Page 173 - Illustrated Pocket Dictionary of Chromatography

SEPARATION FACTOR, a 175

semipreparative HPLC Uses columns that have inner diameters
of 6–20mm and injection masses in the 10 to 1000-mg range. This
technique is used to conduct sample fractionation and purification on
a laboratory scale.

sensitivity The slope of the detector response, R, versus the
analyte concentration, C, i.e., sensitivity =DR/DC for concentration-
based detectors and R versus mass flux, m, i.e., sensitivity =DR/Dm,
for mass-sensitive detectors. High sensitivity allows for better differ-
entiation between analyte concentrations but often results in a narrow
working range. Conversely, a low-sensitivity method generates a wide
working range but a decreased ability to differentiate concentrations.

The slope of the response versus concentration curve is the sensitivity of a tech-
nique. High-sensitivity analyses typically have linear responses over narrower con-
centration ranges. Lower-sensitivity analyses have linear responses over wider
concentrations ranges, but differentiation between concentrations becomes more
difficult because detector error is often more significant in the determination. The
best working area is at the highest sensitivity possible while still maintaining a
linear curve that extends past the working and calibration curves.

separation factor, a The ratio of the capacity factors for two adja-
cent peaks, where k¢ 2 is the later-eluting peak: