EXPERIMENT NO. 11. DETERMINATION OF PARTICLE SIZE OF STARCH GRAINS BY EYEPIECE MICROMETER.

 PHARMACOGNOSY AND PHYTOCHEMISTRY – I PRACTICAL

EXPERIMENT NO.1 1

Aim: Determination of particle size of starch grains by eye piece micrometer.

Reference: Mayur R. Bhurat, Md. Rageeb Md. Usman, Sanjay A. Nagdev, Practical Pharmacognosy & Phytochemistry – I, Published by S. Vikas And Company (Medical Publisher) Ppage. No. 47, 48.

Requirements:

Apparatus: Test Eyepiece micrometer, Stage micrometer, Porcelain dish, Slides etc.

Chemicals: Starch Powder, Lactophenol solution, Iodine solution etc.

Theory:

Starch: 

Biological Source: Starch contains of polysaccharide granules procured from the grains of Maize i.e Zea mays L. or of Rice i.e. Oryza sativa L or of Wheat i.e. Triticum aestivum L. (FamilyGraminae) or from the tubers of the Potato i.e. Solanum tuberosum L, (family. Solanaceae). 

Description: 

Color: White (Rice and Maize starch), 

Cream (Wheat), 

slight yellow (Potato). 

Odor: Odorless. 

Taste : Mucilagenous taste 

Shape: Fine powder or irregular, angular masses. 

Solubility: It is sparingly soluble in cold water and mostly soluble in hot water after cooling it forms gel. 

Chemical Constituents: 

Starch contains generally a mixture of two polysaccharides, amylopectin (aamylose) and amylose (Bamylose). 

(a) Amylopectin is the main constituent of most of the starches (more than 80%) and is present in outer parts of granules. It contains both strait chained and branched glucose unit. It is insoluble in water and is responsible for gelatinizing property. It gives bluish black colour with iodine solution. 

(b) Amylose most starches contain. 20% amylose. It contains straight chained glucose units and is present in inner parts of granules. It is soluble in water and produces blue colour with iodine solution. 

Uses: 

It is mainly used as a dusting powder, Pharmaceutical aid, an antidote for iodine poisoning, Source of Food-nutrition, Protective and demulcent, in paper-sizing, textile industry, in laundry practice. It is the starting product form which liquid glucose, dextrose, dextrin are made. It is also used as a tablet disintegrating agent and diluents. 

Procedure:

Procedure for determination of size of starch grain: 

1. Calibrate an eyepiece micrometer using a stage micrometer and calculate the factor. 

2. ‘Take little quantity of starch powder in porcelain dish and add few drop of lactophenol and drop of iodine solution. 

3. Mix it properly and do not over stain it. 

4. Then make it dry and spread this starch powder on slide. 

5. Measure the length and width of that starch grain by eyepiece micrometer scale.

6. Place the eyepiece micrometer scale horizontal on that starch grain and count number of division Covered by the starch grain for measurement of width. 

7. Similarly keep eyepiece micrometer scale vertically on the starch grain and count number of division covered by the starch grain for measurement of length. 

8. Measure the length and width of 50 starch grain particle and multiply it with factor. 

Size of starch grain = Length x Width x Factor.

9. Calculate the average size of starch grain put this value in the result. 

RESULT: Size of starch grains by using eyepiece micrometer was found to be.......