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Method of Analysis for Acetone


Learn how to analyze the Acetone in pharmaceuticals including Distilling Range, Water content, Residue on evaporation, Reducing substances, Matter insoluble in water and Relative density.

1.0 Description

A volatile clear, colorless liquid.

2.0 Solubility

Miscible with water, with alcohol and with ether.

3. Identification

a. Color Test

Take 1ml of the sample in to a test-tube; add 3ml of dilute sodium hydroxide solution and 0.3 ml of 2.5% sodium nitroprusside solution.
An intense red color is produced. Add 3.5 ml of acetic acid, the color changes to violet.
b. Dilute 0.1ml of sample to 100ml with 50%v/v alcohol. Take 10ml of this solution in a test-tube; add 1ml of 1% nitrobenzaldehyde in 50% v/v alcohol and 0.5ml of strong sodium hydroxide solution. Allow to stand for 2 minutes and acidify with acetic acid. A greenish-blue color is produced.

4. Appearance of solution 

a. Clarity of the solution

Limit: Solution is clear and colorless

Procedure

Reference suspension: Dissolve 1.0gm of hydrazine sulphate with 100ml water and allow to stand for 4 to 6 hours. Add 25 ml of this solution to 25 ml of 10% w/v solution of hexamine mix well and allow to stand for 24 hours. Dilute well and mix 15ml of the suspension to 1000ml with water. Dilute well mix 5ml of this suspension to 100 ml with water.
Sample preparation: Take 10ml of the sample in a Nessler cylinder; add 10ml of water and mix.
Procedure: Into separate Nessler cylinders Place sufficient of the sample solution, water and of the reference suspension, freshly prepared, such that the test tubes are filled to a depth of 40 mm. Five minutes after preparation of the reference suspension, compare the contents of the test tubes against a black background by viewing in diffused daylight down the vertical axes of the tubes. The clarity of the sample preparation is greater than water or reference suspension

b. Color of the solution

Limit: The color intensity of sample is same as that of water or is not greater than that of reference solution B9.

Procedure

Reference solution: Transfer 30ml of Yellow primary solution, 30ml of Red primary solution and 24ml of Blue primary solution. Make up the volume to 100 ml with 1% w/v HCl.
Pipette out 1ml of the above solution and make up the volume with 1% w/v HCl.
Sample preparation: Mix 10ml of sample with 10ml of water.
Procedure: Transfer to a flat-bottomed test tube of neutral glass, 15 to 25 mm in diameter, a suitable volume of the liquid being examined such that the test tube is filled to a depth of 40 mm. Into another matched test tube add the same volume of water and of the reference solution prepared. Examine the columns of liquid in diffused light by viewing down the vertical axis of the tubes against a white background.
The color intensity of sample is same as that of water or is not greater than that of reference solution B9.

5. Acidity or Alkalinity

Limit: NMT 0.5 ml of 0.01 M NaOH or 0.7 ml of 0.01M HCl is required.

Procedure

Take 5ml of sample in a clean 100 ml conical flask, add 5ml carbon-dioxide free water, 0.15ml of Phenolphthalein solution and 0.5ml of 0.01M sodium hydroxide solution, the solution is pink.
Add 0.7ml of 0.01M hydrochloric acid and 0.05ml of methyl red solution the solution turns to red or orange.

6. Relative density at 20°C

Limit: Between 0.790 and 0.793

Procedure

Weigh a clean and dried Pycnometer (W1) fill the Pycnometer with the sample and adjust the temp. to 20°C and adjust the volume (W2). Weigh the contents Empty the Pycnometer, clean it thoroughly fill with the water, adjust the temperature to 20°C and adjust the volume, weigh it again (W3).
                           W2 – W1
Relative density = ------------ x 0.99718
                           W3 – W1


7. Related substances

Limit: Methanol: Not more than 0.05%
2-Propanol: Not more than 0.05%
Other impurities: Not more than 0.05%

