ITB Uji Kuersetin 2024

Identification and Determination of Quercetin Levels

Preparation of Comparison Solution:
Quercetin was weighed and dissolved in HPLC-grade methanol to make a 25 ppm stock solution. This solution was stored in the refrigerator.

Sample Preparation:
CSTRLY product powder was weighed and dissolved in HPLC grade methanol at a concentration of 218.030 ppm, then sonicated for 30 minutes and filtered using a 0.45 µm syringe filter. The solution was stored in a refrigerator.

HPLC System:
The method refers to Rizaldy et al. (2022) with a 360 nm UV detector. The mobile phase was water-methanol with a linear gradient of 40–60% for 5 minutes, then 70% methanol until the 10th minute, and a 40% methanol gradient until the 15th minute. The flow rate was 1 mL/minute. The quercetin content was determined using the one-point method.

Identification Results:
The chromatogram shows that the retention time of the sample is almost the same as the comparator, indicating the presence of quercetin in the product.

Content Calculation:
Based on the AUC chromatogram and one point method, the following was obtained:

Average quercetin content: 0.00425 ± 0.0004 %

Determination of Total Flavonoid Content

Preparation of Comparison Solution:
12.5 mg of quercetin was dissolved in 25 mL of analytical grade methanol as a stock solution. A dilution of 40–110 µg/mL was performed. The solution was mixed with 10% aluminum chloride, 1 M sodium acetate, and distilled water, then incubated for 30 minutes. Absorbance was measured at λ 415 nm.

Sample Preparation:
CSTRLY product powder was dissolved in methanol, sonicated for 30 minutes, filtered, and diluted to a concentration of 63,775 ppm. Each solution was measured in six replicates.

Quercetin Calibration Curve Results:
Quercetin calibration curve data

Quercetin calibration curve

Sample Results:
CSTRLY product contains total flavonoids of 0.101 ± 0.004 g QE/100 g sample.