kiloDalton; a thousand Daltons.
knockout Gene targeting; for instance, a knockout mouse is one in which a single gene is inactivated ("knocked out"), leaving other
genes unaffected; provides the best way to delineate the function of a gene.
Limulus amebocyte lysate assay; detects pyrogenic endotoxins using a reagent that was discovered in the blood of Limulus horseshoe crabs.
laminar flow clean air device A clean bench, clean workstation, and wall or ceiling modules or other devices that incorporate a filter and motor blower
for supplying clean air in one direction for a controlled work space; more correctly referred to as "unidirectional airflow,"
which is air flow having generally parallel streams operating in a single direction and with uniform velocity over its cross
Liquid chromatography/mass spectrometry systems; laboratory instruments that combine two popular analytical methods into one piece of equipment.
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 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.
lepidopteran Belonging to a class of insects that includes the butterflies, moths, and skippers. Insect cell culture most often uses cells
from order Lepidopterus.
Leucine; one of over 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.