Procedure

Sample Solution: Sample as such
Reference Solution: Take 0.5ml methanol and 0.5ml 2-propanol in a 100 ml volumetric flask and dilute to 100ml with the sample. Take 1ml of above solution and further dilute to 10ml with the sample.
Chromatographic conditions
Column: Fused silica column coated with film 0.5mm of macrogol 20000) 50 m x 0.3 mm
Column Temperature
Injector Temp. - 150°C
Detector Temp. - 250°C
Oxygen - 50 kPa
Hydrogen - 50 kPa
Carrier P - 400 kPa
Carrier M - 150 kPa
Injection Volume - 1µl
Procedure
Inject 1µl of the reference solution and test solution. When the chromatograms are recorded the substances are eluted in the following order: Acetone, methanol, 2-propanol. Continue the chromatography for three times the retention time of acetone (which is about 5.3 minute). The test is not valid unless, in the chromatogram obtained with the reference solution, the resolution between the peaks corresponding to methanol and 2-propanol is at least 1.0. In the chromatogram obtained with the test solution: the area of any peak corresponding to methanol or 2-propanol is not greater than the difference between the areas of corresponding peaks in the chromatogram obtained with the reference solution and the areas of the corresponding peaks in the chromatogram obtained with the test solution. The area of any peak, apart from the principal peak and any peak corresponding to methanol and 2-propanol is greater than the difference between the area of the methanol peak in the chromatogram obtained with the reference solution and the areas of the corresponding peak in the chromatogram obtained with the test solution.

8. Matter insoluble in water

Limit: The 5% v/v aqueous solution is clear

Procedure

Reference suspension: Dissolve 1.0gm of hydrazine sulphate in sufficient water to produce 100.0ml and allow to stand for 4 to 6 hours. Add 25ml of this solution to 25ml of 10% w/v solution of hexamine mix well and allow to stand for 24 hours. Dilute well mix 15ml of the suspension to 1000ml with water.
Dilute well mix 5ml of this suspension to 100ml with water.
Sample preparation: Take 1ml of sample in a clean and dry 25 ml glass stoppered test tube, add 19 ml of water and mix.
Procedure: Into separate matched, flat-bottomed Nessler cylinders, 15 to 25 mm in internal diameter and of colorless, transparent, neutral glass, place sufficient of the sample preparation, water and of the reference suspension, freshly prepared, such that the test tubes are filled to a depth of 40 mm. After five minutes, compare the contents of the test tubes against a black background by viewing in diffused daylight down the vertical axes of the tubes. The clarity of the sample preparation is greater than that of water or reference suspension.

9. Reducing substances

Limit: The mixture is not completely decolorized

Procedure

Take 30ml sample in a clean and dried 250ml iodine flask; add 0.1ml of 0.02M potassium permanganate. Keep the flask in dark for 2 hrs. The mixture is not completely decolorized

10 Residue on evaporation

Limit: Not more than 50 ppm

Procedure

Weigh 250 ml glass beaker (W1) previously heated at 105°C for two hrs. Take about 20.0 g (W2) of sample in the beaker. Evaporate the sample on water-bath. When traces of sample remains in the beaker, keep the beaker on hot air oven at 105°C for 30 minutes. Cool the beaker in a desiccator and weigh (W3).
                        W3-W1
ppm of residue: -----------x 1000000
                          W2

11. Water content

Limit: Not more than 0.3%

Procedure

Transfer 20 ml of anhydrous pyridine to the titration vessel, and titrate with K.F. reagent, standardized earlier, to the electrometric endpoint to consume any moisture that may be present. Quickly and accurately add 10 ml substance mix and again titrate with the reagent to the electrometric end point. Calculate the % of water using formula.
Calculation:
                              V x F x 100
Water (% w/w) = --------------------
                                    A

12. Distilling Range

Limit: Not less than 95.0% v/v distills between 55.5°C and 57.0°C

Procedure

Take 100 ml of sample in a clean and dried round bottom flask attached with stopper containing thermometer and condenser. Fix the assembly over the heating mantle and start water circulation in condenser jacket. Add few pieces of glass beads and start the heating in heating mantle and observe the sample. When temperature increases, note the temperature of vapor when first drop distills out. Maintain the temperature at this point. Again note the temperature when 95% of the material has distilled out. 
Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
Email: .moc.enilediugamrahp@ofni Need Help: Ask Question


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