It is well accepted that Rochelle's salt is used for stabilizing the colour. Some include it in DNS reagent and others prefer to add it after incubating the reaction mixture (sample + DNS reagent without Rochelle's salt) for 15 min (as suggested by Miller 1959). Why do we need to use high concentrations (20-40%) of Rochelle's salt? What made researchers to believe that high concentrations of Rochelle's salt is necessary for assaying reducing sugars?
@Dr. Partha saradhi sir: Greetings sir,
Rochelle's salt (Potassium sodium tartarate) known for its high reactivity with hydrogen peroxide which is rich in reactive oxygen species. In the mixture of reducing sugar estimation, the dissolved oxygen might interfere with the glucose oxidation process tampering the originality of the value . Perhaps this may be the reason behind using Rochelle's salt at higher concentration(40%). Not sure though sir.
Dear Kartheek,
Thanks for your answer. Please go through attached paper of Prof. Gail Miller. He and several others prefer adding sulphite or metasulphite for taking care of oxygen (i.e. removing oxygen), and Rochelles salt interferes with the same and hence he advised one to use the same after incubation for 15 min, but immediately after removing from water bath.
Can you please let me know any reference which states that Rochelle's salt reacts with hydrogen peroxide and removes oxygen?
Dear Pardha Saradhi sir: I came across this link and I find it to be quiet relevant to the on going conversation. Kindly look for theory part in the below given pdf file. I hope it will be useful for you sir.
http://www.rsc.org/images/oscillating_tcm18-188828.pdf
Dear Kartheek,
Thanks a lot for the information.
It seems that hydrogen peroxide is oxidizing tartarate and releasing carbondioxide (moreover, it is being catalysed by cobalt), I do not know if oxygen can directly oxidize tartarate. But, I appreciate your thinking power and feel proud (a good researcher always applies his/her mind in different directions looking for an answer/solution).
@ Pardha Saradhi sir: Thank you so much sir. I am extremely honoured for having received appreciation from you.
Thank you.
Regards
Well I think you must use less concentration if we take iin count that this kind of salt have a saturation until maybe 25 to 30 % and 40 % its too high, maybe you can probe with low concentration in range of 2 to 10 percent maybe
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