Chromatographic purity
Ion-pair solution, Mobile phase, System suitability solution, and Chromatographic system
Proceed as directed in the Assay.
Standard solution
Dissolve an accurately weighed quantity of
USP Terbutaline Sulfate RS in
Mobile phase, and dilute quantitatively, and stepwise if necessary, with
Mobile phase to obtain a solution having a known concentration of about 3 µg per mL.
Test solution
Use the Assay preparation.
Procedure
Separately inject equal volumes (about 20 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of each impurity, if present, in the portion of Terbutaline Sulfate taken by the formula:
5000(C/W)(ri / rS)
in which
C is the concentration, in mg per mL, of
USP Terbutaline Sulfate RS in the
Standard solution; W is the weight, in mg, of Terbutaline Sulfate taken to prepare the
Test solution; ri is the peak response for each impurity obtained from the
Test solution; and
rS is the terbutaline peak response obtained from the
Standard solution: the sum of all impurities is not more than 1.0%.
Assay
Ion-pair solution
Transfer 3.15 g of ammonium formate to a 1000-mL volumetric flask, dissolve in about 900 mL of water, adjust the solution with formic acid to a pH of about 3.0, add 5.49 g of sodium 1-hexanesulfonate, dilute with water to volume, and mix.
Mobile phase
Prepare a filtered and degassed mixture of
Ion-pair solution and methanol (77:23). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
System suitability solution
Dissolve accurately weighed quantities of
USP Terbutaline Sulfate RS and
USP Terbutaline Related Compound A RS in
Mobile phase, and dilute quantitatively, and stepwise if necessary, with
Mobile phase to obtain a solution having known concentrations of 1.0 mg per mL and 0.4 mg per mL, respectively.
Standard preparation
Dissolve an accurately weighed quantity of
USP Terbutaline Sulfate 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 50 mg of Terbutaline Sulfate, accurately weighed, to a 50-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 276-nm detector and a 4.6-mm × 15-cm column that contains 5-µm packing L1. The flow rate is about 1 mL per minute. Chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the relative retention times for terbutaline related compound A and terbutaline are 0.9 and 1.0, respectively; the resolution,
R, between terbutaline related compound A and terbutaline is not less than 2.0; the column efficiency is not less than 1500 theoretical plates; the tailing factor for the terbutaline peak is not more than 2.0; and the relative standard deviation for replicate injections determined from the terbutaline peak is not more than 2.0%.
Procedure
Separately inject equal volumes (about 20 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
12H
19NO
3)
2·H
2SO
4 in the portion of Terbutaline Sulfate taken by the formula:
50C(rU / rS)
in which
C is the concentration, in mg per mL, of
USP Terbutaline Sulfate RS in the
Standard preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.