Determination of iron(II) and total iron using flow injection on-line preconcentration with FAAS

A direct, rapid and sensitive method for the determination of Fe(II) and Fe (III) in water samples by flame absorption spectrometry coupled with flow i njection on-line preconcentration with 1,10-phenanthroline (1,10-phen) as t he complex agent was developed. Various parameters affecting the complex fo rmation and its subsequent adsorption, such as pH of the mixture solution, 1,10-phen concentration, sample flow rate etc. were optimized. A 2.5 X 10(- 3) mol/L 1,10-phen in 2.0% ethanol was on-line mixed with aqueous sample so lution of iron in 0.1% (volume ratio) hydrochloric acid and flowed through the microcolumn for 30 s. Fe(II) can be extracted as Fe(II)-phen complex in the C-18 microcolumn and determined within 10 s in the nebulizer of FAAS a fter being eluted by ethanol. Ascorbic acid (0.1 mg/mL) was used for the re duction of Fe(III) to Fe(II). A good precision (RSD = 1.1%, n = 10), high e nrichment factor (19) and sample throughput (80 h) with detection limit 3 m u g/L were obtained. The method has been successfully applied on the water sample for Fe(II) and Fe(III) determination with the recovery 94%-105%.