Single-pulse nebulisation of 10 per cent. m/V iron or steel solutions into a nitrogen-diluted nitrous oxideacetylene flame maintained on a specially designed wide-slot burner is a useful technique for the determination of tin, arsenic and soluble aluminium in iron and steels. Use of this method avoids the need for prior separation of the analyte. A deuterium lamp was found to be unsatisfactory for measuring the background (non-specific) absorption when determining aluminium and tin, the explanation for which is postulated.
The determination of mercury by atomic absorption measurement of its vapour by a flameless method was first popularised by Hatch and Ott.1 Since that time the procedure has been improved considerably by a number of workers,2-4 and several commercial systems are available. The vapour technique has a number of advantages when compared with alternatives such as electrothermal atomisation atomic absorption spectrometry (AAS) and plasma atomic emission spectrometry. The apparatus is relatively inexpensive, as it usually comes in the form of an attachment to an existing atomic absorption spectrometer and sensitivity is good. A disadvantage of the AAS technique is that spectral interferences can, and do, occur. The most severe of these is the non-specific absorption that takes place when organic vapours are released into the absorption cell.5 However, this may often be overcome by using automatic background correction techniques. In common with most absorption techniques the linear calibration range is somewhat limited. The atomic fluoresescence spectrometric determination of mercury, when liberated as a vapour by reduction with acidified SnC12, has been reported by several workers.5-8Atomic fluoresence spectrometry (AFS) appears to be the preferred technique for several reasons. The apparatus can be made simple, hence inexpensive, and superior sensitivities and detection limits are often achieved. Interferences are reduced considerably and calibration is linear over several orders of magnitude.The disadvantages of the fluorescence system described by Thompson and Reynolds6 and subsequently improved by Thompson and Godden7 are that an atomic absorption spectrometer is required and the time and skill that are required to install the accessory correctly. Several workers have designed non-dispersive cold vapour fluorescence systems and many different features have been described. These include the use of a solar blind p h ~t o r n u l t i p l i e r , ~~~ amalgam traps5J0 and a monochromator.10 A much simpler system, using a mercury discharge bulb as the light source, a 10-mm silica tube as the mercury cell and an EM1 9781B photomultiplier tube as the detector, has been described by Hutton and Preston.11 It was considered that a combination of many of the ideas described above could lead to the construction of a simple and very sensitive mercury detector. It would also be possible to automate these determinations further either for on-line applications or, in the laboratory, by the addition of an autosampler system.
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