Questions tagged [chromatography]

collective term for a set of laboratory techniques for the separation of mixtures

43 questions with no upvoted or accepted answers
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108 views

How to make a sephadex slurry

I want to purify crude alpha-amylase with column chromatography. I am using a spehadex 75, But for some reason I can't find any information on how to make the slurry. I can quickly find tons of ...
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406 views

Difference between neutral and basic activated alumina

Sigma Aldrich sells two different types of activated alumina for column chromatography: neutral and basic. Apparently basic alumina is more active and better at adsorbing anions. Why is this the ...
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531 views

Purification of polar NHS esters

What are the options that I might be missing for the purification of a molecule with the following characteristic: Contains an activated ester that reacts with water (NHS) Reacts readily with ...
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70 views

Storage issues with o-phthaldialdehyde (OPA) reagent used to derivatize amino acids

I have made up an o-phthaldialdehyde (OPA) reagent according to Handbook of HPLC page 715 that will be used to derivatize amino acids before an HPLC run. There is no information given on reagent ...
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1k views

Running behavior of glucose, galactose and mannose in TLC

I have separated the sugars glucose, galactose and mannose by thin-layer-chromatography. My question is why these sugar have different running behaviors and a separation is possible. Glucose have the ...
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1answer
62 views

Getting a cleaner GC Peak Resolution

I have a GC with a peak pair I'm interested in separating but are not getting resolved cleanly at the moment. Any tips on what temperature programming tweaks might help me? The problem pair elutes at ...
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1answer
146 views

Gas chromatography analysis - number of peaks?

This is an example in a Princetown Review prep book. I am not understanding the statement "his separation was only partial (because two different peaks are recorded)." This is implying that Compounds ...
2
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1answer
41 views

Why can DAP be used to elute a protein in affinity chromatography?

A little background: as part of my bioinformatics degree I have to take Protein Chemistry course, but I miss chemistry basics (have CS background), so that's why I'm asking the following question. We ...
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19 views

Do I have to change my sample buffer before IEX chromatography?

I will use IEX chromatography to purify a protein and will then use a equilibration buffer Tris-HCl, pH 8 to set the start conditions for my column and optimize the binding of my protein. Then inject ...
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69 views

ApexTrack: peak tail looks like a shoulder

I'm trying to implement ApexTrack algorithm in my software by following the description written by Waters. But many chromatograms that I see have noticeable tailing of peaks: . No matter what ...
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182 views

Pressure in Skoog Instrumental Analysis Problem 27-22b (gas chromatography)

Problem 27-22b in: Skoog; Holler; Crouch. Principles of Instrumental Analysis. Thomson Brooks/Cole (publisher varies by country) asks for corrected retention volumes. A compressibility factor, $j$ ...
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67 views

Visualization of TLC plates

I'd like to know what exactly happens when various agents are used after developing a TLC plate, during the visualization phase, of sugars with anisaldehyde for example. I know that those compounds ...
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289 views

Difference between batch and column mode?

I have heard Ion-exchange chromatography can be used in batch or column mode, have you got any idea how are those modes? I have looked descriptions all over books and web (Skoog for example, both ...
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424 views

Predict polarity (TLC, column) using ChemSketch (-Draw)

I'm currently working on a project where I have to make and isolate often quite similar molecules. But, as I change the functional groups the overall electronic situation and polarity of the product ...
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165 views

Process Chromatography vs Solid Phase Extraction techniques

Process Chromatography is typically performed by flowing eluent from the top to the bottom of the column. The standard method of solid phase extraction at industrial scale e.g. to extract natural ...
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55 views

Dibenzoyl-L-tartaric acid won't show up on HPLC chromatogram

I'm trying to develop a method for HPLC to detect dibenzoyl-L-tartaric acid. Concentration doesn't matter at this point; I'm only concerned with detection. The problem I'm having is the compound won't ...
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703 views

How to calculate weight percentage of each ester after gas chromatography?

I run the GC for algae samples and got the retention and areas for external standards and each sample. But I want to know how much FAME I have. For example, what is the weight percent of C16:00 in my ...
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191 views

How can I increase the signal intensity and precision?

How can I increase the signal intensity and precision when use HPLC or LC-MS/MS ? How Also prevent Contamination and Carryover during Analysis
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319 views

GC-MS unexpected peaks during 1-octanol quantification

Note: This experiment was performed as part of a teaching lab experiment which has concluded, so I would not be able to alter any experimental conditions. I was also unable to modify any of the ...
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60 views

Software platforms with integration of multi vendor mass spectrometer device data?

I know about ACD/Spectrus Processor which is a software platform to integrate analytical chemistry data from multiple mass spectrometer device vendors (e.g. Agilent Technologies, Bruker, Waters) to ...
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1answer
31 views

Organic solvent for cleaning autosampler syringe

I work in a laboratory where gas chromatography is used extensively. We handle phthalates. What are the possible wash solvent for autosampler syringe? I've been using acetone.
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19 views

Change buffer in dialysis?

