A Laboratory Manual of Physical Pharmaceutics

By Sadhan Kumar Dutta and Kalyan Kumar Sen

A Laboratory Manual of Physical Pharmaceutics is introduced to the B.Pharm students for easy understanding of the principles of physical pharmaceutics. The Experimental manual covers experiments to provide fundamental principles of physical pharmacy necessary to design physically and chemically stable dosage forms and ensure their therapeutic safety and efficacy. This manual is a unique in nature as it covers the two necessities of students: text on theoretical principles and its application including illustrative exercises in the form of practical.
· This Book illustrates all the experiments included in various Universities syllabus of physical pharmacy.
· It also provides an integrated understanding of theory and practical applications associated with physicochemical concepts in a very lucid language.
· Reviews the physico-chemical concepts in the design of various dosage forms.
· Provides several experiments related to physical chemical characteristics of any dosage forms.
· Useful to teachers also.

• Language: English
• Publisher: BSP BOOKS
• Release date: Nov 5, 2019
• ISBN: 9789388305198

Book preview

Micellization

Experiment - 1

Required for Physical Pharmacy and Pharmaceutics Laboratory

Required Materials:

1.   Texts: Dutta S.K., Principles of Physical Pharmacy and Biophysical Chemistry Martin A.N., Physical Pharmacy

2.   Laboratory Notebook - bound and duplicate numbered pages

3.   Long white laboratory gowns

4.   Set of metric weights

5.   Box of cleansing tissues

6.   Graph papers

Laboratory Procedure:

1.   All experiments will be performed by pairs or 3 in a group. Each student must record data in his or her own Laboratory Notebook and prepare an individual report to be submitted.

2.   A full comprehension of the assigned work will be expected of each student prior to the actual experimentation. In this maimer, a student can plan his or her work for completion within the assigned timeschedule.

3.   Students are expected to observe proper laboratory etiquette, conduct and attire.

4.   Proper laboratory techniques learned in other courses must be practiced.

5.   Many experiments require the use of delicate and expensive equipments and, as such, special care must be taken under these circumstances.

6.   Laboratory cleanliness in the working areas will be strongly encouraged.

7.   Equipment signed out must be returned clean and dry before leaving the laboratory.

8.   Students must check out with the laboratory instructor before leaving the laboratory.

Laboratory Notebook: The following rules must be adhered to:

1.   Each page must be dated.

2.   All experimental data must be the original record; and not copies of date originally recorded on separate pieces of paper. If some sacrifice of neatness is necessary to adhere to this rule, then it is a worthwhile sacrifice.

3.   Besides data, any observations and calculations made should be included in your notebook.

4.   A carbon copy of your data must be submitted before leaving for the day. No data should be accepted at a later date.

Laboratory Report:

The laboratory report must be handled in at a previously announced time, generally one week after the experiment had been perforated. Failure to submit reports on time will prevent proceeding to the next experiment and also will result in a lower grade for the report.

The report should include:

1.   A brief statement as to the purpose of the experiment

2.   A description of the experimental procedure, concise enough to be repeated by another person

3.   Tabulation of raw data and calculated data.

4.   Sample calculations

5.   Neatly drawn and labeled graphs

6.   Conclusions

7.   Literature references.

EQUIPMENT LIST

(For instructor’s use)

Students should have with them the following items (purchased):

1.   Test tube brush (2) Detergent (3) Glass-marking pencil (4) Wire-gauge 6 x 6

Experiment - 1A

Calibration of a Thermometer

1.   Since a major portion of the laboratory exercises in this course involves measurement of weight, volume, temperature, concentrations, etc. demonstrations of proper techniques, to be used in all laboratories, will be given by the instructor(s). You will be expected to continue to use these techniques throughout the year and subsequent years of your professional career.

2.   Thermometer Calibration: The purpose of this experiment is to acquaint the student(s) with the fact that no instrument is absolutely accurate.

The objective of this experiment is to calibrate a themiometer at two places on its range. This is done using the ice point and boiling point of water, taking into account the necessary corrections.

Procedure:

(a)    Ice-point determination: A 100 mL beaker is fdled with chopped ice. The temperature is determined with the themiometer supplied employing good stirring. Several readings are to be taken (and recorded in the notebook) until successive readings are constant. The use of a towel wrapped around the beaker will act as insulation. Does it make a significant difference? If yes, why? Experimental and theoretical ice-points temperatures are then compared.

(b)    Boiling point determination: A wash bottle, made of glass, is modified by removing the delivery tubing (i.e. the longest piece of tubing) and replacing it with the thermometer supplied. The depth of the thermometer is adjusted so as to minimize steam and steamconvection without risking the danger of splashing water on to the thermometer. It is to be ensured that there is an opening to the atmosphere and that boiling chips are used before heating the water.

