Graphite platform

Fig. 8.3. (A) Scheme of a graphite-ETV modified for ICP-AES work (1) graphite tube, (2) graphite platform, (3) electrical contacts, (4) cooling water chambers, (5) protecting gas chambers, (6) automatic shutter, (7) ETV-ICP connecting interface. (B)Two different ETV-ICP connecting interfaces (b.l) Nozzle-type aluminium-made interface with cooling bypass gas admittance (b.2) same as b.l but with a larger inner diameter prior to the bypass gas entrance. (Reproduced with permission of the American Chemical Society.)...

Metallic ions can be assayed by ICP-AES or ICP-MS and by electrothermal atomization-AAS (FETA-AAS) as well as by polarographic methods. These methods assure reliable information for determination of metallic ions. For example, cadmium is analyzed in baby food with ETA-AAS with a tube and a L vov pyrolytic graphite platform.114 The results obtained for cadmium assay are then compared with the levels of a national standard. There are many standards containing quality requirements for laboratories, but the most important and widely accepted international quality standard for testing laboratories is the ISA/IEC Guide 25 1990 "General requirements for the competence of calibration and testing laboratories."32... 

Fig. 2.10 Mass intensity signals for the decomposition of 12 (Xg of Cu(N03)2 -3H20 heated at 1 K s on a graphite platform (a) volatile and (b) non-volatile species. (Reproduced from [19], with permission.)...

Fig. 16.3 Mass intensity signals in the process of heating (IK s of 8(xg of Cd(N03)2 on a graphite platform [90]...

Uvov platform. A small graphite platform inside the graphite tube on which the sample is deposited. 

Because matrix modification is one aspect of sample preparation, even though it is most often accomplished automatically in GFAA, we will discuss it here. For example, NIOSFI Method 7105 recommends a matrix modifier that consists of a mixture of ammonium dihydrogen phosphate, magnesium nitrate, and nitric acid for the determination of airborne Pb. Because the graphite furnance can be viewed as a chemical reactor whereby the sample with its matrix is placed on a graphite platform (the L vov platform, discussed in Chapter 4) and heated to a very high temperature, reactions can take place that involve both the metal analyte of interest as well as sample matrix components. 

If there is no lead-containing vapour above the graphite platform, the light will pass through the tube without losing any intensity. 

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