The ECDis one of the most sensitive of GC detectors, especially if argon
replaces nitrogen as the carrier gas, but traces of air, oxygen or water in the
gas, liquid stationary phase bleeding from the column or residues from
halogenated solvents used in sample preparation are detrimental to its
performance, and its linear range is very limited. Quantitative analysis is
difficult because response is dependent on solute structure.Components of a modern gas chromatograph include a dedicated microcom-
puter with analogue-to-digital convertor(ADC) to digitize the detector signal,
and software packages that perform the following functions (see also Section H):● Facilitate the setting and monitoring of instrument parameters, i.e.:
(i) carrier gas flow;
(ii) oven temperature and temperature program;
(iii) automated sample injection;
(iv) detector gases, mode and sensitivity.
● Display of chromatograms and other information in real time with high-
resolution color graphics, and electronic integration of peak areas (instru-
mentation may include a separate computing integrator).
● Recording and processing of retention and calibration data, calculations and
statistical assessment of results.
● Storage and retrieval of method parameters for specific analyses.
● Diagnostic testing of the condition and performance of instrumental compo-
nents.
● Communication with the database of a laboratory information and manage-
ment system(LIMS) for further data-processing and archiving of results.Instrument
control and data
processing
148 Section D – Separation techniques