The temperature read on the thermometer and the temperature of the emergent stem are recorded. After stem corrections the experimental and theoretical boiling points are compared.

Barometric pressure is to be noted and the corrected pressure and the corrected boiling point of water at that pressure are recorded in the notebook.

SUMMARY

The corrections which would be necessary in using the laboratory thermometer are to be recorded and used to get a correct reading.

This process is known as calibration which is required for calibrating each and every equipment such as burette, pipette, weight box, etc. which are required for routine laboratory and research works.

Experiment - 1B

Statistical Evaluation of the Data

The purpose of this experiment is to enable the student to use simple statistical procedures in evaluating the data generated.

Procedure:

Accurately measure 100.00 mL of water (may be with the help a standardized burette or pipette in a 100.00 mL graduate) and the content is transferred carefully into the 250 mL beaker that was supplied, allowing all of the water to drain into the beaker. The meniscus is marked by placing a line-mark with a glass-marking pencil and the beaker is emptied of its contents. The beaker is filled up with water up to its calibration mark and the volume of its contents is measured with the 50 mL graduate (estimated to the nearest 0.5 mL).

The process is repeated ten times.

Calculate the mean, median, mode, standard deviation and standard error of the experiment.

Do your results follow a normal distribution curve?

Experiment - 2

Partial Miscibility - Phenol-Water System

Liquids are often miscible in all proportions but there are a number of pairs in which the solubility of each in the other is limited. Usually both liquids become more soluble as the temperature is increased, and eventually a critical solution temperature is reached above which the liquids are miscible in all proportions.

The temperature-composition curve of such systems when experimentally determined permits a complete understanding of the behavior of any system of two liquids, and the interpretation of the curve constitutes an important exercise in the application of the phase rule.

Phenol and water make a particularly suitable pair because the critical solution temperature (CST) occurs at a convenient temperature, below the boiling point of either component. Phenol is not ordinarily a liquid, but the first portion of water lowers the melting point of the solid below room temperature to produce a liquid-liquid system.

Apparatus:

Beckmann molecular weight apparatus, stirring rod, 2 mL and 10 mL pipette, 0°C-100°C thermometer.

Procedure:

5 g of phenol, weighed out to 0.1 g and 5 mL of water are placed into the inner tube along with the glass stirrer and the thermometer. After inserting it into the air-jacket (in order to reduce the rate of heating and cooling) the entire assembly is placed into a 1 L beaker filled with water. The assembly is now heated to raise the temperature to about 60°C by boiling the water and stirring the mixture. At a certain temperature the turbid mixture will suddenly become clear because at this temperature the phenol and water are miscible. The temperature is recorded to the nearest tenth of a degree. The tube is then, lifted out of the hot water and the solution is allowed to cool while being stirred. The solution becomes milky again and the temperature at which first turbidity appears should be the same as previously recorded. Two or three checks should be made with the rising and falling temperatures. Close agreement will be obtained if the temperature changes slowly.

2 mL of water is added from a pipette and the determinations are repeated. This time the temperature of complete miscibility will be higher.

The determinations are repeated 10 times adding 2 mL of water each time. The experiment is continued until the temperature of complete miscibility has risen passed through a maximum and fallen below 60°C.

Calculations:

The percentage-composition by weight (% w/w) of the different mixtures is to be calculated and then a plot of temperature of complete miscibility versus the corresponding composition is to be obtained. The critical solution temperature (CST) may. then, be determined from the graph. This CST is also known as upper consolute temperature.

The other system that shows lower critical solution temperatures or lower consolute temperature can also be studied. One such example is the water-tri-ethyl amine system exhibiting CST at around 18°C-19°C.

Another type exhibiting both upper and lower critical temperature can also be studied. The most common example is the Nicotine Water system showing CST’s of 208°C and 60°C respectively and β-picoline/water system has 153°C/49°C.

Extended Experimentation:

Influence of Foreign substances on CST:

The critical solution temperature is very sensitive to the pressure of any impurity or foreign substance. The CST of phenol-water system would be raised by 20°C if naphthalene be added to make a concentration of only 0.1 M. Again, the consolute temperature (4°C) of the system acetic acid/cyclohexane is raised by about 18°C when 1% water is present in the acetic acid. This fact is utilized in ascertaining the presence and even the amount of impurities present in a sample.

Generally, CST is raised by an impurity if the later is soluble in one of the phases only; the CST is lowered when a third substance present is soluble in both the liquids. The use of soap increases the mutual solubilities of cresols and water and enables us to obtain clear commercial preparations of disinfectant solutions like lysols at ordinary temperature.

Experiment - 2A

Determination of the Percentage of Phenol along the Tie Line (x,y) Drawn at any Temperature in the Phase Diagram Curve: Transition Temperature vs % of Phenol

Materials: Materials and method as in the previous experiment as described; observation as above.