Chemical Analysis by Means of Mattauch-Type Double-Focusing Mass Spectrograph(II):Quantitative Analysis

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Mass spectrograms have been recorded on an Ilford Q-2 plate by suitably varying time of exposure t in our Mattauch-type mass spectrograph with a high-frequency discharge ion source with iron as electrodes. The densities D of the four isotopic lines on one mass spectrogram cover a considerable portion of the log D vs log rt curve, or the D-curve, for the relative abundnaces r of the isotopes differ widely. It has now been found that these portions obtained for different values of t can fuse together, partially overlapping, into one smooth D-curve, if only the values of t are properly adjusted. This adjustment is necessary to correct among others the error of time measurement and the fluctuation of sparking condition, and therefore, less important for larger t. The shape of the D-curve thus obtained for Fe is almost the same as those obtained for Zr, Si, C, and Cu, all in the elementary state and even for Hf contained in a very large amount of Zr. Suppose the D-curve obtained for an element A contained in a certain other element B at the atom fraction f, takes the same shape* and can be brought to the same position with the D-curve obtained for A in the elementary state, when afrt is taken as abscissa instead of rt. If now a, which is a suitably chosen constant, is nearly equal to unity, the D-curve determined with the elementary A may be used as the calibration curve for the impurity analysis of B samples containing A at any atom fraction. If a on the contrary differs appreciably from unity but remains nearly constant for a certain range of f, the D-curve determined with one standrard sample with f within that range may be used for the analysis of any B sample with f falling within the same range. As no standard sample was available, determinations of small impurities ranging from 0.001 to 0.5 wt. per cent have been carried out, assuming tentatively a is unity. The results differ more or less from the figures given in the specifications of the samples used, but the reproducibility within the limit of error±3∼±8 per cent has been obtained for 0.05 per cent Fe in Zr. Elements possessing no isotope* can also be determined in a similar manner with some additional procedures. The whole situation would be improved if the loss in weight of the electrodes or the energy consumption during sparking be introduced instead of time of exposure.The investigation is now under way. (*Recently this has been found really the case for Fe in Zr, and Cu and Mn in"pure"Fe by applying the same adjustments of t used for the construction of the D-curve for the substrate elements Zr and Fe, respectively to the strongest of the four isotopic lines of Fe in Zr, to the two isotopic lines of Cu in Fe, and to the single line of non-isotopic Mn in Fe.)
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Chemical Analysis by Means of Mattauch-Type Double-Focusing Mass Spectrograph(II):Quantitative Analysis

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