: The infra-red absorption spectrum, Appendix 5.4, is concordant with the reference spectrum of captopril or with the spectrum obtained from captopril

off-white, crystalline powder; odour, characteristic, sulphide-like. Solubility: Freely soluble in water, in methanol, in ethanol (95%) and in chloroform.Storage: Store in tightly-closed containers STANDARDSCaptopril contains not less than 97.5 per cent and not more than 102.0 per cent of C9H15NO3S, calculated with reference to the dried substance. Identification: A: The infra-red absorption spectrum, Appendix 5.4, is concordant with the reference spectrum of captopril or with the spectrum obtained from captopril RS. B: Carry out the method for thin-layer chromatography. Appendix 4.6, using silica gel G as the coating substance and a mixture of 75 volumes of toluene, 25 volumes of glacial acetic acid and 1 volume of methanol as the mobile phase, -but allowing the solvent front to ascend 12 cm above the line of application. Apply separately to the plate, in the form of 1-cm bancte, 50 ul of each of the two solutions in methanol containing (1) 0.4% w/v of the substance being examined and (2) 0.4% w/v of captopril RS. After removal of the plate, allow it to dry in air and spray with a freshly prepared mixture of 1 volume of strong ammonia solution and 6 volumes of a 0.04% w/v solution of 5,5'-dithiobcte(2-nitrobenzoic acid) in methanol and allow to stand for 5 minutes. The principal band in the chromatogram obtained with solution (1) corresponds to that in the chromatogram obtained with solution (2).C: Melts between 104° and 110°, Appendix 8.8. Specific optical rotation: Between -125° and -134°, determined in a 1 % w/v solution in ethanol, Appendix 8.9. Heavy metals: Not more than 30 ppm, determined on 0.66 g by Method B, Appendix 3.12. Sulphated ash: Not more than 02%, Appendix 3.22. Loss on drying: Not more than 1.0%, determined on 1 g by drying at 60° at a pressure not exceeding 0.7 kPa, Appendix 8.6. Assay: Weigh accurately about 0.3 g, dissolve in 100 ml of water in a stoppered-flask, add 10 ml of 1.8M sulphuric acid and 1 g of potassium iodide. Titrate with 0.0 25M potassium iodate using 3 ml of starch solution, added towards the end-point, as indicator Each ml of 0.025M potassium iodate is equivalent to 0.03308 g of C9H15NO3S.CAPTOPRIL TABLETS Usual strengths: 12.5 mg; 25 mg; 50 mg. Storage: Store in tightly-closed containers. STANDARDSCaptopril Tablets contain not less than 90.0 percent and not more than 110.0 per cent of the stated amount of captopril, C9H15NO3S. Identification: A Comply with test B described under Captopril, using as solution (1) the clear supernatant liquid obtained by extracting the powdered tab lets equivalent to 100 mg of Captopril with 25 ml of methanol and centrifuging. Dissolution: Comply with the dissolution test far tablets and capsules, Appendix 7.3, using Apparatus 2, as the medium 900 ml of 0.1M hydrochloric acid and rotating the basket at 50 rpm for 20 minutes. Withdraw a suitable volume of the sample and filter. Measure the absorbance of the filtrate, suitably diluted with the dissolution medium, if necessary, at the maximum at about 212 nm, Appendix 5.5. Calculate the content of CGH15NO3S in the medium from the absorbance obtained from a solution of known concentration of captopril RS in the same medium and from the declared content of C9H15NO3S in captopril RS. D: Not less than 80% of the stated amount of C9H15NO3S. Other requirements: Comply with the