Chemistry 366 Widener GC Calibration Techniques Assignment

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to answer some Qs on excel sheet about GC Calibration Techniques

Chemistry 366 Homework Problem Set Widener University Dr. Van Bramer February 2019 GC Calibration Techniques Problem Set A laboratory analyzes the caffeine content of a coffee sample by GC using an internal standard. Determine the coffee concentration for this experiment. 1. A set of standards is run with caffeine and theobrimine in methylene chloride (a xanthine found in chocolate that is similar to caffeine). The standard is prepared by using 1 mL of 500 ppm caffeine and 1 mL of 250 ppm theobrimine and extracting them with 100 mL of methylene chloride. 1.0 µL of this solution is injected into a GC and the following results are obtained: Retention Time Area Caffeine 12.0 min 5267000 Theobromine 13.1 min 3197250 Based upon this information calculate: a. The response ratio for caffeine b. The response ratio for theobromine c. The relative response ratio 2. A unknown sample is prepared by combining 1 mL of coffee and 1 mL of 250 ppm theobrimine and extracting with 100 mL of methylene chloride. 1.0 µL of this solution is injected into a GC and the following results are obtained: Caffeine Theobromine Retention Time 12.0 min 13.1 min Area 5840299 3921750 Based upon this information and the relative response ratio calculate: a. The response ratio for theobromine b. The response ratio for caffeine c. The concentration of caffeine 3. If the injection volume is doubled for this experiment a. How would the response ratio for an individual compound change? b. How would the relative response ratio change?

Tutor Answer

Clari
School: UCLA

Attached.

GC Calibration Technique Problem Set

A laboratory analyzes the caffeine content of a coffee sample by GC using an internal standard. Determine
the coffee concentration for this experiment.

1. A set of standards is run with caffeine and theobrimine in methylene chloride (a xanthine found in
chocolate that is similar to caffeine). The standard is prepared by using 1 mL of 500 ppm caffeine
and 1 mL of 250 ppm theobrimine and extracting them with 100 mL of methylene chloride. 1.0 μL
of this solution is injected into a GC and the following results are obtained:



Based upon this information calculate:
a. The response ratio for caf...

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