Liquid chromatography with tandem mass spectrometry detection a highly selective bioanalytical method using an atmospheric-pressure ionization triple-quadrupole mass spectrometer to measure
the difference in the mass-to-charge ratio of ionized molecules and fragments.
leachable Chemical entity that has the potential to be extracted from a container or closure when exposed to certain conditions of solutions.
Examples of common leachables seen in pharmaceuticals include plasticizers, metals, accelerating agents. Leachables are potential
extractables, and may be evaluated by USP standard tests.
lead 1. A molecule that modulates the activity of a receptor or other target protein. Successful lead compounds become candidates
for drug development. 2. Pb, a toxic heavy metal.
legacy system Old hardware and software applications in which a company has already invested considerable time and money, and which is no
longer state-of-the-art or compliant with regulatory requirements.
Leucine; one of more than 20 naturally occurring amino acids.
ligands Molecules or ions that chemically bind to certain other molecules or ions.
In a binding action, usually the smaller of the two molecules is considered the ligand.
ligase An enzyme that causes molecular fragments (such as DNA, RNA, or peptides) to link together; DNA ligase is used with restriction
enzymes to create recombinant DNA.
light-scattering analysis Analytical method that gives information about the size and shape of molecules based on how they disperse ultraviolet and
Laboratory information management system; computers and software that handle all the data produced by laboratory research and analytical methods.
liquid chromatography Analytical method used to separate mixtures of substances based on the differential distribution of the substances between
a stationary phase (material such as silica gel or silicic acid, usually contained in a column, tube, or capillary) and a
liquid mobile phase (a medium that carries the sample through the stationary phase). This very effective technique can separate
substances that are nearly identical.
liquid fractionation Any of several precipitation or phase-separation methods used to determine the molecular weight distribution of polymers,
based on the tendency of polymers of high molecular weight to be less soluble than those of low weight.
lot A GMP-defined word used to refer to an entire batch of product.
lot release testing Samples from each drug lot (batch) manufactured for clinical trials or (later on) for sale are tested to prove that the batch
meets specifications for content and purity before it is released for use.
luciferase In luminiscent organisms (fireflies, some bacteria, and certain marine organisms), luciferase is an enzyme that acts on species-specific
light-emitting substances known as luciferins. Chemiluminescent assay systems using firefly luciferin-luciferase have detected
small amounts of ATP, the energy-storage compound of a cell. Such systems may serve as alternatives to radioimmunoassays and
lymphocytes White blood cells that produce antibodies.
lyophilization Freeze-drying; a procedure by which a liquid solution is frozen to a glassy state (primary drying), then slightly heated to
remove the unfrozen water by sublimation.
Lysine; one of more than 20 naturally occurring amino acids.
lysed-cell slurry A mixture of the debris formed by disintegrating or breaking cells.
lysis Disruption or breaking of the cellular membrane of cells by chemical, enzymatic or mechanical means. A solution containing
the contents of lysed cells is called a "lysate."
lysosomes Cell organelles containing enzymes, responsible for degrading proteins and other materials ingested by the cell.