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Page 427

Ahmad et al. [27] utilized an alumina column in conjunction with a direct current plasma emission
spectrometer (Spectraspan V. Beckman Instruments) to determine the speciation of chromium in
aqueous samples. The column was 10 cm long, 4.0 mm I.D. and the outlet of the columns was
connected directly to the peristaltic pump inlet system of the spectrometer. The arrangement was
extremely simple and provided very useful sensitivity. The peaks for Cr and Cr from four repetitive
III
VI
samples are shown in figure 10.16.

Figure 10.16
Separation of th Tri and Hexavalent
Chromium Ions on an Alumina Column (ref. 27)

The same mass was injected in each case but the sample was diluted x2, x4 and x8 and appropriately
increasing sample volumes injected onto the column to maintain a constant sample mass. The authors
pointed out that the peaks were not dispersed by the increase in sample volume and approximately the
same peak height was realized. This is hardly surprising, however, considering the relatively large
diameter of the column.

A Liquid Chromatography Atomic Absorption Tandem System Involving Thermochemical
Hydride Generation

As a result of the toxicity of arsenic compounds there has always been a considerable interest in
methods that could quantitatively assay trace amounts of arsenic. As already discussed, the discovery of
the presence of