This document provides information about micromeritics, which is the science and technology of small particles. It discusses several key concepts in micromeritics including particle size, shape, density, and surface area. The document then describes several important applications of micromeritics in the pharmaceutical field related to drug release, absorption, stability, and dose uniformity. Several examples are provided to illustrate how reducing particle size can impact solubility and bioavailability. Different methods for measuring particle size distribution are also summarized, including microscopic, sieving, sedimentation, and conductivity techniques.
R. VIJAYAKUMAR., M Pharm,
Research Scholar
department of Pharmaceutical Technology.
Anna university- BIT
Tiruchirappalli
III Semester.
UNIT-IV / Micromeritics
Powder Technology
Particle analysis in pharmaceuticals
Determination of particle size and surface area
Large scale equipment for powders
Types of powders
R. VIJAYAKUMAR., M Pharm,
Research Scholar
department of Pharmaceutical Technology.
Anna university- BIT
Tiruchirappalli
III Semester.
UNIT-IV / Micromeritics
Powder Technology
Particle analysis in pharmaceuticals
Determination of particle size and surface area
Large scale equipment for powders
Types of powders
Decomposition and stabilization of pharmaceutical productsArshad Khan
Drug stability:Stabilization of medicinal agents against common reactions like hydrolysis & oxidation. Accelerated stability testing in expiration dating of pharmaceutical dosage forms. Photolytic degradation and its prevention.
Description of Construction, Working and Application of Pharmaceutical Machin...Makrani Shaharukh
Description of Construction, Working and Application of Pharmaceutical Machinery Such as Rotary Tablet Machine, Fluidized Bed Coater, Fluid Energy Mill and Humidifier.
Decomposition and stabilization of pharmaceutical productsArshad Khan
Drug stability:Stabilization of medicinal agents against common reactions like hydrolysis & oxidation. Accelerated stability testing in expiration dating of pharmaceutical dosage forms. Photolytic degradation and its prevention.
Description of Construction, Working and Application of Pharmaceutical Machin...Makrani Shaharukh
Description of Construction, Working and Application of Pharmaceutical Machinery Such as Rotary Tablet Machine, Fluidized Bed Coater, Fluid Energy Mill and Humidifier.
The word Micromeritics refers to a discipline of science and technology that deals with studies related to the fundamental as well derived properties of particles. The knowledge and control of the size of particles is of importance in pharmacy and materials science.
Micromeritics study in different formulation • Colloidal dispersion are characterized by
particles that are too small to be seen in the ordinary microscope. • The particles of
pharmaceutical emulsion and suspension and the “fines” of powder fall in the range of the
optical microscope. • Particles having the size of coarser powder , tablet granulation , and
granular salts fall with in the sieve range. Control of particle size and the size range of a drug
can be significantly related to its physical, chemical and pharmacological properties.
Bioavailability, and physical stability in some dosage forms can also be affected by particle
size.Micromeritics is the science and technology of small particles . The unit of particle size
most frequently used in micromeritics is micrometer, also called as a micron.
Assignment 01: Discuss the different ways of particle diameter expression. Also to calculate the equation of particle number for 1 gram of powder sample. A little assignmen on the topic based on micromeritics.
a complete description of the particle size distribution of particles in different categories. Sedimentation is a phenomenon that completely work with the size of particles.
Standardization of Acids and bases.
2. Determination of pKa and pKb values
3. Preparation of solutions of different pH & buffer capacities.
4. Determination of phase diagram of binary systems.
Determination of distribution coefficients.
6. Determination of molecular weight by Victor Meyer’s Method.
7. Determination of heats of solutions by measuring solubility as a function of temperature
(Van’t Hoff equation.)
A. Qualitative analysis of metal ions and acid radicals:
Na+, K+, Ca+2, Ag+, Mn+4, Fe+2, Fe+3, Co+2, Mg+2, Al+3, Cu+2 and acid radicals CO3,
halides, Citrate
SO4-2, NO3-, SO3-2, etc.
