465. tandem quadrupole mass spectrometry A quantitative tandem mass spectrometer consists of two quadrupole mass spectrometers in series, with a (non-mass- resolving) radiofrequency (RF)-only quadrupole between them to act as a cell for collision-induced dissociation. The first (Q1) and third (Q3) quadrupoles serve as mass filters. Precursor ions selected in Q1 are dissociated in the collision cell in the presence of an inert gas such as Ar, He or N2. Resulting fragments are passed through to Q3 where they may be filtered or scanned. This configuration is sometimes referred to as a triple quad mass spec and is often abbreviated QqQ.
466. target Biological molecule or process with which a drug (or compound) is assumed to interact.
467. target candidate Biological molecule or process with a strong therapeutic potential, for which the activity and specificity of chemical entities have been optimized.
