Separation Techniques: Principl and Applications of Chromatography in Pharmacy

SEPARATION TECHNIQUES - PRINCIPLES AND APPLICATIONS OF CHROMATOGRAPHY IN PHARMACY

DEFINITION

• Separation Techniques:

  • Definition: Techniques that separate two different states of matter, specifically liquids and solids.

  • Overview: A methodology for achieving mass transfer phenomena, converting a mixture of substances into two or more distinct product mixtures.

  • Importance: Essential for purifying components of interest from mixtures, distinguishing between pure and impure substances. Separation is a refining process.

NEED FOR SEPARATION TECHNIQUES

• Identification of Components:

  • To determine what needs to be separated from a mixture.

• Obtaining Pure Substances:

  • Essential for obtaining important and pure substances.

• Removal of Unwanted Particles:

  • Purity is critical in various applications.

TYPES OF SEPARATION TECHNIQUES

Classification

• Based on the type of mixtures:

  • Solid in Liquid Mixtures:

  • Homogenous:

    1. Evaporation

    2. Distillation

    3. Centrifugation

  • Heterogenous:

    1. Sedimentation/gravitation

    2. Filtration

    3. Magnetic separation

    4. Fractional distillation

  • Liquid in Liquid Mixtures:

  • Homogenous:

    1. Simple or fractional distillation

    2. Chromatography

  • Heterogenous:

    1. Partition separation using a funnel

MAGNETIC SEPARATION

• Definition:

  • A method to separate magnetic substances from non-magnetic substances using a magnet.

• Principle:

  • Utilizes the physical property of magnetism, effective for certain substances like:

  • Ferromagnetic Materials: Strongly affected by magnetic fields.

  • Paramagnetic Materials: Less affected but noticeable interaction with magnetic fields.

• Applications:

  • Waste management.

  • Water purification for low-magnetic field separation.

  • Removal of metal contaminants from pharmaceutical product streams.

  • Combined with PCR (polymerase chain reaction) in cancer and hereditary diseases research to enhance sensitivity and specificity of results.

DECANTATION

• Definition:

  • A process to separate mixtures of immiscible liquids or a liquid and solid mixture like a suspension.

• Process:

  • Utilizes differences in density to provide better separation.

  • Example: Separating oil from water.

  • A Separatory Funnel is often used, featuring a valve at the bottom to drain off the bottom layer.

• Applications:

  • Frequently used in nanotechnology for synthesizing high-quality silver nanowire solutions and fabricating high-performance electrodes.

CRYSTALLIZATION

• Definition:

  • A process by which a solid forms from a solution, where atoms or molecules organize into a crystal structure.

• Purpose:

  • Used to separate a heat-liable dissolved solid (solute) from a solution.

• Overview of the Process:

  • Solution is heated to evaporate solvent, resulting in a hot and nearly saturated solution.

  • As the solution cools, solubility decreases, and excess solute crystallizes out.

  • Crystals are separated from remaining solution by filtration.

DISTILLATION

• Types:

  • Simple Distillation:

  • Used for liquid mixtures boiling without decomposition, with significant differences in boiling points.

  • Applications:

    • Separation of acetone and water, alcohol distillation.

  • Fractional Distillation:

  • Used for mixtures of two or more miscible liquids with boiling point differences less than 25K.

  • Apparatus:

    • Similar to simple distillation, with a fractionating column added.

  • Applications:

    • Separation of different fractions from petroleum products, methanol, and ethanol mixtures.

FILTRATION

• Definition:

  • A process utilizing the physical properties of matter—size and solubility in liquids.

• Key Terms:

  • Residue: The substance left behind in the filtration medium.

  • Filtrate: The liquid passing through the filtration medium.

• Overview:

  • Mechanically separates solids from fluids (liquids or gases) using a medium that allows only fluid to pass.

CENTRIFUGATION

• Definition:

  • Used to separate mixtures where solid particles do not settle quickly, particularly when the particles are small.

• Principle:

  • Involves applying centrifugal force to separate particles based on size, shape, density, viscosity of the medium, and rotor speed.

• Centrifuge:

  • A device that spins a rotor to separate components.

• Process:

  • More dense components move outward while less-dense components move inward.

• Specifications:

  • Rate of centrifugation is defined in terms of angular velocity (RPM) or acceleration (g).

• Applications:

  • Used in diagnostic laboratories for blood and urine tests and separation of proteins using purification techniques.

  • Differential centrifugation is used to separate organelles in cells.

SUBLIMATION SEPARATION

• Definition:

  • Sublimation is the transition of a substance directly from solid to gas, avoiding the liquid phase.

• Principle:

  • Separates solids containing a sublimable component through heating.

• Example:

  • Separation of iodine from sand.

• Applications:

  • Used in forensic sciences and as a purification method for volatile compounds.

EVAPORATION

• Definition:

  • A vaporization type occurring at the surface of a liquid, converting liquid to gas.

• Purpose:

  • To separate solutes from a solvent by boiling the solution, vaporizing the solvent.

• Factors Affecting Evaporation:

  • Concentration, flow rate of air, pressure, temperature, surface area, intermolecular forces.

• Applications:

  • Recovering salts, drying/concentrating samples for analyses, demineralization of water.

CHROMATOGRAPHY

• Definition:

  • A widely used separation technique in labs for analysis, isolation, and purification, essential in the chemical process industry.

• Scale of Use:

  • Ranges from separating minute quantities (<1 ng) to hundreds of kilograms per hour.

• Chromatography Overview:

  • A physical method of separation utilizing two phases: a stationary phase (fixed) and a mobile phase (moving).

  • Separation occurs through repetitive sorption/desorption events as samples move along the stationary phase driven by the mobile phase flow.

CHROMATOGRAPHY TERMS

• Chromatograph:

  • Equipment for advanced separation (examples include gas chromatography and liquid chromatography).

• Eluent:

  • The fluid entering the column/solvent that carries the analyte.

• Eluate:

  • Mobile phase leaving the column.

• Stationary Phase:

  • The immobilized phase on support particles or column wall (example: silica layer in thin layer chromatography).

• Solvent Front:

  • Distance that the solvent has traveled up the stationary phase.

• Retention Time (tR):

  • Time taken by a compound to travel through the column and reach the detector during analysis.

FUNDAMENTAL PRINCIPLE OF CHROMATOGRAPHY

• Separation is based on interaction between components with the two phases.

  • Each component has a unique preference that influences retention time.

  • Factors include solubility, adsorption, and molecular affinity.

TYPES OF CHROMATOGRAPHY

• Thin Layer Chromatography (TLC):

  • Involves a thin layer of silica gel on a flat substrate.

  • Polar solvents (like water) often serve as the mobile phase.

• Liquid Chromatography:

  • Utilizes liquid as the mobile phase and a solid as stationary phase, often referred to as high-performance liquid chromatography (HPLC).

• Gas Chromatography (GC):

  • Analyzes volatile samples using gas (like helium/nitrogen) as the mobile phase.

PARTITION COEFFICIENT

• Definition:

  • Represents the equilibrium constant for distribution of a component between two phases.

• Formula:

  • $K<em>P = \frac{[A</em>{stationary}]}{[A_{mobile}]}$

  • Where [A{stationary}] is the concentration in the stationary phase and [A{mobile}] is the concentration in the mobile phase.

THIN LAYER CHROMATOGRAPHY

• Setup:

  • Samples are applied as small spots on the stationary phase (silica gel) just above the solvent level in a covered tank.

  • The solvent rises by capillary action, carrying components with it.

• Retardation Factor (Rf):

  • Defined as the ratio of the distance traveled by the component to the distance traveled by the solvent front.

  • Formula:

  • $Rf = \frac{D<em>c}{D</em>s}$

  • Where $D<em>c$ is the distance the component travels and $D</em>s$ is the distance of the solvent front.

LIQUID CHROMATOGRAPHY

• Modern Techniques:

  • High-performance liquid chromatography (HPLC) uses high pressure to force solvent through the column.

GAS CHROMATOGRAPHY

• Definition:

  • Analyzes volatile samples in gas phase using a gas as mobile phase to transport the sample through a tube (column).

APPLICATIONS OF CHROMATOGRAPHY IN PHARMACY

• LC-MS for Drug Metabolites:

  • Quantifies metabolites in blood samples, aiding clinical assessments.

• GC-FID for Residual Solvents:

  • Detects trace solvents in active pharmaceutical ingredients (APIs) for purity verification.

• Ion Exchange for mRNA Purification:

  • Crucial for isolating high-quality mRNA in vaccine manufacturing.

• SEC for Monoclonal Antibody Analysis:

  • Confirms purity and aggregation status of monoclonal antibodies for biopharmaceutical quality control.

• TLC for Counterfeit Antibiotics Testing:

  • Provides rapid assessments to detect illicit products, safeguarding public health.