Flashcards on Chromatography Techniques (copy)

Thin-Layer Chromatography (TLC)

Liquid chromatography with a thin stationary phase layer on a plate.

Normal TLC Plates

TLC plates with 0.25 mm stationary phase thickness and 5-12 μm particle sizes.

High-Performance TLC (HPTLC) Plates

TLC plates with 0.1-0.2 mm stationary phase thickness and 2-10 μm particle sizes.

Concentration Zone

Area on a TLC plate for concentrating sample volumes before separation.

Retention Factor (Rf)

Measure of analyte retention in TLC, calculated as analyte distance traveled divided by mobile phase front distance.

Normal Phase Chromatography

TLC mode with polar stationary phase and non-polar mobile phase.

Reversed Phase Chromatography

TLC mode with non-polar stationary phase and polar mobile phase.

Mobile Phase Saturation

Equilibrating the development tank with mobile phase vapors to prevent solvent evaporation.

Two-Dimensional Development

Rotating and developing a TLC plate a second time with a different mobile phase.

Horizontal Development

HPTLC development mode with horizontal mobile phase migration.

Fluorescence Quenching

Visualization technique where analytes appear as dark spots on a fluorescent background.

Derivatization

Treating a developed TLC plate with reagents to visualize non-colored analytes.

Suitability Test

Test in pharmacopoeial methods to ensure sufficient chromatographic separation capability.

Semi-quantitative Limit Test

Test comparing impurity spot size and intensity with a reference substance.

Densitometry

Instrumental technique for quantitative analysis in TLC based on peak area measurements.

Hyphenation with Mass Spectrometry

Coupling TLC with mass spectrometry for identifying unknown substances.

Silica Gel

Common polar stationary phase in TLC for normal phase separations.

Alumina (Aluminum Oxide)

Stationary phase sometimes used in TLC for separating polar analytes.

Cellulose

Polar stationary phase in TLC for highly polar analyte separations.

Binder

Polymer added to TLC stationary phase to increase plate layer robustness.

Eluent Strength

Mobile phase ability to elute analytes from the stationary phase.

Eluotropic Series

Series of solvents ranked by elution strength in TLC.

Ion-Pair Formation

Addition of modifiers to suppress ionic interactions in TLC.

Vertical Development

Standard TLC development mode with a vertical plate orientation.

Molecular Size Marker

Known molecular weight substances on a TLC plate for estimating component weights.

Sodium Dodecyl Sulfate (SDS)

Detergent for denaturing and coating proteins in SDS-PAGE.

SDS-Polyacrylamide Gel Electrophoresis (SDS-PAGE)

Protein separation by molecular weight after denaturation with SDS.

Isoelectric Point (pI)

pH where a protein carries no net charge, used in isoelectric focusing.

Polyampholytes

Molecules with varying pI values for establishing pH gradients in IEF gels.

Immobilized pH Gradient (IPG) Gel

IEF gel with immobilized pH gradient for separation.

Rayleigh Scattering

The majority of the scattered light that has the same wavelength as the incident beam in Raman spectroscopy.

Raman Scattering

The inelastic scattering of monochromatic light by molecules, resulting in shifts in wavelength that provide structural information.

Raman Shift

The difference in wavelength between the observed Raman scattering bands and the Rayleigh scattering, which depends on the chemical structure of the molecule.

Stokes Lines

Raman scattering bands observed at lower frequencies (wavenumbers) than the Rayleigh scattering in a Raman spectrum.

Anti-Stokes Lines

Raman scattering bands observed at higher frequencies (wavenumbers) than the Rayleigh scattering in a Raman spectrum.

Capillary SFC

A mode of supercritical fluid chromatography that uses narrow-bore capillary columns similar to those used in gas chromatography (GC).

Packed-Column SFC

A mode of supercritical fluid chromatography that uses packed columns similar to those used in high-performance liquid chromatography (HPLC).

Gradient Elution (SFC)

In SFC, increasing the elution strength of the mobile phase during the chromatographic separation by gradually increasing the pressure (density) of the supercritical fluid or by adding organic modifiers.

Restrictor

A narrow capillary at the end of the chromatographic column in supercritical fluid chromatography (SFC) that creates a high pressure in the column by restricting the flow of the supercritical fluid.

Radiofrequency

The range of electromagnetic radiation frequencies used in Nuclear Magnetic Resonance (NMR) spectroscopy to excite and observe the nuclei of interest.

Fourier Transform

A mathematical operation used in NMR spectroscopy to convert the time-domain signal into a frequency-domain spectrum.

Chemical Shift

The difference in the applied magnetic field strength required for a particular set of equivalent protons (or other nuclei) to absorb in NMR spectroscopy, which provides information about their chemical environment.

Spin-Spin Splitting

The splitting of a signal into multiple peaks in an NMR spectrum, which provides information about the environment of a proton with respect to nearby protons.

Gyromagnetic Ratio

A constant that relates the energy required to flip the spin of a nucleus in an external magnetic field to the strength of the magnetic field, specific for each type of nucleus.

Potentiometric Titration

A type of titration where the potential difference between an electrode and a reference electrode is measured continuously during the titration process to detect the endpoint.

Endpoint Detection

The process of determining the endpoint of a titration, which can be done potentiometrically by monitoring the potential difference between electrodes.

Ion-Selective Electrode

An electrode that responds selectively to a certain type of ion, allowing for potentiometric determination of ionic concentrations.

Ionophore

Molecules present in the ion-selective membrane that selectively bind to the intended type of ions, enabling the electrode's selective response.

Standard Addition

A technique used with ion-selective electrodes to avoid matrix interferences, where the sample is measured before and after adding a known amount of standard solution.

Liquid-based Ion-Selective Electrode

An ion-selective electrode where the ion-selective membrane is a polymeric film, allowing the selective binding of intended ions.