Page 134 - Illustrated Pocket Dictionary of Chromatography

N

narrowbore Columns that have an inner diameter of approxi-
mately 2–4mm are classified as narrowbore columns. The packing
material used in narrowbore columns typically ranges from 2 to 5mm
in diameter and the lengths range from 3 to 10cm. Flow rates used
range from 0.3 to 1.5mL/min.
nebulizer Used to turn a liquid flowing stream into a uniform dis-
persion of small droplets (i.e., aerosol) that ultimately enter the detec-
tor. Nebulizers are found at the interface of a column effluent and the
detector inlet. Two types of detectors that utilize nebulizers are mass
spectrometers and evaporative light scattering detectors.

net retention volume, V N Calculated from the adjusted reten-
tion volume, V R¢ and the compressibility factor, j:

V N =¥ V R ¢
j
nitro-bonded phase Nitro bonded phases range from alkyl- to
phenyl based. The phenyl based may have one or more substituted
nitro group. The advantage of this type of column is that the p-
electron acceptor characteristic of the NO 2 group gives unique sele-
ctivity to highly conjugated and aromatic compounds.

R' R'
Surface Si O Si (CH 2 ) n NO 2 Surface Si O Si CH 2 CH 2 CH 2 NO 2

R R
NO 2
R'
Surface Si O Si (CH 2 ) n
R Nitro bonded phases
n = 0-3
NO 2

Illustrated Pocket Dictionary of Chromatography, by Paul C. Sadek.
ISBN 0-471-20021-2 Copyright © 2004 John Wiley & Sons, Inc.
133