Instrumental Analysis

Chemical equilibrium

The state in which the forward and reverse reactions of a chemical reaction occur at equal rates.

Solubility

The ability of a substance to dissolve in a solvent.

Acid-base chemistry

The study of the behavior of acids and bases in aqueous solutions.

Electrochemistry

The branch of chemistry that deals with the relationship between electricity and chemical reactions.

Redox reactions

Chemical reactions in which there is a transfer of electrons from one species to another.

Titration

A technique used to determine the concentration of a substance in a solution by reacting it with a known reagent.

UV spectrometry

An instrumental analytical technique that uses ultraviolet light to analyze compounds.

UV-VIS spectrophotometry

An analytical technique that uses ultraviolet and visible light to measure the absorption or transmission of light by a sample.

Photoluminescence

The emission of light by a substance after it has absorbed photons.

Chromatography

A technique used to separate and analyze mixtures based on their different physical-chemical properties.

Analyte concentration

The amount or concentration of the substance being analyzed in a sample.

Electroanalytical chemistry

The branch of chemistry that focuses on the study of electrochemical processes and their applications in analysis.

Redox chemistry

The study of oxidation-reduction reactions and their role in chemical processes.

Potentiometry

A technique used to measure the potential difference between two electrodes in a chemical system.

Voltammetry

A technique used to measure the current flowing through an electrochemical cell as a function of applied potential.

Fluorescence

The emission of light by a substance after it has absorbed and then re-emitted photons.

Absorbance

The measure of how much light is absorbed by a sample.

Liquid-Liquid Extraction

A separation technique that involves partitioning a solute between two immiscible solvents.

Equilibrium constant (KD)

A measure of the distribution of a solute between two phases in a liquid-liquid extraction.

Partition coefficient

log P:A measure of the distribution of a compound between two phases, such as octanol and water.

Hydrophilicity

The property of a compound that "likes" water and is polar.

Hydrophobicity

The property of a compound that "fears" water and is non-polar.

Log P value

A numerical value that indicates the hydrophilicity or hydrophobicity of a compound, with higher values indicating higher hydrophobicity.

Paper Chromatography

A technique used to separate compounds based on their affinity for paper, with a stationary phase of paper and a mobile phase of water.

Thin-Layer Chromatography (TLC)

A quick analytical test similar to paper chromatography, where compounds are separated based on their interaction with a polar stationary phase (silica) and a non-polar mobile phase (e.g., hexane).

Retention

The amount of slowing down or interaction a compound has with the stationary phase in chromatography.

Normal-Phase Liquid Chromatography

A type of column chromatography where the stationary phase is polar and the mobile phase is non-polar.

Column Chromatography

A technique used to separate and analyze compounds based on their interactions with a stationary phase and a mobile phase.

Eluent

The solvent or mixture of solvents that is added at the top of the column in column chromatography.

Eluate

The mixture of compounds that comes out of the column in column chromatography.

Stationary phase

The solid/liquid phase, typically silica particles, in column chromatography that interacts with the compounds being separated.

Retention

The ability of a compound to stay on the stationary phase in column chromatography.

Polar

Referring to a compound that has a positive and negative charge distribution, causing it to interact more strongly with the stationary phase in column chromatography.

Non-polar

Referring to a compound that does not have a positive and negative charge distribution, causing it to interact less strongly with the stationary phase in column chromatography.

Adsorption Chromatography

A type of chromatography where compounds are retained based on their electrostatic interactions with the stationary phase.

Partition Chromatography

A type of chromatography where compounds are retained based on their distribution between two liquid phases, one of which is stationary.

Molecular Recognition chromatography

Affinity. A type of chromatography where compounds are retained based on specific interactions, such as antibodies binding specifically to certain proteins.

Molecular Exclusion/Inclusion chromatography

A type of chromatography where compounds are retained based on their size, with larger molecules being excluded or included in the stationary phase.

Gas chromatography (GC)

A type of chromatography where the mobile phase is a gas and the stationary phase is a solid or liquid.

Liquid chromatography (LC)

A type of chromatography where the mobile phase is a liquid and the stationary phase is a solid or liquid.

Qualitative analysis

Determining which compounds are present in a sample using chromatography.

Quantitative analysis

Determining the concentration of a specific compound in a sample using chromatography.

Chromatogram

The graphical representation of the compounds detected by a detector at the end of the column in chromatography.

Retention time

The time it takes for a compound to travel from the injection point to the specific peak in a chromatogram.

Relative retention

The ratio between the retention times of two compounds, indicating their relative affinities for the stationary phase.

α = 𝒕′𝒓𝟐/ 𝒕′𝒓𝟏

Capacity factor

The ratio between the time spent in the stationary phase and the time spent in the mobile phase for a compound in chromatography.

k’ = 𝒕′ 𝒓/𝒕𝒎

Resolution

The separation of two peaks in a chromatogram, expressed mathematically as the difference in retention times divided by the baseline width of the peaks.

R = 𝜟𝒕𝒓/𝒘𝒂𝒗

Band Broadening

The spreading of bands in chromatography due to diffusion and increasing elution times.

Standard Deviation of Band (Ã)

The measure of the width of a band in chromatography.

