Search: TLC

Number of results: 133

chromatography
The closest I can find to a reason for streaking is that the sample spot was overloaded. Here is the link and it's at the end of the page. http://orgchem.colorado.edu/hndbksupport/TLC/TLC.html
Sunday, April 26, 2009 at 10:17pm by DrBob222

TLC purity
@ Johnny: TLC stands for thin layer chromatography. TLC is used for monitoring the process of a reaction, identifying compounds, and determining the purity of a substance. When conducting an experiment on TLC, you can determine the purity of an unknown analgesic by examining ...
Friday, October 13, 2006 at 11:29pm by Taylor

TLC error correction
Why shouldn't I applied too much of one compound on the TLC plate?
Saturday, October 14, 2006 at 7:32pm by Jectoroz

chemistry
How can you tell which mobile phase is more polar in TLC? (hexane/ethyl acetate/ethanol vs. isopropanol/ammonia)? the hexane/ethyl acetate/ethanol travelled up the TLC faster, does this make it more polar? The TLC is silica gel!
Monday, September 28, 2009 at 9:17pm by L

TLC error
When a TLC plate was developed, the solvent front ren off the top of the plate. why?
Tuesday, September 30, 2008 at 5:50pm by jane

Organic Chem
What is the problem of spotting TOO much sample on a TLC plate initially? Also, why is it bad to have too much solvent in the TLC jar?
Monday, May 9, 2011 at 7:54pm by Jim

TLC purity
TLC is used for thin layer chromatography, not for determining purity.
Friday, October 13, 2006 at 11:29pm by johnny

CHEMISTRY
Here are two web sites. The first describes thin layer chromatography; the second describes paper chromatography. The medium for TLC is SiO2; the medium for paper chromatography is, of course, paper. http://orgchem.colorado.edu/hndbksupport/TLC/TLC.html http://en.wikipedia.org...
Sunday, October 14, 2007 at 6:48pm by DrBob222

chemistry
Q#1:what would you look for in a tlc experiment to determine whether or not your sample was pure? Q#2:could you determine the extent to which your sample may be contaminated with the tlc technique?
Tuesday, November 13, 2012 at 12:52am by Anonymous

Chemistry - thanks
In a thin layer chromatography (TLC)experiment,the TLC plate was pre-developed in the development chamber containing the mobile phase (to remove any contaminants before use),then air dried. On the same day,the TLC plate was then spotted with the sample & standard and ...
Tuesday, January 31, 2012 at 4:14pm by Anne

Thin Layer Chromotography
Can you use TLC to distinguish various isomers from one another? In what kind of substance can you NOT distinguish the isomers from each other? i think it is not possible to distinguish If I have an unknown sample containing several ketones and want to use TLC to identify the ...
Sunday, November 5, 2006 at 6:00pm by Sarah

science(chemistry)
I have a question about TLC plate solvents. What solvents will leave stains on a plate with a TLC plate out of the ones below and why?) (n-Octane, n-Hexane, Decane, Acetone, 1-Propanol, 2-Propanol, Ethanol, Toluene, Cyclohexane, Methanol, n-Heptane, n-Pentane, Butanol) I saw 2...
Friday, April 24, 2009 at 10:32pm by ~christina~

CHEMISTRY
I'm not an expert on TLC but the way I see it it can't be A or B. Capillaries are not involved and multiple spotting has nothing to do (at least I don't think so) with the solvent evaporation. I didn't pick C earlier because that applies only to "VISIBLE&...
Sunday, August 19, 2012 at 3:13pm by DrBob222

Chemistry
You and another student were each given an unknown compound. Both samples contained colorless material. You each used the same brand of commercially prepared TLC plate and developed the plates using the same solvent. Each of you obtained a single spot of Rf=0.75. Were the two ...
Tuesday, February 2, 2010 at 11:08pm by Judy

Chemistry
You can run TLC plates with more solvents and compare the Rfs. An alternative that works well is to spot the two compounds together on the corner of a square TLC plate. Run the TLC plate in one solvent (e.g. the one in the question) so that the spot is about 2/3 of the way ...
Tuesday, February 2, 2010 at 11:08pm by Dr Russ

