Particle Size and Shape
84 Questions
8 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the initial method for starting particle size measurement?

  • X-ray diffraction
  • Dynamic light scattering
  • Electron microscopy
  • Optical light microscopy (correct)

    • Which factor does NOT influence the accuracy of particle size measurement?

  • Color of the particles (correct)
  • Size distribution to be measured
  • Quantity of powder available
  • Formulation type

    • What must be considered regarding materials with a low occupational exposure limit (OEL)?

  • They require a smaller sample size.
  • They have no impact on particle size techniques.
  • They need to be kept at room temperature.
  • They must be adequately contained during measurement. (correct)

    • Which of the following is a mechanism involved in the liquid dispersion of particles?

    <p>Surface tension reduction</p> Signup and view all the answers

    What is often measured by techniques that do not directly measure particle size?

    <p>Particle volume</p> Signup and view all the answers

    In a sampling scheme, what is crucial to avoid bias in particle selection?

    <p>Randomization of samples</p> Signup and view all the answers

    What property of powder may affect its particle behavior before size measurement?

    <p>Water solubility</p> Signup and view all the answers

    What is a primary characteristic to consider when preparing a particle size measurement?

    <p>The physical properties of the powder</p> Signup and view all the answers

    What is the primary reason for assessing particle size during formulation?

    <p>To select appropriate excipients and ensure uniformity</p> Signup and view all the answers

    How does particle size affect the flow properties of powders?

    <p>Flow rate is inversely proportional to particle size</p> Signup and view all the answers

    What type of particles is preferable for lung delivery applications?

    <p>Very fine particles to reach deep lung areas</p> Signup and view all the answers

    Which statement best describes the impact of particle size on drug release?

    <p>Particle size influences the available surface area affecting release rates</p> Signup and view all the answers

    Which method is used for particle size analysis in the content provided?

    <p>Laser light diffraction after dispersion in butan-1-ol</p> Signup and view all the answers

    Why is it critical to control particle size during manufacturing?

    <p>To influence processing operations and product performance</p> Signup and view all the answers

    What is the magnification level of the photomicrograph of salbutamol sulphate micronised powder?

    <p>x 5560</p> Signup and view all the answers

    What effect do fine particles have when used in suspensions?

    <p>Reduce the likelihood of a 'scratchy' feeling on the skin</p> Signup and view all the answers

    What is meant by an equivalent sphere in particle measurement?

    <p>A sphere that matches the particle in the property being measured</p> Signup and view all the answers

    What is Feret's diameter used to measure?

    <p>The distance between two tangents on opposite sides of the particle</p> Signup and view all the answers

    Which particle size method requires one dimension for regular geometric figures?

    <p>Methods for spheres, cubes, and regular tetrahedrons</p> Signup and view all the answers

    What does the equivalent volume diameter represent?

    <p>Diameter of a sphere with a volume equal to that of the particle</p> Signup and view all the answers

    Which term describes characteristics of particle shape according to the British Pharmacopoeia?

    <p>Descriptive terms</p> Signup and view all the answers

    How are particle size and shape characterized for non-spherical particles?

    <p>Through multiple dimensions and identification of shape</p> Signup and view all the answers

    What is the primary characteristic of powder particles discussed?

    <p>Their shape as a fundamental property</p> Signup and view all the answers

    What is the main effect of particle size on the combustion of black powder?

    <p>Fine grained powder burns faster than larger particles.</p> Signup and view all the answers

    Why was black powder made with larger particles historically?

    <p>To slow down the rate of burn and prevent explosions.</p> Signup and view all the answers

    What characteristic of fine powdered black powder made it more powerful?

    <p>It had a larger surface area for combustion.</p> Signup and view all the answers

    What was a disadvantage of using fine grained black powder?

    <p>It built up too much pressure too quickly.</p> Signup and view all the answers

    How does the combustion of black powder mainly occur?

    <p>On the surfaces of the particles.</p> Signup and view all the answers

    Which particle shape is characterized by the property of sphericity?

    <p>Round</p> Signup and view all the answers

    Which method does NOT contribute to the quantitative characterization of particle shape?

    <p>Qualitative description of shape</p> Signup and view all the answers

    What is the principle behind the Coulter counter in particle size measurement?

    <p>It detects changes in electrical conductivity as particles pass through an orifice.</p> Signup and view all the answers

    Which of the following is a limitation of the Coulter counter method?

    <p>Particles can clump together and give inaccurate readings.</p> Signup and view all the answers

    When studying powder packing, which particle characteristic should be primarily assessed?

    <p>General geometric shape</p> Signup and view all the answers

    What is the primary advantage of using laser light scattering for particle size analysis?

    <p>It provides high speed and high reproducibility.</p> Signup and view all the answers

    Which particle shape characterization is typically assessed using projected area ratio?

    <p>Angular</p> Signup and view all the answers

    What is a significant challenge in sieve analysis for particle size measurement?

