Teledyne 340CF ELSD, Инструкция по установке и эксплуатации, Страница: 15 / 46

2-1
340CF ELSD
Section 2 Introduction
2.1 Overview
ELSDs are near universal detectors, primarily used in High Per-
formance Liquid Chromatography (HPLC) though they have
been used successfully in other types of chromatography as well.
Their principal requirement is that the analyte be less volatile
than the mobile phase. An ELSD cannot detect highly volatile
analytes. However, most analytes of interest are less volatile
than the eluting solvents.
Evaporative light scattering detectors complement ultraviolet
(UV) detection because they can detect most analytes, even those
that do not absorb UV radiation, are stable during gradient elu-
tions, and respond to the relative mass of the analyte – an
important feature that is useful when detecting unknown mate-
rials. The ELSD is superior to the refractive index detector
(RID), it can be used with gradient chromatography, it is not sus-
ceptible to ambient temperature changes, and it does not produce
negative peaks, which can be difficult to quantify. The ELSD does
not respond to the mobile phase disruption seen as solvent front
peaks in the void volume with UV and RI detectors, so early
eluting analytes can be easily quantified. Mass spectrometry
(MS) detection is also a universal detector, but its high cost and
complexity have kept it from being widely used.In fact, the oper-
ation requirements of MS closely match that of the ELSD. This
allows the less expensive and complicated ELSD to be used as a
method development detector for methods to be used on the MS
systems.
2.2 Servicing
A periodic maintenance kit is available from Teledyne Isco (part
#60-5247-024). The kit contains instructions, parts, and
equipment for servicing the ELSD. Contact the factory for more
information.
The ELSD should be cleaned and calibrated once a year by a
qualified technician. Use water with a mild detergent, or for
tougher stains, use Isopropyl Alcohol (IPA).
2.3 Operating Principles
The ELSD employs a unique method of detection. The process
involves the nebulization of the column eluent, transforming it
into an aerosol cloud. As this cloud travels through a heated zone
within the instrument, the more volatile mobile phase evapo-
rates, leaving a smaller cloud of analyte particles. These particles
pass through a beam of light, scattering some of the light, which
is converted into an electronic signal.