Purity trace analysis

From our point of view, this is exactly what commercial ionic liquid production is about. Commercial producers try to make ionic liquids in the highest quality that can be achieved at reasonable cost. For some ionic liquids they can guarantee a purity greater than 99 %, for others perhaps only 95 %. If, however, customers are offered products with stated natures and amounts of impurities, they can then decide what kind of purity grade they need, given that they do have the opportunity to purify the commercial material further themselves. Since trace analysis of impurities in ionic liquids is still a field of ongoing fundamental research, we think that anybody who really needs (or believes that they need) a purity of greater than 99.99 % should synthesize or purify the ionic liquid themselves. Moreover, they may still need to develop the methods to specify this purity. 

SFE and SFC require a high-purity feedstock of liquid C02 (electron capture impurities below 100 ppt, and mass responsiveness impurities below lOppb). Impurities can be detrimental to the use of SFE in trace analysis. Hinz and Wenclawiak [323] have investigated SFE/SFC grade C02 by means of GC with FID, ECD and MS detection. Quantification of the impurities, using FID or ECD, was achieved introducing an internal standard into the C02 flow. 

Applications ICP-MS has become the technique of choice for the determination of elements in a wide range of liquid samples at concentrations in the ng L 1 to [igL-1 range. Typical applications of ICP-MS are multi-element analysis of liquids (even with high solid contents) element speciation by hyphenation to chromatographic techniques continuous on-line gas analysis multi-element trace analysis of polymers and trace analysis in high-purity materials. ICP-MS is routinely used for quality control purposes. 

ULTRA TRACE ANALYSIS High-purity materials for microelectronics... 

Volatile amines from Ci to C(, and ammonia were separated on a PoraPLOT column, with or without a temperature gradient, depending on volatility. The method is applicable to determination of the purity of manufactured amines. Trace analysis of these amines can be performed by capillary GC-FID and of ammonia by GC-ELCD101. 

Trace element concentrations are obtained in the semi-quantitative mode by ICP-MS, LA-ICP-MS, SSMS or SNMS with an error factor of about 0.3-3 for most elements. The results of semi-quantitative trace analysis, e.g., for high purity materials, are sometimes sufficient to estimate the purity of the matrix investigated. 

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.

Table 9.8 Results of trace analysis in high purity reactor graphite measured by LA-ICP-MS and SSMS.

Table 9.9 Selected applications of inorganic mass spectrometry in trace analysis of high purity conducting materials.

Similar to the analytical procedure for trace analysis in high purity GaAs wafers after matrix separation, discussed previously,52 the volatilization of Ga and As has been performed via their chlorides in a stream of aqua regia vapours (at 210 °C) using nitrogen as the carrier gas for trace/matrix separation.58 The recoveries of Cr, Mn, Fe, Ni, Co, Cu, Zn, Ag, Cd, Ba and Pb determined after a nearly quantitative volatilization of matrix elements (99.8 %) were found to be between 94 and 101 % (except for Ag and Cr with 80 %). The concentrations of impurities measured by ICP-DRC-MS (Elan 6100 DRC, PerkinElmer Sciex) after matrix separation were compared with ICP-SFMS (Element 2, Thermo Fisher Scientific) and total reflection X-ray fluorescence analysis (TXRF Phillips). The limits of detection obtained for trace elements in GaAs were in the low ngg-1 range and below.58... 

Table 9.10 Results of trace analysis on high purity GaAs measured by GDMS and ICP-MS (concentration in ppb-at)46.

Several applications of inorganic mass spectrometry (TIMS,86 GDMS,53 LIMS, ICP-MS 66,8i,87-89 LA-ICP-MS61,62,81 90 and ETV-ICP-MS66) in the trace analysis of high purity nonconducting materials are collected in Table 9.14. 

Table 9.19 Application of ICP-MS in trace analysis of high purity solutions used in microelectronics.

Neutron activation is not a widely used method (Fig. 17.8). Some of its applications include characterisation of materials (e.g. high purity metals, semiconductors), the study of the distribution of chemical elements within fossils, ultra-trace analysis in archaeology and geology, and the study of volcanoes. 

For trace analysis (analysis of species at ppm and lower levels), impurities in reagent chemicals must be extremely low. For this purpose, we use very-high-purity, expensive grades of acids such as trace metal grade" HN03 or HC1 to dissolve samples. We must pay careful attention to reagents and vessels whose impurity levels could be greater than the quantity of analyte we seek to measure. 

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