Assay
Standard preparation
Dissolve an accurately weighed quantity of
USP Isoproterenol Hydrochloride RS in freshly prepared sodium bisulfite solution (3 in 1000) to obtain a solution having a concentration of about 2.5 mg per mL. Transfer 5.0 mL of this solution to a 50-mL volumetric flask, dilute with 0.17 N acetic acid to volume, and mix to obtain a solution having a known concentration of about 250 µg per mL.
Assay preparation
Transfer about 125 mg of Isoproterenol Hydrochloride, accurately weighed, to a 25-mL volumetric flask, dissolve in sodium bisulfite solution (3 in 1000), dilute with sodium bisulfite solution to volume, and mix. Transfer 5.0 mL of this solution to a 100-mL volumetric flask, dilute with 0.17 N acetic acid to volume, and mix.
Chromatographic system
(see
Chromatography 621)The liquid chromatograph is equipped with a 278-nm detector and a 30-cm × 4-mm stainless steel column that contains packing L1. The mobile phase is 0.17 N acetic acid having a flow rate of about 1.5 mL per minute. Chromatograph five replicate injections of the
Standard preparation, and record the peak responses as directed for
Procedure: the relative standard deviation is not more than 3.0%.
Procedure
Using a microsyringe or sampling valve, chromatograph 10 µL of the
Standard preparation, and adjust the specimen size and other operating parameters, if necessary, until satisfactory chromatography and peak responses are obtained. Chromatograph equal volumes of the
Standard preparation and the
Assay preparation, and measure the peak responses. Calculate the quantity, in mg, of C
11H
17NO
3·HCl in the portion of Isoproterenol Hydrochloride taken by the formula:
0.5C(hU / hS),
in which
C is the concentration, in µg per mL, of
USP Isoproterenol Hydrochloride RS in the
Standard preparation; and
hU and
hS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.