Chapter 20, Problem 3Q

Interpretation Introduction

(a)

Interpretation:

The effect of flow rate of carrier gas on ${\text{R}}_{\text{f}}$ should be specified.

Concept introduction:

Gas chromatography is efficiently used for the compounds that have high vapor pressures which allow them to pass through a GC column.

A gas chromatography does not identify compounds if unknown samples are loaded into the column. GC is one of type of partition chromatography, where the sample that has to be analyzed get adsorbed on the stationary phase.

The stationary phase is formed by high boiling nonvolatile liquid, usually a polymer. An inert gas like helium or nitrogen is utilized to form mobile phase. In GC, no interaction of compound with mobile phase occurs, unlike LC and TLC. The inert gas that makes the mobile phase carries the compound down the column when it is in vapor state. The compounds present in the mixture divide themselves between the gas phase and the liquid phase in the column in an equilibrium.

The components of gas-liquid chromatography are as follows:

• High-pressure pure carrier gas source
• Flow controller
• Heated injection port
• Column and column oven
• Detector
• Recording device or data station

Interpretation Introduction

(b)

Interpretation:

The effect of temperature of the column on ${\text{R}}_{\text{f}}$ should be specified.

Concept introduction:

Gas chromatography is efficiently used for the compounds that have high vapor pressures which allow them to pass through a GC column.

A gas chromatography does not identify compounds if unknown samples are loaded into the column. GC is one of type of partition chromatography, where the sample that has to be analyzed get adsorbed on the stationary phase.

The stationary phase is formed by high boiling nonvolatile liquid, usually a polymer. An inert gas like helium or nitrogen is utilized to form mobile phase. In GC, no interaction of compound with mobile phase occurs, unlike LC and TLC. The inert gas that makes the mobile phase carries the compound down the column when it is in vapor state. The compounds present in the mixture divide themselves between the gas phase and the liquid phase in the column in an equilibrium.

The components of gas-liquid chromatography are as follows:

• High-pressure pure carrier gas source
• Flow controller
• Heated injection port
• Column and column oven
• Detector
• Recording device or data station