Page 45 - Illustrated Pocket Dictionary of Chromatography

40 CONCENTRATION

concentration A unit of measure used to describe the level of
analyte in a sample. Common concentration units are molarity (M):
mol/L; percent (%): g/100g sample; parts per million (ppm): mg/g
sample; normality (N): equivalents/L.

concentration detector A nondestructive detector whose signal
is not affected by the rate at which the sample is passed through it.
For example, a thermal conductivity detector or a UV detector will
register the same response over time if the flow is stopped with the
sample in the detector cell (not necessarily true for a mass detector).
conditioning The term used in GC work to describe the process
that removes adsorbed species (e.g., solvents) from liquid-solid
columns before their use. In HPLC conditioning refers to the process
of equilibrating the column with the mobile phase (e.g., ion-pair
reagents). In GC conditioning involves running the column through a
series of temperature programs that run the entire temperature range
that will be routinely used for analyses. In HPLC numerous column
volumes of mobile phase are passed through the column to condition
it. In SPE conditioning is the step that is used to wet the packing ma-
terial with solvent.
conductivity detector Detector is used in LC work to monitor
the mobility of ions in solution under an applied electrical field. The