Detector, atomic spectrometer concentration sensitivity

Both Q and SF mass spectrometers are scanning (sequential) analyzers and multiisotope analysis can be achieved at the expense of the measurement sensitivity and precision. The sequential measurement of m/z at different points within a time-dependent concentration proble of a transient signal can result in peak distortions and quantisation errors commonly referred to as spectral skew. The alternative is TOF-MS which features the ability to produce a complete atomic mass spectrum in less than 50 xs and thus allows very brief transient signals to be recorded with high bdelity. This is especially useful in the on-line isotope ratio determination. However, a 10-fold loss in sensitivity of a TOF-ICP-MS instrument in comparison with the latest Q instruments often creates an obstacle for the wider application of TOF-ICP-MS as a detector in the CE of metallobiomolecules in biological samples. 

CE)] with a sensitive and element-specific atomic detector (usually an atomic absorption, emission or mass spectrometer) have become fundamental tools for speciation analysis, as can be seen in a special journal issue devoted to such application. Some of the hyphenated techniques available for spedes-selective analysis in biological and environmental materials are schematically shown in Figure 1.12. The choice of hyphenated technique depends primarily on the objective of the research. Speciation analysis in environmental and/or biological samples faces two main challenges because of the usually low concentrations of the analytes (below 1 pgg ) and the complexity of the matrix itself. 

The conductivity detector was set at a sensitivity that would have produced an acceptable signal for the selenium compounds in the absence of the other ions. Because of the high sensitivity setting on the detector and the high concentrations of chloride, sulfate, and phosphate relative to selenite and selenate, the recorder pen is off the chart for retention times between 8 and 25 minutes, and signals for selenite and selenate cannot be reliably located. However, when a graphite furnace atomic absorption spectrometer was employed as the selenium-specific... 

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