To identify the amount of caffeine in my coffee using an HPLC instrument, standard solutions of caffeine were prepared and analyzed using a 10-mL fixed-volume injection loop. Results for the standards: concentration (ppm) signal (arb. units) 8, 500 16, 900 25, 220 60.0 120.0 180.0 240.0 33, 585 300.0 42, 008 The sample was prepared by placing 10 g of coffee in a small beaker and adding 100 mL of methanol. After allowing the extraction of caffeine and filtration, the extract was quantitatively transferred to a 250-mL volumetric flask and diluted to volume with methanol. A 1.00mL aliquot was transferred to a 10-mL volumetric flask and diluted to volume with methanol. When analyzed by HPLC, the signal for caffeine was found to be 21,500. Create a linear calibration curve; determine the concentration of caffeine in the 10 mL solution in the volumetric flask that was introduced to the injector; and calculate the milligrams of caffeine in the 100 grams of coffee.
To identify the amount of caffeine in my coffee using an HPLC instrument, standard solutions of caffeine were prepared and analyzed using a 10-mL fixed-volume injection loop. Results for the standards: concentration (ppm) signal (arb. units) 8, 500 16, 900 25, 220 60.0 120.0 180.0 240.0 33, 585 300.0 42, 008 The sample was prepared by placing 10 g of coffee in a small beaker and adding 100 mL of methanol. After allowing the extraction of caffeine and filtration, the extract was quantitatively transferred to a 250-mL volumetric flask and diluted to volume with methanol. A 1.00mL aliquot was transferred to a 10-mL volumetric flask and diluted to volume with methanol. When analyzed by HPLC, the signal for caffeine was found to be 21,500. Create a linear calibration curve; determine the concentration of caffeine in the 10 mL solution in the volumetric flask that was introduced to the injector; and calculate the milligrams of caffeine in the 100 grams of coffee.
Chapter4: Least-squares And Calibration Methods
Section: Chapter Questions
Problem 10P
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