Standard Operating Procedures for QC of Ayurvedic Herbs

                        Determination of Alcohol Soluble Extractive:

1. Mix 5 gm of the air dried drug, coarsely powdered, with 100 ml of alcohol of specified strength in a closed flask.
2. Macerate the sample for twenty-four hours, shaking frequently during six hours and allowing to stand for eighteen hours
3. Filter rapidly, taking precautions against loss of solvent, evaporate 25 ml of the filtrate to dryness in a tared flat bottomed shallow dish
4. Dry the dish at 105 C, to constant weight and weigh.
5. Calculate the percentage of alcohol-soluble extractive with reference to the air-dried drug.      

                 

Determination of Acid-Insoluble Ash

1.      Add 25 ml of dilute hydrochloric acid To the crucible containing total ash

2.      Collect  the insoluble matter on an ashless filter paper ( Whatman 41 ) and wash with hot water until the filtrate is neutral.

3.      Transfer the filter paper containing the insoluble matter to the original crucible, dry on a hot-plate and ignite to constant weight.

4.      Allow the residue to cool in a suitable desiccator for 30 minutes and weigh without delay.

5.      Calculate the content of acid- insoluble ash with reference to the air – dried drug.

Determination of Moisture Content (Loss on Drying)

Procedure set forth here determines the amount of volatile matter (i.e.,water drying off from the drug). For substances appearing to contain water as the only volatile constituent, the procedure given below, is appropriately used.

1. Place about 10 g of drug (without preliminary drying) after accurately weighing

(accurately weighed to within 0.01g) it in tared evaporating dish .

Note : For unground or unpowdered drug, prepare about 10 g of the sample by cutting shredding so that the parts are about 3 min in thickness.

Seeds and fruits, smaller than 3 mm should be cracked. Avoid the use of highspeed mills in preparing the samples, and exercise care that no appreciable amount of moisture is lost during preparation that the portion taken is representative of the official sample.

2. After placing the above said amount of the drug in the tared evaporating dish, dry

            in Infra-red moisture analyzer.

3. Continue the drying and weighing at one hour interval until difference between two successive weighing corresponds to zero.
4. Calculate the percentage of moisture in sample by using formula.

Determination of Total Ash

1. Incinerate about 2 gm accurately weighed , of the ground drug in a tared platinum or silica dish at a temperature not exceeding 450 until free from carbon
2. cool the ash obtained and weigh.
3. If a carbon free ash cannot be obtained in this way, exhaust the charred mass with hot water,collect the residue on an ashless filter paper, incinerate the residue and filter paper, add the filtrate, evaporate to dryness, and ignite at a temperature not exceeding 450.
4. Calculate the percentage of ash with reference to the air-dried drug.

Determination of Volatile Oil in drugs

             The determination of volatile oil in a drug is done by distilling the drug with a      mixture of water and glycerin collecting the distillate in a graduated tube in which the   aqueous portion of the distillate is automatically separated and returned to the distilling flask, and measuring the volume of the oil. The content of the volatile oil is expressed as a percentage v/w.

Instrument and instructions for its cleaning-

The Clevenger`s apparatus is recommended for this process.

The apparatus is cleaned before each distillation by washing successively with acetone and water, then inverting it, filling with chromic sulphur acid mixture, after closing the open and at G, and allowing to stand, and finally rinsing with water.

Method of determination:

1. Put a suitable quantity of the coarsely powdered drug together with 75 ml of glycerine and 175 ml of water in the one litre distilling flask, and a few pieces of porous earthen ware and one filter paper 15 cm cut into small strips, 7to12 mm wide in the distilling flask, which is then connected to the still head.
2. Before attaching the condenser, water is run into the graduated receiver, keeping the tap T open until the water overflows, at P. Any air bubbles in the rubber tubing a-b are carefully removed by pressing the tube. The tap is then closed and the condenser attached.
3. Now heat the contents of the flask and stir frequent agitation until ebullition commences. The distillation is continued at a rate, which keeps the lower end of the condenser cool.
4. Rotate the flask occasionally to wash down any material that adheres to its sides.
5. Discontinue heating at the end of the specified time (3 to 4 hours) and allow the apparatus to cool for 10 minutes.
6. Open the tap T and lower the tube L1 slowly, as soon as the layer of the oil completely enters into the graduated part of the receiver, close the tap read the volume.

              The tube L1 is then raised till the level of water in it is above the level of B, when the tap T is slowly opened to return the oil to the bulb. The distillation is again continued for another hour and the volume of oil is again read, after cooling the apparatus as before. If necessary, the distillation is again continued until successive readings of the volatile oil do not differ.

Determination of Water Soluble Extractive :

Proceed as directed for the determination of alcohol- soluble extractive, using

chloroform-water instead of alcohol.

Foreign Matter

        The sample shall be free from visible signs of mold growth,  sliminess,  stones, rodent excreta, insects or any other noxious foreign matter when examined as given below.

       

1. Take a representative portion from a large container or remove the entire content of the packing if 100 gm or less, and spread in a thin layer in a suitable dish or tray.
2. Examine in daylight with unaided eye.
3. Transfer suspected particles,if any,to a Petri dish , and examine with 10x lens in daylight.

