2.10. Assay of curcumin in C. longa extract
20 mg of curcumin standard was weighed and transferred to a
20 mL volumetric flask and dissolved in 15 mL of methanol. The
volumetric flask was shaken using ultrasonicator for 5 min. The
solution was diluted to volume with methanol. 20 mg of C. longa
extract powder was weighed and transferred to a 20 mL volumetric
flask and dissolved in 15 mL of methanol. The volumetric flask was
shaken using ultrasonic vibrator for 5 min. The solution was
diluted to volume with methanol. The stock standard solution of
curcumin and C. longa extract powder had a concentration of
1 mg/mL of curcumin. 0.2 mL of standard and extract powder solution
was transferred to 10 mL volumetric flask and dissolved in
methanol to give a concentration of 20 lg/mL. This sample was
injected into HPLC in triplicate to determine the potency of C. longa
extract powder. The content of curcumin in C. longa extract powder
was calculated by dividing ratio of C. longa extract with ratio of
standard times the potency of standard, where the ratio of standard
or C. longa extract are calculated by dividing peak area of curcumin
in standard or C. longa extract with the total area of three