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 ( II ) in water samples by flame absorption spectrometry coupled with flow injection on-line preconcentration with 1,10-phenanthroline (1,10-phen) as the complex agent was developed. Various parameters affecting the complex formation and its subsequent adsorption, such as pH of the mixture solution, 1,10-phen concentration, sample flow rate etc. were optimized. A 2.5×10-3mol/L 1,10-phen in 2.0% ethanol was on-line mixed with aqueous sample solution 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 C18 microcolumn and determined within 10 s in the nebulizer of FAAS after being eluted by ethanol. Ascorbic acid(0. 1 mg/mL) was used for the reduction of Fe( II ) to Fe( II ). A good precision(RSD=1. 1%, n= 10), high enrichment factor(19) and sample throughput(80 h) with detection limit 3 μg/L were obtained. The method has been successfully applied on the water sample for Fe ( II ) and Fe ( II ) determination with the recovery 94%-105%.