Indium, trace analysis

Table 9.4 Result of trace analysis of high purity indium and zinc measured by spark source mass spectrometry (SSMS) and glow discharge mass spectrometry (GDMS), respectively.

Choice of an Internal Standard. One of the difficulties in the spec-trometric trace analysis of coal ash samples, in addition to choosing a suitable comparison standard matrix, is choosing an internal standard. The first choice in both analytical methods was indium, which was used as a constant internal standard added to the graphite powder diluent-buffer. The results obtained had poor reproducibility, as previously... 

Indium produces characteristic lines in the indigo-hlue region and may be detected by spectroscopic analysis. iVt trace concentrations In may be determined by lame-AA, fumace-AA, ICP-AES, x-ray fluorescence, or neutron activation analysis. 

In the analysis of high purity metals, trace elements were pre-concentrated by partial dissolution of the matrix. The remaining small part of the matrix retains all trace elements that are electrochemically less noble than the matrix [79,80]. In this way the trace elements were pre-concentrated from silver-, cadmium-, gallium-, indium-, zinc-, lead-, manganese-, aluminium-, and lead-antimony alloys. 

The technique involves the use of an inductively coupled plasma to convert trace elements to their gaseous ions followed by analysis of these ions by mass spectrometry. Examples include the quantitative analysis of trace copper by isotope dilution and the analysis of trace contaminants in boron, indium phosphide and reagent acids. 

Grahn, E., Karlsson, S., Karlsson, U. and Duker, A. (2006) Historical pollution of seldom monitored trace elements in Sweden-Part B Sediment analysis of silver, antimony, thallium and indium. J Environ Mon, 8 (7), 732-744. 

Following the assay protocol summarized in Fig. 25, a characteristic anodic wave corresponding to released indium appears at —588 mV as seen in Fig. 26. The wave at —633 mV, which also appears in blank analysis, is attributable to trace cadmium associated with the commercial immunologic reagents. The wave at —588 mV is resolvable in the presence of that at —633 mV, and HSA effectively displaces HDI bound to the... 

Measurements at different heating rates may lead to different amounts of instrument-lag, i.e., the temperature marked on the DSC trace can only be compared to a calibration of equal heating rate and baseline deflection. A simple lag correction makes use of the slope of the indium melting peak when plotted vs. sample temperature as a correction to vertical lines on the temperature axis, hi some commercial DSCs this lag correction is included in the analysis program. It must be considered, however, that different samples have different thermal conductivities and thermal resistances so that different lags are produced as shown, for example, in Fig. 4.94, for an analysis with TMDSC. 

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