FLOW-INJECTION FLAME ATOMIC-ABSORPTION SPECTROMETRY FOR SLURRY ATOMIZATION - DETERMINATION OF IRON, CALCIUM AND MAGNESIUM IN SAMPLES WITH HIGH-SILICA CONTENT
Il. Garcia et al., FLOW-INJECTION FLAME ATOMIC-ABSORPTION SPECTROMETRY FOR SLURRY ATOMIZATION - DETERMINATION OF IRON, CALCIUM AND MAGNESIUM IN SAMPLES WITH HIGH-SILICA CONTENT, Talanta, 40(11), 1993, pp. 1677-1685
A study on the use of slurries in flame atomic absorption spectrometry
is reported. Samples with a very high silica content are ground and t
hen slurried in a solution containing 2% hydrochloric and 3% v/v hydro
fluoric acids. The suspensions are prepared in the 0.01-1% m/v range a
nd introduced into the flame by means of a simple flow injection manif
old. Relative standard deviations for the measurements of iron, calciu
m and magnesium in diatomaceous earth samples are in the 1.5-2.8, 2.2-
5.3 and 2.8-5.0% ranges, respectively. To avoid the use of suspensions
prepared with a very low percentage of solid sample and to improve th
e reproducibility, an on-line dilution manifold is tried. The use of a
n easy-to-construct variable volume dilution chamber allows the on-lin
e dilution of the slurries, thus permitting the determination of calci
um and magnesium over a wide range of concentrations. Calibration is p
erformed using aqueous standards. The experimental conditions, optimiz
ed for the determination of iron, calcium and magnesium in diatomaceou
s earth samples, can also be applied to other silica-based materials,
as is shown by the analysis of several standard reference materials.