Mass spectrometer inlet systems for

The mass spectrometer inlet system for liquid chromatography, often termed the interface between the two component techniques, must therefore remove as much of the unwanted mobile phase as possible while still passing the maximum amount of analyte into the mass spectrometer. This must be done in such a way that the mass spectrometer is still able to generate aU of the analytical information of which it is capable. 

Hoch, G. Kok, B., A mass spectrometer inlet system for sampling gases dissolved in liquid phases, Arc/t. Biochem. Biophys. 1963, 101, 160. 

Hoch, G., Kok, B. (1963) A Mass Spectrometer Inlet System for Sampling Gases Dissolved in Liquid Phases. Arch. Biochem. Biophys. 101 160-170. 

A similar flow and mass spectrometer inlet system has been developed by Lossing for the investigation of photochemical systems. Mercury photosensitization was used so that the concentration of radicals should be within the limits of sensitivity of the mass spectrometer. With the light intensities used in experiments with acetone 80 % of the reactant could be decomposed with an exposure time of 0.002 sec. Later modifications 1 permitted variation of the exposure time by altering... 

In one instrument, ions produced from an atmospheric-pressure ion source can be measured. If these are molecular ions, their relative molecular mass is obtained and often their elemental compositions. Fragment ions can be produced by suitable operation of an APCI inlet to obtain a full mass spectrum for each eluting substrate. The system can be used with the effluent from an LC column or with a solution from a static solution supply. When used with an LC column, any detectors generally used with the LC instrument itself can still be included, as with a UV/visible diode array detector sited in front of the mass spectrometer inlet. 

Apart from ES and APCI being excellent ion sources/inlet systems for polar, thermally unstable, high-molecular-mass substances eluting from an LC or a CE column, they can also be used for stand-alone solutions of substances of high to low molecular mass. In these cases, a solution of the sample substance is placed in a short length of capillary tubing and is then sprayed from there into the mass spectrometer. 

Electrospray is both an atmospheric-pressure (API) liquid inlet system for a mass spectrometer, and, at the same time, it is an ionization source. 

Practical inlet systems for attaching a high-pressure liquid chromatography (HPLC) column to a mass spectrometer utilize atmospheric-pressure ionization (see Chapters 8 and 11). 

One of the instruments obtained by ERDA will be evaluated at ORNL to assess its potential as a monitor for hazardous by-products from alternative energy sources. Investigations to determine the desirability of a membrane inlet system for concentrating organic vapors are planned. The feasibility of using a portable gas chromatograph with the portable mass spectrometer, when a complex mixture analysis is required, is also being studied. 

H9. Hawk, R. E., and Jennings, R. W., Construction of a leak-inlet system for the LKB 9000 gas chromatograph-mass spectrometer. Appl. Spectrosc. 24, 543-544 (1970). 

It might be noted at this stage that some mass spectrometer inlets are also ionization sources. For example, with electrospray ionization (ES) and atmospheric pressure chemical ionization (APCI), the inlet systems themselves also provide the ions needed for mass spectrometry. In these cases, the method of introducing the sample becomes the method of ionization, and the two are not independent. This consideration can be important. For example, electrospray produces abundant... 

A mass spectrometer produces an enormous amount of data, especially in combination with chromatographic sample inlets [42]. Over the years, many approaches for analysis of GC-MS data have been proposed using various algorithms, many of which are quite sophisticated, in efforts to detect, identify, and quantify all of the chromatographic peaks. Library search algorithms are com monly provided with mass spectrometer data systems with the purpose to assist in the identi cation of unknown compounds [43]. 

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