Chemistry
You haven't said if you know what group of compounds you might be looking at. You also have not said if this is Normal, Reverse or Ion exchange SPE. A quick technique is to use TLC against known samples. This will show how many compounds in each fraction and may identify ...
Tuesday, December 9, 2008 at 12:05am by Dr Russ

Organic Chem
There are a couple of possible reasons. I don't know what red leaf extract is?? Is it red tea extract? I take it that the stationary phase of the TLC is silica gel? It is quite likely that the extact contains a number of nitrogen containing compounds, such as alkaloids (it...
Tuesday, December 6, 2011 at 12:44am by Dr Russ

Social Studies
Check this site for the Texas constitution that spells out its responsibilities. http://tlo2.tlc.state.tx.us/txconst/toc.html
Friday, April 18, 2008 at 9:07pm by Ms. Sue

Organic Chemistry
I assume that this is TLC on silica. The more polar solvent is needed to move the more polar molecule. b) are the least polar molecules and so you would try hexane to separate them. a) are the next polar pair, so as you say methylene chloride would be a good choice. c) the ...
Saturday, March 7, 2009 at 9:55am by DrRuss

Chemistry-help needed
I have a question on thin layer chromatography (TLC). My mobile phase (i.e. developing solvent) is a mixture of 2 non-polar solvents. After preparing the mobile phase, is it necessary to pour some into the developing chamber to saturate the chamber or should we only pour the ...
Tuesday, January 31, 2012 at 8:47am by Anne

science(chemistry)
Even after reading the thread I am not sure I understand the questions. The solvents you list will not themselves leave a stain on the plate. However, depending on the make of plate and how it has been manufactured some of the polar solvents do shown a slight change in the ...
Friday, April 24, 2009 at 10:32pm by DrRuss

Organic Chemistry
For the first question, look up the structures and compare the polarity of the two molecules. You would expect the component with the larger Rf value to be less polar because it isn't attracted to the adsorbent on the TLC plate as much as the more polar compound. This ...
Thursday, October 23, 2008 at 9:52pm by DrBob222

chem
The Rf value of compound A is .34 when the TLC plate is developed in hexane and .44 when the plate is developed in diethyl ether. Compound B has an Rf value of .42 in hexane and .60 in diethyl ether. Which solvent would be better for seperating a mixture of compounds A and B ...
Tuesday, October 21, 2008 at 12:36pm by Jason

cosmetics science
For TLC?
Sunday, November 28, 2010 at 9:07am by sine

chemistry
the TLC is silica gel
Monday, September 28, 2009 at 8:42pm by L

Chemistry/ OChem
http://siggy.chem.ucla.edu/VOH/136/TLC.pdf The above site explains a little about why some analytes move fast and some slow. Check my thinking on these. a. Aren't the Hs at the double bond slightly acidic? But I would expect 1-4 dimethylbenzene to be less polar. The fact ...
Thursday, October 9, 2008 at 3:28pm by DrBob222

TLC purity
You're all gay
Friday, October 13, 2006 at 11:29pm by Emrah

chemistry
How are the spots on the TLC plates observed?
Thursday, March 29, 2012 at 2:30pm by mzrins

Chemistry
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. a) a two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of .95. The solvent uses was acetone. b) a two-...
Sunday, October 3, 2010 at 2:50pm by Jordyn

chemistry
Isn't D the choice? Are capillaries involved in TLC? Then A can't be right.
Saturday, August 18, 2012 at 11:15pm by DrBob222

chemistry
How to know if in TLC and HPLC if it is going forward or reverse?
Wednesday, December 1, 2010 at 6:28pm by Ben

TLC error
It was left in the solvent too long or do you know that already.
Tuesday, September 30, 2008 at 5:50pm by DrBob222

Organic Chemistry
You have not stated the conditions for the oxidation. If it is cold KMnO4 then you will form a mixture of diols, CH(CH3)-CH2-CH(OH)-CH(OH)-CH2-CH2 |_____________________________| You will need to check my assignments, but I make it that the two products are (1R,2R,4R)-4-methyl...
Sunday, October 31, 2010 at 11:55pm by Dr Russ

pharmacy
suggest a technique , other than tlc, to confirm the purity of the samples
Thursday, April 19, 2012 at 7:12am by pavan

