Analytical Chemistry

A quantitative technique that measures how much light a chemical substance absorbs at a given wavelength. The Beer-Lambert Law states that absorbance is directly proportional to the concentration of the absorbing species and the path length of the sample cell (A = εbc).

A family of separation techniques in which components of a mixture are distributed between a stationary phase and a mobile phase. Different affinities cause different migration rates, separating the mixture into its components.

An analytical technique that measures the mass-to-charge ratio (m/z) of ions. Molecules are ionized, separated according to m/z, and detected, producing a mass spectrum that serves as a molecular fingerprint for identification and quantification.

A classical quantitative technique in which a solution of known concentration (titrant) is gradually added to a solution of unknown concentration (analyte) until the reaction reaches its equivalence point, determined by an indicator or instrumental endpoint detection.

The process of establishing the relationship between instrument response and known analyte concentrations by analyzing a series of standards. The resulting calibration curve allows quantification of unknowns by interpolation.

Techniques that measure electrical properties of a solution (potential, current, charge, or conductance) to obtain analytical information. Major subtypes include potentiometry, voltammetry, coulometry, and conductometry.

A classical quantitative method in which the analyte is converted into an insoluble precipitate of known composition, which is then filtered, washed, dried or ignited, and weighed to determine the amount of analyte.

A group of techniques (atomic absorption, atomic emission, and inductively coupled plasma spectroscopy) that measure the absorption or emission of light by free atoms or ions, used primarily for elemental analysis of metals and metalloids.

The systematic process of demonstrating that an analytical method is suitable for its intended purpose by evaluating parameters such as accuracy, precision, linearity, range, limit of detection, limit of quantitation, specificity, and robustness.

The critical first steps of any analysis: collecting a representative sample from the bulk material and converting it into a form suitable for the chosen analytical technique. Errors at this stage can invalidate all subsequent measurements.