    <p>It can be influenced by the moisture content of the particles.</p> Signup and view all the answers

    In laser light scattering, what is the relationship between scattered light angle and particle size?

    <p>Larger particles scatter light at a smaller angle.</p> Signup and view all the answers

    What assumption is made about the particles when calculating scattering in laser light scattering?

    <p>Particles are spherical and opaque to light.</p> Signup and view all the answers

    What type of distribution is typically observed in the number of fine particles compared to coarser particles?

    <p>Positive skew.</p> Signup and view all the answers

    In particle size distribution analysis, what does a 50% cumulative undersize represent?

    <p>The median size of the particles.</p> Signup and view all the answers

    When considering a particle size distribution plot, what do the values representing the lower and upper quartile indicate?

    <p>25% and 75% of the total number of particles.</p> Signup and view all the answers

    Which parameter is NOT used in the optical microscopy example for determining particle size?

    <p>Cumulative undersize distribution.</p> Signup and view all the answers

    What is suggested by a positive skew in the particle size distribution?

    <p>The distribution is centered around smaller particle sizes.</p> Signup and view all the answers

    What is the purpose of using a data processing unit in the context of laser light scattering?

    <p>To analyze and interpret the scattering data.</p> Signup and view all the answers

    What is a key influence of particle size on the uniformity of drug dosage forms?

    <p>Affects excipient compatibility</p> Signup and view all the answers

    In the context of the manufacturing process, which aspect is directly affected by particle size?

    <p>The efficiency of drug dissolution and absorption</p> Signup and view all the answers

    What type of particle size is ideal for producing smooth-feeling suspensions?

    <p>Fine particles to avoid a scratchy feeling</p> Signup and view all the answers

    What defines an equivalent sphere in particle measurement?

    <p>A sphere that matches the particle in the physical parameter being measured</p> Signup and view all the answers

    Which statistical diameter measures the distance between two tangents on opposite sides of a particle?

    <p>Feret's diameter</p> Signup and view all the answers

    Which of the following considerations is critical before conducting a size measurement?

    <p>The degree of precision required in sampling</p> Signup and view all the answers

    What aspect is essential for characterizing a particle besides its size?

    <p>Particle shape</p> Signup and view all the answers

    What is an effect of using very broad size distributions of particles?

    <p>Increased tendency to segregate</p> Signup and view all the answers

    Which of the following describes the equivalent volume diameter?

    <p>Diameter of a sphere with a volume equal to that of the particle</p> Signup and view all the answers

    What is the primary mechanism by which surfactants promote better dispersion of particles in a liquid medium?

    <p>Reducing surface tension</p> Signup and view all the answers

    When is the ideal situation to consider using fine particles in a formulation?

    <p>For effective lung delivery of drugs</p> Signup and view all the answers

    What term does the British Pharmacopoeia use to describe qualitative characteristics of particle shape?

    <p>Descriptive terms</p> Signup and view all the answers

    What was identified as a limitation in sampling schemes involving powders?

    <p>Selection of a sample that does not affect others</p> Signup and view all the answers

    What is the typical range of sieve diameters used in sieve analysis as stated in the content?

    <p>45 μm to 1000 μm</p> Signup and view all the answers

    During sieve analysis, what condition determines when to stop the analysis based on the mass on any sieve?

    <p>When the mass does not change by more than 5% or 1 g</p> Signup and view all the answers

    Why is it important to control particle size during the manufacturing of dosage forms?

    <p>To influence processing operations and product quality</p> Signup and view all the answers

    Which of the following particle size fractions was mixed with ipratropium bromide in the example provided?

    <p>α-lactose monohydrate size fraction of 63-90 μm</p> Signup and view all the answers

    What effect does adjusting the pH of the liquid medium have on particles during dispersion?

    <p>It can maximize repulsion and prevent aggregation</p> Signup and view all the answers

    What additional dimensions are necessary for measuring regular geometric figures like cubical particles?

    <p>Only one dimension</p> Signup and view all the answers

    What is the commonest form of equivalent diameter used in particle measurement?

    <p>Equivalent circle diameter</p> Signup and view all the answers

    Which of the following describes how high-frequency ultrasound aids in particle dispersion?

    <p>By causing rapid pressure changes</p> Signup and view all the answers

    What approach is typically used to conduct sieve analysis for particle size measurement?

    <p>A series of sieves with progressively coarser meshes is used</p> Signup and view all the answers

    What characteristic of liquid dispersion is influenced by the thickness of the electric double layer around particles?

    <p>The surface charge and inter-particle interactions</p> Signup and view all the answers

    In the context of particle size methods, what is a key distinction in the concept of 'accuracy'?

    <p>It can vary significantly based on analytical methods used</p> Signup and view all the answers

    What shape factor is most relevant when assessing the flowability of a powder?

    <p>Sphericity</p> Signup and view all the answers

    Which of the following is NOT a method for particle size measurement mentioned?

