Assay
Citric acid buffer
Transfer 2.5g of citric acid to a 500-mLvolumetric flask,add 400mLof water,and swirl to dissolve.Adjust the solution with 2Nsodium hydroxide to a pHof 6.0,dilute with water to volume,and mix.
Mobile phase
Dissolve 930mg of sodium octyl sulfate in 740mLof water,add 8mLof 3.6Nsulfuric acid,mix,and pass through a 1-µm or finer porosity filter.To the filtrate add 250mLof acetonitrile,mix,and degas.Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Standard preparation
Transfer about 50mg of
USP Atenolol RSto a 100-mLvolumetric flask,add 80mLof
Citric acid buffer,and sonicate for about 30seconds to achieve dissolution.Dilute with
Citric acid bufferto volume,and mix.Transfer 4.0mLof this solution to a 10-mLvolumetric flask,dilute with
Citric acid bufferto volume,and mix.This solution contains about 0.2mg of
USP Atenolol RSper mL.
Assay preparation
Transfer an accurately measured volume of Injection,equivalent to 2mg of atenolol,to a 10-mLvolumetric flask,dilute with Citric acid bufferto volume,and mix.
Chromatographic system
(see
Chromatography á621ñ)The liquid chromatograph is equipped with a 275-nm detector and a 4.6-mm ×25-cm column that contains 5-µm packing L1.The flow rate is about 1.7mLper minute.Chromatograph the
Standard preparation,and record the peak responses as directed for
Procedure:the tailing factor is not more than 2,and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure
Separately inject equal volumes (about 10µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of C
14H
22N
2O
3in each mLof the Injection taken by the formula:
10(C/V)(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Atenolol RSin the
Standard preparation;Vis the volume,in mL,of Injection taken;and
rUand
rSare the atenolol peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.