I am performing an DNS assay for sucrose. Is there any acid hydrolysis method apart from the invertase enzyme method?? And while using enzyme it converts sucrose in glucose and fructose, how do I quantify both or should I carry isomerization reaction to convert in a single product(Glucose)
Hello, Aditya
DNS methos is used to measure reducing sugar, thereof you need hridrolize sucrose to glucose and fructose, this due sucrose isn´t a reducing sugar, yes there is an acid method to sucrose hidrolise, you can use HCl 1N at 40-45 C. If you need quantify both, glucose and fructose, you need to use a HPLC method, due the DNS quantifies the reducing sugar, and It doesn´t specific for molecules
Best regard
Hader
It is true DNSA method is used for reducing sugars. For sucrose it need to be hydrolyzed
using enzyme invertase or acid hydrolysis. To quantify both glucose and fructose it is recommended to analyze by polerometer or HPLC, or both can be used.
Respected Tandon Sir,
I have to develop an spectrophotometric assay for quantifying the fructose and glucose. If I want to quantify only glucose from mixture of glucose,fructose and sucrose then fructose becomes a problem in DNSA method.As fructose is also a non reducing sugar.
I also wanted to ask you whether anthrone reacts differently with glucose and fructose?? I have come across a paper saying (At room temperature, anthrone forms a blue chromogen with fructose, whereas a similar chromogen is obtained with glucose only after heating). Is it true??
For determining only glucose contents the option is GOD POD( Glucose Oxidase- Per oxidase) method. The glucose oxidase is specific for glucose. The kits are easily available foe spectroscopic method. It is considered to be very accurate method.
Anthrone will give you total sugars(glucose + fructose).
Can we use dextrose as standard for sugar using DNSA method instead of glucose?
Sucrose being a disaccharide has to be hydrolyzed first to separate the glucose & Fructose constituents. This hydrolysis can be done either with enzyme invertase or acidic hydrolysis. After the hydrolysis it becomes a mixture of glucose + fructose . DNSA method will give total sugars. GOD POD/ glucose oxidase method will give only glucose contents in it. If a Polarimeter is used one can easily find contents of glucose & fructose separately.
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