Assay—
Sodium perchlorate buffer—
Prepare a 0.14 M solution of sodium perchlorate in water, and adjust with 10 N sodium hydroxide or 0.05 M phosphoric acid to a pH of 3.0.
Mobile phase—
Prepare a filtered and degassed mixture of
Sodium perchlorate buffer and acetonitrile (69:31). Make adjustments if necessary (see
System Suitability under
Chromatography 
621
).
Standard preparation—
Dissolve an accurately weighed quantity of
USP Gallamine Triethiodide RS in
Mobile phase, and dilute quantitatively, and stepwise if necessary, with
Mobile phase to obtain a solution having a known concentration of about 1.0 mg per mL.
Assay preparation—
Transfer about 25 mg of Gallamine Triethiodide, accurately weighed, to a 25-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with a 200-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 1.0 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed under
Procedure: the column efficiency is not less than 5000 theoretical plates, the tailing factor is not more than 1.4, and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 10 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C
30H
60I
3N
3O
3 in the portion of Gallamine Triethiodide taken by the formula:
25C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Gallamine Triethiodide RS in the
Standard preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
;)
for 4 hours: it loses not more than 1.5% of its weight.