Department of Physical Electronics
Faculty of Science, Masaryk University, Brno
Plasma Diagnostics and Simulation
Task: Gas Chromatography
Exercises
1. Identification of organic vapors.
2. Identification of organic components in the sample solution.
Introduction
Gas chromatography is a powerful method for identification and quantification of organic
compounds in gas and liquid mixtures and their solutions in organic solvents. The analyzed
compounds should be sufficiently volatile (high vapor pressure, low boiling point) and thermally
stable. Various components of a mixture are separated according to their distribution coefficients
between stationary phase and mobile phase (helium) in the capillary chromatographic column
(compound with larger distribution coefficient value remains in the stationary phase for longer time
and thus has longer retention time in the column). After separation on the column, separated
components are detected in a detector: flame ionization detector (FID) or quadrupole mass
spectrometer (MS) are commonly used. Parallel usage of both detectors (MS and FID) improves
selectivity (some compounds like permanent gases, carbon monoxide and dioxide, water,
fomaldehyde, etc., are not active in the FID detector) and sensitivity of the system.
Gas chromatography device Agilent Technologies 7890B enables two different methods of sample
input:
A. Injection of a liquid sample to the chromatograph inlet using microsyringe (via autosampler
or manually).
B. Loading of a mixture of gases or organic vapors using six port injection valve (via highvolume
syringe or online interconnection with a reactor).
Non-polar chromatographic capillary column HP-5 (5% phenyl 95% dimethylpolysiloxane; 30 m
length, 0.32 mm diameter, 0.25 µm thickness of the stationary phase film), installed in the
chromatograph, give good performance in a wide range of applications. The column for is splitted
parallelly to two detectors: flame ionization detector and Agilent Technologies 5977A quadrupole
mass spectrometer. The results will be shown as chromatograms: detector signal vs. time. Individual
components are visible in the chromatograms as peaks occured in particular time (time between
injection of the sample and time of maximum for a peak is called “retention time”).
Measurement
Exercise 1: Identification of organic vapors
1. On the upper menu bar of the MassHunter software click to Method > Load Method and
choose method Exercise1.m. Wait, till Status icons turn to green.
2. Click to Method > Run Method, fill the sample name and click to OK and Run Method
button. Wait till window GC Aquisition for valve switching will occur.
3. Take the organic vapors with 50 ml plastic syringe from bottle containing sample vapors.
4. Inject vapors from the syringe to the plastic tube connected with six port injection valve and
then click to Start run button on the GC Acquisition window for valve switching.
5. When the analysis is finished, click on a green offline icon in the computer main desktop.
6. Offline version of the MassHunter software window will open and then click to View > MSD
ChemStation Data Analysis in the main menu bar and data analysis window will be opened.
7. In the data analysis window browse the sample name in the column on the left part of the
window. Both chromatograms, from MS and FID detectors, will occur in the window.
8. In the upper bar click to Chromatogram > AutoIntegrate and red baseline and retention time
values will occur for the both chromatograms.
9. In the upper bar click to Chromatogram > Integration Results and tables with integration
results (retention times, peak areas, etc.) for MS and FID chromatograms will occur. Using
Copy button, the tables can be paste to any text or spreadsheet software.
10. Click (right-click) to any peak in mass spectrometry (TIC) chromatogram (upper). Mass
spectrum of related compound will occur. Then click to Spectrum > NIST Search in the upper
bar of the Data Analysis window and most probable reference spectrum will be found in a
new NIST window.
Exercise 2: Identification of organic components in the sample solution
1. On the upper menu bar click to Method > Load Method and choose method Exercise2.m.
Wait, till both Run Status and Instrument Status indicator bands turn to green.
2. Put the sample vial with solution to position 1 in the autosampler.
3. Click to Method > Run Method, fill the sample name and click to OK and Run Method
button. The autosampler then automatically inject the sample and start the analysis.
4. The other steps, concerning analysis of results, are the same like in the Exercise 1.