Organic Chemistry Lab
I'm no TLC man but my thinking is the same as yours.
Sunday, March 21, 2010 at 9:55pm by DrBob222

Chemistry/ OChem
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. a) a two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of .95. The solvent uses was acetone. b) a two-...
Thursday, October 9, 2008 at 3:28pm by Neets

science(chem)
[b]1.[/b]Is TLC a qualitative or quantitative analysis? Is there any way that it can be both? Explain. ~I say it can be both since it can be used to go and determine what exactly is in a sample of mixed compounds which would be qualitative analysis. It can also be quantitative...
Saturday, October 13, 2007 at 7:51pm by ~christina~

chemistry
For a TLC lab,the stationary phase I think you mean the mobile phase? is the mixture of isopropanol and ammonia or the mixture of hexane,ethyl acetate and ethanol, the stationary phase is silica gel. text some dyes and drugs. The isopropanol and ammonia solvent mix is the more...
Wednesday, September 29, 2010 at 12:52am by Dr Russ

Organic Chemistry
Why would the presence of crystals of sample at the starting line cause streaking on a TLC plate?
Monday, March 19, 2012 at 4:21pm by Sally

Chemistry
Can anyone please tell me what can you say about the purity of the compound extracted based on your TLC results? Thanks
Tuesday, February 9, 2010 at 6:45pm by Andy

Mobility and Rf
We did a column chromatography then a TLC on extracted spinach pigments. Question: Why are the chlorophylls less mobile on column chromatography and why do they have lower Rf values than the carotenes? My answer: The chlorophylls are more polar than the carotenes so they ...
Sunday, October 22, 2006 at 2:27pm by Sheryl

Organic Chemistry Lab
How do we correct the problem if during TLC development the solvent ran off the plate?
Thursday, October 21, 2010 at 1:24pm by Jeanne

science(chemistry)
I assume you mean to make a KBr pellet from the solid obtained from one of the layers. Most organic solvents will evaporate and I don't think there will be interference to worry about. Yes, I mean to add the dry solid to KBr to form a pellet. The chance of interference was...
Friday, April 17, 2009 at 5:03pm by ~christina~

science(chemistry)
I have a question about solvent evaporation. If I had an organic layer and an aqueous layer in an unknown mixture of liquids and wanted to obtain the solid of a compound(s) dissolved in the layers, is it reasonable to assume that I can run the compound in the IR spectrometer (...
Friday, April 17, 2009 at 5:03pm by ~christina~

Organic Chemistry
Thin Layer chromatography TLC experiment What does it mean when it says with to much sample the spots will tail
Friday, October 26, 2012 at 8:25am by Nathalie

science(chemistry)
Using a GC to determine the solvent is good; however, whether to use that solvent or not is not the question. That solvent may not be suitable for separating the compounds with TLC. As for which solvent to choose, since you know nothing to little about the compounds, it's ...
Friday, April 17, 2009 at 5:03pm by DrBob222

chemistry
why we just see a light spot of benzaldehyde after tlc in iodine chamber which soon vanishes and does not appear again?
Saturday, August 20, 2011 at 6:36am by manoj

Purity
The question asked is: Using yur results as a guide, comment on the purity of the material in the green and yellow bands. (from a TLC of spinach extraction pigments.) I'm not quite sure what they want here and my plate is in the lab, not here. There were yellow and green ...
Sunday, October 22, 2006 at 3:01pm by Sheryl

chemistry
Different compounds have different polarities and are attracted to the various substrates of the TLC plates.
Tuesday, April 30, 2013 at 3:17am by DrBob222

TLC purity
Emrah- plz, for the love of god go back and finish grade school. also, thanks for the answer sheryl, helped me out a bit.
Friday, October 13, 2006 at 11:29pm by Jamaal

