dual stage preconcentration system for flame atomic absorption spectrometry using flow injection on-line ion-exchange followed by solvent extraction |
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Authors: | Guanhong Tao and Z Fang |
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Institution: | (1) Flow Injection Analysis Research Center, Box 332, Department of Chemistry, Northeastern University, Shenyang, 110006, China, CN |
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Abstract: | A dual stage preconcentration system based on flow injection on-line ion-exchange and solvent-extraction has been developed
for flame atomic absorption spectrometry. Lead is taken as a model trace element. A column packed with Amberlite IRC-718 cation
exchanger is incorporated into the FI manifold. The analyte is retained on the column by time-based sample loading and eluted
by 1 mol/L HNO3. The eluate is subsequently merged with potassium iodide and tetrabutylammonium bromide (TBABr), and isobutyl methyl ketone
(IBMK). Lead is extracted on-line into IBMK as the ion-pair formed between the iodoplumbate anion and tetrabutylammonium cation.
The organic phase is separated from the aqueous phase by a gravity phase separator. 50 μL of concentrate is introduced into
the nebulizer-burner system of the spectrometer. An enhancement factor of 550 is achieved with a 30 mL sample consumption
at a sampling frequency of 30/h. The precision (relative standard deviation) is 2.4% at 10 μg/L level and the detection limit
is 0.3 μg/L (3 σ). The method was successfully applied to the determination of lead in water samples.
Received: 19 March 1997 / Revised: 24 June 1997 / Accepted: 27 June 1997 |
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