    <p>Laser diffraction</p> Signup and view all the answers

    In particle size distribution analysis, what does a positive skew indicate?

    <p>A greater number of fine particles than coarser particles</p> Signup and view all the answers

    Which term defines the distribution of particle sizes where 50% of particles fall below a given size?

    <p>Median size</p> Signup and view all the answers

    Which type of distribution is used to represent the size distribution of particles in terms of weight vs number?

    <p>Cumulative distribution</p> Signup and view all the answers

    What technique is specifically mentioned as having limitations in directly measuring particle size?

    <p>Conductivity measurement</p> Signup and view all the answers

    When evaluating particle size using microscopy, what is the equivalent area diameter typically used for?

    <p>Determining average size in a sample</p> Signup and view all the answers

    In the context of powder handling, which property should be specifically selected when making spherical pellets?

    <p>Sphericity</p> Signup and view all the answers

    What is the primary function of cavitation in particle dispersion?

    <p>To generate bubbles that release energy and aid dispersion</p> Signup and view all the answers

    Why is ultrasonic agitation important in the Coulter counter method?

    <p>It breaks up particle aggregates to avoid inaccuracies</p> Signup and view all the answers

    What does the scattering angle in laser light scattering indicate about a particle?

    <p>It is directly proportional to the particle's size</p> Signup and view all the answers

    What is a significant limitation of using laser light scattering for particle size measurement?

    <p>Particles must be evenly shaped to yield accurate results</p> Signup and view all the answers

    What main issue arises if the particle suspension in the Coulter counter method is not dilute enough?

    <p>More than one particle being counted as a single pulse</p> Signup and view all the answers

    In the Coulter counter method, what parameter is directly proportional to the volume of a particle?

    <p>The frequency of voltage pulses</p> Signup and view all the answers

    What assumption is made in laser light scattering regarding the scatter efficiency of particles?

    <p>Particles must be perfectly spherical and opaque to light</p> Signup and view all the answers

    What is the lower size limit for particle measurement using the Coulter counter method?

    <p>0.3 mm</p> Signup and view all the answers

    Study Notes

    Particle Size Importance

    • Particles from crystallization and size reduction need size knowledge during manufacturing and dosage form use.
    • Choosing appropriate excipients for powders is important to avoid segregation.
    • Uniform powder flow is related to particle size.
    • For low-dose drug mixtures, uniformity of content related to particle size is important.
    • Fine particles in suspensions avoid a "scratchy" feeling and rapid settling, according to Stoke's law.
    • Fine particles deliver drugs to deep lung areas.
    • Particle size affects drug release, bioavailability, and absorption rates as surface area increases with smaller particle size.
    • Particle size is crucial for product quality and performance during manufacturing processes.

    Considerations Before Measurement

    • Visual techniques (optical light microscopy) provide a starting point for size measurement.
    • The use of size data in regard to its controlling of particle behavior should be considered before measurement.
    • The medium for sample presentation (e.g. formulation type) influences measurement.
    • The size distribution of the sample is important (micron or very broad?).
    • The amount of material available impacts the measurement.
    • Safety is paramount. Materials with low occupational exposure limits require adequate containment.

    Particle Size and Shape

    • Information on particle size and shape needed to characterize a particle.
    • Regular shapes (sphere, cube, tetrahedron) require only one dimension.
    • An equivalent sphere equals a real particle in physical parameters.
    • Particle size grades (coarse, medium-fine, fine, very fine, micronised) are defined by size ranges.
    • Feret's and Martin's diameters are statistical measures.
    • Measurement requires many samples for statistical significance.

    Particle Shape Factors

    • Qualitative shape descriptions (e.g., acicular, angular) are used.
    • Quantitative characterization uses microscopy and image analysis with 2D and 3D shape characteristics.
    • Shape factors include projected area ratio, circularity, image analysis, and conductivity.
    • Particle properties related to processing, like pellet making and packing, influence testing methods.

    Particle Size Distribution Measurement

    • The number of fine particles often exceed coarse particles, showing a positive skew.
    • Histograms are typical, showing a left-shifted distribution.
    • Graphical representations (log-probability paper) show the size distribution, including number and weight versus particle size.
    • Optical microscopy is used for measurement with (e.g eyepiece graticule).
    • Percent cumulative undersize distribution is useful to plot data.

    Measurement Techniques

    • Sieve analysis is a common method for particles above 64µm.
    • A sieve shaker with different sizes is used.
    • Liquid dispersion methods are also used.
    • Coulter counter uses electrical conductivity changes to measure particles.
    • Laser light scattering analyzes particles in a dispersed liquid.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Particle Size and Shape PDF

    Description

    Explore the essential concepts and techniques related to particle size measurement in this quiz. Learn about factors influencing accuracy, mechanisms of dispersion, and the significance of particle size in formulation. Test your understanding of key terminologies and methods used in this critical field.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser