Page 25 - Illustrated Pocket Dictionary of Chromatography

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“octadecyl” bonded-phase material. The stationary phase is often
identified by its prevalent functional group, hence “octyl” rather than
“dimethyloctyl.”

BPC (bonded-phase chromatography) A liquid chromato-
graphic technique based on the use of support materials that are
chemically modified to produce stationary-phases of varying polarity
and functionality. Bonded phases run the range from reversed phase
to normal phase to chiral to affinity, etc.

breakthrough Typically used in flow injection analysis and solid-
phase extraction, breakthrough represents the time (or volume) when
a defined percentage (e.g., 1%) of the solute elutes from the column.

breakthrough volume For a defined system and set of operating
conditions, the volume of eluent needed to elute a defined percentage
of solute (e.g., 1%). This parameter is particularly important for
flow injection analysis (determines the time between injections) and
solid-phase extraction (determines the fraction to discard or collect).
It is a function of system volume, flow rate, and the retention of the
analyte.
Brockmann activity scale Used in the characterization of
alumina support materials and based on the amount of water
adsorbed to the support material.

Brockmann Activity %Added Water %Water Total

I 0 ~2
II 3 ~4.5
III 6 ~7.5
IV 10 ~11.5
V 15 ~16.5

brush phase See monomeric bonded phase.

B term The component of the van Deemter and Knox equations
that describes the impact that longitudinal diffusion has on the band
broadening process.
buffer Used to minimize changes in a critical solution parameter
when the solution is subjected to change. A typical buffer application