How to Be a Man
Essay by review • December 22, 2010 • Study Guide • 845 Words (4 Pages) • 1,066 Views
Extraction Method
Extraction:
Take a 150 mL Erlenmeyer flask, and add to it 8 g of coffee grounds.
Add to it 50 mL of methylene chloride.
Allow the coffee to extract for 5 minutes.
Remove the bulk coffee grounds from the solution.
If coffee is allowed to remain longer, caffeine may become overrepresented in the sample.
Some methylene chloride will be retained by the coffee ÐC this is an acceptable loss, and no dilution is necessary.
Preparation:
Separate the coffee extract from above into three equal portions; assuming some loss of methylene chloride, as above, these portions will be about 15 mL each.These will become the ÐŽ®highЎЇ, ÐŽ®mediumЎЇ, and ÐŽ®lowЎЇ concentrations.One portion can be set aside and sealed ÐC this will be the ÐŽ®mediumЎЇ concentration sample source.The other two portions will be made into the ÐŽ®high and ÐŽ®lowЎЇ solutions.The ÐŽ®highЎЇ sample is prepared by leaving uncovered to allow the methylene chloride to evaporate until about 1 mL remains.
The ÐŽ®lowЎЇ sample is prepared by a 10x dilution.
Due to the volatility of methylene chloride, all samples should be stored in airtight containers well below room temp.Store in the refrigerator, or if space permits, the freezer.
Standards:
Standard solutions of caffeine in methylene chloride should be made to these concentrations:500, 100, and 20 ng/uL. Shown in other units, this is
Extraction Method
Extraction:
Take a 150 mL Erlenmeyer flask, and add to it 8 g of coffee grounds.
Add to it 50 mL of methylene chloride.
Allow the coffee to extract for 5 minutes.
Remove the bulk coffee grounds from the solution.
If coffee is allowed to remain longer, caffeine may become overrepresented in the sample.
Some methylene chloride will be retained by the coffee ÐC this is an acceptable loss, and no dilution is necessary.
Preparation:
Separate the coffee extract from above into three equal portions; assuming some loss of methylene chloride, as above, these portions will be about 15 mL each.These will become the ÐŽ®highЎЇ, ÐŽ®mediumЎЇ, and ÐŽ®lowЎЇ concentrations.One portion can be set aside and sealed ÐC this will be the ÐŽ®mediumЎЇ concentration sample source.The other two portions will be made into the ÐŽ®high and ÐŽ®lowЎЇ solutions.The ÐŽ®highЎЇ sample is prepared by leaving uncovered to allow the methylene chloride to evaporate until about 1 mL remains.
The ÐŽ®lowЎЇ sample is prepared by a 10x dilution.
Due to the volatility of methylene chloride, all samples should be stored in airtight containers well below room temp.Store in the refrigerator, or if space permits, the freezer.
Standards:
Standard solutions of caffeine in methylene chloride should be made to these concentrations:500, 100, and 20 ng/uL. Shown in other units, this is
Extraction Method
Extraction:
Take a 150 mL Erlenmeyer flask, and add to it 8 g of coffee grounds.
Add to it 50 mL of methylene chloride.
Allow the coffee to extract for 5 minutes.
Remove the bulk coffee grounds from the solution.
If coffee is allowed to remain longer, caffeine may become overrepresented in the sample.
Some methylene chloride will be retained by the coffee ÐC this is an acceptable loss, and no dilution is necessary.
Preparation:
Separate
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