•Many instruments combine two techniques to provide more detailed and rapid information about the sample.
•The most commonly used combination is that of mass spectroscopy and chromatography.
•The advantage of gas chromatography-mass spectroscopy (GC-MS) and high pressure liquid chromatography-mass spectroscopy (HPLC-MS) is that the chromatography can separate the sample into its individual components and then the components can be identified using MS.
Which technique to use?
Assessing analytical techniques is based on Chemical factors and Economic factors.
Analyte – what are the samples characteristics? Metal? Coloured? Volatile?
Sample – amount available, concentration, physical state etc.
Time – how fast do you need the results?
Cost of equipment - $$$$ versus $
Expertise – does someone know how to operate the machine?
Quality data – quality costs more.
Combined techniques practice.
The chemical detectives app. gives practice in combined techniques- H NMR, C NMR, MS and IR- Excellent app!