Glow-discharge sampling calibration

Models and calibration in methods involving glow-discharge sampling... 

As the sample volatilization is due to cathodic sputtering only, matrix interferences as a result of the thermochemical properties of the elements do not occur. This has been shown impressively in early comparative studies of glow discharge atomic spectrometry and spark emission spectrometry with aluminum samples (Fig. 107) [480]. It must be stated, however, that with advanced sparks, where through the use of fiber optics only those parts of the spark plasma are observed that are not involved in sample ablation, matrix interferences in the case of spark emission spectrometry are also lower. The analysis of similar alloys with different metallographic structures by glow discharge atomic spectrometry can often be carried out with one calibration. 

Pajo et al. (2001a) used GD-MS to measure impurities in uranium dioxide fuel and showed that these impurities could be used to identify the original source of confiscated, vagabond nuclear materials. De las Heras et al. (2000) used GD-MS to determine neptunium in Irish Sea sediment samples. The sediment samples were compacted into a disk that was used with a tantalum secondary cathode in the glow discharge. Using a doped marine sediment standard for calibration, detection limits down to the mid pg/g level were determined. 

Generally, AES systems are calibrated with multi-element standard samples. In the case of sparks, arcs, glow discharges, and laser ablation, solid samples are required, which are rarely available in large enough numbers to provide a satisfactory calibration. Hence, in solid sample analysis secondary standards are usually prepared. 

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