Test conditions
(a) Use Apparatus 2 and rotate the paddle at 50 revolutions per minute.
(b) Use 900 mL of phosphate buffer pH 5.8 at a temperature of 37°, as the medium.
PROCEDURE
After 45 minutes, withdraw a 20 mL sample of the medium and filter. Carry out the method for liquid chromatography, using the following solutions.
For Paracetamol
(1) Sample: withdraw a 20 mL sample of the medium and filter. Dilute 10 mL of the filtrate to 100 mL with the phosphate buffer pH 5.8, if necessary, to produce a solution expected to contain 0.005% w/v Paracetamol.
(2) Standard: 0.005% w/v paracetamol ws in phosphate buffer pH 5.8.
Take 50 mg quantity of the paracetamol ws with 70 mL of the phosphate buffer pH 5.8 for 10 minutes, dilute to 100 mL with the same solvent, filter through a glass-fibre filter (Whatman GF/C is suitable) and dilute 5 mL of the filtrate to 50 mL with the phosphate buffer pH 5.8.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octylsilyl silica gel for chromatography (5 µm) (Zorbax Rx C8 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1.5 mL per minute.
(d) Use a column temperature of 35°.
(e) Use a detection wavelength of 245 nm.
(f) Inject 50 µL of each solution.
(g) For solution (1), allow the chromatography to proceed for 12 times the retention time of the principal peak.
DETERMINATION OF CONTENT
Calculate the content of C8H9NO2 in the medium using the declared content of C8H9NO2 in paracetamol ws.
Dissolution (%) =
Area of spl. x wt of std.x 5 x 900
x 100 x std. potency x 100
Area of std. x 100 x 50 x 500
x 10 x 100
(1) Sample: withdraw a 20 mL sample of the medium and filter. Dilute 10 mL of the filtrate to 25 mL with the phosphate buffer pH 5.8, if necessary, to produce a solution expected to contain 0.001% w/v of Caffeine.
(2) 0.001% w/v solution of caffeine ws in phosphate buffer pH 5.8.
Take 10 mg quantity of the caffeine ws with 70 mL of the phosphate buffer pH 5.8 for 10 minutes, dilute to 100 mL with the same solvent, filter through a glass-fibre filter (Whatman GF/C is suitable) and dilute 5 mL of the filtrate to 50 mL with the phosphate buffer pH 5.8.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under assay for paracetamol may be used but with a detection wavelength of 220 nm.
DETERMINATION OF CONTENT
Calculate the content of C8H10N4O2 in the medium using the
declared content of C8H10N4O2 in caffeine ws.
Area of spl. x wt of std. x
5 x 900 x 25 x std. potency x 100
Area of std. x 100 x 50 x 30 x 10 x 100
Dissolution : NLT 70%
