Dear Luveni,

TCA with molecular weight 163.39 g/mol is prepared by chlorination of acetic acid. As for its physicochemical properties, such as melting point (57-58 Degrees Celsius) and boiling point (196-197 Degrees Celsius), it is soluble in water, alcohol, and ether. But I think deionized (DI) water is the best solvent for it. DI water is a common solvent for TCA solution preparation in malondialdehyde assay.

Sincerely yours, Homayoon. 

Water is the best solvent for dissolving TCA

Dear Luveni, typically for the test you want to do, trochloracetic acid at 10% w/v is used. Then if you need 10 mL of this reagent, weigh 1 g of TCA, dissolve in distilled or deionized water and complete to a final volume of 10 mL. If you need a different amount of this reagent, do the preparation maintaining the same weight-volume relationship.

The following document describes a procedure to perform the SRB test that may be of interest to you: Article Sulforhodamine B colorimetric assay for cytoxicity screening

During MDA assay I used distilled water for dissolving TCA .

Distilated water is best solvent for TCA. Mostly I prepare stock solution (500g TCA into 350 ml water/deionized water) and store room temperature.

Dear Serhat Kaya , Sigmaaldrich's specification sheet states that the solubility of TCA in water is 1 g / 10 mL. In 350 mL of solution no more 35 g of TCA would be dissolved. How do you prepare that oversaturated stock solution? Do you dissolve in hot water?

Dear José Luis Duque-Rivera;

I use this protocol from a book ; Autoimmunity: Methods and Protocols (https://www.springer.com/us/book/9781607617198) page 57. I'm working on a magnetic stirrer with a heater (30 Celsius) for half an hour to solve TCA. Also Fluka data sheet (https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Datasheet/6/91228dat.pdf) (Sigma-Aldrich) states "100% (w/v) solution of TCA can be made by the addition of 227 ml of water to 500 g of TCA"

Dear Luveni,

TCA with molecular weight 163.39 g/mol is prepared by chlorination of acetic acid. As for its physicochemical properties, such as melting point (57-58 Degrees Celsius) and boiling point (196-197 Degrees Celsius), it is soluble in water, alcohol, and ether. But I think deionized (DI) water is the best solvent for it. DI water is a common solvent for TCA solution preparation in malondialdehyde assay.

Sincerely yours, Homayoon. 

Serhat Kaya, on its website Sigmaaldrich currently offers 7 solid TCA options. In the specifications of all these products there is no consensus on the solubility of TCA:

- Products T6399 and T4885: solubility = 1 g / 10 mL (10% w/v).

- Products T9159 and 91228: solubility = 0.5 M at 20 ºC (8.17% w/v).

- Product T8657: solubility: 1 g / mL (100% w/v).

- Product 91230 and 27242: solubility = 81.7 g / L at 20 ºC (8.17% w/v).

However, it is clear that it is possible to prepare solutions with concentrations above 10% w/v, as established by the procedures that you pointed out and others that I consulted in which the TCA is used in cellular fixation or protein precipitation.

On the other hand, the concept of solubility is a property of saturated solutions, but if a solution is capable of accepting more solute, then it is a supersaturated solution, it is possible that this is the case of TCA.

PS1: The 100% TCA solution challenges the accepted concept that a solute is the minority component or in a lesser proportion in a solution. If this solution is obtained by dissolving 500 g of TCA in 227 mL of water, then will the water be the solute?

PS2: Source on Sigmaaldrich: https://www.sigmaaldrich.com/catalog/search?term=Trichloroacetic+acid&interface=Product%20Name&N=0+&mode=mode%20matchpartialmax&lang=en®ion=VE&focus=productN=0%20220003048%20219853286%20219853274.

Dear; José Luis Duque-Rivera

TCA procedures vary according to the area used. Besides; the different options on the Sigma-Aldirch site are produced for different situations. However, I think we can both agree on this, TCA is best dissolved in water. Sigma data sheet and some procedure show that; 350 mL (even 227 mL) water can solve 500g TCA.

Yes of course. We can agree on that. However, the TCA raises other controversies or discrepancies, notes that both the Fluka sheet and the book Autoimmunity: Methods and Protocols, indicate for the same solution of 100% of TCA two different preparations: 500 g TCA / 227 mL water and 500 g TCA / 350 mL water. I think that only one of the two resulting solutions should be called 100% TCA, the ambiguity can lead to errors when preparing diluted solutions, such as 10% TCA.

Yes, when I need to procedure I confused because of this, but finally found working procedure for me. I use Autoimmunity: Methods and Protocols to my works and it offer to 500 g TCA in 350mL water.

That book is from a prestigious publisher and its information should be considered reliable but check the link below, it's from another prestigious source of information: Cold Spring Harbor Protocols. There it is indicated that 100% TCA consists of adding 227 mL of water to 500 g of TCA. Dear Serhat Kaya, we have to clarify this.

http://cshprotocols.cshlp.org/content/2006/1/pdb.rec10513.full?text_only=true

José Luis Duque-Rivera

I know this web link, I seen before and agree with you that is a good information source. I use 500g TCA/350 mL water because I obtained a good result in my experiments. At the same time if anyone want to use TCA I recommended to start with 500g TCA/227 mL water because it can dilute this mixture. I use my protocol in small invertebrate hemolymph and tissue homogenate and its working. Also, the manufacturer recommends 500g TCA/227 mL water, we should consider that. I think, researchers must test their samples firstly with 500g TCA/227 mL water and after with 500g TCA/350 mL water; depending on which dilution gives good result, simply use that.

Hello everyone,

I am ever so grateful for all your responses, I will perform the experiment tomorrow and will update soon. José Luis Duque-Rivera , the article was extremely helpful as well.

Thank you so very much.

I am pleased. Good luck in your experiment.

Serhat Kaya, I've kept thinking about who's right: Cold Spring Harbor or Springer? The key seems to be in the same Sigma-Aldrich technical sheet for TCA ((https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Datasheet/6/91228dat.pdf).

In this sheet it is indicated that the density of 100% w/v TCA is 1.45 g / mL. Based on this figure in the attached figure I present some calculations that elucidate this controversy.

Dear José Luis Duque-Rivera

I appologise to being late, because of my work. I try to find out which preparation method are better, but can't decide. But I think for protein experiments 500gr TCA/ 350 ml formula is right decision. I've keep thinking about that; and also ask that problem to manufacturer, but they haven't answer me yet.

Checking with the manufacturer has been a good idea. By the way, in the attached image of my previous comment I meant "mass rate" instead of "masic relation".