I followed the Thermo Scientific steps for preparing the ellmans reagent solution. When added 4g of Ellmans reagent to the 1000 uL buffer solution, the solution turned a faint pale yellow. Is this normal?
I did not see any yellow color change when adding to my sample. I just want to make sure that the Ellmans reagent is working.
Dear Sid Jandhyala thank you for your interesting technical question. For some potentially useful answers please have a look at the following closely related RG thread entitled
What's the color of Ellman's reagent solution?
https://www.researchgate.net/post/Whats_the_color_of_Ellmans_reagent_solution
Dear Sid Jandhyala P.S. According to the attached data sheet, Ellman's reagent (= 5,5'-Dithio-bis (2-nitrobenzoic acid)) is a yellow solid. Thus it is not surprising that a stock solution of this reagent has a pale yellow color.
https://www.interchim.fr/ft/0/01566H.pdf
Hello Sid Jandhyala , I used DTNB solutions for acetilcholinesterase assay. My solutions were always colorless when prepared but it turned to pale yellow with time. As the analysis was based on the dissociation of the DTNB to TNB ion, I always prepared little volume stock solutions so I always had a clean one to work with, avoiding interference of possible early dissociation of the DTNB. Also, I used a much less concentrated solution than you. Maybe what you have there is a disperse non soluble reagent.
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