMPLES BY LIQUID-LIQUID EXTRACTION COMBINED WITH LOW-TEMPERATURE ELECTROTHERMAL VAPORIZATION (ETV) ICP-AES

摘要

The use of 1-phenyl-3-methyl-4-benzoylpyrazolone (PMBP) as extractant for separation of Fe(Ⅲ) and Fe(Ⅱ) and low-temperature vaporization of the Fe(Ⅲ)-PMBP chelate into ICP-AES for their speciation analysis was investigated. The factors affecting the formation of Fe(PMBP)_3 chelate and its vaporization behavior were investigated in detail. PMBP was used not only as the extractant for the separation of Fe(Ⅲ) and Fe(Ⅱ) but also as the chemical modifier for the low-temperature ETV-ICP-AES determination of iron. Under the optimized conditions, the detection limit for iron(Ⅲ) and iron(Ⅱ) are both 3.2 ng/mL, with relative standard deviations of 3.9 and 4.5%, respectively. The proposed method was applied to the determination of trace iron in biological standard reference materials and the species in East Lake water samples, and the results obtained were satisfactory.