It is better to prepare DNS reagent with Rochelle salt (sodium potassium tartarate) before. Adding that salt at the end will may be give you wrong result by giving false color to it. The following have the principle and preparation of DNS reagent with calculation for cellulase activity. All d best.
Dear it is always better to use rochelle salt in dns reagent. you can refer to protocol of TK gosh "measurement of cellulase activity" for a better understanding
I hv read that in measuring pure sugars(like glucose,xylose standards),it is better to use DNS without Rochelle salt and adding it at the end.But in case of crude samples of cellulase,xylanase, it is advisable to use DNS with Rochelle salt? Is it? What makes the difference?(Ref:Miller 1959)
What if in case of using crude enzyme samples?, which we knew the properties of the crude enzyme is not pure and heterogenous. Is it better to use the DNS (with rochelle salt before) or use the DNS reagent first and rochelle salt at the end of the reaction?