Thin Layer Chromatography (TLC)

Thin – layer chromatography is a technique in which a solute undergoes distribution between two phases, stationary phase acting through adsorption and a mobile phase in the form of a liquid. The adsorbent is a relatively thin, uniform layer of dry finely powdered material applied to a glass, plastic or metal sheet or plate. Precoated plates are most commonly used. Separation may also be achieved on the basis of partition or a combination of partition and adsorption, depending on the particular type of support, its preparation and its use with different solvent.

Identification can be effected by observation of spots of identical Rf value and about equal magnitude obtained, respectively, with an unknown and a reference sample chromatographed on the same plate. A visual comparison of the size and intensity of the spots usually serves for semi-quantitative estimation.

Determination of pH Value

The pH value of an aqueous liquid may be defined as the common logarithum of  the reciprocal of the hydrogen ion concentration expressed in gram per litre.

The pH value of a liquid can be determined potentiometrically by means of the glass electrode, a reference electrode and a pH meter either of the digital or analogue type. pH strip is used to determine approximate pH value

Operation of pH meter-

1. Calibrate the pH meter by using standard buffer solutions.
2. Now measure the pH of unknown liquid using the calibrated pH meter.
3. Ensure that the electrode is cleaned thoroughly after every use.

Determination of Acid Value:

The acid value is the number of mg of potassium hydroxide required to neutralize the free

Acids in 1 g of the substance, when determined by the following method:

1. Weigh accurately about 10 g of the substance (1 to 5) in the case of a resin into a 250 ml flask and add 50 ml of a mixture of equal volumes of alcohol and solvent ether, which has been neutralized after the addition of 1 ml of solution of phenolphthalein.
2. Heat gently on a water-bath, if necessary until the substance has completely melted, titrate with 0.1 N potassium hydroxide, shaking constantly until a pink colour which persists for fifteen seconds is obtained. Note the number of ml required.
3. Calculate the acid value from the following formula:

                                  a × 0.00561 × 1000

Acid Value = --------------------------------

                                                W

Where ‘a’ is the number of ml of 0.1 N potassium hydroxide required and ‘W’ is the weight in g of the substance taken.

Determination of Saponification Value:

The saponification value is the number of mg of potassium hydroxide necessary to neutralize the free acids and saponify the esters, resulting from the complete hydrolysis of 1 g of the oil or fat, when determined by the following method :

1. Dissolve 35 to 40 g of potassium hydroxide in 20 ml water, and add sufficient alcohol to make 1,000 ml.
2. Allow it to stand overnight, and pour off the clear liquor.
3. Weigh accurately about 2 g of the substance in a tared 250 ml flask, add 25 ml of the alcoholic solution of potassium hydroxide, attach a reflux condenser and boil on a waterbath for one hour, frequently rotating the contents of the flask cool and add 1 ml of solution of phenolphthalein and titrate the excess of alkali with 0.5 N hydrochloric acid.
4. Note the number of ml required (a).
5. Repeat the experiment with the same quantities of the same reagents in the manner omitting the substance.
6. Note the number of ml required (b)
7. Calculate the saponification value from the following formula:—

                                                       (b–a) × 0.02805 × 1.000

Saponification Value = ------------------------------------

                                                                         W

Where ‘W’ is the weight in g of the substance taken.

Determination of Total Solids:

Note: Determination of total solids in dosage forms like Asava/ Aristha is generally required. Asava/ Aristha containing sugar or honey should be examined by method 1, sugar or honey free Asava/Aristha and other material should be examined by method 2.

Method 1:

1. Transfer accurately 50 ml of the clear Asava/ Aristha an evaporable dish and evaporate to a thick extract on a water bath.
2. Unless specified otherwise, extract the residue with 4 quantities, each of 10 ml, of dehydrated ethanol with stirring and filter.
3. Combine the filtrates to another evaporating dish which have been dried to a constant weight and evaporate nearly to dryness on a water bath, add accurately 1 g of diatomite (dry at 1050 for 3 hours and cooled in a desiccator for 30 min), stir thoroughly, dry at 1050 for 3 hours, cool the dish in a desiccator for 30 min, and weigh immediately.
4. Deduct the weight of diatomite added, the weight of residue should comply with the requirements stated under the individual monograph.

Method 2:

1. Transfer accurately 50 ml of the clear Asava/ Aristha to an evaporable dish, which has been dried to a constant weight and evaporate to dryness on a water bath, then dry at 1050 for 3 hours.
2. After cooling the dish containing the residue in a desiccator for 30 min, weigh it immediately.
3. The weight of residue should comply with the requirements stated under the individual monograph

  

Determination of Specific Gravity:

The specific gravity of a liquid is the weight of a given volume of the liquid at 250 (unless otherwise specified) compared with the weight of an equal volume of water at the same temperature, all weighing being taken in air.

1. Select a thoroughly clean and dry pycnometer. Calibrate the pycnometer by filling it with recently boiled and cooled water at 250 and weighing the contents. Assuming that the weight of 1 ml of water at 250 when weighed in air of density 0.0012 g per ml, is 0.99602 g.
2. Calculate the capacity of the pycnometer. (Ordinary deviations in the density of air from the value given do not affect the result of a determination significantly). Adjust the temperature of the substance to be examined, to about 200 and fill the pycnometer with it.
3. Adjust the temperature of the filled pycnometer to 250, remove any excess of the substance and weigh. Substract the tare weight of the pycnometer from the filled weight of the pycnometer.
4. Obtain the specific gravity of the liquid by dividing the weight of the liquid contained in the pycnometer by the weight of water contained, both determined at 250 unless otherwise directed in the individual monograph.