Analytical Chemistry Glossary

A measure of the amount of light absorbed by a sample, defined as the negative logarithm of transmittance (A = -log T).

The specific chemical species being identified, measured, or quantified in an analysis.

A sample containing all reagents and solvents but no analyte, used to measure background signal and correct for interference.

A graphical representation of instrument response versus known analyte concentrations used to quantify unknowns.

A plot of detector response versus time (or volume) obtained from a chromatographic separation, showing peaks for each separated component.

A part of a molecule responsible for absorbing ultraviolet or visible light, typically involving conjugated double bonds or aromatic systems.

A titration in which a chelating agent (usually EDTA) reacts with metal ions to form stable complexes.

The solvent or solvent mixture used as the mobile phase in chromatography to carry analytes through the column.

The point in a titration where the amount of titrant is stoichiometrically equal to the amount of analyte.

The region of an infrared spectrum (approximately 600-1500 cm⁻¹) that contains complex absorption patterns unique to each molecule.

An analytical method based on the measurement of mass of a substance of known composition that is chemically related to the analyte.

High-Performance Liquid Chromatography; a technique using high-pressure pumps to separate compounds in liquid mobile phases through packed columns.

Any species other than the analyte that contributes to the measured signal, potentially causing error in the analysis.

The process of converting atoms or molecules into ions, a critical step in mass spectrometry for generating detectable charged species.

The lowest concentration of analyte that can be reliably distinguished from the blank, typically defined as 3σ of the blank.

The influence of other components in the sample on the measurement of the analyte, which can enhance or suppress the analytical signal.

The gas or liquid that carries analytes through the stationary phase in a chromatographic system.

A proportionality constant in the Beer-Lambert Law that indicates how strongly a substance absorbs light at a given wavelength, in units of L·mol⁻¹·cm⁻¹.

An electroanalytical technique that measures the potential difference between two electrodes at zero or near-zero current flow.

The time elapsed between sample injection and the appearance of a component's peak maximum in a chromatographic analysis.

The ability of an analytical method to measure the analyte accurately in the presence of other interfering substances.

An instrument that measures the intensity of light transmitted through or absorbed by a sample as a function of wavelength.

A statistical measure of the dispersion of a set of measurements around the mean, indicating the precision of the method.

The immobile phase in chromatography (solid or liquid coated on a solid support) that interacts with analytes to effect separation.

A quantitative analytical method based on measuring the volume of a solution of known concentration required to react with the analyte.