For solution (2) dilute 1 volume of solution (1) to 200 volumes with the mobile phase. Solution

with anhydrous sodium sulphate, filter. evaporate the filtrate to dryness on a water-bath and dry the residue at 105* for 1 hour. The infra-red absorption spectrum of the residue. Appendix 5.4, is concordant with the reference spectrum of atenolol or with the spectrum obtained from atenolol RS. B: The light absorption in the range 230 to 360 nm of the solution obtained in the Assay exhibits two maxima at about 275 nm and 262 nm, Appendix 5.5 Related substances: Carry out the method for high performance liquid chromatography, Appendix 4 3, using the following solutions, For solution (1) shake a quantity of the powdered tablets equivalent to 0.2 g of Atenolol with 20 ml of the mobile phase and mix with the aid of ultrasound for 20 minutes. Allow the solid matter to settle for 15 minutes and use the supernatant liquid. For solution (2) dilute 1 volume of solution (1) to 200 volumes with the mobile phase. Solution (3) contains 1 % w/v of atenolol for. performance test RS in the mobile phase. The chromatographic procedure may be carried out using (a) a stainless steel column (20 cm x 5 mm) packed with stationary phase LCI (5 pm), (b) as the mobile phase with a flow rate of 1 ml per minute a mixture of 600 volumes of a 0.166% w/v solution of sodium octyl sulphate, 10 volumes of sulphuric acid (10%) and sufficient methanol to produce a chrornatograrn with solution (3) closely resembling that of the reference chrcmatogram supplied wilh the reference standard (400 volumes of methanol is usually suitable) and