How to Analyze a Gas Sample

2013-08-22 10:12:30 liting

A gas chromatography machine is used to analyze gas samples. The machine determines how many components are in a sample. It is also used to separate components. The instrument has a injection block, a column and a detector. The gas sample is vaporized and carried through the chamber by a carrier gas, usually helium.
Place the tip of a syringe needle into a liquid sample. Draw a small amount of liquid into the syringe and push the liquid back out of the syringe. Repeat this rinse process two more times. Fill the syringe again halfway. Use the syringe to inject a sample into a GC column. Examine the syringe to search for large air bubbles. If found, release the liquid from the syringe and refill. A very large air bubble can affect the GC reading.
Use the syringe to inject the sample into the GC injection port. Immediately, press the recorder's start button. Force the needle into the instrument to the base of the needle. Remove the syringe.
Wait as the compound flows through the instrument. The carrier gas will influence how fast the sample travels through the GC machine. Write down the settings for the column temperature, injection port temperature and detector temperature. The GC conditions will assist in duplicating your results in later experiments.
Observe the recorder. Two devices, an integrating recorder and a computer program, will record gas components. If a two-component mixture is used the GC instrument may determine the percentage of each in the sample. Compounds pass through the instrument and the detector at different rates