i determine flavonoid content by spectrophotometric method and i want to make standard curve , i have quercetin glycoside but, all use quercetine in standard curve , so can i use quercetin glycoside in making standard curve after hydrolysis with HCL?
Dear Dalaia Youssef,
It is true that quercetin glycoside (QG) compounds can be used as a source of quercetin (Q) compounds. There are various methods of hydrolysis and HCl hydrolysis is the simplest one. Even though enzymatic hydrolysis yields more percent recovery of QG compounds it is considered as a long and tedious process.
Even though the QG com[pounds yield Q compounds the yield may vary from 70 to 100% depending on the methodology, environmental conditions, purity of the samples, concentration of the substrate and HCL, length of the process and various other parameters. Again the Q compounds should be standardised with an external Q standard using an HPLC method.
When quantifying flavonoid contents it is necessary to use an external standard Q compound or a standardised extracted Q compound using a standard protocol and standard equipment approved by international standard laboratories. The method of conversion of the QG compound to Q compounds also should be completely validated.
These are the common protocols and I would like to recommend you the following paper for further references. All the best
sorry, Thiruchenduran Somasundaram you agree with the idea point however you want me validate the conversion method of GQ to Q it is right ?
Yes Dalia, The standardization is a must when you develop a new method or standard. Method validation is also a must. If the recovery is less than 880% thaen the method is also under scruitiny
Quercetin is a flavonol that is a typical antioxidant and characterize by good stability compared to other flavonoids for example myricetin. You should use quercetin without hydrolysis! making first stock solution then make 6-7 dilutions from the stock. please find my attached work
A.R. Abdel-Moemin, To investigate the antioxidant properties of dietary flavonoids in human metabolism. PhD Thesis, The Queen's University of Belfast, United Kingdom, 2004
Thesis Chapter 2-TO INVESTIGATE THE ANTIOXIDANT PROPERTIES OF DIETA...
thannnnks Thiruchenduran Somasundaram,
Aly R Abdel-Moemin, did you mean that i must use quercetin only , or you mean that i use quercetin glycoside in standard as it ?
Phillip Morris , thannnks you mean it is better that i use glycoside than aglycon !
thannnks Aly R Abdel-Moemin , i will do , God is the conciliator with us all
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