General comments on GC-MS techniques in water analysis

Combinations of gas chromatographic techniques of separation with indication by mass spectrometry are used in water analysis for specific purposes, for example to ensure the detection of organic compounds in gas chromatography, and also to clarify their structure. For GC see Section 2.12 schematic diagram of mass-selective detector see Fig. 39 a-d. 

The GC-tVlS technique in water analysis is a typical example of the application of modern technology. Computer-controlled GC-MS coupling is preferred. Small, compact quadrupole mass spectrometers are frequently used for mass spectrometry. The preliminary gas chromatographic separation is preferably conducted with capillary separation columns. 

In addition to the quadrupole mass spectrometer, which is used relatively frequently in water analysis, electron impact ionization, chemical ionization, qualitative multiple ion selection and quantitative multiple ion selection (with a certain mass as the internal standard and direct admission of the substances, e.g. for mass calibration) are also used. 

The range of sensitivity of the mass spectrometer following preliminary separation by gas chromatography lies well below the pg range and, under favourable conditions, even reaches the nanogram region. 

In addition to low-resolution devices (quadrupole or magnetic devices), high-resolution devices are also used, such as double-focusing sector-field devices or maximum-resolution sector field devices such as the triple-quad system, although the latter devices are now hardly encountered in practical 

---