I have a protein that I purified in PBS buffer, pH 7. I will do dialysis to remove salt and will then further purify the protein with ion exchange chromatography. I will need to use another buffer (...
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31 views

Protein purification pressure limits confusion, about the X-MPa limit for FPLC?

I have always been a bit confused about column pressure limits. I have to elaborate a bit on the problem to get to my question: In protein purification we use the äkta purification machines (e.g. ...
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37 views

Impediments to GC-MS characterization of petroleum products

In an attempt to characterize, and sometimes to 'match' oil on feathers of birds, a laboratory utilize gas chromatographic - mass spectrometry. Persons likely to encounter oiled birds are advise to ...
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110 views

can you separate inorganic ions with chromatography?

For example, if you run a solution of sodium and potassium chloride through a colum? I am just wondering if i can get pure potassium chloride from a mixture of sodium and potassium chloride.
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160 views

Quantitative information from silica gel TLC plate?

I have a general question about thin-layer chromatography using silica gel. Can we get quantitative information from a TLC analysis? Is this mainly just the Rf or can we tell more? I'm guessing ...
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91 views

Variation within a chromatography with the same sample

What are some possible explanations to why the exact same sample in SEC HPLC differ in their peak heights, although it's the same chromatographic profile? The sample contains cell culture medium (...
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760 views

What is the reason for an increase of back-pressure of HPLC column?

Recently i have observed that the back pressure in my HPLC reverse phase column increased almost twice, and sometimes after sample injection the pressure increased so high that removed the connector ...
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201 views

What are some Internal Standards used for Ion Chromatography?

What are some internal standards (ISTDs) used for ion chromatography (IC)? For experienced IC users, what ISTDs have you used for your sample analysis?
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102 views

What are the strategies to deal with fluorescence from oil in Raman Spectroscopy?

I have a sample (for the purpose of this question let's call this Sample A) consisting of oil (edible olive oil) mixed with a contaminant (Contaminant B) from the Polycyclic Aromatic Hydrocarbons ...
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293 views

Choosing Stationary Phase Column Chromatography

When using column chromatography to purify an amine, alumina is the best choice of stationary phase (rather than silica gel.) Could this be due to alumina being slightly basic and thus the impurities ...
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104 views

Chromatography types and techniques

Are HPLC and GC comparable in term to size exclusion, ion exchange, sequential injection chromatography? Or they are two different terms, HPLC and GC refers to the equipment and phase of the analyte, ...
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42 views

Perovskite characterization

Does anyone know of groups working on water sorbtion testing and/or the use of inverse gas chromatography for characterizing Perovskites (as a class of materials)? Especially with regard to ...
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1answer
36 views

When to use chromatographic separation vs vacuum-assisted rectification distillation?

I'm trying to understand a bit more about industrial scale separation processes. One particular element I'm interested in is the question as to when chromatography (HPLC or Simulated Moving Bed) may ...
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1answer
87 views

How to pool fractions after chromatography?

I used chromatography to purify my protein and now I have fractions with different concentrations ranging from 1-16 mg/ml. Should I pool all these fractions or just the ones with high concentration (...
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33 views

Monitoring amino acid esterification

I am trying to monitor the esterification of a non UV active amino acid.I used thionyl chloride and Methanol as reagents. As amino group is unprotected, Ninhydrin should give positive result for both ...
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28 views

how could I make a file conversion from .spc (thermo fisher) in .cdf (Shimadzu) format file?

how could I make a file conversion from .spc (thermo fisher) in .cdf (Shimadzu) format file?
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How to divide the peaks of two anion ions using ion chromatography?

I used an ion chromatography system (Dionex IC-2000) to determine the inorganic ions and acid from the samples collected in the atmosphere. For measuring $\ce{SO4^2-, NO3, Cl-}$, and low molecular ...
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54 views

Simplified Chromatography - will this work?

I am interested to separate a sample matrix via a method very similar to chromatography. The reason I am asking about this is because I am planning to integrate this method with my SERS application. ...
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48 views

Can we make chromatography less troublesome?

Thin Layer Chromatography is a very powerful method in analytical chemistry for separating complicated chemical matrices. As an engineer, I am interested to build device capable of automating TLC ...
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1answer
255 views

In which pH range are silica-based TLC plates stable?

I am trying to understand why the experiment asks for raising the pH of a fairly acidic solution. The analytes should not be affected by it, so I thought the silica plate might be. Are silica-plates ...
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1answer
68 views

Can I get feedback on assignment? (chromatography)

HW question asks me why samples can be separated into their components by chromatography. My answer is that each component in the mixture will have different affinity for the solvent (mobile) phase as ...
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1answer
2k views

Single Point vs. 5 Point Calibration in HPLC

Single-Point calibrations aren't that useful for quantitative analysis and there is more room for error in result readings as compared to a 5-Point calibration. Is this why a 5-Point calibration is ...