There must not be any air bubbles in the syringe If there are any air bubbles

There must not be any air bubbles in the syringe if

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There must not be any air bubbles in the syringe. If there are any air bubbles present expel the Ibuprofen sample into a Kimwipe and refill. 4. On the GC–FID machine push the “prep run” button and wait until the red “not ready” light disappears. 5. Expel sample from the syringe into a Kimwipe until the syringe contains only 1 μL of sample. Wipe the needle with a Kimwipe and insert the syringe all the way down into the GC injection port. Be careful as the injection port is hot and the syringe must be placed in the port close to vertically. Attention to this proper injection technique is important in order to get well resolved peaks in the chromatogram. Quickly press down on the syringe in a smooth, rapid motion to inject the entire 1 μL sample. Press the start button on the GC and carefully remove the syringe from the injection port. The run will stop when the temperature program is completed (after about 10 minutes). 6. While the run is in progress rinse the syringe with solvent several times, expelling the solvent into a Kimwipe. 7. When the run is complete print out a copy of the total ion chromatogram, noting the retention time of each peak. 8. Repeat the procedure (steps 1–7) for the remaining two standard solutions. B. Determination of the composition of an unknown mixture 9. Obtain from your instructor a solution of unknown composition. Make sure to write down the number of your unknown sample in your lab notebook. 10. Repeat steps 1–7, this time injecting your unknown sample into the GC–FID. 11. Compare the total ion chromatogram for your unknown sample to the chromatograms of the standards in order to determine the contents of your unknown. Check your conclusions with your lab instructor or TA.
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Organic Chemistry I Laboratory Manual (prepared by D. G. Hamilton, Aug. 2006, revised by M. Joralemon Shaw, Aug. 2008) 41 CLEAN UP The unknown solution can be poured into the non-halogenated waste container. REPORT Include all of the total ion chromatograms, which you printed out, for each of the known samples and for your unknown. Explain how you interpreted the peaks in the total ion chromatogram of your unknown sample and employed this reasoning to determine the contents of your unknown. QUESTIONS 1. What functions do the mobile phase and stationary phase perform in GC? 2. When injecting your sample into the GC–FID, why is it essential that the syringe be carefully rinsed before and after each use?
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Organic Chemistry I Laboratory Manual (prepared by D. G. Hamilton, Aug. 2006, revised by M. Joralemon Shaw, Aug. 2008)43The first extraction technique involves removal of the chlorophyll a and chlorophyll b pigments from the leaves by stirring in a hot organic solvent, under reflux. The second technique, a classical and important one in organic chemistry, is liquid–liquid extraction. You will use this second technique to separate the colored pigments from accompanying water–soluble compounds. The resulting organic extracts will then be evaporated under reduced pressure (rotary-evaporation) and the highly colored pigment residue analyzed by thin layer chromatography. Reflux A system is in reflux
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  • Fall '10
  • Chromatography, M. Joralemon Shaw, Chemistry I Laboratory Manual, Darren Hamilton, D. G. Hamilton

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