Gas Chromatography Retention Times

The video tutorial explains how to interpret GC data, identify peaks, and calculate areas using response factors. It covers the process of matching retention times to identify solvents, calculating actual areas by dividing area counts by response factors, and determining the percentage composition of hexane and toluene in a sample. The tutorial emphasizes ignoring the dichloromethane peak as it is just a solvent.

What is the purpose of a chromatogram in GC data analysis?

• To determine the color of the solvents

• To calculate the mass of the sample

• To identify the retention times of different solvents

• To measure the temperature of the sample

Which solvent is identified by a retention time of approximately 1.9 minutes?

• Ethanol

• Dichloromethane

• Toluene

• Hexane

How do you identify hexane in the chromatogram?

• By its color

• By its retention time of 2.35 minutes

• By its retention time of 1.9 minutes

• By its retention time of 3.65 minutes

What is the retention time used to identify toluene?

• 4.0 minutes

• 3.65 minutes

• 2.35 minutes

• 1.9 minutes

What is the first step in calculating the actual area of a peak?

• Subtract the response factor from the area counts

• Divide the area counts by the response factor

• Multiply the area counts by the response factor

• Add the area counts to the response factor

What is the response factor for hexane used in the calculation?

• 1.25

• 1.18

• 1.32

• 1.10

What is the response factor for toluene?

• 1.18

• 1.32

• 1.10

• 1.25

How do you calculate the percentage of hexane in the sample?

• Divide the hexane area by the total area

• Subtract the hexane area from the total area

• Divide the total area by the hexane area

• Multiply the hexane area by the total area

What should the sum of the percentages of hexane and toluene equal?

• 50%

• 150%

• 100%

• 75%

Why is the dichloromethane peak ignored in the analysis?

• It is too small to measure

• It has no retention time

• It is the solvent and not part of the sample

• It is not a solvent