B. Identification of inorganic drugs in their formulation:
1. Ca+2, from supplied preparations
2. Fe+2 from supplied preparations
3. Al+3 from supplied preparations
4. Mg+2 from supplied preparations
5. K+ from supplied reparations
6. Na+ from supplied preparations
C. Conversion of different water insoluble or sparingly soluble drugs into water soluble
forms:
1. Na/ K – salicylate from salicylic acid
2. Na/ K – benzoate from benzoic acid
3. Na/ K – citrate from citric acid
Plants in complimentary and traditional systems of medicine MANIKanikImran Nur Manik
Plants in complimentary and traditional systems of medicine: Introduction-different types of
alternative systems of treatments (e.g. Ayurvedic, Unani and Homeopathic medicine). Contribution
of traditional drugs to modern medicines. Details of some common indigenous traditional drugs:
Punarnava, Vashaka, Anantamul, Arjuna, Chirata, Picrorhiga, Kalomegh, Amla, Asoka, Bahera,
Haritaki, Tulsi, Neem, Betel nut, Joan, Karela, Shajna, Carrot, Bael, Garlic, Jam and Madar.
Crude drugs: A general view of their origin, distributions, cultivation, collection, drying and
storage, commerce and quality control.
a) Classification of drugs.
b) Preparation of drugs for commercial market
c) Evaluation of crude drugs.
d) Drug adulteration.
Carbohydrate and related compounds: Sugars and sugar containing drugs. Sucrose,
dextrose, glucose, fructose etc. Polysaccharides and polysaccharide containing drugs,
Starches, dextrins etc. Gums and mucilages, tragacanth, acacia, sterculia, sodium
alginate, agar and cellulose.
Volatile oils and related terpenoids-Methods of obtaining volatile oils,
chemistry, their medicinal and commercial uses, biosynthesis of some important
volatile oils used as drugs.
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New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
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NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
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Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
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Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
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The four main behavioral effects of AUD are impaired control over
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the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
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Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
1. Page 1 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Micromeritics
Shahin Sarker
Lecturer
Department of Pharmacy
Jashore University of Science
and Technology (JUST)
Jaytirmoy Barmon Likhon
Lecturer
Department of Pharmacy
Varendra University, Rajshahi
Md Minhajul Islam
12th
Batch Student
Department of Pharmacy
Varendra University, Rajshahi
Micromeritics
Micromeritics is the science and technology of small particles. It is the study of a number of
characteristics, including particle size and size distribution, shape, angle of repose, porosity,
true volume, apparent density and bulkiness.
Important in pharmaceutical field:
The study of particle has a number of applications in the field of pharmacy which are given
below:
a) Drug release and dissolution:
Particle size and surface area influence the release of a drug from a dosage form that is
administered orally, rectally, parenterally, and topically. Higher surface area brings about
intimate contact of the drug with the dissolution fluids in vivo and increases the drug solubility
and dissolution.
b) Absorption and drug action:
Particle size and surface area influence the drug absorption and subsequently the therapeutic
action. Higher the dissolution faster the absorption. Hence quicker the drug action.
c) Physical stability:
Particle size influences the physical stability of suspensions and emulsions. Smaller the size
better is the physical stability (as it would take more time for particles to agglomerate)
d) Dose uniformity:
Particle size and shape also governs flow properties of powders and granules in tableting.
Powder with different particle size does not have uniformity of dose like tablet, capsule,
creams, ointments, suspensions, emulsions etc. (except solution).
Any interference in the flowability of powders or granules may alter the weight of the powder
blend and thus amount of drug incorporated into the tablet or capsules and thereby reduce the
uniformity of the dose.
Examples:
Reduction of particles size improves surface area and can help in improving solubility
of certain drugs. e.g. The solubility of Griseofulvin can be greatly increased by particle
size reduction.
Reduction of particles size can increase the rate of absorption of and consequently
bioavailability of many drugs e.g. tetracycline, aspirin, sulphonamides, nitrofurantoin
etc.
2. Page 2 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Q. What are the fundamental properties & derived properties of powders?
Fundamental properties:
These properties relate to the individual particle.
The following are the five fundamental properties of collection of particles can be derived.
A. Particle size and size distribution.
B. Particle shape.
C. Particle volume.
D. Particle number.
E. Particle surface area.
Derived properties:
They are dependent on fundamental properties & define the factors relating to their
measurement.
A. Density of powders (a) bulk density (b) true density/tapped density
(c) granular density
B. Flow properties of powders
C. Porosity
D. Bulkiness
Q. What are the different means of expressing particle size?
Measurement for expressing particle size:
Particle size expressing is an indicating what sizes of particles are present in what proportions
in the sample particle group to be measured.
There are different means of expressing particle size e.g.
