oxygen flask bpharm pharmaceutical analysis

bpharm

1. Oxygen-flask-combustion method 1

2. Oxygen-flask-combustion method First proposed by schoniger in 1955 for organically combined halogen. In presence of oxygen in a closed assembly , organic compound is burned, organic matter get destroyed and halogen is released which is absorbed in a appropriate solution, which subsequently analyzed. By this method fluorine, chlorine, bromine, iodine and sulphur is determined. Method is simple, rapid , accurate and can be applied to formulated products such as tablets , capsule , cream and ointments. 2

3. apparatus Thick walled conical 500ml iodine flask, fitted with a ground-glass stopper Which is fused a platinum wire about 13cm long and 1mm diameter It attached to a piece of platinum gauge(2cm x 1.5 cm in diamention and is no is 36 sieve. It must be well cleared and free from even track of organic solvents. 3

4. method Solid substance should be finely groud and thoroughly mixed before the specified quantity is weighed. For the liquid samples use gelatin capsule or mix with methyl cellulose power and place on ashless grade paper Ointment/cream weigh the sample in grease proof paper before wrappinf in filter paper 4

5. procedure Weigh accurately a suitable quantity of sample(about 20mg) if solid on a halide free filter paper of 5cm x 3cm, wrap it and pace in the platinum gauze sample holder. Insert one end of narrow strip of filter paper in the roll to serve as a fuse. Flush the flask with oxygen, moisten the neck with water and place specified quantity of absorbing liquid in the flask, fill it with O2 and light the free end of paper strip and immediately insert stopper. Hold the stopper firm during combustion of the sample, then shake the flask vigorously for about 5min. Place few ml of water in the cup, carefully remove the stopper and rinse the stopper, platinum wire and gauze with water 5

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7. bromine Absorbing liquid is 15ml of mixture of 1 volume of hydrogen peroxide(30%) and 9 v of 1N H2SO4. After rxn complete add 5ml of 2N nitric acid + 10ml of 0.1Nsilver nitrate and titrate with 0.05N ammonium thiocyanate using ferric ammonium sulphate as indicator Blank Difference between the titrations represent the number of ml of silver nitrate required for the spl . Each ml of 0.05N silver nitrate is equivalent to 0.003995g of Br 7

8. chlorine AL: 20ml of 1M NaOH After rxn complete add 2.5ml of nitric acid + 2.5ml H2O +10ml of 0.1M silver nitrate and titrate with 0.05M ammonium thiocyanate using ferric ammonium sulphate as indicator Conduct Blank Difference between the titrations represent the number of ml of silver nitrate required for the spl . Each ml of 0.05N silver nitrate is equivalent to 0.001773g of Cl. 8

9. fluorine AB: 20ml of water After combustion of spl add sufficient water to produce 50ml. To 2ml of above add 20ml H2O + 10ml alizarin fluorine blue soln + 3ml of soln containing 2 percent sodium acetate + 6%w/v glacial acetic acid + 10ml cerous nitrate and sufficient water to produce 50ml Allow this to stand in dark for one hour and measure the extinction in 1cm cell at 610 nm. Blank calculate the flurine content from reference curve preparing using suitable quantity of sodium fluoride soln. Carried out in silica or soda glass flask. 9

10. AL: mixture of 10ml H2O + 2Ml of 1N NaOH . After rxn complete add excess of acetic-bromine soln (5-10ml) and allow to stand for two minutes. Remove excess bromine by addition of formic acid 1ml. Drive off vapour of bromine with current of air. Add 1 g k.iodide and titrate with 0.02N sodium thiosulphate using starch as indicator towards the end of the titration. Each ml of 0.02N sodium thiosulphate is equivalent to 0.000423g of l . iodine 10

11. sulphur 2 method 1-in the absence of halogens and phosphorous 2-in presence of halogens and phosphorous 11

12. Method i AL; 10ml H2O + 0.1 ml H2O2 (30%) Process complete cool t he soln 15 min Boil(2min) cool + ethanolic acetic ammonia buffer(3.7) Titrate with 0.05M barium perchlorate using 0.3ml alizarin red S as indicator orange pink clr Each ml of 0.05M barium perchlorate is equivalent to 0.001603g of S. 12

13. Method ii AL; 15ml H2O + 1 ml H2O2 (10%) Process complete Boil(10min ) cool + ethanol(60ml) Titrate with 0.01M barium perchlorate using 0.1ml of 2.0% thoron and 0.1ml of 0.0125% methylene blue as indicator yellow to pink clr Each ml of 0.01M barium perchlorate is equivalent to 0.00032g of S. 13

14. Thank you 14