A: Infrared Absorption 197K.

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

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: 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%.

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 (C12H19NO3)2·H2SO4 in the portion of Terbutaline Sulfate taken by the formula: 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.