Unit Conversion in meter (m)
Millimeter (mm) 1 mm = 10-3
m
Micrometer (µm) 1 µm = 10-6
m
Nanometer (nm) 1 nm = 10-9
m
Picometer (pm) 1 pm = 10-12
m
Femtometre (fm) 1 fm = 10-15
m
Q. Describe the method or technique of particle size distribution or size analysis?
Particle size distribution:
When the number or weight of particles lying within a certain size range is plotted against the
size range or mean particle size, a so-called frequency distribution curve is obtained. This is
important because it is possible to have two samples with the same average diameter but
different distributions. The following techniques/methods are generally used for particle size
determination (PSD):
A. Microscopic Technique (Range: 0.2–100 μm).
B. Sieving Technique (Range: 40–9500 μm).
C. Sedimentation Technique (Range: 0.08–300 μm).
D. Conductivity Method (Range: 0.5–500 μm).
3. Page 3 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
A. Microscopic Technique:
o Microscopy is the technique used to view objects that cannot be seen by the naked eye.
o Particle size in the range of 0.2 – 100 μm can be measured.
o This method gives number distribution which can be converted to weight distribution
o Optical microscope lens has limited resolving power.
o Advanced microscopes have better resolving power and can measure size in nano
range: Ultramicroscope, Electron microscope- Scanning Electron microscope (SEM),
Transmission Electron microscope (TEM).
Method description:
Procedure:
Eye piece of the microscope is fitted with a micrometer.
This eye-piece micrometer is calibrated using a standard stage micrometer.
The powder sample is dispersed in a suitable vehicle in which it does not dissolve and
its properties are not altered. (e.g. water, paraffin oil.)
This sample is mounted on a slide and placed on the stage under the objective of
microscope.
Special notes:
At least 300-500 of particles that must be counted to obtain a good estimation & data
analysis.
In general around 625 particles are visualized. Their diameter is noted and mean is
computed.
Application: Particle size analysis in suspensions, aerosols, globule size analysis in
emulsion
Advantages
One can view particles
Any aggregates detected
Contamination of particles detected
Use of cover slip for arresting motion of particles
Easy and simple
4. Page 4 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Disadvantages
Length and breadth can be detected but depth or thickness of particles cannot be
measured
Slow, time consuming, tedious, inaccurate
Number of particles to be measured is more
Large sample required
B. Sieving Technique
o Sieving method is an ordinary and simple method.
o Sieving is defined as a method in which two or more components of different sizes are
separated from a mixture on the basis of the difference in their sizes.
o It is widely used as a method for the particle size analysis
o Sieve analysis is usually carried out using dry powders. Although, for powders in liquid
suspension or which agglomerate during dry sieving, a process of wet sieving can be
used.
o Sieving method directly gives weight distribution.
o It find application in dosage form development of tablets and capsules.
o Normally, 15% of fine powder should be present in granulated material to get proper
flow of material and achieve good compaction.
o Thus percent of coarse, moderate, fine powder is estimated by this method.
Method description:
Theory & Apparatus:
Sieve analysis utilizes a wire mesh made of brass, bronze or stainless steel with known
aperture (hole) diameters which form a physical barrier to particles.
The standard sieve sizes are as per the pharmacopoeia
Most sieve analyses utilize a series, stack (layer) of sieves which have the coarser mesh
at the top of the series and smallest mesh at the bottom above a collector tray (The mesh
size goes on decreasing from top to bottom)
A sieve stack usually comprises 6-8 sieves.
5. Page 5 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Procedure:
Powder is loaded on to the coarsest sieve of the stack and then it is subjected to
mechanical vibration for specified time, e.g. 20 minutes.
After this time, the powder retained on each sieve is weighed
The particles are considered to be retained on the sieve mesh with an aperture
corresponding to the sieve diameter.
The size is estimated as per the standards given in pharmacopoeia
Precaution:
Care should be taken to get reproducible results.
The type of motion, time of operation, speed and weight of powder should be fixed and
standardized.
Advantages:
Most widely used method for measuring particle size.
It is inexpensive, simple and rapid.
Generally useful for course particle.
Give reproducible results if parameters are standardized
Disadvantages:
The particle may aggregate during sieving due to generation to electrostatic charge.
Moisture can also lead to aggregation of powder and actual particle size may not be
obtained.
Sieve loading and duration of mechanical shaking can influence the result.
Attrition between particles during the process may cause size reduction giving
inaccurate results.
