Chromatography Glossary



A molecule that binds to another molecule. In a binding action, usually the smaller of the two molecules is considered the ligand.

Ligand Exchange Chromatography

Technique where chelating ligands are added to the mobile phase and undergo sorption onto a packing material. These sorbed molecules can then act as chelating agents with solutes. Chelating resins work in a similar fashion; chelating groups are chemically bonded to the polystyrene backbone.

Linear Amplifier

In mass spectrometry, a type of electronic amplifier used in detector signal processing.

Linear Dynamic Range

Refers to the sample concentration range through which a detector produces a linear response.

Linear Gradient

Gradient profile in which the rate on increase of strong solvent is constant.

Linear Range

The range of concentrations injected into the chromatograph which gives a linear calibration curve.

Linear Velocity

The velocity of eluent through the column. Measured by dividing the length of the column by the retention time of a non-retained component (t0) and expressed in cm/s.


Proportionality between the detector response and the amount of sample; a calibration curve (plot) with a slope of 1.0 is the ideal case.

Liquid-Liquid Extraction/LLE

Sample preparation technique in which an immiscible liquid is mixed with the sample/matrix in order to selectively partition the target analyte(s) into one phase, while the contaminants partition into the other phase.

Liquid-Solid Adsorption Chromatography

A chromatographic mode in which retention and separation of sample components is based on competition between analyte molecules and solvent molecules for active sites on the sorbent.

Liquid-Solid Extraction

A sample preparation technique based on the separation mechanisms of liquid-solid chromatography. The intermolecular interactions between sample components, sorbent and solvent are optimized to effect retention of analytes on the solid phase extraction cartridge, followed by elution in a minimal volume of solvent. Two modes of solid phase extraction are trace enrichment and matrix removal.

Load Capacity

The maximum weight of sample that can be injected onto a given column without causing more than a 10% change in retention factor (k').


The amount of stationary phase bonded onto a solid support. In bonded phase chromatography (BPC), the loading is expressed as μmol/m² or %C.


In chromatography, abbreviation of Limit Of Detection. Defined as the sample concentration which gives a peak height equal to three times the peak - to - peak noise. Also called the minimum detectable quantity (MDQ) or minimum detectable limit (MDL).

Logarithmic Amplifier

In mass spectrometry, a type of electronic amplifier used in detector signal processing.

Logical Loss

A term used in Mass Spectrometry for a feature in the mass spectrum that is explainable based on chemical and fragmentation mechanisms.

Longitudinal Diffusion

B-term in the van Deemter equation. Same as Molecular diffusion term.


A piece of tubing in a sample injector that holds the sample to be injected and determines it's volume.

Low Pressure Mixing

Refers to gradient systems that mix the eluents before the pump. (ie., the low pressure side of the pump.) Thus a single pump, often a hybrid dual piston pump, is required to deliver the premixed (variable) composition. An electonic gradient controller opens and closes micro-valves, normally on a time basis, to allow the desired proportion of each solvent to be metered over each pump suction cycle.

Low Vacuum

In mass spectrometry, the pressure region between atmospheric and about 10^3 Torr. This pressure range is achievable by a rough pump.

Lower Control Limit

The lower limit in a control chart indicating when the controlled parameter is out of specification. Usually defined as equal to the mean minus three standard deviations.

Luer Lock

A pressure- locked connection between two devices, e.g., the cartridge end and the outlet tubing, or the syringe body and the needle.

Luer Tip

A standardized adapter such as that on the tip of a syringe barrel that is available in both male and female configurations in order to allow the connection of one device with another.


A support matrix with pores greater than 900Å in diameter.

Macroporous Resins

Macroporous resins are crosslinked ion exchange resins that contain both micropores of molecular dimensions and macropores several hundred Å wide (usually greater than 900Å. They are very porous resins with a large internal surface area which is accessible to large molecules.

Magnetic Sector

A term used in Mass Spectrometry for a mass filter that uses a direction-focusing device to produce a magnetic field perpendicular to the direction of ion travel. For a given field strength, only ions of a given momentum with the same mass to charge ratio will reach the detector opening.


