: For penicillins - Weigh accurately about 70 mg, dissolve in 20 ml of methanol, add 5 ml of water and 5 ml of 1 M sodium hydroxide and allow to stand

: For penicillins - Weigh accurately about 70 mg, dissolve in 20 ml of methanol, add 5 ml of water and 5 ml of 1 M sodium hydroxide and allow to stand for 15 minutes. Add 5 ml of IM nitric acid, 20 ml of acetate buffer pH 4.6 and 20 ml of water and titrate at 35° to 40° with 0. 02M mercuric nitrate. Titrate slowly so that the titration takes about 15 minutes Determine the end-point potentiometrically using a platinum or mercury -indicator electrode and a mercury mercurous sulphate reference electrode. (Cleaningthe reference electrode with dilute nitric acid and the indicator electrode with a 10% w/v solution of sodium thiosulphate followed by rinsing with distilled water is recommended after each assay). Ignore any preliminary inflection on the titration curve. Each ml of 0.02M mercuric nitrate is equivalent to 0.009091 g of total penicillins, calculated as C16H20N2(C16H18N2O4S)2 To a further 0.25 g dissolved in 50 ml of methanol add 25 ml of acetate buffer pH 4.6 and shake until solution is complete. Titrate immediately at room temperature with 0. 02M mercuric nitrate determining the end-point as above. Each ml of 0.02M mercuric nitrate is equivalent to 0.009091 g of degradation products, calculated as C16H20N2(C16H18N2O4S)2 Calculate the percentage content of total penicillins and the percentage content of degradation products. The difference between the two percentages is the content of penicillins. For N,N'-dibenzylethylenediamine - Weigh accurately about 1 g, add 30 ml of a saturated solution of sodium chloride and 10 ml of 5M sodium hydroxide, shake well and extract with four quantities, each of 50 ml, of ether. Wash the combined extracts with three quantities, each of 10 ml, of water, extract the combined washings with 25 ml of ether and add the extract to the main ether solution. Evaporate the ether solution to a low bulk, add 2 ml of ethanol and evaporate to dry ness Dissolve the residue in 50 ml of anhydrous glacial acetic acid and carry out Method B for non-aqueous titration, Appendix 3.45, using 1 ml of naphtholbenzein solution as indicator. Perform a blank determination and make any necessary correction. Each ml of 0.1M perchloric acid is equivalent to 0.01202 g of C16H20N2. Benzathine Penicillin intended for use in the manufacture of injectable preparations complies with the following additional requirements. Pyrogens: Complies with the test for pyrogens, Appendix 2.6, using per kg of the rabbit's weight 1 ml of the supernatant liquid obtaind by suspending 40 mg in 20 ml of water for injection, shaking thoroughly and centrifuging. Sterility: Complies with the tests for sterility, Appendix 9.5 BENZATHINE PENICILLIN INJECTIONBenzathine Berizylpenicihin Injection, Benzathine Penicillin G Injection Benzathine Penicillin Injection is a sterile suspension of Benzalhine Penicillin in Water for Injection. It is prepared by adding to the contents of a seated container the requisite amount of Water for Injection, the seated container, may contain suitable buffering agents and other 'pharmaceutical aids. Usual strength: 450 mg (600,000 Units) (Each mg of Benzathine Penicillin is