Dear Abdualrahman,

What about TLC using precoated plates? I prefer this method rather then other ones. It take 10 - 25 min to make a test for 1 compound using 1 eluent with precoated TLC plates. You can not only control your compound purity, but make some tests for the functional groups (ArOH, RNH2, RCONHR', etc.). There are many suppliers of TLC precoated plates for a broad purposes spectra. Furthermore it is a lot of literature concering TLC practice and theory. I can reccommend to put your attention on the excellent book:

Тechniques of Chemistry Volume XIV

Thin-Layer Chroмatograpнy Second Edition bу Justus G. Кlrchner, Retired Senior Scientist The Coca-Cola Соmраnу. Edmond S. Реггу, Editor А Wiley-Interscience Publication (http://www.amazon.com/Thin-Layer-Chromatography-Justus-Kirchner/dp/094163325X),

or another one, available online from Wiley Interscince:

http://onlinelibrary.wiley.com/book/10.1002/9783527610259

Good luck with TLC

to be check for Chromatographic purity whether HPLC or GC.

The guickest and simplest way is a melting point determination for solids (melting point should ne in close interval no more 2-3 C) or refractive index for liquids (for known compounds)

thankd for comment, Vasily Miluykov... this is in case known compounds...what do you suggest in the case of newly synthesized comp?

For solid compounds is a melting point interval from start to whole liuid a good characteristic. Any impurities lead to significant enlargment melting interval.

Do you "know" how the product should look like?

What about simple combustion/elementary analysis and/or ICP-AES (or similar) methods to check for elements (and impurities hereof). However, for elements below a mass of 10 (esp. fluorine) you will need XPS.

Dear Abdualrahman,

What about TLC using precoated plates? I prefer this method rather then other ones. It take 10 - 25 min to make a test for 1 compound using 1 eluent with precoated TLC plates. You can not only control your compound purity, but make some tests for the functional groups (ArOH, RNH2, RCONHR', etc.). There are many suppliers of TLC precoated plates for a broad purposes spectra. Furthermore it is a lot of literature concering TLC practice and theory. I can reccommend to put your attention on the excellent book:

Тechniques of Chemistry Volume XIV

Thin-Layer Chroмatograpнy Second Edition bу Justus G. Кlrchner, Retired Senior Scientist The Coca-Cola Соmраnу. Edmond S. Реггу, Editor А Wiley-Interscience Publication (http://www.amazon.com/Thin-Layer-Chromatography-Justus-Kirchner/dp/094163325X),

or another one, available online from Wiley Interscince:

http://onlinelibrary.wiley.com/book/10.1002/9783527610259

Good luck with TLC

@Sergey Lyakhov: thanks a lot for precious info.

First check the solubility of the starting materials and final product.Now choose the best solvent and wash the final compound with three times (but solvent could not dissolve the final compound). Recrystallize the final compound with same solvent with its boiling temperature then filter and evaporate at room temperature up to to some solvent remaining left it and finally discard the remaining solvent (do three times) finally you get pure product.

for purity check mp should be relevant even for new synthesized compounds (just in matter of purity not structure)...you can check also by a rapid proton NMR. However it is supposed that you have an idea of the structure of your desired product. (if there are not surprises or unexpected things)

As suggested by someone else too....TLC or HPLC is the best way to check the purity a new compound. On TLC you can not be sure if it is 100% pure or not. But for going in to NMR your compound must be >98% pure and for that best option is the HPLC, if available; otherwise you can go with TLC/2D TLC.

Hope it works for you....!

do CHNS analysis, amount needed for analysis ~ 2mg.

TLC is the the easiest, just be sure your compound does not decompose on silica, othervise this method might be misleading.

GC, LC, GC-MS, LC-MS are also quite good options, plus with the last two you get a clue if what you get, is what you need.

To me Recrystallization and Column chromatography are the best and reliable purification techniques, column may take time for purification but then you get HPLC grade purity with it.