6. Page 6 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Example Math-I: Suppose 250 gm of materials is passed through sieving technique and 120
gm, 80 gm, 50 gm materials is retained in sieve-1, sieve-2 and sieve-3 respectively. Calculate
the percentage of materials retained in each sieve.
We know,
Percentage of materials retained in a single sieve = (Retained quantity ÷ Total quantity) × 100
Sieve-1: (120 gm ÷ 250 gm) × 100 = 48 %
Sieve-2: (80 gm ÷ 250 gm) × 100 = 32 %
Sieve-3: (50 gm ÷ 250 gm) × 100 = 20 %
Practice Math-01: Suppose 715 gm of materials is passed through sieving technique and 350
gm, 200 gm, 165 gm materials is retained in sieve-1, sieve-2 and sieve-3 respectively. Calculate
the percentage of materials retained in each sieve.
Practice Math-02: Suppose 1250 gm of materials is passed through sieving technique and 250
gm, 500 gm, 375 gm, 125 gm materials is retained in sieve-1, sieve-2, seive-3 and sieve-4
respectively. Calculate the percentage of materials retained in each sieve.
Practice Math-03: Suppose 811 gm of materials is passed through sieving technique and 131
gm, 170 gm, 70 gm 95 gm, 345 gm materials is retained in sieve-1, sieve-2, seive-3, seive-4
and sieve-5 respectively. Calculate the percentage of materials retained in each sieve.
C. Sedimentation Technique:
In this method particle size can be determined by examining the powder as it sediments out.
Description:
Sample preparation:
o Powder is dispersed in a suitable solvent.
o If the powder is hydrophobic, it may be necessary to add dispersing agent to aid wetting
of the powder.
o In case where the powder is soluble in water it will be necessary to use non- aqueous
liquids or carry out the analysis in a gas.
Principle of Measurement
Particle size analysis by sedimentation method can be divided into two main categories
according to the method of measurement used.
One of the type is based on measurement of particle in a retention zone. Another type
uses a non-retention measurement zone.
Here we will discuss only non-retention zone measurement. An example of a non-
retention zone measurement is known as the pipette method.
Andreasen pipette method:
One of the most popular of the pipette methods was that developed by Andreasen and
Lundberg and commonly called the Andreasen pipette.
In this method, known volumes of suspension are drawn off and the concentration
differences are measured with respect to time.
It involves measuring the % of solids that settle with time in a graduated vessel.
7. Page 7 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Construction:
■ The Andreasen fixed-position pipette consists of a 200 mm graduated cylinder which
can hold about 500 ml of suspension fluid.
■ A pipette is located centrally in the cylinder and is held in position by a ground glass
stopper so that its tip coincides with the zero level.
■ A three way tap allows fluid to be drawn into a 10 ml reservoir which can then be
emptied into a beaker or centrifuge tube.
Method:
A 1% suspension of the powder in a suitable liquid medium is placed in the pipette.
At a given intervals of time, samples are withdrawn from a specified depth without
disturbing the suspension.
The amount of powder can be determined by weight following drying or centrifuging;
alternatively, chemical analysis of the particles can be carried out.
The particle size is determined in terms of stokes’ diameter (the diameter of a particle
measured during sedimentation at constant rate) using modified Stokes' equation.
Here,
dst: stokes’ diameter
n: viscosity of medium
h: sedimentation height
ps- pf: difference in density of particle and fluid
Fg: force of gravity
t: sedimentation time
A pipette is located centrally in the cylinder and is held in position by a ground glass
stopper so that its tip coincides with the zero level.
A three way tap allows fluid to be drawn into a 10 ml reservoir which can then be
emptied into a beaker or centrifuge tube.
The amount of powder can be determined by weight following drying or centrifuging.
The data of cumulative weight is used for the determination of particle weight
distribution, number distribution etc..
8. Page 8 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Advantages:
The apparatus is inexpensive and the technique is simple.
The results obtained are precise provided the technique is adequately standardized.
Disadvantages:
The method is laborious since separate analyses are required for each experimental
point on the distribution curve.
Very small particle cannot be determine accurately since their setting is unduly prolong
and is subjected to interference due to convection, diffusion and Brownian motion.
