These free B.Pharm notes on physicochemical parameters of crude drugs cover chapter 14 of Introduction to Pharmacognosy, a first-semester subject. Read the key points below, then study the complete chapter PDF. You can browse every chapter in the Introduction to Pharmacognosy category.
Table of Contents
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Overview of physicochemical parameters of crude drugs
This chapter describes the physical and chemical standards used to judge crude drugs. It covers extractive values, moisture content, foreign matter, ash values, bitterness value, foaming index, haemolytic index, swelling index, viscosity, optical rotation, refractive index, and acid, saponification, ester, iodine and sulphated ash values.
Key points on physicochemical parameters of crude drugs
- Moisture content is measured by loss on drying, azeotropic distillation or Karl Fischer titration, because excess moisture encourages microbes, fungi, insects and enzymatic breakdown.
- Ash is the inorganic residue left after complete incineration, and three types are determined: total ash, acid-insoluble ash and water-soluble ash.
- A high acid-insoluble ash value shows contamination with sand and soil, since this ash mainly consists of silica and siliceous earth.
- Foaming index is the minimum concentration of a plant extract that gives a stable foam 1 cm high after 15 minutes, and it indirectly measures saponin content.
- Swelling index is the volume in ml occupied by 1 gm of plant material, and it is used for drugs containing mucilage, gums and pectin.
Relevance to pharmacy practice
Pharmacopoeias set limits for these parameters so that herbal drugs reach patients in a pure and consistent form. Pharmacists who understand them can judge quality, spot adulterated or exhausted material and understand why a product fails a standard.
Every chapter in this subject builds on the one before it, so do not skip topics that look simple. Definitions, classifications and examples are the parts that examiners return to most often, and a clear understanding here will also make later subjects easier to follow in the coming semesters.
Frequently asked questions on physicochemical parameters of crude drugs
What are ash values and why are they determined?
Ash values show the inorganic residue left after incineration. They help detect contamination, adulteration, improper preparation and exhausted material, and the three types are total, acid-insoluble and water-soluble ash.
What is the difference between acid value and saponification value?
Acid value is the mg of KOH needed to neutralise free fatty acids in 1 gm of oil, while saponification value is the mg of KOH needed to neutralise free acids and saponify esters.
How is the bitterness value determined?
It is found by comparing the threshold bitter concentration of a plant extract with that of standard quinine hydrochloride solution, using the formula 2000 x R divided by (C x V).
Quick revision checklist
Use this self-test after reading the chapter on physicochemical parameters of crude drugs. If you can do all of the following without looking at your notes, you are ready for the exam.
- I can explain: extractive values and their methods
- I can explain: the methods of finding moisture content
- I can explain: total, acid-insoluble and water-soluble ash
- I can explain: bitterness, foaming and haemolytic values
- I can explain: acid, saponification and iodine values
Study and exam tips
Start by reading the chapter once for the overall idea, then revise physicochemical parameters of crude drugs using headings, definitions, classifications and examples. Short-answer questions in the university exam usually ask for definitions, features, advantages, disadvantages and examples, so write these in your own words and practise drawing the tables and flow charts that the chapter has.
For wider reading, standard textbooks and open resources such as the NCBI Bookshelf help you confirm terms and see more examples. Revise physicochemical parameters of crude drugs again a day later and again a week later, because spaced revision improves long-term memory.
This page is part of the Introduction to Pharmacognosy series for first-semester B.Pharm students on B.Pharm Guru, where every chapter has a short summary and a full PDF. Bookmark this page and share it with classmates who are preparing for the same exam.
Related notes: 16. PRIMARY AND SECONDARY METABOLITES OF PLANTS, 17. ALKALOIDS, GLYCOSIDES AND FLAVONOIDS.
Next: 15. BIOLOGICAL METHODS AND DNA BARCODING. Back to the Introduction to Pharmacognosy category.
