Gas Chromatography (GC)

Front

What is the principle of gas chromatography?

Back

Gas chromatography is a technique for separating components based on their volatilities, which are determined by differences in boiling points.

Front

What are the two types of gas chromatography?

Back

1. Gas-liquid chromatography (GLC) - mobile phase is gas, stationary phase is liquid. 2. Gas-solid chromatography (GSC) - mobile phase is gas, stationary phase is solid.

Front

What is the function of the carrier gas in gas chromatography?

Back

The carrier gas transports the analyte through the column without interacting with it.

Front

What are the typical carrier gases used in gas chromatography?

Back

Helium and nitrogen are typical carrier gases.

Front

What is the role of the injector in gas chromatography?

Back

The injector is a hollow, heated, glass-lined cylinder where the sample is introduced into the GC.

Front

What are the two modes of sample injection in gas chromatography?

Back

1. Split Mode - introduces a small amount of sample for concentrated samples. 2. Splitless Mode - most of the sample is introduced for low concentration samples.

Front

What are the two types of columns used in gas chromatography?

Back

1. Packed column - 1-5m in length, 2-4mm internal diameter. 2. Capillary column - 10-100m in length, very small internal diameter.

Front

What are the advantages of using a packed column?

Back

1. Large sample size. 2. Ease and convenience of use.

Front

What are the advantages of using a capillary column?

Back

1. High resolution. 2. Short analysis time. 3. High sensitivity.

Front

What is the importance of column temperature in gas chromatography?

Back

The optimum column temperature affects the resolution and elution time of the sample components.