Example Math-II: A sample of powdered zinc oxide, density 5.60 g/cm3
is allowed to settle
under the acceleration of gravity, 981 cm/sec2
at 25°C. The rate of settling v is 7.30 × 10-3
cm/sec the density of the medium is 1.01 g/cm3
and its viscosity is 1 centipoise = 0.01 poise or
0.01 g/cm sec. Calculate the Stokes diameter of the zinc oxide powder.
Solution:
We know, Stokes law,
Practice Math-04: A sample of powdered aluminium oxide, density 3.95 g/cm3
is allowed to
settle under the acceleration of gravity, 981 cm/sec2
. The rate of settling v is 6.17 × 10-3
cm/sec
the density of the medium is 1.06 g/cm3
and its viscosity is 1 centipoise = 0.01 poise or 0.01
g/cm sec. Calculate the Stokes diameter of the aluminium oxide powder.
Practice Math-05: A sample of powdered CaCO3, density 2.71 g/cm3
is allowed to settle under
the acceleration of gravity, 981 cm/sec2
at 25°C. The rate of settling v is 3.58 × 10-3
cm/sec the
density of the medium is 1.03 g/cm3
and its viscosity is 1 centipoise = 0.01 poise or 0.01 g/cm
sec. Calculate the Stokes diameter of the CaCO3 powder.
D. Conductivity Method:
There are various subtypes. Two popular methods are-
i. Electrical stream sensing zone method (Coulter counter)
ii. Laser light scattering methods:
It is based on the principle of change in light intensity. The measurement of this change in light
intensity gives estimate of particle size.
Electrical stream sensing zone method (Coulter counter)
Sample Preparation:
o Powder samples are dispersed in an electrolyte to form a very dilute suspension.
o The suspension is usually subjected to ultrasonic agitation to break up any particle
agglomerates.
o A dispersant may also be added to aid particle deagglomeration.
9. Page 9 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Apparatus & Method:
A coulter counter is an apparatus for counting and sizing particles suspended in electrolytes. It
consists of two electrode one of them whose is dipped into a beaker the other electrode is dipped
into the electrolytic solution contained in a glass tube the glass tube has a very small artifice at
its lower in through the particle are shake into the inner glass tube.
A known volume of the suspension is pumped through the orifice. So that only one particle
passes at a time. As the particle passes through the orifice. The orifice electrical resistance
increase. Electrical resistance is directly proportional to the volume of the particle. By
measuring determine the volume of the particle.
Advantages:
Very rapid operation a single count packing
less than 30 sec.
The more reliable result since a large number
are counting particle.
Since the apparatus is automatic, operator
variability is avoided.
Disadvantages:
Aggregation of a particle can forgive results.
The material has to be suspended in an
electrolytic before measurement.
10. Page 10 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Particle Shape:
Particle shape also has influence
on surface area, flow properties,
packing and compaction of the
particles. Spherical particles
have minimum surface area and
better flow properties. The more
asymmetric a particle, the
greater is the surface area per
unit volume. Shape can also
have influence on rate of
dissolution of drugs.
Surface area
The surface area of a solid object is a measure of the total area that the surface of the object
occupies.
Specific surface area i.e. surface area per unit weight (Sw) or unit volume (Sv) can be
estimated as follows:
Sv = surface area of particles ÷ volume of particles
Sv = (number of particles × surface area of each particle) ÷ (number of particles × volume of
each particle)
Surface area is an important parameter as the bioavailability of certain drugs is dependent on
surface area. e.g. Bephenium (anthelminitic), Griseofulvin (antifungal) - if the surface area is
less than specified, the absorption decreases.
Derived properties of powders
Porosity of powder:
Porosity is defined as the ratio of the total pore volume to the apparent volume of the particle
or powder.
Suppose a powder, such as zinc oxide, is placed in a graduated cylinder and the total volume
is noted. The volume occupied is known as the bulk volume, Vb. If the powder is nonporous,
that is, has no internal pores or capillary spaces, the bulk volume of the powder consists of
the true volume of the solid particles plus the volume of the spaces between the particles.
The volume of the spaces, known as the void volume, v, is given by the equation:
Void volume, V = Vb – Vp
Where Vp is the true volume of the particles.
The porosity or voids € of the powder is defined as the ratio of the void volume to the bulk
volume.
11. Page 11 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Porosity,
€ =
V
𝑉𝑏
€ =
Vb − Vp
Vb
€ = 1 −
𝑉𝑝
𝑉𝑏
Density of powder:
The density of powder defines the mass per unit volume of the powder.
