Tragacanth: Physical and chemical tests / Analysis of crude drugs
To identify the chemical characters of given sample.
Unorganized drugs, as the name suggests, are drugs that show no definite cellular structure. These are derived from plant, animal or mineral sources by some process of extraction and followed by purification if necessary. Unorganized drugs are fairly homogenous and may be solids, semisolids or liquids. These may be differentiated by observing the solubility in alcohol and then applying other physical and chemical standards.
Tragacanth is the dried gummy exudation from the stem of Astragalusgummifer, Labillardiere and other species of Astragalus (Fam. Leguminosae). It occurs in flat or curved ribbon shaped flakes. Odourless,n almost tasteless, white or pale yellowish-white, somewhat translucent, horny; fracture short.
Chemicals Required :
Hydrochloric acid, Sodium hydroxide solution, Fehling’s solution, Barium chloride solution, Lead acetate, Ruthenium red, Iodine Caustic potash.
1). To 4 ml of 0.5% w/v solution, add 0.5 ml of hydrochloric acid and heat for 30 minutes on a water bath. Divide the liquid into two parts. (a). To one part, add 1.5 ml of sodium hydroxide solution and Fehling’s solution, warm on water bath: red precipitate is produced. (b). To the second part, add barium chloride solution (10%): No precipitate is obtained (distinction from agar)
2). To a 0.5% w/v solution of the gum, add 20% w/v solution of lead acetate: A voluminous flocculent precipitate is obtained (distinction from acacia)
3). Mount a small quantity of powder in ruthenium red and examine microscopically: Particles do not acquire pink colour (distinction from Indian tragacanth)
4). To 0.1 g of powder, add N/50 Iodine: The mixture acquires an olive green colour (distinction from acacia and agar).
5). Powder is warmed with 5% aqueous caustic potash: Canary yellow colour will obtain. Indian tragacanth is obtained from Sterculiaurens Roxburgh; (Fam: Sterculiaceae). It is insoluble in alkali. It has acetous (acetic acid like) odour and starch is absent. It gives brownish colour when boiled with aqueous KOH. It is stained pink by solution of Ruthenium red.
From the above morphological characters and chemical tests the given crude drug is identified as Tragacanth.
1.Kokate CK. Practical Pharmacognosy, 4 edition, Vallabh Prakashan. Delhi; 1994: 98
Fehling’s solution is a chemical reagent used to test for the presence of reducing sugars, such as glucose, fructose, and maltose. The solution is made up of two separate solutions, Fehling’s A and Fehling’s B, which are mixed together just before use. Here’s how to prepare Fehling’s solution:
Fehling’s A solution:
Dissolve 69 g of copper(II) sulfate pentahydrate (CuSO4 · 5H2O) in about 500 ml of distilled water.
In a separate container, dissolve 346 g of sodium hydroxide (NaOH) in about 500 ml of distilled water.
Slowly pour the sodium hydroxide solution into the copper sulfate solution, stirring constantly.
Dilute the resulting solution to 1 liter with distilled water.
Store the solution in a dark bottle.
Fehling’s B solution:
Dissolve 160 g of potassium sodium tartrate (KNaC4H4O6 · 4H2O) in about 500 ml of distilled water.
In a separate container, dissolve 40 g of sodium hydroxide (NaOH) in about 500 ml of distilled water.
Combine the two solutions and dilute to 1 liter with distilled water.
Store the solution in a dark bottle.
To use Fehling’s solution, mix equal volumes of Fehling’s A and Fehling’s B solutions just before use, and heat the mixture until it boils. The solution will turn from blue to brick red if reducing sugars are present.
Barium chloride is a common laboratory reagent used for various applications, such as in the preparation of other chemicals, water treatment, and in medical imaging. Here’s how to prepare a standard solution of barium chloride:
Barium chloride (BaCl2) dihydrate, about 20 g
Distilled water, about 1 liter
A glass container with a lid
A magnetic stirrer (optional)
Weigh out about 20 g of barium chloride dihydrate and transfer it to a clean, dry glass container with a lid.
Add about 500 ml of distilled water to the container and stir to dissolve the barium chloride.
If the barium chloride is not dissolving completely, heat the solution gently while stirring until all the solid has dissolved.
Once all the solid is dissolved, add more distilled water to the container to bring the total volume up to 1 liter.
Mix the solution thoroughly, either by stirring or by using a magnetic stirrer if available.
Store the solution in a clean, labelled container with a tight-fitting lid.
Note: Barium chloride is toxic, so it is important to handle it with care and follow appropriate safety precautions. Avoid inhaling the powder or solution, and wear appropriate personal protective equipment such as gloves, safety glasses, and a lab coat. Dispose of any unused solution appropriately, in accordance with local regulations.
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