2.11. Assay of curcumin in emulsion
50 mg of curcumin standard was weighed and transferred to a
50 mL volumetric flask and dissolved in 45 mL of methanol. The
volumetric flask was shaken using ultrasonicator for 5 min. The
solution was diluted to volume with methanol. The stock standard
solution of curcumin had a concentration of 1 mg/mL of curcumin.
1 g of emulsion (w/w) was transferred into a 50 mL volumetric
flask containing methanol. The flask was heated in water-bath at
60 C until the emulsion melted and diluted to the mark with
methanol. The flask was shaken for 15 min manually. The flask
was then subjected to sonication for 15 min. The resulting solution
was centrifuged at 4000 rpm for 10 min. 0.2 mL of the supernatant
was diluted with methanol in a 10 mL volumetric flask to give a
concentration of 20 lg/mL. The content of curcumin in emulsion
was calculated using the following equation:
Assay ð%Þ ¼
x
50 1
50
y
1000 1
50
Ratio ðemulsionÞ
Ratio ðstandardÞ
potency of standard
where x is weight of standard and y is weight of emulsion sample.