Therefore, when selecting the type of column to use, the volatility and functional groups of the analytes should be considered to match them to the stationary phase.
Once in the analytical column, the sample components are separated by their different interactions with the stationary phase. For high concentration samples only a portion of the sample is transferred to the analytical column in split mode, the remainder is flushed from the system through the split line to prevent overloading of the analytical column. Credit: Anthias Consulting.Īfter injection into the GC inlet, the chemical components of the sample mixture are first vaporized, if they aren’t already in the gas phase. For low concentration samples the whole vapour cloud is transferred into the analytical column by the carrier gas in what is known as splitless mode.
#How to view gc chromotography grah on pasco capstone software#
The signal is recorded by the acquisition software on a computer to produce a chromatogram (Figure 1 (6)).įigure 1: A simplified diagram of a gas chromatograph showing: (1) carrier gas, (2) autosampler, (3) inlet, (4) analytical column, (5) detector and (6) PC.
The outlet of the column is inserted into the detector (Figure 1 (5)) which responds to the chemical components eluting from the column to produce a signal. The analytical column is held in the column oven which is heated during the analysis to elute the less volatile components. Connected to the inlet is the analytical column (Figure 1 (4)), a long (10 – 150 m), narrow (0.1 – 0.53 mm internal diameter) fused silica or metal tube which contains the stationary phase coated on the inside walls. The sample is injected into the GC inlet (Figure 1 (3)) through a septum which enables the injection of the sample mixture without losing the mobile phase. The sample is first introduced into the gas chromatograph (GC), either with a syringe or transferred from an autosampler (Figure 1 (2)) that may also extract the chemical components from solid or liquid sample matrices. The carrier gas transports the sample molecules through the GC system, ideally without reacting with the sample or damaging the instrument components.
Strengths and limitations of gas chromatographyĪs the name implies, GC uses a carrier gas in the separation, this plays the part of the mobile phase (Figure 1 (1)). Taking gas chromatography into multiple dimensions How do you read a chromatogram and what does it tell you? Adding mass spectrometry to gas chromatography (GC-MS)
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