Using a nonpolar stationary phase and a mobile phase consisting of a 50:50 mixture of aqueous...
Using a nonpolar stationary phase and a mobile phase consisting of a 50:50 mixture of aqueous acetic acid and methanol, rank the following compounds in order of elution off of a HPLC column:
Acetaminophen, caffeine, aspirin and benzoic acid
Homework Answers
Order of elution
1. Acetaminophen
2. Caffeine
3. Asprin
4. Benzoic avid.
Here stationary phase is non polar so highly polar compound eluets first. Acetaminophen is most polar .
The above said order is decreasing polarity.
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Using a nonpolar stationary phase and a mobile phase consisting
of a 50:50 mixture of aqueous...
In reverse-phase HPLC, the liquid stationary phase is _____ polar than the mobile phase, and elution...
In reverse-phase HPLC, the liquid stationary phase is _____ polar than the mobile phase, and elution of the ______ polar compounds occurs first, with the ______ polar compounds adsorbed more tightly to the stationary phase. Select one: a. less, less, less b. more, more, more c. less, more, less
Why was it important to filter and degas the mobile phase and the samples? How is...
Why was it important to filter and degas the mobile phase and the samples? How is the “reversed-phase” HPLC used here different from “normal-phase” with regard to stationary and mobile phases, and order of elution? Mobile Phase Composition (a) If the mobile phase composition was changed from 65:35:1 (v/v/v) to 75:25:1 (v/v/v) water:methanol:acetic acid, how would the time of elution (expressed as retention time) for caffeine be changed, and why would it be changed? (b) What if it was changed...
Why was it important to filter and degas the mobile phase and the samples? How is...
Why was it important to filter and degas the mobile phase and the samples? How is the “reversed-phase” HPLC used here different from “normal-phase” with regard to stationary and mobile phases, and order of elution? Mobile Phase Composition (a) If the mobile phase composition was changed from 65:35:1 (v/v/v) to 75:25:1 (v/v/v) water:methanol:acetic acid, how would the time of elution (expressed as retention time) for caffeine be changed, and why would it be changed? (b) What if it was changed...
1. Select an appropriate type of column for separating these steroids and give the rationale for...
1. Select an appropriate type of column for separating these steroids and give the rationale for your selection. HO HO ОН OH Prednisolone Prednisone 2. You are using a C18 Reverse Phase column and the parameters shown below to separate Acetaminophen, Caffeine, and Benzoic Acid. You observe three peaks in your chromatogram (Huzzah!). Which corresponds to which compound? Explain the rationale behind your assignment. OH C18 REVERSED PHASE COLUMN Acetaminophen HC N H, O Caffeine Column: Legacy L1 Size: 4.6...
7. Given a non-polar stationary phase C18 (reverse phase) and a slightly polar mobile phase (15%...
7. Given a non-polar stationary phase C18 (reverse phase) and a slightly polar mobile phase (15% water 85% acetonitrile) predict the order of elution for the following compounds (with 1 being the fastest and 4 being the slowest) (6 pts) Methanol CH OH 1-florobutane CH CH CH2CH2F Butanol CH,CH CHCHOH Cyclohexane CoH12 Briefly justify how you made your choice(s) Now increase the polarity of the mobile phase to 85% water and 15 % acetonitrile. Explain the relative shifts in retention...
please answer part a and b. thank you Problem 8: Assume that an aqueous sample contained...
please answer part a and b. thank you
Problem 8: Assume that an aqueous sample contained traces of the following compounds listed in the table and that you extracted the aqueous Octanol-Water Distribution Coefficients COMPOUND NAME Benzene Toluene o-Xylene m-Xylene p-Xylene pk 2.13 2.73 3.12 3.20 3.15 ple with an aliquot of octanol. The distribution coefficients are given as pKD values. List the compounds in order of increasing concentration in the octanol phase at equilibrium Assume that you analyzed an...
4) What is the order of elution of the following compounds from a reverse-phase packed HPLC...
4) What is the order of elution of the following compounds from a reverse-phase packed HPLC column? Briefly justify your reasoning. Benzyl alcohol (C6H5CH2OH), benzaldehyde (C6H5CHO), benzoic acid (C6H5COOH), Acetophenone (C6H5C(O)CH3)
4) (10 pts) What is the order of elution of the following compounds from a reverse-phase...
4) (10 pts) What is the order of elution of the following compounds from a reverse-phase packed HPLC column? Briefly justify your reasoning. Benzyl alcohol (C.HSCH-OH), benzaldehyde (C6HSCHO), benzoic acid (C6HCOOH), Acetophenone (C6H5C(O)CH3)
1. What is the purpose of column chromatography 2. What is the stationary phase? Mobile phase?...
1. What is the purpose of column chromatography 2. What is the stationary phase? Mobile phase? 3. What is the purpose of the cotton (glass wool) in column chromatography? 4. What is the purpose of the sand? 5. Why is it important to prevent the column from drying? 6. What can happen if you disrupt your even layer of silica gel? 7. Which compounds come off the column first, polar or nonpolar? 8. Keyon synthesized acetylferrocene (orange) in organic chemistry...
8.2 Rank the following solvents in order of increasing polarity: dichloromethane, acetic acid, methanol, and diethyl...
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1. Select an appropriate type of column for separating these steroids and give the rationale for your selection. HO HO ОН OH Prednisolone Prednisone 2. You are using a C18 Reverse Phase column and the parameters shown below to separate Acetaminophen, Caffeine, and Benzoic Acid. You observe three peaks in your chromatogram (Huzzah!). Which corresponds to which compound? Explain the rationale behind your assignment. OH C18 REVERSED PHASE COLUMN Acetaminophen HC N H, O Caffeine Column: Legacy L1 Size: 4.6...
7. Given a non-polar stationary phase C18 (reverse phase) and a slightly polar mobile phase (15% water 85% acetonitrile) predict the order of elution for the following compounds (with 1 being the fastest and 4 being the slowest) (6 pts) Methanol CH OH 1-florobutane CH CH CH2CH2F Butanol CH,CH CHCHOH Cyclohexane CoH12 Briefly justify how you made your choice(s) Now increase the polarity of the mobile phase to 85% water and 15 % acetonitrile. Explain the relative shifts in retention...
please answer part a and b. thank you
Problem 8: Assume that an aqueous sample contained traces of the following compounds listed in the table and that you extracted the aqueous Octanol-Water Distribution Coefficients COMPOUND NAME Benzene Toluene o-Xylene m-Xylene p-Xylene pk 2.13 2.73 3.12 3.20 3.15 ple with an aliquot of octanol. The distribution coefficients are given as pKD values. List the compounds in order of increasing concentration in the octanol phase at equilibrium Assume that you analyzed an...
4) (10 pts) What is the order of elution of the following compounds from a reverse-phase packed HPLC column? Briefly justify your reasoning. Benzyl alcohol (C.HSCH-OH), benzaldehyde (C6HSCHO), benzoic acid (C6HCOOH), Acetophenone (C6H5C(O)CH3)
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8.2 Rank the following solvents in order of increasing polarity: dichloromethane, acetic acid, methanol, and diethyl ether. (Hint: refer to Appendices 1 and 3). 8.3 Rank the following compounds in the order in which they would elute off an alumina column: benzoic acid, benzene, benzaldehyde, and benzyl alcohol. S
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