Adsorption Chromatography Basics
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Adsorption Chromatography Basics

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Questions and Answers

Which of the following statements about adsorption chromatography is true?

  • Polar components move faster than non-polar components.
  • It exclusively uses liquid as the mobile phase.
  • It operates based on competition between a sample and mobile phase for absorptive sites. (correct)
  • It is the most commonly used form of chromatography in laboratories.

    • Silica Gel is considered a weak adsorbent in chromatography.

    False

    The ______ is the oldest form of chromatography.

    adsorption chromatography

    Name two properties of a good adsorbent.

    <p>Insoluble in the solvents used, small particle size.</p> Signup and view all the answers

    Match the following adsorbents with their classifications:

    <p>Alumina = Strong Adsorbent Calcium Carbonate = Intermediate Adsorbent Sucrose = Weak Adsorbent Silica Gel = Strong Adsorbent</p> Signup and view all the answers

    Which factor influences the strength of an adsorbent?

    <p>Surface area of the adsorbent</p> Signup and view all the answers

    The greater the rate a zone travels in an elution experiment, the stronger the adsorbent.

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

    What is the primary basis for separation in partition chromatography?

    <p>Differences in solubility of components in two immiscible solvents.</p> Signup and view all the answers

    Which of the following adsorbents is used in gel filtration chromatography?

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

    Ion-exchange chromatography separates molecules based solely on their molecular size.

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

    What is the purpose of varying pH in ion-exchange chromatography?

    <p>To control the strength of ion binding and facilitate separation.</p> Signup and view all the answers

    Which of the following best describes the process of partition chromatography?

    <p>Separation is based on the relative solubility of solutes in two immiscible liquids.</p> Signup and view all the answers

    In cation exchange chromatography, positively charged molecules are attracted to a __________ charged solid support.

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

    The partition coefficient is defined as the ratio of solute concentration in the mobile phase to that in the stationary phase.

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

    Which type of resin is used to attract anions in ion-exchange chromatography?

    <p>Anion Exchange Resin</p> Signup and view all the answers

    What happens to polar molecules during the partition chromatography process?

    <p>They remain in the aqueous solvent.</p> Signup and view all the answers

    Match the following chromatography methods with their descriptions.

    <p>Gel filtration = Separates based on size using hydrophilic beads Gel permeation chromatography = Uses hydrophobic gel beads in non-aqueous phase Ion-Exchange chromatography = Separates based on charge and affinity Partition chromatography = Relies on different affinities for stationary and mobile phases</p> Signup and view all the answers

    The stationary phase in partition chromatography is composed of a __________ liquid that is partially miscible with the flowing liquid.

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

    What is one of the primary uses of ion-exchange chromatography?

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

    Match each term with its correct description:

    <p>Partition Coefficient = Ratio determining solute movement between phases PSEUDO-LIQUID STATIONARY PHASES = Chemically bonded to an insoluble polymer support Aqueous Solvent = Phase where polar molecules are retained Organic Solvent = Phase for extraction of nonpolar molecules</p> Signup and view all the answers

    The stationary phase in ion-exchange chromatography consists of __________ polymers.

    <p>large substituted benzene</p> Signup and view all the answers

    Which factor influences the rate at which a solute moves between the two phases in partition chromatography?

    <p>Partition coefficient of the solute</p> Signup and view all the answers

    A separatory funnel is often used for the simple implementation of partition or extraction processes.

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

    In partition chromatography, the two immiscible liquids are usually an organic solvent and a __________ solvent.

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

    Study Notes

    Adsorption Chromatography

    • Oldest form of chromatography
    • Utilizes competition between the sample and the mobile phase for spots on the stationary phase
    • Most soluble = moves fastest
    • Preferred as a preparative method for separating large quantities of mixtures with varying polarities and structures
    • Requires the adsorbent to be insoluble in the solvent used
    • Adsorbent strength is measured by the rate a zone travels in an elution experiment
    • Strong adsorbents include alumina, fuller's earth, charcoal, and silica gel
    • Intermediate adsorbents include magnesia, calcium carbonate, and calcium phosphate
    • Weak adsorbents include sucrose, starch, talc, and inulin
    • The ability to separate mixtures depends on the polarity of the functional groups
      • Acidic polar stationary phases (ex. Silica Gel) are paired with a single solvent
      • Basic polar stationary phases (ex. Alumina) utilize a mixture of two or more solvents
      • Non-polar stationary phases (ex. Charcoal) also use a mixture of solvents

    Partition Chromatography

    • Separation is based on relative solubility in organic and aqueous solvents
    • The stationary phase is a liquid partially miscible with the mobile phase
    • Stationary phase may be coated on an inert chromatographic support
    • Results in the partitioning of solute molecules in two phases
    • The partition coefficient determines the rate a solute moves between phases
    • Compounds most soluble in the mobile phase move faster and are easily eluted
    • Compounds with high partition coefficients are retained in the stationary phase

    Steric Exclusion Chromatography

    • Separates solutes based on size and shape
    • Early methods include: gel filtration, gel permeation chromatography
    • Gel filtration: uses hydrophilic beads of cross-linked dextran, polyacrylamide gel, or agarose
    • Gel permeation chromatography: uses hydrophobic gel beads of polystyrene

    Ion-Exchange Chromatography

    • Separates solutes based on charges
    • Utilized to remove interfering substances from a solution
    • Used for amino acid and hemoglobin analysis
    • Used to separate mixtures of small organic and inorganic ions and charged molecules
    • Concentrates dilute ion solutions
    • Separates ions based on magnitude and change through ion exchange
    • Solutes are eluted with a solution of low to medium salt concentration containing competing counter ions
    • Change in pH and ionic concentration allows separation of organic and inorganic ions
    • Separates charged molecules based on their attraction to a charged stationary phase
    • Cation exchange resin
      • Cations are free to react with hydrogen ions
      • Sodium is used for cation exchange
      • Positively charged molecules are attracted to a negatively charged solid support
    • Anion exchange Resin
      • Anions are free to react with hydroxyl ions
      • Chloride is used for anion exchange
      • Negatively charged molecules are attracted to a positively charged solid support

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    Chromatography Part 1 PDF

    Description

    This quiz explores the fundamental principles of adsorption chromatography, the oldest form of chromatography. It covers the competition between samples and the mobile phase, the characteristics of various adsorbents, and methodologies for separating mixtures based on polarity. Test your knowledge on how different stationary phases work with solvents.

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