Flame Atomic Absorption Spectrometric Detection Research Articles

Determination of chromium(III) and chromium(VI) in water using flow injection on-line preconcentration with selective adsorption on activated alumina and flame atomic absorption spectrometric detection

A rapid and sensitive method for the species-selective determination of chromium(III) and chromium(VI) in water samples by flame atomic absorption spectrometry using online preconcentration on a microcolumn packed with activated alumina (acidic form) has been developed. Sequential species-selective sorption was possible by using the Clark-Lubs systems with pH 7 for Cr(III) and pH 2 for Cr(VI). The preconcentrated species were eluted directly from the column to the nebulizer-burner system using 1.0 mol/L nitric acid and 0.5 mol/L ammonia for Cr(III) and Cr(VI), respectively

On-line microwave digestion of slurry samples with direct flame atomic absorption spectrometric elemental detection

A flow injection (FI) system for on-line microwave digestion of slurried samples with direct elemental determinations by flame atomic absorption spectrometry is described. Organically based elemental reference samples were prepared as slurries in 5% v/v HNO3 and the system was optimized for slurry mass, acid strength and tube and microwave cavity geometry. Bubble formation during digestion was controlled by post-digestion cooling and pressure regulation. Comparison of direct and FI calibrations indicated no apparent loss in sensitivity. Various samples were examined and elemental recoveries for Ca, Fe, Mg and Zn were typically found to be in the range 94–107% with precisions of less than 4.5% relative standard deviation. The major source of error was found to be in the dispersion of solids (<180 µm) as slurries in dilute HNO3. The through put of samples in the system developed was found to be 1–2 min per sample.

The determination of trace amounts of heavy metals in waters by a flow-injection system including ion-exchange preconcentration and flame atomic absorption spectrometric detection

The flow-injection system combines on-line ion-exchange preconcentration with atomic absorption spectrometry (a.a.s.) for the determination of traces (μg l −1) of heavy metals in water samples. Miniature columns packed with 60–100 mesh chelating resin (122) with a salicylic acid functional group are used for preconcentration. A multifunctional rotary sampling valve which incorporated two parallel sampling columns allows sampling, exchange, elution and a.a.s. to be achieved sequentially. The increases in sensitivity for nickel, copper, lead and cadmium were 20–28-fold at a sampling rate of 40 h −1 with 5-ml samples. Relative standard deviations were 1.5–4.1%. The recoveries of these four metals added to tap, sea and polluted waters were generally satisfactory, except for cadmium in polluted water. The effects of column diameter and elution flow rates on sensitivity are discussed. Possible interferences are described.