Liquid Chromatography Case Study

1044 Words 5 Pages
Kate Byrne
DT299/4
CHEM 4128 Applied Physical & Analytical Chemistry Assignment
Liquid Chromatography High Resolution Mass Spectrometry

Hyphenated Techniques

The term “hyphenated technique” was introduced by Hirschfeld in 1980. It refers to the combination of a chromatographic separation technique and a spectroscopic detection technique to form a new, more efficent instrument. The technique which will be discussed in this case is LC-MS. The aim of combining both techniques is to purify and identify the analyte of interest using a single analytical technique. 1, 2 Figure 1: Diagram showing the different chromatographic separation techniques and detection techniques combining to form a hyphenated technique. 1. LC-MS Interface Technology
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Initially this was not a popular technique as there were incompatibility problems between the two instruments.
Liquid Chromatography Mass Spectrometry
Flow Rate: 1ml/min = 500ml/min gas flow 10ml/min gas flow
Liquid Phase Operation Vacuum Operation
25-50oC 200-300oC
Table 1: Requirements for both liquid chromatography and mass spectrometry
In order to overcome the incompatibility issues, technological interfaces for LC-MS were developed. Without an interface, upon injection of the analyte the liquid would vaporize and large amounts of gas would get into the MS unit. The interface transfers the analyte in solution phase from the LC column to the high vacuum of the MS as a single molecule in the gas phase. Two interfaces will be discussed: Electrospray Ionisation Interface (ESI) Atmospheric Pressure Chemical Ionisation (APCI) Interface

Electrospray Ionisation Interface (ESI) Figure 2: Schematic Diagram of Electrospray Ionisation

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