2. Thin layer chromatography was performed tofind the most effective mobile phase needed toseparate a mixture containing three compounds(using silica gel as the stationary phase). TLCanalyses were performed using five differentmobile phases: (A) pure petroleum ether; (B)25:75 ethyl acetate:petroleum ether; (c) 50:50ethyl acetate:petroleum ether (D) 75:25 ethylacetate:petroleum ether; and (E) pure ethylacetate. Using the TLC results provided, indicatewhether an effective separation was achievedfor each of the five mobile phases. Be sure toprovide a brief explanation for your answer andidentify which mobile phase(s) could be usedto offer an effective separation of this mixtureusing column chromatography.ADE

Step 1: The thin-layer chromatography (TLC) results provide insight into the effectiveness of…

Answered: 2. Thin layer chromatography was…

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter33: High-performance Liquid Chromatography

Section: Chapter Questions

Problem 33.15QAP

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1) Study the chromatograph (below) of a mixture of Compounds A and B, run on the GCs in the teaching labs at CU Boulder. Compound A has the shorter retention time. STAAT 61 1.11 227 RT TYPE AREA XXXX XXXX XXXX AREAS 0.009 55874 44.117 ARIHT 0.61 XX XX XX 1.11 2.27 XX XX XX TOTAL AREA=XX MUL FACTOR=XX 1. What is the retention time of compound A? Compound B? 2. Which compound is present in a larger amount? 3. Which compound has the lower boiling point? 4. What would happen to the retention times of compounds A and B if the column temperature were raised? 5. You suspect that compound B is octane. What can you do to provide supporting evidence for this hypothesis?
When a mixture of three compounds ( is purified by column chromatography using different concentrations of solvents, the following is observed. 1) 50 ml 100 % Hexane-compound 1 elutes 2) 50 ml 20: 80 ether: hexane- compound 2 elutes 3) 100 % ether- compound 3 elutes based on the observations above, choose all the correct statements O compound 3 retains least on the column and is the least polar. O compound 2 is most likely a hydroxyl compound( 2 naphthol) and is somewhat polar O compound 1 retains longest on the column. and is the most polar O compound 1 is most likely a neutral compound (e.g. naphthalene), and is almost non polar O compound 3 is most likely a carboxylic acid like compound ( benzoic acid), and is very polar O compound 2 retains on the column more than 1 but less than 3 because it is a neutral compound.
2. Different marker inks were analyzed using a simple paper chromatographyexperiment. Two marker inks were dissolved separately in a solvent and spottedin the chromatogram. The mobile phase used was 1% NaCl and three inkstandards (A-copper-phthalocyanine blue, B-diarylide yellow,C- lithol rubine red)were spotted beside the two sample markers. After the chromatography, thechromatogram showed a separation of colors in the two inks (D and E).a. Calculate the retention factor for each spot from lanes A to E .b. Which ink standard was the most polar? least polar?c. What is the composition of ink D ?
Which of the following pairs of compounds would be most easily separated by thin layer chromatography: n-octyl alcohol and 1-octene, hexadecane and octadecane, or chlorobenzene and bromobenzene?
Is it possible to detect metal complexes of organic acids with thin layer chromatography?
Iman has a mixture of two compounds A and B. A is a protein, and B is a lipid. He plans to separate the mixture using a column chromatography technique. He packed the column with amino bonded with siloxane material and use a mixture of 20:80 of water: hexane as the mobile phase. i) Sketch the apparatus set up for the chromatographic technique used by Iman. Use the correct chromatographic terminologies to label all of the apparatus, materials, and phases. ii) Predict the sequence of elution when the mixture was loaded onto the separation column. Justify your answer. iii) After the first compound was eluted, Iman discovered that the second compound was taking too long to pass through the column. Please suggest any strategies that could be used to aid the elution process.
These chromatograms were recorded using reverse phase HPLC. |1,2,3 Peaks: 1. Benzyl alcohol 2. Phenol 5. Ethyl benzoate 6. Toluene 7. 2,6-Dimethoxytoluene 8. o-Methoxybiphenyl 8 3. 3,4-Dimethoxyacetophenone 4. Benzoin 6,7 |2,3 51 5 8 5 5 10 15 20 25 Time (min) Time (min) → a) Give an example of a mobile phase for this type of separation. b) Give an example of a detector that might be used for these compounds. c) Give an example of a stationary phase that might be used for these separations. Chromatogram A Chromatogram B
Use a suitable model to explain how separation and identification of a mixture of organic compounds can be achieved with a thin layer chromatographic (TLC) technique.
Which solvent mixture is best for TLC chromatography of syn- and azobenzene: 75:25 DCM: Hexanes 25:75 Hexane: Acetone 90:20 Hexanes: Ethanol
The following data give the recovery of bromide from spiked samples of vegetable matter, measuredusing a gas–liquid chromatographic method. The same amount of bromide was added to each specimen(Roughan, J.A., Roughan, P.A. and Wilkins, J.P.G., 1983, Analyst, 108: 742).Tomato: 777 790 759 790 770 758 764 ug/gCucumber: 782 773 778 765 789 797 782 ug/g(a) Test whether the recoveries from the two vegetables have variances which differ significantly.(b) Test whether the mean recovery rates differ significantly.
The substances in the table below were chromatographed on a gel filtration column. Estimate the molecular weight of the unknown. Compound Blue Dextran 2000 Molecular weight 2 x 106 158 000 V. (mL) 17.7 Aldolase 35.6 Catalase 32.3 210 000 Ferritin 28.6 440 000 Thyroglobulin 25.1 669 000 Unknown 30.3
2-pentanone has a retention index of 987 on a poly(ethylene glycol) column (also called Carbowax). (a) Between which two straight-chain hydrocarbons is 2-pentanone eluted? (b) An unretained solute is eluted from a certain column in 1.80 min. Decane (C10H22) is eluted in 15.63 min and undecane (C11H24) is eluted in 17.22 min. What is the retention time of a compound whose retention index is 1 050?

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