Development and validation of HPLC method for determination of flavonoids in herbal preparations

Introduction - Flavonoids are a large group of polyphenolic components possessing benzo-γ-pyronic structure and widely distributed in plants. The chemical nature and the biological activity of flavonoids depends on the structural class to which they belong, the degree of hydroxylation, the degree of polymerization, and the presence of other substituents and bonds. Today, there are a large number of herbal preparations containing plant extracts rich in flavonoids in the pharmacies across Republic of Macedonia, and therefore it is necessary to develop methods for controlling and monitoring their quality. Aim - Development and validation of HPLC method for determination of rutin and quercetin in tablets containing 1200 mg dry leaf of Ginkgo biloba. Method - Simple HPLC method with gradient elution (acetonitrile: 0.3% phosphoric acid), flow rate of 1,2 ml/min, column temperature of 25°C and UV detection (rutin at 255 nm, quercetin at 375 nm) of rutin and quercetin in herbal preparation containing dry leaf of Ginkgo biloba. Results - The method showed high specificity, excellent linearity for the concentration in the range of 0,01-0,08 mg/ml. Correlation coefficient (R2) for rutin is 1, while for quercetin is 0.999. Precision, which was determined by six repetitions of the analysis of 0,05 mg/ml standard solution, showed a relative standard deviation of less than 1% for rutin and quercetin. Conclusion - The method is simple, easy to perform and specific for determination of rutin and quercetin in herbal preparations containing dry leaf of Ginkgo biloba, and can be used for routine analysis