Spark source mass relative sensitivity

The thermal ion mass spectrometer was specifically developed for the measurement of isotope abundances and is capable of excellent precision. Although the spark source mass spectrometer used in this work lacks some of this precision, it has proved very useful in stable isotope dilution work. It has a number of advantages, including greater versatility, relatively uniform sensitivity, and better applicability to a wide range of elements. 

Wcssman reviewed a number of instruments used for uranium analyses and ranked their relative measurement sensitivities [32]. The methods include atomic absorption spectrophotometry, colorimetry, neutron bombardment, fission etched track detectors, fluorimetry, laser-induced fluorescence spectrometry, a-spectrometry, isotope dilution mass spectrometry, and spark source mass spectrometry. The majority of urinary bioassay measurements have been performed by fluorimetry, while environmental survey and baseline measurements have been performed by fluorimetry, a-spectrometry, and induced coupled plasma source mass spectrometry. 

Since the spark source mass spectrograph does not provide a consistent precise relative exposure measurement, it is necessary to treat each exposure as a separate entity. Thus the data available to establish the density versus intensity relationship (calibration curve) are restricted to density readings on individual exposures. The only independent and absolute intensity scale available is that provided by the isotopic ratios of individual elements. Varying sensitivities do not allow use of lines due to different elements, even though their concentrations might be known from other analytical techniques. 

Conzemius, R.J. and H.J. Svec, 1973a, Relative sensitivity coefficients for rare earths in spark source mass spectrometry. Talanta 20, 575. 

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