Chromatography Definition and 51 Threads

Astatine (Z=85) is one of those elements without a stable isotope, which makes it difficult to study. It is a halide like bromine and iodine. https://www.azom.com/news.aspx?newsID=63119 210At is the most stable isotope with a half-life of 8.1 hrs, while 211At has a half-life of 7.216 hrs.

"Resolution of enantiomers can be accomplished using column chromatography. When enantiomers are passed through a traditional column, they travel at the same rate because their properties are identical. However, if a chiral adsorbent is used, the enantiomers interact with the adsorbent...

I am learning about protein purification in my Biochemistry class, and I have a question about protein elution in antibody affinity chromatography. My understanding of the mechanism for the technique is that proteins that do not bind to the antibody will be separated first as it runs down the...

I need to measure trichloroethylene (TCE) in water samples using headspace gas chromatography. Obviously, I will need a set of standard solutions to make a standard curve for concentration vs area. How exactly do you prepare the standard solutions? What I don't understand is that, say I prepare...

Hello all I am using the method of lines to solve the following PDE: ## \frac {\partial C} {\partial t} + F\frac {\partial q} {\partial t} + u \frac {dC} {dz} = D_{ax} \frac{\partial^2 C} {\partial z^2} ## ## \frac {\partial q} {\partial t} = k (q^{*}-q) ## With these initial conditions: ##...

Homework Statement A purified protein fraction containing buffer with salt can be desalted by one of the following techniques: (1) Gel filtration chromatography (3) Paper chromatography (2) Affinity chromatography (4) Thin layer chromatography2. The attempt at a solution Well, the analyte...

Homework Statement [/B] Two proteins of similar molecular weight (<900 Da), same net charge in the solution but with different amino acid composition is to be separated. Which one should be used? a. Cation exchange b. Anion exchange c. gel filtration d. Reverse phase 2. My attempt: Since the...

Does anyone here have any experience with GC? I am developing a method for analyses and I understand all the settings but there is one related to the TCD called Temperature(pre). Does anyone have any ideas? Thanks for any suggestions!

Homework Statement For this chromatography graph there are 2 peaks: One of them is propanoic acid and another one is pentanoic acid. The more polar compound will have a longer retention time. Which peak belongs to which compound. Homework EquationsThe Attempt at a Solution The answers says...

The kinetic theory says that temperature is the measure of the average kinetic energy. That would mean then : The temperature rises with the rise in kinetic energy. We know that when matter changes state 'latent heat' helps in 'breaking the bonds' at the transition phase and that this 'extra...

In chromatography, the upper portion of the moving water solvent has more kinetic energy, than the lower portion of the moving water solvent because the lower portion of water molecules have to face more obstacles in the way because of the absorbed water molecules. Is it true?

Hello Everyone, This is a PhD student in Chemical engineering from Australia. I am working on Simulation of many operations (hence my name is SimOpera) one of which is chromatography. Would like to further indulge in technical discussions ahead. Currently working on simulation of hydrophobic...

I performed column cromatography on an oil, and used carbon boiling chips but got some weird IR. I used hexanes and acetone as solvents, I am trying to figure out some of the spikes, soo I am thinking that maybe the boiling stone being carbon could acted as activated carbon and absorbed some...

My gas chromatography instrument ran out of air while cooling down and now it won't turn on, nor the computer it is hooked up to? Can this be fixed?

Dear all, We all know that chromatography is a separation technique. In paper or TLC,the mixture is differentiated according to their relative affinities with the solvent on the paper or glass plate. How do we really separate the mixture. Kindly, help me how to extract the components...

Hi, I am studying for my biochemistry lab exam. While going over one of the questions... I came across one that I can't answer...help will be appreciated. Question under analysis is related to a previous question. (Previous question) A gel filtration (size exlcusion) is set up and the...

So I have been asked to separate a polymer (polyurethane) into high molecular weight and low molecular weight components. I have access to Sephadex LH-20, a simple glass column, acetone (a List II chemical), ethyl acetate, and hexane. I may be able to get access to other solvents, as long as it...

Homework Statement Hi, I did a lab where benzophenone was dissolved in ethanol and reacted with sodium borohydride (NaBH4) and chromatography was done on the reaction at different points in time. There was no HCl work up of this though. When I developed the TLC (silica) plate, it looked like...

I'm reading about gas chromatography at the moment and the notes I'm reading mentioned a "generic scouting gradient" but didn't explain what it is. I've been googling it and found a few HPLC tutorials (in GC its temperature gradient whereas in the HPLC tutorials they're talking about mobile...

Homework Statement why during chromatography must the paper NOT touch the sides of the test tubes in which the experiment is being carried out? Homework Equations The Attempt at a Solution I am not sure but could our results get smudged or distroted? if so I still can't work out how? could it...

I recently ran a baylis-hillman reaction of 2nitrobenzaldehyde and acrylonitrile (DABCO catalyst) and after my reaction had gone to completion (determined by tlc) i extracted with chloroform/washed with brine, dried, filtered, rotovaped etc etc I ran a crude NMR and determined I did have my...

Today in a lecture on chromatography the lecturer gave an explanation which seems pure ******** to me. The example she used was a handful of solutes, each taking a different path through the stationary phase, obviously some paths will be longer than others and thus each solute will have a...

Hey guys! It seems that there are a few users here, so I will post the same question I posted over at chromforum.org: -------------------------------------------------- Hello All! :smile: I am quite new here and to GC in general, so I hope you can bear with me. I will try to keep this...

Hello people! I am wondering if anyone uses this machine? I am a mechanical engineering student and I have one in my laboratory. I have quite a bit of documentation on the machine, however, a lot of it is like a foreign language to me. Before I start asking any questions, I wanted to...

I did an experiment in which I used an anion exchange resin to separate nickel from cobalt but I don't understand the theory behind it. What I know is that the ion exchange resin uses quaternary ammonium groups as its cations but that's about it. First we packed a column with the resin then...

If you had to prove that your method for cleaning chromatography columns works and you had different sizes and shapes of columns, which one would you pick as a worst case to focus on? You have tall, skinny columns and short, fat columns, as well as different sizes. These are cylindrical glass...

Homework Statement How would you use chromatography to determine whether an unknown pure liquid is 1-pentene, cis-2-pentene, or trans-2-pentene? Homework Equations The Attempt at a Solution I looked up the boiling points of the three and see that 1-pentene is lower, but the cis...

Homework Statement The problem requires the scale up of a linear gradient ion exchange chromatography column by a factor of 150 (throughput). The lab scale column is 1 cm (ID) x 20 cm (bed height) with 20 micron particle size and 30 cm/hr superficial velocity. Resolution must be kept constant...

Why do ten molecules of toluene that enter a GC column at exactly the same time not reach the detector at the same time? Why are London Dispersion forces of the sample molecules strongly influencing GC measurements? And why are they negligible in TLC experiments on silica gel? I have no...

Homework Statement In detail, explain the theory behind the use of chromatography as a a.)separation technique. b.) identification technique. Homework Equations The Attempt at a Solution I know that chromatography can be used as a separation technique and also indetification...

1. Why are some pigment spots larger (area and volume) than others? I understand that pigments move up the porous paper by capillary action, from research. But why are some pigment colours (areas) larger? THanks

Homework Statement How does heating affect the spots on the TLC? Homework Equations None The Attempt at a Solution I have no clue, unless heating evaporates the solution and therefore the spots disappear? or Perhaps the elutent evaporated due to heat rather then the solution?

I have a project that I want to do; really it is an experiment that would prove useful to another project of mine. I want to build a gas chromatograph. The specs. Capillary column Helium carrier Thermal Conductivity Detector The analyte is a mixture of CH4,N2 (for now) I already...

Chromatography: Please help! What is the visualizing reagent used for Cu(II), Cd (II), Ni(II) and Co(II) ions when performing paper chromatography? Are there any special visualizing reagents for transition metals?

Homework Statement What procedures would you use to obtain gram quantities of each of the following compounds, free of each of the other compounds? Glycine - monoamino, monocarboxylic amino acid Glucose - non-ionic monosaccharide Starch - non-ionic large polysaccharide Glucose -...

In our analytical lab we were given an unknown solution containing up to 4 anions - fluoride, chloride, nitrate, sulphate and phosphate. It was diluted, run through the chromatograph and a chromatogram was printed for 3 trials. Then we printed chromatograms for two different standard solutions...

[SOLVED] paper chromatography Homework Statement Which reagent is the best to develop Mn+2? Briefly explain. Homework Equations Mn^+2 + 2OH- -> Mn(OH)_2 (s)(pale pink) Mn^+2 + C_2O_4^-2 -> MnC2O4 (s)(pale pink) 2Mn^+2 + [Fe(CN)_6]^-4 -> Mn_2Fe(CN)_6 (s pale green) 2Mn^+2 +...

Is it possible to separate cis/trans isomers of diazo compound using Thin-layer chromatography?

Hello everyone, I was poor on TLC before, and am poor now :smile: I want to ask a question to you guys. Please look at the attached zip file with a tif image. My question is very simple: Is it possible to fully isolate the impurities (yellow spot and light olive-mustard-colored...

Hi does anyone know why it is imporatnt not to permit the solvent front to reach the top of the chromatogram?

I calculated the total exchange capacity of a column per gram of dry weight of resin to be 2.74 meq/g. This value comes from experimental values. However, the manufacturer's specifications for the number of exchange sites is 3.4 meq/g. 1. What's meq? :blushing: I know this means...

i hope for good links about GC. thanks!

it says when i choose the liquid stationary phase, then i have to use the rule; "like dissolves like". i wonder if the compound i am interested in is polar, this means that the stationary phase i choose must also be polar, right? how would you predict the retention time of my compound? would it...

what does it mean when it says; "the areas under the two peaks are directly proportional to the molar amounts of A and B in the mixture? directly proportional? can anyone give an example of it? many thanks!

Hi for biology we had to do a lab which we separated the plant pigments by chromatography of spinach. We used a solvent of 90% petroleum ether:10% acetone. After we did the experiment we ran out of time in class so the teacher went and recorded everyones results on there paper. The problem with...

chromatography...using acetone! the protocol: Vg = volume not accessable to solvent (volume of the gel matrix) Vg cannot be measured directly. However, it should apparent that: Vg = Vt - volume accessable to solvent We can measure the volume accessable to the solvent, using a small...

hi guys! as you know i am doing the chromatography stuff and am now having the problem with understanding the protocol. it says; "set a clen after gradient value to 100% buffer B over 2 CV”? :bugeye: does any of you know what it tries to tell me? thanks!

hi guys! i am doing the chromatography. in scaling up i have to increase my volumetric flow rate but maintain my linear flow rate. my problem is i don't know how to calculate the column cross sectional area (cm2). i hope you guys who work with this area can tell me how i can calculate it...

is bed length the heigh of the column or is that the heigh of the matrix/gel? i don't know where to put this question, but since it is about proteins then i guess here is the place :approve: thanks!

I did an experiment in class on Chromatography and extracting pigment material from a leaf and such. We took a piece of some special paper put a base line in pencil at the bottom and covered it with leaf extract. Then putting a pin through the top set it in a beaker of acetone and the...