Salam my friend : in addition to all of the mentioned by partners ,just check the m.p. if your molecule is solid ,sharp m.p gives u a good indication the ur product is pure and in the same manner if ur sample is liquid check the TLC , if u gave single spot without tailing that's also a good evidence about the purity .good luck..

If you know exactly the name of your product, just measure its boiling or melting point. The less the difference between the measured and the theoretical point, the cleaner the product is. You can also measure the refraction index and compare with the theoretical value. The impurities can be identified by IR, at the end. Good luck!

Try TLC with three different solvent systems varying in polarities FOR SINGLE SPOT, secondly even 1% impurity in NMR will render you sharp peaks, AS is the case with CDCl3

It depends on the nature of the ipurities and the tolerance levels/specifications. For organic impurities above 5% aprox. use NMR; for organic impurities below this level, GC/HPLC is slower but better (although not every impurity you inject will get detected for sure). Inorganic impurities require other approaches. Water: Use Karl Fischer.-

IR do not depend on purity. It simply provides a qualitative information on the functional groups present in your mixture. NMR do not detect inorganic impurity and organic impurity below 5%. TLC is also qualitative, and do not show impurities, which are non.UV acitve or iodine active. HPLC and GC also depends on the detector you use. RI detector is most sensitive

TLC may not be accurate,but if we go for HPTLC where even we can get enough sample for NMR/IR.Here we can get the pure sample by marking it on the monitor.This is possible only with HPTLC having this facility

Standard workflow for compunds is TLC, MS, IR and NMR. TLC is often more sensitive than NMR unless you are using 600 MHz or more. To know ACTUAL purity, including salts, etc., you must perform an elemental analysis but it must be highly pure to begin with. It depends on what level of purity you need. To publish a novel compound in a good chemical journal you will generally need H and C NMR, MS and elemental analysis. Often you can replace elemental analysis with high resolution MS. Be sure to obtain 2D NMR if you can't definitively assign structure from the 1D. Powder difraction studies are another method that is becoming more popular, particular for complex molecules, but again, you need high purity including high chiral purity.

To me the simplest and quickest method is recrystallization and measuring the melting point and compare it to the melting point of the standard pure compound, if the compound is pure, there wouldnt be much difference between them.

TLC is a good way for this purpose. Do it with different percentages of ethyl acetate and n-Hexane in mixture. The pure compound usually shows one spot in TLC test, note that the enantiomers of a compound shouldn't separate in TLC method and they apear in the same spot.

For liquid substances with low b.p. GC is suitable. The refractive index measurement is a good method for perviously known liquids.

gc or gcms technique is the best for volatile compound. you may play for best separation method. TLC, may be application for just to check the probable number of compound present in a mixture. sometimes they may not have good separation on TLC plate with the desire mobile phase or some compound may not have response in UV or Iodine.

TLC is the best and quickest simple way to to test the purity of a compound

Possible and quickest analytical tools to check the purity of product after synthesis. :

1. If product is Solid , then go for melting point if it is sharp melted and different than starting reactant then product is pure [ considering Reactant melting point are known].

2. Similarly go for boiling point and frizzing point. .

3. Solubility , if your starting reactant is insoluble in particular solvent , and product is soluble , then check solubility in that particular solvent , if there is no insoluble , it means your starting material converted into product. Soluble product is possibly free of reactant impurity.

4. TLC : Initially to develop this method , It is time consuming , For this you should know the solubility of your product and reactant in different dielectric constant solvents , then again you have to standardize the perfect mobile phase to separate the impurities in your product including reactant , for this you to do lot of trial and error exercise of reactant and product on your TLC plate , once it is established , then this is the quickest method to check the purity of synthesized product.

This is applicable for mobile phase soluble products only.

If product is insoluble in all solvent [ including water ]then this is not applicable.

5. GC / GC-TLC, HPLC/HPLC-TLC /IR/UV/NMR/MASS: ONCE EVERYTHING FOR YOUR PRODUCT IS STANDARDIZE THESE METHOD ALSO USEFUL TO CHECK THE PURITY AND ALSO BEST ACCEPTABLE ACCURACY.

