Medium: water; 500 mL.

Apparatus 2: 50 rpm.

Time: 30 minutes.

pH 8.2 buffer— Prepare as directed under Assay.

Copper sulfate reagent— Mix 10 mL of copper sulfate solution (5 g copper sulfate pentahydrate in 100 mL of water) with 40 mL of pH 8.2 buffer. [NOTE—The solution must be clear.]

Standard preparation— Dissolve an accurately weighed quantity of USP Trientine Hydrochloride RS in water to obtain a solution having a known concentration of about 0.5 mg per mL.

Procedure— Pipet an aliquot of a filtered portion of the solution under test, estimated to contain about 5 mg of trientine hydrochloride, into a 50-mL centrifuge tube. Into a similar centrifuge tube, pipet an equivalent volume of water to provide a reagent blank, and into a third centrifuge tube pipet 10 mL of Standard preparation. Into each tube, pipet 5 mL of Copper sulfate reagent, stopper, and mix immediately using a vortex mixer. Determine the absorbances of the solutions from the Standard preparation and the test solution at 580 and 410 nm, with a suitable spectrophotometer, against the reagent blank. Calculate the quantity in mg of trientine hydrochloride dissolved by the formula: in which C is the concentration, in mg per mL, of USP Trientine Hydrochloride RS in the Standard preparation, V is the volume, in mL, of the aliquot of test solution used, AU and AS are the absorbances at 580 nm of test and standard solutions, respectively, and AUX and ASX are the absorbances at 410 nm of test and standard solutions, respectively.

Tolerances— Not less than 80% (Q) of the labeled amount of C6H18N4·2HCl is dissolved in 30 minutes.

(Official January 1, 2007)

Copper reagent— Dissolve 5 g of copper sulfate pentahydrate in water to make 100 mL, and mix.

pH 8.2 buffer— Dissolve 20.74 g of anhydrous dibasic sodium phosphate, 6.72 g of anhydrous citric acid, and 0.535 g of monobasic sodium phosphate in 400 mL of water, adjust with sodium hydroxide solution (1 in 2) to a pH of 8.2 ± 0.05, dilute with water to make 500 mL, and mix.

Standard preparation— Dissolve an accurately weighed quantity of USP Trientine Hydrochloride RS in methanol to obtain a solution having a known concentration of about 2.5 mg per mL. Transfer 5.0 mL of this solution to a glass-stoppered, 50-mL conical flask.

Assay preparation— Remove, as completely as possible, the contents of not less than 20 Capsules. Weigh the contents, and determine the average weight per capsule. Mix the combined contents, and transfer an accurately weighed quantity of the powder, equivalent to about 250 mg of trientine hydrochloride, to a 100-mL volumetric flask. Add about 70 mL of methanol, and shake or sonicate to dissolve. Dilute with methanol to volume, mix, and filter, discarding the first few mL of the filtrate. Transfer 5.0 mL of this solution to a glass-stoppered, 50-mL conical flask.

Procedure— To each of the flasks containing the Standard preparation and the Assay preparation and to a similar flask containing 5.0 mL of methanol to provide the blank, add 10.0 mL of pH 8.2 buffer and 1.0 mL of Copper reagent, and mix. Concomitantly determine the absorbances of the solutions at the wavelength of maximum absorbance at about 580 nm, with a suitable spectrophotometer, against the blank. Calculate the quantity, in mg, of C6H18N4·2HCl in the portion of Capsules taken by the formula: in which C is the concentration, in mg per mL, of USP Trientine Hydrochloride RS in the Standard preparation, and AU and AS are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.