Type of density:
a. Bulk density.
b. True density.
c. Granule density.
Before tapping
After tapping
a. Bulk density: Bulk density is defined as the ratio of the mass of powder to the bulk volume
of powder. Bulk density is denoted by ρb.
ρb =
Mass of powder
Bulk volume of powder
ρb =
m
𝑉b
b. True density/Tapped density: True density is defined as ratio of the mass of powder and
its true volume. True density is denoted by ρt.
ρt =
Mass of powder
True volume
ρt =
m
vt
12. Page 12 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
c. Granule density: Granule density is defined as the ratio of granular powder to the volume
of the granule. Granule density is denoted by ρg.
ρg =
Mass of granules
Volume of Granules
ρg =
mg
Vg
Applications
i. Decides the size of the capsule based on bulk and tapped volume of a given sample -
Higher the bulk volume, lower the bulk density and bigger the size of the capsule.
ii. Helps to decide proper size of a container or packing material.
Bulkiness:
The reciprocal of bulk density is known as bulkiness.
Bulkiness =
Bulk volume
Mass of powder
=
Vb
m
Q. How can you determine the true density of the powder?
Liquid displacement method:
In this method a liquid in which the solid is insoluble in generally used. The powder whose
density is to be determined is added into a standard flask of known volume and the weight
determine. An ordinarypycnometer is suitable for this purpose. Now, a liquid which the powder
insoluble is introduced into the pycnometer. The liquid fills up to the void space between the
particles until the hold volume of the pycnometer occupied. The pycnometer is again weighted.
The contents of the pycnometer are emptied and only the liquid is filled into it and weighted.
The true density of is obtained as the ratio between the weight of the material and the weight
of the liquid is displaced.
Wt. of pycnometer: w1
Wt. of pycnometer +
sample: w2
Sample wt.:
w3= w2-w1
Wt. of pycnometer +
sample + solvent: w4
Wt. of liquid displaced
by sample:
w5 = w4-w2
Thus, true density
= w3/ w5
Limitations:
For non-porous powders only. In case of porous powders need Helium displacement method.
13. Page 13 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Flow properties of powder:
The specific properties of a powder that affect its flow are known as flow properties. Examples
of flow properties include bulk density, permeability, and cohesive strength. The flow property
of powder is an important parameter to be considered in the production of the pharmaceutical
dosage form. Such as tablet, capsule etc.
The poor flow of powder due to the reasons:
i. Cohesiveness or stickiness between particle due to the presence of van der Waals force,
surface tension and electrostatic force.
ii. Adhesion between particles at the container wall due to the above force.
iii. Friction between the particles due to the surface roughness.
iv. The physical interlocking of the particle due to their irregular shape.
v. Presence of moister causes for poor flow of powders.
Due to the poor flow there are also some bad effect on pharmaceutical dosage form. These are:
i. Tablet weight variation in the dosage.
ii. Segregation of granules.
iii. Demixing may take place which causes: a. Color variation b. Variation of therapeutic
effect.
Q. Describe the different tests to evaluate the flowability of a powder?
A. Housner ratio.
B. Carr's compressibility index.
C. The angle of repose.
A. Housner ratio:
The Hauser ratio is a number that is correlated to the flow ability of a powder or granular
material. The Hauser ratio is calculated by the formula,
H =
ρT
ρB
Where,
ρT is the tapped density of the powder.
ρB is the bulk density of the powder.
Bulk density =
Weight
Bulk volume
Tapped density =
Weight
Tapped volume
So, we can write,
Housner ratio =
Bulk volume
Tapped volume
14. Page 14 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
B. Carr's compressibility index:
The Carr index is an indication of the compressibility of a powder. The Carr index is
calculated by the formula,
Carr's compressibility index (%) =
Tapped density−Bulk density
Tapped density
× 100
C =
ρT− ρB
ρT
× 100
Where,
ρT is the tapped density of the powder.
ρB is the bulk density of the powder.
Example Math-III: If a material weight 371 mg and bulk volume 121 ml in a cylinder. The
material is subjected to 50 times tapping and volume observed after tapping is 113 ml. Calculate
the Hausner ratio and Carr’s compressibility index including comment about flow ability.
Given that,
Weight = 371 mg
Bulk volume = 121 ml
Tapped volume = 113 ml
Housner ratio =?
Carr’s compressibility index (%) =?
