Ethyl Acetate Lab Report

Experimental: In this experiment, dilutions of 250 ppm, 200 ppm, 100 ppm, and 25 ppm of 12C solution was prepared from a caffeine stock solution using ethyl acetate as the solvent. 250 µL of each dilution was added to a respective 0.6 mL vials with 50 µL of 13C and mixed. Next, three 15 mL centrifuge tubes were labeled as “Unknown A,” three were labeled as “Unknown B” and one was labeled “Control.” To each tube, 4 mL of ethyl acetate and 1 mL of the respective unknown or control (100 ppm 12C solution) was added to the respective flasks. Each tube was placed in a sonicator for 2 minutes and then centrifuged for 30 seconds. With each solution mixed and separated into an organic layer and aqueous layer, 1 mL of the organic layer for each solution was transferred to a labeled 2 mL vial. To each vial, about 0.1 g of anhydrous magnesium sulfate was added. Each solution was vortexed and 250 µL of each solution was added to a respective 0.6 mL vial. 50 µL of an
The GC used was a Trace 1300 paired with an ITQ 700 MS. Using Xcalibur software, the method, CH456_Caffeine.met, was selected. The parameters were set to 230˚C for the GC ion source, full scan mode and the start time for MS was adjusted to 4 minutes. In the “Sequence Set-up” window of Xcalibur, samples were selected for 6 unknowns and 1 control using a 1 µL injection volume. With the sequence set up, the samples were then prepared to run by clicking “Actions” and then “Run This Sample.” When both instruments were ready, the sample was injected by using a syringe, where the 1 µL of air is taken up, then 1 µL of sample and another 1 µL of air. The syringe was injected into the injector port, where it was held for 3 seconds to allow the injector port to heat up and the sample was injected. The syringe was removed from the port and then the “Start” button was hit on the GC device. The sample ran for 7 minutes. The process was repeated for the rest of the