A: The RFvalue of the principal spot obtained from the Test preparationcorresponds to that obtained from Standard solution Ain the chromatograms obtained as directed in the test for Related compounds.

B: Shake a quantity of the powdered Tablets,equivalent to about 4mg of Albuterol,with 10mLof water and filter:the filtrate responds to the tests for Sulfate á191ñ.

Medium: water;500mL.

Apparatus 2: 50rpm.

Time: 30minutes.

Mobile phase,Standard preparation,and Chromatographic system— Prepare as directed in the Assay.

Procedure— Inject a suitable volume (about 100µL)of a portion of the solution under test,previously passed through a 0.45-µm nylon filter,into the chromatograph,record the chromatogram,and measure the response for the major peak.Calculate the quantity of C13H21NO3dissolved by comparing this peak response with the major peak response similarly obtained on chromatographing the Standard preparationpreviously diluted,if necessary,with a mixture of water and methanol (6:4)to obtain a Standard solution having a known concentration of USP Albuterol Sulfate RSapproximately corresponding to the concentration of the solution under test.

Tolerances— Not less than 80%(Q)of the labeled amount of C13H21NO3is dissolved in 30minutes.

Test preparation— Place a quantity of finely powdered Tablets,equivalent to 48mg of albuterol,into a suitable container.Add 60mLof diluted alcohol (1in 2),and shake by mechanical means for 30minutes.Filter the mixture,and wash the filter with small portions of alcohol,combining this with the filtrate.Evaporate the filtrate to dryness under reduced pressure at a temperature below 40.Dissolve the residue as completely as possible in 2mLof water.

Standard solutions— Prepare solutions of USP Albuterol Sulfate RSin water having known concentrations of 0.580mg per mL(Solution A),0.218mg per mL(Solution B),and 0.073mg per mL(Solution C)equivalent to 0.483mg,0.183mg,and 0.061mg,respectively,of albuterol.

Procedure— Apply 10µLaliquots (in two successive portions of 5µL,allowing the solvent to evaporate between applications)of the Test preparationand each of Standard solutions A,B,and Cto separate points to a suitable chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Air-dry,and place the plate in a saturated chromatographic chamber.Develop the chromatograms with a solvent system consisting of a mixture of methyl isobutyl ketone,isopropyl alcohol,ethyl acetate,water,and ammonium hydroxide (50:45:35:18:3)until the solvent front has moved about 17cm.Remove the plate from the developing chamber,air-dry,and spray first with 3-methyl-2-benzothiazolinone hydrazone hydrochloride TS,then with ammoniacal potassium ferricyanide TS,and finally again with 3-methyl-2-benzothiazolinone hydrazone hydrochloride TS.Examine the plate and estimate the responses of any secondary spots observed in the lane of the Test preparationby comparison with those of Standard solutions A,B,and C.No major secondary spot is greater in size or intensity than the principal spot produced by Standard solution A(2.0%).No other secondary spot is greater in size or intensity than the principal spot produced by Standard solution B(0.75%).No more than two other secondary spots are equal in size or intensity than the principal spot produced by Standard solution C(0.25%).The sum of the intensities of all secondary spots obtained from the Test preparationcorresponds to not more than 3.5%.

1%Acetic acid— Transfer a 20-mLportion of glacial acetic acid to a suitable volumetric flask,and dilute with water to 2000mL.

Mobile phase— Dissolve 1.13g of sodium 1-hexanesulfonate in 1200mLof water,add 12mLof glacial acetic acid,and mix.Prepare a filtered and degassed mixture of this solution and methanol (6:4).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Transfer about 12mg of USP Albuterol Sulfate RS,accurately weighed,to a 100-mLvolumetric flask.Add 60mLof 1%Acetic acid,sonicate for 5minutes,dilute with methanol to volume,and mix.Pipet 25mLof this solution into a 100-mLvolumetric flask,dilute with a mixture of water and methanol (6:4)to volume,and mix.

Assay preparation— Transfer a number of whole Tablets,equivalent to about 50mg of albuterol,to a 2000-mLvolumetric flask.Add 1200mLof 1%Acetic acid,shake by mechanical means for 45minutes,sonicate for 10minutes,allow to cool to room temperature,dilute with methanol to volume,and mix.Pass through a suitable filter having a 0.45-µm or finer porosity.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 276-nm detector and a 4.6-mm ×15-cm column that contains packing L1.The flow rate is about 1.5mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency determined from the analyte peak is not less than 800theoretical plates;the tailing factor for the analyte peak is not more than 2.5;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 25µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of albuterol (C13H21NO3)in the number of Tablets taken by the formula: in which 239.32and 576.71are the molecular weights of albuterol and albuterol sulfate,respectively;Cis the concentration,in mg per mL,of USP Albuterol Sulfate RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.