A: The retention time of the codeine peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay for codeine phosphate.

B: The retention time of the guaifenesin peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay for guaifenesin.

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FOR SYRUP PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.USP28

Add the following:

FOR SYRUP PACKAGED IN MULTIPLE-UNIT CONTAINERS: meets the requirements.USP28

Standard stock solution— Dilute 10.0mLof dehydrated alcohol with water to 100.0mL.

Internal standard solution— Dilute 10mLof acetone with water to 100mL.

Standard preparation— Transfer 10.0mLof Standard stock solutionand 8.0mLof Internal standard solutionto a 100-mLvolumetric flask,dilute with water to volume,and mix.Transfer 5.0mLof this solution to a 250-mLvolumetric flask,dilute with water to volume,and mix.This solution contains 0.02%(v/v)of alcohol.

Test preparation— Transfer 25/kmLof Syrup (kbeing the labeled percentage [v/v]of C2H5OHin the Syrup),accurately measured,to a 25-mLvolumetric flask,add 2.0mLof Internal standard solution,dilute with water to volume,and mix.Transfer 5.0mLof this solution to a 250-mLvolumetric flask,dilute with water to volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector and a 2-mm ×1.8-m column that contains 5%liquid phase G16on 100-to 120-mesh support S1A,and is programmed to maintain the column temperature at 50for 5minutes after injection,to increase to 100at the rate of 20per minute,to maintain the temperature at 100for 2minutes,and then to return to 50before the next injection.The injection port is maintained at about 200,and the detector block is maintained at about 250.The carrier gas is dry helium flowing at a rate of about 30mLper minute.Chromatograph the Standard preparation,and record the chromatogram as directed for Procedure:the relative retention times are about 0.3for acetone and 1.0for alcohol (C2H5OH);the resolution,R,between the acetone and alcohol peaks is not less than 2;the tailing factors for the acetone and alcohol peaks are not more than 1.5;and the relative standard deviation for replicate injections is not more than 2%.

Procedure— Separately inject equal volumes (about 2µL)of the Test preparationand the Standard preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the percentage (v/v)of alcohol (C2H5OH)in the portion of Syrup taken by the formula: in which Pis the percentage (v/v)of alcohol (C2H5OH)in the Standard preparation;Vis the volume,in mL,of Syrup taken to prepare the Test preparation;and RUand RSare the ratios of the responses of the alcohol peak to the acetone peak obtained from the Test preparationand the Standard preparation,respectively:between 90.0%and 115.0%of the labeled amount of alcohol (C2H5OH)is found.

Internal standard solution— Place about 45mg of hydrocodone bitartrate in a flask containing about 5mLof water,add 1mLof 0.5Nsodium hydroxide and 50mLof chloroform,insert the stopper into the flask,and shake by mechanical means for about 20minutes.Allow the layers to separate,and filter the chloroform layer.

Standard preparation— Prepare a Standard stock solution of USP Codeine Phosphate RSin 0.1Nhydrochloric acid having a known concentration of about 2mg per mL.Transfer 5.0mLof this Standard stock solution to a suitable flask.Add 2mLof 2.5Nsodium hydroxide,8.0mLof Internal standard solution,and 40mLof chloroform,insert the stopper,and shake by mechanical means for 1hour.Allow the layers to separate,and collect the chloroform layer.

Assay preparation— Transfer an accurately measured volume of Syrup,equivalent to about 10mg of codeine phosphate,to a 200-mLflask containing about 5mLof water,and swirl.Add 2mLof 2.5Nsodium hydroxide,8.0mLof Internal standard solution,and 40mLof chloroform,insert the stopper,and shake by mechanical means for 1hour.Allow the layers to separate,and collect the chloroform layer.

Chromatographic system (see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector and a 2-mm ×0.6-m column that contains 3%liquid phase G3on 100-to 120-mesh support S1A,and is stabilized for isothermal operation.The column is maintained at about 210,the injection port at about 250,and the detector block at about 300.The carrier gas is dry helium flowing at a rate of about 25mLper minute.Chromatograph the Standard preparation,and record the chromatogram as directed for Procedure:the relative retention times are about 0.75for codeine and 1.0for hydrocodone;the resolution,R,between the codeine and hydrocodone peaks is not less than 1;and the relative standard deviation for replicate injections is not more than 2%.

Procedure— Separately inject equal volumes (about 2µL)of the Assay preparationand the Standard preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of codeine phosphate hemihydrate (C18H21NO3·H3PO4·½H2O)in each mLof the Syrup taken by the formula: in which 406.37and 397.37are the molecular weights of codeine phosphate hemihydrate and anhydrous codeine phosphate,respectively;Cis the concentration,in mg per mL,of USP Codeine Phosphate RSin the Standard stock solution used to prepare the Standard preparation;Vis the volume,in mL,of Syrup taken to prepare the Assay preparation;and RUand RSare the ratios of the responses of the codeine peak to the hydrocodone peak obtained from the Assay preparationand the Standard preparation,respectively.

Internal standard solution— Prepare a solution of dipropyl phthalate in chloroform containing about 12.5mg per mL.

Standard preparation— Prepare a Standard stock solution of USP Guaifenesin RSin 0.1Nhydrochloric acid having a known concentration of about 4mg per mL.Transfer 5.0mLof this Standard stock solution to a suitable glass-stoppered flask,add 2mLof 2.5Nsodium hydroxide,8.0mLof Internal standard solution,and 40mLof chloroform,insert the stopper,and shake by mechanical means for 1hour.Allow the layers to separate,and collect the chloroform layer.Extract the aqueous layer with two 20-mLportions of chloroform,and combine the three chloroform extracts.Transfer 5.0mLof the combined chloroform extracts to a suitable glass-stoppered flask,add 1mLof trifluoroacetic anhydride,and allow to stand for not less than 1hour.

Assay preparation— Transfer an accurately measured volume of Syrup,equivalent to about 20mg of guaifenesin,to a 200-mLflask containing about 5mLof water,and swirl.Add 2mLof 2.5Nsodium hydroxide,8.0mLof Internal standard solution,and 40mLof chloroform,insert the stopper,and shake by mechanical means for 1hour.Allow the layers to separate,and collect the chloroform layer.Extract the aqueous layer with two 20-mLportions of chloroform,and combine the three chloroform extracts.Transfer 5.0mLof the combined chloroform extracts to a suitable glass-stoppered flask,add 1mLof trifluoroacetic anhydride,and allow to stand for not less than 1hour.

Chromatographic system (see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector and a 4-mm ×1.2-m column that contains 3%liquid phase G6on 100-to 120-mesh support S1A.The column is maintained at about 170,the injection port at about 250,and the detector block at about 300.The carrier gas is dry helium flowing at a rate of about 45mLper minute.Chromatograph the Standard preparation,and record the chromatogram as directed for Procedure:the relative retention times are about 0.6for the trifluoroacetyl derivative of guaifenesin and 1.0for the trifluoroacetyl derivative of dipropyl phthalate;the resolution,R,between the guaifenesin and dipropyl phthalate peaks is not less than 1;and the relative standard deviation for replicate injections is not more than 2%.

Procedure— Separately inject equal volumes (about 1µL)of the Assay preparationand the Standard preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of guaifenesin (C10H14O4)in the portion of Syrup taken by the formula: in which Wis the quantity,in mg,of USP Guaifenesin RStaken to prepare the Standard preparation;Vis the volume,in mL,of Syrup taken to prepare the Assay preparation;and RUand RSare the ratios of the responses of the guaifenesin peak to the dipropyl phthalate peak obtained from the Assay preparationand the Standard preparation,respectively.