TOX 3300 Chapter Notes - Chapter 23: Gel Permeation Chromatography, Volumetric Flow Rate, Peaks

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harlequinbutterfly554

8 Nov 2017

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In the vast majority of real analytical problems, we must separate, identify, and measure one or more components from a complex mixture. Extraction is the physical transfer of a solute from one phase to another. Common reasons to carry out an extraction in analytical chemistry are to isolate or concentrate the desired analyte or to separate it from species that would interfere in the analysis. The most common case is the extraction of an aqueous solution with an organic solvent. Chromatography operates on the same principle as extraction, but one phase is held in place while the other moves past it. A solution containing solutes a and b is placed on top of a column packed with solid particles and filled with solvent. When the outlet is opened, solutes a and b flow down into the column. Fresh solvent is then applied to the top of the column and the mixture is washed down the column by continuous solvent flow.

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Does this analytical methods has an internal standard (IS) or QC sample, why is this so?

Analytical Method

Plasma imatinib concentrations were determined us- ing a high-performance liquid chromatography/tan- dem mass spectrometry (HPLC/MS/MS) assay.16 This method was validated for both monkey and human plasma. Plasma samples were prepared using a C18 solid-phase extraction procedure (3M Empore C8 ex- traction disk). Sample extracts were analyzed using reversed-phase chromatography with a Waters Sym- metry column (Waters Corp., Milford, MA) followed by detection with a Sciex API 3000 mass spectrometer (PE Biosystems, Foster City, CA). The lower limit of quanti- fication was 4 ng/mL, and the assay was fully vali- dated. The accuracy and precision from prestudy vali- dation were 97.8% Â± 6.4% at the lower limit of quantification and 91.5%-102% Â± 0.4%-8.2% over the entire concentration range of 1 to 10,000 ng/mL.

any help or suggestions for a 1-2 page lab report on this???

If you were to use THF, or tetrahydrofuran instead of dicholormethane for this experiment, could you still successfully extract your caffeine? Why or why not? (Consider what is necessary for an extraction to work)

If you were to use an acidic water solution for this extraction rather than a basic one, could you still perform the extraction?â

The experiment is below. Just answer the above questions.

Introduction Caffeine is one of three legal, mind-altering drugs available in the U.S without a prescription. Two common sources of this drug are tea and coffee, both of which are prepared via extraction of the solid foodstuff with liquid water. In this lab you will extract caffeine from food samples with liquid solvents and quantify the amount obtained. Laborator Hypothesis: We can rank various tea and coffee samples by caffeine content by performing a solid-liquid extraction from the foodstuff, followed by analysis via thin-layer chromatography. Experiment: In a 50 mL Erlenmeyer flask were placed 2.0 g of black tea. Dichloromethane (15 mL) and 0.2 M NaOH (5 mL) were added successively, and the stoppered flask was swirled gently by hand for 10 minutes (note: avoid vigorous shaking, as it will cause an emulsion to form). The dicloromethane layer was separated from the leaves and the aqueous layer by vacuum filtration through 7 g Celite 545, and the leaves were washed with a further 15 mL dichloromethane. The combined dichloromethane solution was placed in a 50 mL round bottom flask and concentrated to a minimal volume (ca. 1 mL) via simple distillation. The remaining dichloromethane solutions was transferred to a watch glass via pipet, and the solvent was evaporated in a fume hood. The sample was evaluated by TLC (a mixture of methanol and ethyl acetate as the mobile phase, co-spotted with authentic caffeine). Data: What was your crude yield of caffeine? What was the mass percentage of caffeine in your food source'? Given that the materials we are interested in are UV active, compared to the TLC standard how would you characterize the purity of your caffeine extracts? Conclusions: Can you comment on the purity of your caffeine sample? For all samples your class worked with where does your foodstuff rank in terms of caffeine content? How much caffeine is reported for the typical serving of coffee or tea? How did your extraction and isolation compare with the typical serving?

TOX 3300 Chapter Notes - Chapter 23: Gel Permeation Chromatography, Volumetric Flow Rate, Peaks

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