Graphite tube methods low salt content

The furnace atomiser is readily used for trace determinations and also in the case of oxide materials it provides extremely low detection limits. Because of the inhomogeneity of the sample materials, the sample may frequently be no smaller than 1 g (or with extremely small concentrations up to 5 g), so the solution volume is limited as far as possible. 

Furthermore, it is useful to limit the salt content of the solution. This generally means that the furnace technique should only be used to determine trace elements soluble in acids — possible after pressure bomb decomposition. In this case the time of analysis becomes irrelevant. An example is the determination of Cd-traces in iron ores and related oxides. 

Samples are dissolved in the acid mixture by a long reaction. The solution evaporates in the furnace atomiser where it is transformed into atomic vapour and the absorption of light intensity is measured. (Addition method.) 

Operating conditions. AAS-device with graphite tube furnace and deuterium background corrector. Wave-length, 228.8nm EDL, Cd (6 W). 

50ngml 1 are pipetted into the graduated flasks B, C, D, in this sequence. All graduated flasks are topped up to 50 ml and stored in polythene bottles. The dummy solutions are produced by corresponding additions to 40 ml of the initial solution. At 3 minute intervals 5 pi of the test solutions at a time are injected into the furnace by a flask ejector pipette. 

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