Difusion Coefficient (D)

The measure of how quickly a compound diffuses in a given medium.

Time (t)

The duration it takes for a compound to elute in chromatography.

Theoretical Plate

Each exchange of molecules between the stationary and mobile phase in chromatography.

Height Equivalent to a Theoretical Plate (HETP)

The height of a column required for one theoretical plate.

Plate Height (H)

The measure of the width of a band in chromatography.

H = σ2/𝑥

Plate Number (N)

The number of theoretical plates in a chromatographic column.

N = 16t²/w²

Van Deemter Equation

An equation that relates plate height to flow rate in chromatography.

𝐻 ≈ 𝐴 + 𝐵/ux + 𝐶∙𝑢𝑥

A-term

The term in the Van Deemter Equation that represents multiple paths in chromatography.

B-term

The term in the Van Deemter Equation that represents longitudinal diffusion in chromatography.

C-term

The term in the Van Deemter Equation that represents mass transfer in chromatography.

Fronting

Asymmetric peaks in chromatography due to overloading.

Tailing

Asymmetric peaks in chromatography due to stronger retention of some molecules.

Oftentimes interactions with bare Si-OH groups on Si-C18 columns (lab course).

Partition Coefficient (K)

The ratio of the concentration of a compound in the stationary phase to the concentration in the mobile phase.

K = 𝑪𝒔/𝑪𝒎

Capacity Factor (K')

The measure of the time a molecule spends in the stationary phase relative to its time in the mobile phase.

k’ = 𝒕′ 𝒓/𝒕𝒎

High-Performance Liquid Chromatography

A technique used to separate compounds based on their retention and partition over a stationary phase and mobile phase.

Column

The part of the HPLC system where the separation of compounds occurs

Guard column

A column that removes unwanted substances (dust, particles) before the main column in HPLC.

Elution process

The process of compounds being separated and eluted from the column in chromatography.

Isocratic elution

A type of elution where the solvent composition remains constant throughout the separation.

Gradient elution

A type of elution where the solvent composition changes over time, resulting in faster elution of strongly retained species.

HPLC Pumps

Pumps used in HPLC systems to generate high pressures (up to 400 bars) and deliver a constant flow of eluent to the column.

Injection valve

A valve in the HPLC system that allows the sample to be loaded and injected into the column.

UV detector

The most common type of detector used in HPLC, which measures the absorbance of compounds with UV absorbance.

Lambert-Beer

A formula that relates the absorbance of a compound to its concentration, using the molar absorptivity, path length, and concentration.

Calibration curve

A curve used to determine the concentration of an unknown compound by comparing its detector signal to the signals of known concentrations.

Ion-exchange chromatography

A chromatographic technique where the separation of compounds is based on their charge and interactions with an ion-exchange resin.

RP-HPLC

Reverse-phase high-performance liquid chromatography, a technique that uses a hydrophobic stationary phase and an aqueous mobile phase to separate compounds.

Ion pairing

A technique used in RP-HPLC where anionic surfactants with hydrophilic heads and hydrophobic tails are added to the stationary phase to enhance the retention of cations.

HPLC

High-performance liquid chromatography, a technique used to separate, identify, and quantify compounds in a mixture.

Assay

The analysis of the quantity and purity of a substance or compound.

HPLC Applications in Pharmaceutical Sciences

Purity

The degree to which a substance is free from impurities or contaminants.

HPLC Applications in Pharmaceutical Sciences

Therapeutic Drug Monitoring (TDM)

The process of monitoring the concentration of a drug in a patient's blood to ensure therapeutic levels are maintained.

HPLC Applications in Pharmaceutical Sciences

Clinical toxicology

The branch of toxicology that focuses on identifying and quantifying toxins in patients.

HPLC Applications in Pharmaceutical Sciences

Chromatography

A technique used to separate and analyze compounds based on their distribution between a stationary phase and a mobile phase.

Selectivity

A measure of how well a chromatographic process can separate different compounds.

Efficiency

A measure of how well a chromatographic process can separate compounds in a given time.

Wall-coated open tubular column (WCOT)

A type of gas chromatography column where a thin film of liquid is coated on the walls of a capillary column.

Support-coated open tubular column (SCOT)

A type of gas chromatography column where particles are coated with a stationary liquid phase on the wall.

Porous layer open tubular column (PLOT)

A type of gas chromatography column where particles are present on the wall of the column.

Stationary phase

The phase in chromatography that does not move and interacts with the compounds being separated.

Mobile phase

The phase in chromatography that moves and carries the compounds through the column.

Sample injection

The process of introducing a sample into a gas chromatography system.

Volatile

Compounds that are easily evaporated.

Split injection

A sample injection method where a small fraction of the carrier gas mixed with the sample is injected into the column.

Splitless injection

A sample injection method where most of the sample is injected into the column after evaporating inside the hot injector.

On-column injection

A direct injection of the sample into the column.

Flame ionization detector

The most common detector used in gas chromatography, which measures the current produced by the reaction of organic compounds with hydrogen and oxygen.

Retention time

The time it takes for a compound to elute from the column.

Resolution

The ability of a chromatographic system to separate two adjacent peaks.

Plate number

A measure of the efficiency of a column in gas chromatography.

Column length

The length of the column used in gas chromatography.