Liquid Chromatography - Mass Spectrometry
The instrument we used here to identify and quantify trace aconitine in deceased sample is LC-MS, which is HPLC (High Performance Liquid Chromatography) coupled with MS (Mass Spectrometry).
This method allows physical separation of components by HPLC and also mass analysis by MS. With this technique, high selectivity and sensitivity applications are performed.
HPLC (high performance liquid chromatography)
A higher improved form of column chromatography. High pressure is used to force the solvent down the column, which makes it much faster. Physical separation of compounds is based on the interaction between the stationary phase and the analytes. HPLC allows smaller particle size for column packing material which gives a much larger surface area for better separation.
MS (mass spectrometry)
An analytical method where components, after being separated by HPLC or other separation techniques, will undergo ionization to generate charged molecules/fragments and the identity of each component will be determined based on the distribution of the fragments' mass to charge ratios.
In this way, accurate and precise quantitative and qualitative results can be achieved by coupled LC-MS (HPLC-MS).
As the mass spectrometry technique is new and foreign, this is a video behind to how it works.
Link: http://www.youtube.com/watch?v=tOGM2gOHKPc
Summary:
Sample is auto injected into HPLC
Sample passes through column to be separated (usually by reversed phase)
Metabolites at the end of the column will enter the mass spectrometer
They are ionized and form positively charged ions
The ions are deflected and separated by electromagnetic field according to mass-to-charge ratios.
The beam of ions that passes through is detected electrically.
