Detector, atomic spectrometer choice

During the last decade, research efforts in the field of LC-MS have changed considerably. Technological problems in interfacing appear to be solved, and a number of interfaces have been found suitable for the analysis of flavonoids. These include TSP, continuous-flow fast-atom bombardment (CF-FAB), ESI, and APCI. LC-MS is frequently used to determine the occurrence of previously identified compounds or to target the isolation of new compounds (Table 2.11). LC MS is rarely used for complete structural characterization, but it provides the molecular mass of the different constituents in a sample. Then, further structural characterization can be performed by LC-MS-MS and MS-MS analysis. In recent years, the combination of HPLC coupled simultaneously to a diode-array (UV-Vis) detector and to a mass spectrometer equipped with an ESI or APCI source has been the method of choice for the determination of flavonoid masses. Applications of LC-MS (and LC-MS-MS) in flavonoid... 

The atom-probe field ion microscope is a device which combines an FIM, a probe-hole, and a mass spectrometer of single ion detection sensitivity. With this device, not only can the atomic structure of a surface be imaged with the same atomic resolution as with an FIM, but the chemical species of surface atoms of one s choice, chosen from the field ion image and the probe-hole, can also be identified one by one by mass spectrometry. In principle, any type of mass analyzer can be used as long as the overall detection efficiency of the mass analyzer, which includes the detection efficiency of the ion detector used and the transmission coefficient of the system, has to be close to unity. 

Transient signals are typically obtained in atomic spectrometry when samples are introduced by flow injection techniques or when the spectrometer is used as an element-specific detector in hyphenated techniques. Inductively coupled plasma mass spectrometry has nowadays become the detection technique of choice for multielement-specific detection in speciation as it allows multielemental... 

The physico-chemical properties of the analytes and the way they reach the detector have made atomic spectroscopy the detection technique of choice in most instances. A heated quartz cell or a similar device is connected directly to the gas outlet of the separation cell [26]. The use of an atomic fluorescence detector has provided methods for selenium [25,27] and mercury [28,29] that possess excellent analytical features and use inexpensive instruments. On a less affordable level are ICP emission [30] and atomic emission cavity spectrometers [31]. 

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. 

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