Introduction - Determination of Anions in Natural and Treated Waters - page 41

Advanced gradient system
For optimum functionality in automated systems designed primarily for reversed-phase
chromatography and other gradient techniques, the LKB advanced-gradient system is
recommended (Fig 1.3(c)). Key features include the following:
• a configuration that provides the highest possible reproducibility of results;
• a two-pump system for highly precise and accurate gradient formation for separation of
complex samples;
• separation of complex samples;
• full system control and advanced method development provided from a liquid
chromatography controller;
• precise and accurate flows ranging from 0.01 to 5ml min − 1 .
This system is ideal for automatic method for development and gradient optimisation.
The inert system
By a combination of the use of inert materials (glass, titanium, and inert polymers) this
system offers totally inert fluidics. Primary features of the system include (Fig. 1.3(d)):
• the ability to perform isocratic or gradient elution by manual means;
• full system control from a liquid chromatography controller;
• precise and accurate flows from 0.01-5mL min −1 .
This is the method of choice when corrosive buffers, eg those containing chloride or
aggressive solvents, are used.
Chromatographic detector
Details concerning the types of detectors used in high-performance liquid
chromatography are given in Table 1.8. The most commonly used detectors are those
based on spectrophotometry in the region 185-400nm, visible ultraviolet spectroscopy in
the region 185-900nm, post-column derivativisation with fluorescence detection (see
below), conductivity and those based on the relatively new technique of multiple
wavelength ultraviolet detectors using a diode array system detector (described below).
Other types of detectors available are those based on electrochemical principles,
refractive index, differential viscosity and mass detection.
Electrochemical detectors
These are available from several suppliers (Table 1.8). PSA supply the model PS 5100A
coulochem multi-electrode electrochemical detector. Organics, anions and cations can be
detected by electrochemical means.
The Gilson Aspec automatic sample preparation system is a fully automated system for
solid-phase extraction on disposable columns and on-line high performance liquid
chromatography analysis. The Aspec system offers total automation and total control of
the entire sample preparation process including clean-up and concentration. In addition,
Aspec can automatically inject prepared samples into on-line high performance liquid
chromatographic systems.
Aspec is designed to receive up to 108 samples. The system is compatible with most