Chromatographic methods, in particular those coupled with mass spectrometry, are among the most frequently used analytical techniques. However, while a number of users increases to encompass their broader range, the understanding of chromatographic methods by these users declines. This training will cover basics and practical approaches to quantization using GC-MS. The first part of this training is learning to process data using specific software features within the homework on quantization. This will be followed by actual lab preparing set of calibration standards, and quantification in test and unknown sample.
Homework on Quantitation
The GC data (ChemStation) files should be copied to the folder for HP ChemStation in the folder c:\msdchem\1\data\homework (the files may be already uploaded in the computer lab).
The instructions and videos how to work with the data are provided below in the Lab assignment.
Lab: GC-MS Quantitation
Gas chromatography coupled with mass spectrometry (GC-MS) is an analytical method used for the identification and quantification of numerous volatile compounds. The qualitative GC-MS analysis is conducted by matching the retention time of given unknowns and mass spectra of known chemicals, typically electron ionization (EI) mass spectra with known standards or libraries. The quantitative analysis in a total ion current mode (TIC) can be performed as a traditional GC analysis based on the total peak area, however the correct approach to quantification is based on the peak area of a specific ion. In addition to the instrumentation, quantification is also dependent on the type of the calibration method used. Various calibration methods such as external standard calibration, internal standard calibration, and method of standard addition may be performed. Today the most common in gas chromatography is the internal standard calibration.
The aim of this lab assignment is to pursue GC-MS analyzes using the internal standard calibration with selected compounds of interest to the trainee; determine their instrumental limits of quantification and validate method based on replicate determination of the targeted compound in an evaluation sample of a defined (known) and unknown composition.
- Lab Assignment
- Example: MS Excel spreadsheet of data organization for stock solutions
- Example: MS Excel spreadsheet of calibration
- Tutorial for calibration curve in MS Excel (2007)
- Lab stock preparation from a chemical in a solid state
- Lab stock preparation from a chemical in a liquid state
- Performing serial dilution for internal standard calibration
- Storing and transferring the data for GC-MS dada processing
- View chromatograms and mass spectra in MSD Chemstation
- Extracted ion integration in MSD ChemStation