SCIENCE 9 URGENT!!
http://tlc.howstuffworks.com/family/male-reproductive-system.htm http://www.urologyhealth.org/urology/index.cfm?article=12
Wednesday, November 7, 2012 at 7:46pm by Ms. Sue

chemistry
why do different compounds give different retention factors (Rf values) in thin layer chromatography (TLC)
Tuesday, April 30, 2013 at 3:17am by jessica

Sample purity
Question: A student spots an unknown sample on a TLC plate and develops it in pentane solvent. Only one spot, for which the Rf value is 0.05, is observed. Is the unknown a pure compound? What can be done to verify the purity of the sample using TLC? My answer: It's not ...
Sunday, October 15, 2006 at 4:16pm by Sheryl

Chemistry
How do i calculate plate number, distribution constant, mobile phase and stationary phase volume for tlc not HPLC/ GC
Wednesday, July 27, 2011 at 4:10pm by Pharmacy

Music
Check out these sites. http://www.familycorner.com/family/kids/crafts/9_musical_instruments.shtml http://tlc.howstuffworks.com/family/musical-instruments-for-kids.htm
Thursday, April 26, 2012 at 7:52pm by Ms. Sue

TLC purity
Question: A student spots an unknown sample on a TLC plate and develops it in dichloromethane solvent. Only one spot, for which the Rf value is 0.95, is observed. Does this indicate that the unknown material is a pure compound? What can be done to verify the purity of the ...
Friday, October 13, 2006 at 11:29pm by Sheryl

Medical Terminology
I can give you an example where using abbreviations wasted time and money. Amines can be separated by thin layer chromatography (TLC) and one way of seeing the spots on the TLC plate is to spray the plate with iodoplatinic acid (IPA). Years ago I worked for a pharmaceutical ...
Wednesday, September 24, 2008 at 2:35am by Dr Russ

Chemistry
suppose you carry out a TLC separation of acetaminophen and phenacetin on silica gel using a non polar developing solvent. which should have a higher Rf value, and why?
Wednesday, October 21, 2009 at 9:14pm by Anonymous

accounting
how can i tell which users are internal or external? like bank mangaer parent owner toy suppier cleaner contracted by tlc daycare canada customs and revenus agency
Saturday, October 4, 2008 at 8:56pm by Anonymous

Organic Chemistry 1
Why does iodine absorb organic molecules? This question is referring to the effect of the iodine chamber used in TLC.
Friday, October 24, 2008 at 6:40pm by Audrey

Spinach
I did a column chromatography on spinach and then a TLC. On the TLC I got five visible bands of colors. On the extracted yellow substance I got one yellow band (carotene) and on the green I also got only one green band. I thought there would be more bands on the green but ...
Monday, October 23, 2006 at 5:45pm by Sheryl

TLC peru balsam
what is the rf value for peru balsam in order of identification?
Monday, September 14, 2009 at 10:17pm by ira

chemistry
see if on tlc silica if the polar solvent moves slowly then does even polar substances rf value is low? and the nonpolar rf is high?
Tuesday, February 23, 2010 at 2:18am by KKSAI

science(chemistry)
I don't know but it's easy enough to spot the plates with those solvents and see. I'm not an ace on TLC chromatography; I didn't know any of those compounds would leave a spot.
Friday, April 24, 2009 at 10:32pm by DrBob222

Organic Chemistry
Identify the error in the following scenario and indicate how you would fix the error: A TLC of a two component mixture of pentene and 1,3-diethylbenzene was run in acetone. An Rf value of 0.90 was reported.
Sunday, October 28, 2012 at 2:55am by Sarah

ochem lab
this deals with TLC chromatography: if 2 compounds have same Rf under identical conditions, does it show that they have identical structures? i think it does. but im not sure why. thanks mucho.
Friday, November 2, 2007 at 4:42pm by christine

science(chem)
Consider the following errors that could be made when running the TLC. Indicate what should be done to correct the error. a) A 2 component mixture containing 1-octene and 1,4- dimethylbenzene gave only 1 spot with and Rf value of 0.95. The solvent used was acetone b) A 2 ...
Monday, October 8, 2007 at 11:51pm by ~christina~

organic chemistry
when 2 propanol was used as the developing solvent, two substances moved with the solvent front (Rf=1) during TLC analysis on a silica gel plate. can you conclude that they are identical? if not what additional experiments would you perform?
Wednesday, October 17, 2012 at 11:22pm by lili