We know,
Bulk density =
Weight
Bulk volume
=
371 mg
121 ml
= 3.06 mg/ml
Tapped density =
Weight
Tapped volume
=
371 mg
113 ml
= 3.28 mg/ml
Hence,
Housner ratio =
Tapped density
Bulk density
15. Page 15 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
=
3.28 mg/ml
3.06 mg/ml
= 1.07
Result: Housner ratio 1.07
Comment: Excellent flow
Now, Carr's compressibility index (%) =
Tapped density−Bulk density
Tapped density
× 100
=
(3.28−3.06) mg/ml
3.28 mg/ml
× 100
= 6.70 %
Result: Carr's compressibility index 6.70 %
Comment: Excellent flow
Practice Math-06: If a material weight 275 mg and bulk volume 89 ml in a cylinder. The
material is subjected to 50 times tapping and volume observed after tapping is 81 ml. Calculate
the Hausner ratio and Carr’s compressibility index including comment about flow ability.
Practice Math-07: If a material weight 401 mg and bulk volume 156 ml in a cylinder. The
material is subjected to 50 times tapping and volume observed after tapping is 141 ml. Calculate
the Hausner ratio and Carr’s compressibility index including comment about flow ability.
C. The angle of repose:
It is defined as the maximum angle possible between the surface of a pile of the powder and
the horizontal plane. It is an indication of the resistance to flow of the powder.
The Angle of repose is calculated by the formula,
tan 𝛼 =
h
r
Where,
α = Angle of repose
h = Height of powder concentration
r = Radius of powder concentration
Remember one thing, r =
d
2
(where, d is the diameter)
16. Page 16 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Example Math-IV: If height of a powder cone is 2.5 m and diameter 600 cm, calculate the
angle of repose and comment about flow properties of that powder.
Given that,
Hight = 2.5 m
Diameter, d = 600 cm
= 6 m [1 meter = 100 cm]
Angle of repose = ?
We know,
Radious, r =
d
2
=
6 m
2
= 3 m
So, Angle of repose,
tanѲ =
h
r
Ѳ = tan−1
(
h
r
)
Ѳ = tan−1
(
2.5
3
)
Ѳ = tan−1
(0.83)
Ѳ = 39.69°
Result: Angle of repose 39.69°
Comment: Fair flow
Practice Math-08: If height of a powder cone is 4.5 m and diameter 900 cm, calculate the
angle of repose and comment about flow properties of that powder.
Practice Math-09: If height of a powder cone is 1.5 m and radius 3.7 m, calculate the angle of
repose and comment about flow properties of that powder.
Practice Math-10: If height of a powder cone is 4.6 m and radius 2.3 m, calculate the angle of
repose and comment about flow properties of that powder.
17. Page 17 of 17
Edited By: Jaytirmoy Barmon Micromeritics
Lecturer, Pharmacy, Varendra University
Factors affecting the flow properties of powder.
Related questions:
Q. How can you improve the flow properties of a powder?
Flow properties of powders can be improved by one or more of the following methods-
i. Altering the particle size:
Increasing the average particle size of particles improves the flow properties due to reduction
in the cohesive forces. During tableting, fine powders are converted to course granules in order
to impart good flow properties to them.
ii. Removal or addition of fines:
Presence of small proportion of fines in a powder or granular mass may improve the flow
properties by filling up the pits and crevices on the surface of the particle. On the other hand,
larger proportion of fines may retard the flow properties. So, an optimum concentration of fines
is desirable for best results.
iii. Altering the particle shape and texture:
Spherical particles tend to better flowability as compared to irregular particles. Hence
techniques like spray drying may be used to give spherical particles with good flow properties.
Alteration of crystallization conditions may also produce particles of desired shape and texture.
iv. Altering surface forces:
Reduction of electrostatically charges on particle surface by reducing the frictional contents
such as during transfer or during process (e.g. sieving) can improve the flow properties.
v. Removing the extra moisture:
Drying of powders in order to remove moisture from surface can improve the flow properties
by decreasing the cohesiveness.
vii. Adding lubricants or glidants:
Flow properties of pharmaceutical powders may be improved significantly by the addition of
materials which known as lubricants or glidants. They improve flow flowability of powders
reducing adhesion and cohesion. For example: magnesium stearate, talc, starch etc.
Note:
Lubricants- reduce friction between surfaces in mutual contact
Glidants- reduce interparticular friction.