COLORIMETRIC METHOD
- 1. BCDACOLLEGEOFPHARMACYAND TECHNOLOGY NAME : AMIT MIA ROLL NO : 20101921032 REG.NO: 212010201910019 SUBJECT: PHYSICAL PHARMACEUTICS 1(CA1) CODE: PT 316 TOPIC: COLORIMETRIC METHOD TO DETERMINE pH
- 2. CONTENTS INTRODUCTION Principle Method Precautions Advantage Disadvantage Reference
- 3. COLORIMETRIC METHOD : Colorimeter method is used to determine the PH of the solution up to +- 0.2 units in the range of PH 3 to 11.0 based on the colour changes. INTRODUCTION
- 5. PRINCIPLE The principleinvolves thecomparisonof color of the test solutionwith that of the standard solutionof the definite pH values colors are developed by adding universal indicator to both test and standard solution.
- 6. Several standard solutions are available commercially, which are premixed solution of buffer and indicator. CAPILLARIES : The buffer solution and universal indicator are mixed and placed in capillary tubes. A set of such standard solution is known as capillators. COMPARATORS : For large volumes, comparators are used, The test sample is also mixed with universal indicators.
- 7. METHOD a) Standard buffer solution of known PH values ranging from 3.0 to 11.0 are prepared with 1.0 PH intervals. b) A few drops of the universal indicators are added to each buffer solution different color produces. c) A few drops of indicators are added to the test solution. d) The color of unknown solution is matched with the standard colors produced by buffer solution. e) Based on the approx. PH value obtained in step (d), the PH interval is reduced to a narrow range. f) Steps from (b) to (d) are repeated and the exact PH of test solution reported.
- 9. PRECAUTIONS : • Standard solution must be protected from light to prevent color fading. • All tubes should be of same dimensions.
- 10. ADVANTAGE • Colorimetric method is less expensive. • It is useful for the study of acid base reactions in non aqueous solution. DISADVANTAGE • It is particularly Used when the solution is not colored or not turbid. • Errors may result by the presence of salts , protein etc. • This method is less accurate and less convenient.
- 11. REFFERENCE • C.v.s subrahmonyam ,DR. Ashok A hajare.