Chemistry
I think you can use both methods. The first one if you compare the move up the plate IF you know that the TLC plate is coated with a polar/non-polar material. The second IF you know the polarity of the dyes.
Friday, September 26, 2008 at 9:33am by DrBob222

Chemistry
A.) Use methylene chloride for the TLC with 2 - phenylethanol and acetophenone. B.) Use Hexane for the bromobenzene and p-xylene. C.) and acetone for benzoic acid, 2,4-dinitrobenzoic acid, and 2,4,6-trinitrobenzoic acid.
Thursday, October 9, 2008 at 4:53pm by Anonymous

Organic Chem Lab
If I have separate solutions of the compounds benzoic acid and benzaldehyde, and they are spotted on an alumina gel TLC plate and run using CH2Cl2 as the eluant, which compound will have the higher Rf value? Explain.
Sunday, October 11, 2009 at 7:58pm by Sarah

chemistry
What's the substrate on the TLC? SiO2? If so that is polar and it should hold the more polar components back (travel slower). My best intuition thinks that ammonia would be more polar than ethanol.
Monday, September 28, 2009 at 8:42pm by DrBob222

Ochem Lab
why is it important to spot samples directly on the marks made on the TLC plate? This is for Thin Layer Chromotography. Is this important so that the solvents move directly up the plate and can be identifies easily? Thanks
Sunday, October 24, 2010 at 6:25pm by Adam

Organic Chem
Too much sample leads to poor separation of the bands. Too much solvent means the solvent may touch the spot thus contaminating the solvent and "feeding the TLC plate with more of the spotted stuff" continuously.
Monday, May 9, 2011 at 7:54pm by DrBob222

TLC error correction
Question: Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. A. A two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of 0.95. The solvent used was acetone. In ...
Saturday, October 14, 2006 at 7:32pm by Sheryl

Lab conclusion- HELP!
I' am currently trying to wrie a couple of lab conclusions and having a hard time coming up with good points to make for the following lab experiment: Thin layer chorotography If anyone has a few minutes to give me a couple tips on how to improve this. I think it sounds ...
Monday, February 5, 2007 at 10:46pm by Richard

anatomy
I have 2 problems/questions I am unsure of the answers. The first one is "how would you demonstrate the Valsalve maneuver using the model lung?" and 2. If a woman is breathing rapidly and deeply after exercise, would TLC, RV, TV, IRV, and ERV stay the same, increase ...
Monday, March 12, 2012 at 5:50pm by Mary

A&P II
I have 2 problems/questions I am unsure of the answers. The first one is "how would you demonstrate the Valsalve maneuver using the model lung?" and 2. If a woman is breathing rapidly and deeply after exercise, would TLC, RV, TV, IRV, and ERV stay the same, increase ...
Sunday, March 11, 2012 at 4:00pm by Mary

Chemistry
Chromatography How can I tell which of two mobile phases is more polar? Does the fact that one solvent (e.g. isopropanol/ammonia) moves up the TLC plate slower than another solvent (e.g. hexane/ethyl acetate/ethanol)? Or should I look at how far up the dyes have moved?
Friday, September 26, 2008 at 9:33am by H

Chemistry
Do I assume this is chromatography? I wonder what kind. If TLC, you can use different solvents, you can use two dimensional chromatography, or you can use different method entirely and use infra red or MS.
Wednesday, April 7, 2010 at 12:34pm by DrBob222

chemistry
-Suppose you carry out TLC separation of acetaminophen and ibuprofen on silica ggel using a nonpolaar developing solvent. which should have a higher Rf? -Assuming that the drug components whose spots you identified dissolved completely when you stirred the tablet with 1:1 ...
Monday, November 29, 2010 at 9:58am by tristan

chemistry
For a TLC lab,the stationary phase is the mixture of isopropanol and ammonia or the mixture of hexane,ethyl acetate and ethanol, the stationary phase is silica gel. text some dyes and drugs. what is the relationship between the polarity of molecules and the Rf values?
Tuesday, September 28, 2010 at 11:52pm by Leon