In Mass Spectrometry, a part of the ion source used to collimate a beam of electrons. The magnets are positioned on opposite sides of the ionization chamber. The magnets shape the electron beam and direct ions along an axial path.


A reference substance chromatographed with the sample to assist in identifying the components.

Mass Assignment

The process used to adjust mass spectrometer and/or data system parameters so that the observed mass spectral peaks accurately match the mass of the ion fragments known to be present in a calibration compound.

Mass Calibration

Using a known compound to adjust and calibrate the instrument during tuning.

Mass Detector

Also known as a evaporative light scattering detector (ELSD). The effluent from the chromatograph is passed through a nebulizer where it is converted to a fine mist. The mist passes thorough a heated vaporization tube where the solvent is completely vaporized. Any solute in the eluent is then converted to a cloud of fine particles. Peaks are detected by the light scattered from the solute particles.

Mass Filter

A term used in Mass Specctrometry for part of the mass spectrometer where ions are separated according to their mass-to-charge ratios.

Mass Spectrometer

An instrument that measures atomic or molecular mass. One of the most powerful detectors which can be interfaced with the liquid chromatograph. Not only can a Mass Spectrometer quantitate sample components, it can provide complete structural information to reveal chemical identity.

Mass Spectrum

A plot of ion mass/charge ratio versus intensity. A fragmentation pattern results from the impact upon a given molecule from an ionizing source. The impact produces a family of particles whose mass distribution is characteristic of the parent molecule. Qualitative information is provided by a mass spectrum.

Mass Transfer

The process of solute movement into and out of the stationary or mobile phase. The C-term of the van Deemter equation is referred to as the mass transfer term. The speed of mass transfer is related to the efficiency of the column; the faster the transfer, the more efficient the column. The mass transfer is the most important factor in determining column efficiency. Mass transfer is increased by using small-particle packings, low-viscosity mobile phases, thin layers of stationary phase and high temperatures. The movement of solute molecules between the stationary and mobile phases.

Mass-Flow Sensitive Detector

A device the response of which is proportional to the amount of sample component reaching the detector in unit time.

Mass-Flow Sensitive Detector

A device the response of which is proportional to the amount of sample component reaching the detector in unit time.

Mass-To-Charge Ratio (M/Z)

A term used in Mass Spectrometry for the mass (in daltons) of an ion divided by the number of charges on the ion. In most cases the ion is singly charged and the mass-to-charge ratio value is identical to the mass of the ion in atomic mass units("amu").

Mathieu Equation

In mass spectrometry, a mathematical equation that predicts the regions of stability for an ion in a quadrupole.


The physical characteristics or state of the sample, eg., pharmaceutical formulation, extraction, serum, urine.

Matrix Interference

The influence of the sample matrix or sample components upon the ability to qualitatively identify and quantitatively measure compounds in a given sample.

Matrix Removal

A sample preparation technique in which undesirable matrix components are extracted by the sorbent while the analyte(s) passes through the column in the sample solution.

Matrix Spike

An aliquot of a sample fortified (spiked) with known quantities of specific compounds and subjected to the entire analytical procedure in order to indicate the appropriateness of the method for the matrix by measuring recovery of the spike.

Minimum Detectable Limit

The sample concentration which gives a peak height equal to three times the peak - to - peak noise. Also called the minimum detectable quantity (MDQ) or Limit Of Detection(LOD).

Mean Pore Diameter

Is a term referring to the average pore diameter of the pores in porous packing. The pore diameter is important as it must allow free diffusion of solute into and out of the pore so that the solute can interact with the stationary phase.

Mean-Free Path

In Mass Spectrometry, the average distance traveled by a molecule in normal kinetic motion before it encounters another molecule.


Methyl Cyanide, also known as ACN or acetonitrile. MW 41.05, Boiling Point 81.60 C, Polarity Index 5.8, Solubility in water miscible in all proportions, UV cutoff 190nm. Common solvent used in reversed phase chromatography.


A unit of pressure; one MPa equals about 10 bar (atmospheres) or 150 pounds per square inch (psi).


Abbreviation of methanol. MW 32.04, Boiling Point 64.7 C, Polarity Index 5.1, Solubility in water miscible in all proportions, UV cutoff 205nm. Common solvent used in reversed phase chromatography.