about 0.8,Appendix 5.5.C A 1% w/v solution is acid to methly red solution D Melts between 121° and 123*, Appendix 8.8 Clarity

about 0 4 g and dissolve in a mixture of 25 ml of hydrochlonic acid and 50 ml of water Cool to 10° and carry out the nitrite tiration. Appendix 344 Each ml of 0 1M sodium nirtrite is equivalent to 0.01652 9 of C9 H11 NO2 BENZOIC ACIDCaltgory Antifungal agent, pharmaceutical aid (antimicrobial preservative) Description Colourless, light Crystals, scales or needles, odour, Slight and charactenstic Solubility Freely soluble in ethanol (9S%)h in chloroform and in ether: slightly soluble in water but soluble in boiling water It is soluble in fixed oils Storage Store in well-closed containers STANDARDSBenzoic Acid contains not less than 99 5 per cent and not more than 100 5 per cent of C7H6O2, calculated with reference to the anhydrous substance Identification A Warm gently 02 g with 20 ml of water, add 1 ml of IM sodium hydroxide and filter To The filtrate add ferric chloride test solution, a buff coloured precipitate is produced.B The light absorption in the range 220 to 360 nm of a 0 001% w/v solution in methanol exhibits a maximum only at about 225 nm, absorbance at about 225 nm. about 0.8,Appendix 5.5.C A 1% w/v solution is acid to methly red solution D Melts between 121° and 123*, Appendix 8.8 Clarity and colour of solution A 5% w/v solution in ethanol (95%) is clear, Anpendix 6 1, and colorless Appendix 6 2. Arsenic Mix Win 5 g with 3 g of anhydrous sodium carbonate, add 10 ml of bromine solution and max thoroughly Evaporate to dry ness on a water-balh, gently ignite and dissolve the cooled residue in 16 ml brominated hydrochloric acid and 45 ml of water Remove the excess of bromine with 2 ml of stannous chloride AsT. The resulting solution complies with the limit lest for arsenic. Appendix 3.9 (2 ppm) Heavy metals Not more than 10 ppm, determined by (the following method Dissolve 20 g in 25 ml of acetone and add 2 ml of water and 10 ml of hydrogen sulphide solution, any colour produced is nol more intense than that of a solution prepared wrth 25 ml of acetone. 20 ml of lead standard solution (10 ppm Pb) and 10 ml of hydrogen sulphide solution Readily oxidisable substances Add 1 ml of sulphuric acid to 100 ml of water, heat to boiling and add dropwise 0 1M potassium permanganate until the pink colour persists for 30 seconds Dissolve exactly 1 g in the hot solution and titrate'wrth0.1 IM potassium permanganate to a pink colour that persists for 15 seconds, not more than 0.5 ml of 0 1M potassium permanganate is required Readily carbonisable substances Dissolve 0 50 g 5 ml of sulphunc acid and allow to stand for 5 minutes The colour of the solution is not more intense than that of reference solulion YS5. Appendix 6.2 Cinnarnic acid Warm 0 .1 9 with 0 1 g of potassium permanganate and 5 ml of dilute sulphuric acid, no odour of benzaldehyde is developed Chlorinated compounds. Dissolve 0 33 g in 5 ml of 0 5M sodium carbonate evaporate to dryness and heat Ihe residue until completely charred, keeping the temperature below 400* Extract the residue with a mixture of 10 ml of waler and 12 ml of dilule nitric acid and filter, the filtrate complies with the limit test for chlorides, Appendix 3 10 Sulphated ash Nol more than 0 1%, Appendix 3 .22 Water Not more than 0 .7% w/w. determined on 0. 25 g and using a mixture of I volume of methanol and 2 volumes of pyridine as the solvent, Appendix 3.24. Assay: Weigh accurately about 1.0 g and dissolve in 15 ml of warm ethanol (9S%) previously neutralised to phenolphthale in solution. Add 20 ml of water and titrate with 0. 5M sodium hydroxide using phenolphthalein solution as indicator Each ml of 0.5M sodium hydroxide is equivalent to 006106 g of C7O2COMPOUND BENZOlC ACID OlNTMENTBenzoic and Salicylic Acids Ointment, Whirtheld's Ointment"Compound Banzoic Acid Ointment is an ointment containing 6.0% w/w of Benzoic Acid -and 30% w/w of Salicylic Acidin a suitable ointment base. Other strengths may also be prepared with Benzoic Acid and Salicylic Acid being in the ratio of about 2. to 1. Category Antifungal (topical) Storage; Store in well-closed containers at a temperature not exceeding 30° STANDARDS Com pound Benzoic Acid Ointment contains not less than 5.7 per cent and not more than 6.3 per cent w/w of benzoic acid, C7 -H6O2, and not less than 2.85 par cent and not more than 3.15 percent w/w of salicylic acid C7H6O3 Identification Carry out the method for thin -layer chromatography, Appendix 4.6, using silica gel GF254 as the coating substance and a mixture of 80 volumes of toluene and 20 volumes of glacial acetic acid as the mobile phase. Apply separately to the plate 2 ul of each of the following solutions For solution (1) warm 1 g of the ointment with 10 ml of chloroform, cool and filter Solution (2) contains 06% w/v of benzoic acid and 0.3% w/v of salicylic acid in chloroform. After removal of the plate, allow it to dry in a current of air and examine under ultra-violet light (254 nm). The two principal spots in chromatogram obtained with solution (1) correspond to those in the chromatograrn obtained with solution (2) Examine the plate under ultra violet light (365 nm) A blue fluorescent spot in the chromatogram obtained with solution (1) corresponds m colour and position to the one in the chromatogram Obtained with solution (2) Spray the plate with feme chloride test-solution. The chromatogram obtained with solution (1) shows a purple spot corresponding in position to the blue fluorescent spot observed under ultra-violet