Biology Question
I have 2 problems/questions I am unsure of the answers. The first one is "how would you demonstrate the Valsalve maneuver using the model lung?" and 2. If a woman is breathing rapidly and deeply after exercise, would TLC, RV, TV, IRV, and ERV stay the same, increase...
Sunday, March 11, 2012 at 9:02pm by Mary

Chemistry/ OChem
Read the web site I highlighted in response below and see if that gives you some ideas. The trick is to look at the components to be separated and make an educated guess about their polarity, then match that to a solvent that will move the components at different speeds up the...
Thursday, October 9, 2008 at 3:22pm by DrBob222

Chemistry
After placing the spot on the TLC plate and developing it, if you obtain more than one spot you know that more than one material was extracted. If just one spot develops you are relatively sure (but not positive) that the product is pure.
Tuesday, February 9, 2010 at 6:45pm by DrBob222

biology
I have 2 problems/questions I am unsure of the answers. 1. how would you demonstrate the Valsalve maneuver using the model lung? 2. If a woman is breathing rapidly and deeply after exercise, would TLC, RV, TV, IRV, and ERV stay the same, increase or decrease? Thank you for any...
Tuesday, March 13, 2012 at 9:34am by Wendy

TLC
The following two solvents systems were found to separate compounds x and y by flash column chromatography: X- hexanes/ethyl acetate 10:1 Y- hexanes/ethyl acetate 10:4 which is more polar X or Y? Which solvent system must be used first?
Sunday, February 18, 2007 at 11:36am by sue

chemistry
In TLC, why do you spot multiple times? Select one or more correct answers. A. To fill the capillary almost instantly by capillary action. B. So the developing chamber solvent does not evaporate. C. The higher compound concentration facilitates visualization. D. To acheive a ...
Saturday, August 18, 2012 at 11:15pm by Hannah

psychology
Thank you for using the Jiskha Homework Help Forum. Mostly there are PDF files to download: 1. courses.durhamtech.edu/tlc/www/html/Resources/learnin... 2. seab.envmed.rochester.edu/jeab/articles/2002/jeab-77- 3. www.behavior.org/journals_BP/2004/08Harzem.pdf -
Tuesday, September 18, 2007 at 9:44am by SraJMcGin

college chemistry
If i have a highly polar mobile phase, what will happen to the non-polar or less polar compounds during chromatography? will they move less up the TLC plate or actually even more because the mobile phase itself is so polar.
Tuesday, February 12, 2013 at 6:45pm by Anonymous

chemistry
out of orthonitroaniline and paranitroaniline which one will go at the top of TLC plate and why It depends upon the stationary phase and the mobile phase, to some extent; however, o-nitroaniline is LESS polar than p-nitroaniline. A polar adsorbent will hold the para isomer ...
Monday, April 9, 2007 at 9:44am by pawam

Difference?
What is the difference between these two questions? They look the same to me, like they're asking the same thing. Not likely. Question: A student spots an unknown sample on a TLC plate and develops it in dichloromethane solvent. Only one spot, for which the Rf value is 0....
Saturday, October 14, 2006 at 10:07pm by Sheryl

Organic Chemistry
What is/are the product(s) of the potassium permanganate reaction with (R)-4-methyl cyclohexene? Is the product a meso molecule, racemic mixture, or other mixture, and if so, what kind of mixture? If the product is a mixture, do you expect the compounds to have the same or ...
Sunday, October 31, 2010 at 11:55pm by Anonymous

ochem
Consider a sample that is a mixture composed of biphenyl, benzoic acid, and benzyl alcohol. Predict the order of elution of the components in this mixture on the TLC plate when solvent system a, b or c is used. a)Cyclohexane: Methylenechloride:100%:0% b)Cyclohexane: ...
Tuesday, May 7, 2013 at 11:25pm by bez

Chemistry
Each of the solvents given should effectively separate of the following mixtures by TLC. Match the appropriate solvent with the mixture that you would expect to separate well with the solvent. Select your solvent from the following: hexane, methylene chloride, or acetone. (a) ...
Thursday, October 9, 2008 at 4:53pm by Nina

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