Page 20 - Illustrated Pocket Dictionary of Chromatography

AZEOTROPE 13

Mathematically,

A x = b a

and x is the % peak height at which the asymmetry was calculated.
Peaks that are perfectly symmetric have A = 1.0, whereas tailed peaks
have A > 1.0 and fronted peaks have A < 1.0.

A term The component of the van Deemter and Knox equations
that describes the impact that eddy dispersion has on the band broad-
ening process.
atmosphere A unit of measure for pressure in a chromatographic
2
system equaling 14.7lb/in (psi) or 760torr.
atmospheric pressure ionization (API) Describes an inlet
ionizer to a mass spectrometer that produces ions at atmospheric
pressure. This basic inlet is coupled with electrospray or chemical
ionization to produce detectable ion fragments.

autosampler An automated injection system that is programmed
to inject a preprogrammed volume of sample (or set of samples) one
or more times. Some autosamplers can dilute and mix samples before
injection. The autosampler takes the place of manual injection and is
advantageous with regard to both precision and efficiency.

average Term used interchangeably with the term mean. The
average is the best mathematical estimate of the value for related
results. See mean.

axial diffusion See longitudinal diffusion.

azeotrope A mixture of liquids that, under constant conditions,
boils at a constant composition (i.e., the liquid and the vapor above it
have the same composition). The azeotropic condition is particularly
useful for the distillation of mixtures to produce constant-ratio
blends.