Dear AMA,

We don't have any ultimate method to analyze the purity of compounds. Indeed, you need to do TLC, HPLC, UV absorption too.......

Hi dear Abdualrahman

You can use these two methods to check the purity of certain materials:

1. If your materials are proteins, one step SDS-PAGE can visualize your materials purity.

2. On the other hand, you can run an gel filtration column chromatography with G-100, G-50 or G-25 gel beads and the use spectroscopy to evaluate the purity.

Cheers

Proton NMR, if that's not viable, TLC may show impurities, but you would need to try many eluents and stains to ensure you get as much information as possible.

Melting point is the easiest and fastest method. A pure compound should have a very sharp melting point.

It depends on the accuracy of the purity you need to know and the kind of contaminant you are able to accept. Most of the methods proposed are good for known substances with known standards.

From my point of view quantitative 1H-NMR with internal standard is by far one of the most accurate methods for the determination of purity, specially if it is a new compound or if there is no certified commercial standard to compare with. A simple 1H-NMR spectrum shows only the impurities that are soluble, contain H and are within the range of ppm you are measuring.

GC is only trustable if the product has been freshly distilled since low volatility impurities don't appear in the chromatogram. HLPC is the same thing but with column affinity.

TLC and Melting point both are quicker option to check either compound is pure or not, and if impure then up to which extent it is impure(may have more than a type of impurities). If we do not have pre-coated TLC plate then we can prepare it using powder of silica gel to make slurry with water and then mounting it on a glass slide followed by activation of TLC plate.For TLC plates are usually commercially available, with standard particle size ranges t. They are prepared by mixing the adsorbent, such as silica gel, with a small amount of inert binder like calcium sulfate (gypsum) and water. This mixture is spread as a thick slurry on either glass, thick aluminum foil, or plastic (inert materials). The resultant plate is dried and activated by heating in an oven for thirty minutes at 110 °C. The thickness of the absorbent layer is typically around 0.1 – 0.25 mm for analytical purposes and around 0.5 – 2.0 mm for preparative TLC. After having such prepared plates we can use them for a longer period ,making sure that it is intact in aspect of adsorbant layer and protected from atmospheric chages. Several spots after proper development of TLC indicates numerous impurities as per the number of spots..!!! While a single spot indicates a pure compound.

Melting point range of purest compound is about one degree centigade. In case of impure compound this range can expand beyond two degree or far more.

Both these techniques are best and time saving at laboratory level but make sure all parameters are set correct to avoid false results.

In my opinion, the simple test can be used; Archimedes' principle. If you have a little error, you can check your materials with ICP.

IR,UV, NMR, MASS all are secondary things no need on initial level, first check completion of reaction by TLC only atleast up to finishing of starting material, then u can go for HPLC to check reaction completion and product purity. if there are not more impurities then by HPLC only u can check assay of your product, so u cant find exact purity.

Chromatographic technique is only way to check the purity , and you will get a pure crystalline compound than only go for IR,MASS and NMR otherwise it is wastage of time and money both.

In my opinion, you can check the purity by TLC and melting point. If the compound isn't pure, the column chromatography and (or) crystallize are necessary.

If LC-MS is available, it's the best choise since you want combine fast and simplist way. 'Cause it can quantify your product since HPLC is the broadest way to quantify a chemical. As to TLC, it's also fast and simple, but it can only semi-quantify your product.

TLC is the best option before go for IR and NMR

The most popular sequence would be: TLC, HPLC or GC, NMR, MS.

But the ultimate prof of purity would be CHN analysis.

TLC is appropriate option for this, It is easy to check the remaining starting material or formation of by product.

Applied Thin-Layer Chromatography: Best Practice and Avoidance of Mistakes, Second Edition

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In my opinion, TLC is the best way to test the purity of a compound after synthesis. For optimal results, make sure your TLC capillary and TLC chamber should be clean, and also make sharp to the edges of TLC for smooth running

Please indicate the nature of your compounds? Protein, Carbohydrate, Lipid and... .

TLC is not an indicator of purity. its the confirmation test for formation of new compounds