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NMR und Biomaterialien - Was kann man über plasmagespritzte Apatitschichten und Cellulose lernen?
(2002)
Inspired by the globule arc technique a new electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP OES) method was developed for the analysis of high-purity copper materials. The performance of the method was investigated for the analytes Ag, Al, As, Bi, Cd, Co, Cr, Fe, Mg, Mn, Ni, P, Pb, S, Sb, Se, Si, Sn, Te, Ti, Zn and Zr. ETV parameters were optimized regarding the release of the analytes, the transport efficiency and the quality of analytical results in terms of precision, trueness and power of detection. The influence of CCl2F2, CHClF2, C2H2F4 and CHF3 as gaseous halogenation modifiers was investigated. A sufficient in situ analyte matrix separation was achieved by using CHF3 as halogenating reagent avoiding a high matrix input from the molten copper sample into the ETV system and the plasma. A complete release from the samples was obtained for all investigated analytes except Se and Te. Acceptable results for the determination of the trace elements Ag, Al, As, Bi, Cd, Co, Cr, Fe, Mg, Mn, Ni, P, Pb, S, Sb, Si, Sn, Ti, Zn and Zr in high-purity copper were achieved. The method includes a preceding sample preparation step of oxidizing the surface of copper samples which results in a significantly enhanced sensitivity. In addition to the calibration with copper samples, the feasibility of the calibration with liquid multi-element solutions was investigated. Except for Ag, Mg and Ni all analytes could be analyzed using aqueous calibration solutions. The trueness of the method was tested by the determination of analyte contents of certified reference materials. Limits of quantification ranging from 0.6 ng g-1 to 29 ng g-1 were achieved. The developed direct solid sampling method is time and cost effective and well suited for the characterization of high-purity copper materials. The method can be automated to a large extent and is applicable for processes accompanying analyses. In contrast to all other investigated trace elements, Se and Te were not released from the matrix at measurable levels under the used conditions. The determination of these elements is still under investigation and will be reported in a succeeding publication.
In supplementary work to the one published earlier, experiments with SF6, NF3, CF4 and H2 as new modifier gases for the matrix studied were performed. Our investigations were continued to improve the described analytical method and to achieve additional insights into the mechanism of analyte release. Our new survey is split in two parts. At first fluorinating modifiers were used to investigate the behaviour of a variety of trace elements (Ag, Al, As, Au, Bi, Cd, Co, Cr, Fe, Mg, Mn, Ni, P, Pb, Sb, Se, Si, Sn, Te, Ti, Zn and Zr). Most of them (exceptions Au, Se, and Te) could be effectively released from the copper matrix by thermo-halogenation reactions and by partial sub-sample evaporation. Using SF6 and NF3 as modifier gases, low limits of quantification (LOQs) were achieved for the 19 well released trace elements (typical ≤0.1 mg kg-1). Most elements (exceptions Ag, Mg, and Ni) could be calibrated by using aqueous calibration solutions without any sample pretreatment. For the trace determination of Se, Te, and Au, a further analytical method of ETV-ICP OES is described in the second part based on thermo-hydrogenation reactions by using a hydrogen/argon mixture as a modifier gas. The determination of Se and Te with very high analytical performance (LOQ < 0.1 mg kg-1) can either be carried out in a second analytical step succeeding the halogenation procedure, or the sub-sample is directly treated with H2 without previous halogenation procedure whereby the sub-sample can either be partially or totally evaporated. In this case some other analytes (Ag, Au, As, Bi, Cd, Fe, Mg, Ni, Pb, Sb, Sn, and Zn) can additionally be quantified simultaneously with Se and Te.
The certification of a boron carbide reference material for chemical composition is described. The mass fractions of 16 elements and two boron species are certified in an international interlaboratory comparison with 35 participating laboratories from six different countries. Beside chemical characterization the certification process includes homogeneity and stability testing of the candidate material boron carbide (type F360, 305M422). Details of the analytical methods used for chemical characterization and of the calculation of the uncertainties of the certified mass fractions are given. The new reference material ERM®-ED102 with certified mass fractions of 18 parameters (elements and species) and of the amount fraction of the isotope 10B is a valuable tool for laboratories working in the field of advanced ceramic materials analysis to improve their analytical results.