Topics - LC Detectors
There are a number of LC detectors available but only a relative few are in general analytical use. There are two basic types of LC detectors, ‘bulk property detectors’ and ‘solute property detectors’. The first measures some overall physical property of the column eluent (e.g. the refractive index detector responds to changes in the refractive index of the column eluent). The second respond to some unique property of the solute (e.g. the UV detector that responds to changes in transmitted light through the sample due to UV absorption). In general the ‘bulk property’ detectors are les sensitive than the ‘solute property’ detectors. LC detectors can exhibit a range of sensitivities from 10-6 g per ml (e.g. the refractive index detector) to about 10-10 g per ml (e.g. the electrochemical detector). All LC detectors must have a linear, or close to linear, response over a reasonable concentration range (e.g. three orders of magnitude) for effective use in quantitative analysis. LC detectors must also have relatively small sensor volumes (e.g. 5 micro-liters or less) to prevent peak dispersion and, thus, loss of resolution. The three most commonly used LC detectors are probably the UV absorption detector, the fluorescence detector and the electrical conductivity detector.