Fixed wavelength detector

There are two types of UV detector the fixed wavelength detector and the multi-wavelength detector. A diagram of a fixed wavelength UV detector is shown in figure 5. 

The detector consists of a small cylindrical cell (2.0 to 10.0 pi in volume) through which flows the eluent from the column. UV light from an appropriate UV lamp passes through the cell and falls on a UV photoelectric cell. In a fixed wavelength detector the wavelength of the light... 

By the use of very small sensing cells and electronic systems with very small time constants, the fixed wavelength detector can be designed to give a very fast response at high sensitivity and very low dispersion and... 

Most of these fixed-wavelength detectors can be filtered with a series of filters and or phosphors to detect at wavelengths varying from 280 to 546 nm. Wavelengths in the range 214-229 nm can be monitored by the use of zinc and cadmium source lamps, respectively [46]. 

ASTM has issued a recommended standard practice for testing fixed wavelength detectors in LC it is ASTM 685-79. In contrast to normal practice, they have defined noise in absorbance units (AU) per unit cell length. Otherwise the specifications follow the discussions presented in Chapter 7. 

Clove oil may be obtained from cloves by steam distillation. A number of other spices may be used for extracting other oils (9,10) whose structures are shown in Table 16-1. The essential oils are rich in one main compound and since all components are UV absorbing, the fixed wavelength detector at 254 nm is adequate for detection. Liquid chromatography is a rapid analytical tool in analyzing the essential oils. 

Many organic compounds absorb at 254 nm and hence a fixed-wavelength detector has many uses. However, a variable-wavelength detector can be invaluable to increase the sensitivity of detection... 

The separation of some aromatic hydrocarbons by exclusion chromatography on a very high efficiency column (efficiency 250,000 theoretical plates) monitored by a fixed wavelength detector is shown... 

An interesting example of a very simple fixed wavelength detector suitable for use in preparative chromatography is shown in Figure 4. This detector was invented by Miller and Strusz [7] and originally manufactured by GOW-MAC Instruments. 

Fixed-wavelength detector using mercury, zinc, or cadmium lamps with wavelength selection by filters... 

Verpoorte and Baerheim Svendsen reported the analysis of a series of alkaloids on microparticulate silica gel using diethyl ether or chloroform with various percentages of methanol as mobile phase (Table 2.4). The optimum wavelength of detection for fixed wavelength detectors of 254 and 280 nm for the alkaloids investigated were also reported, c... 

Verpoorte and Baerheim Svendsen2 determined the optimum wavelength of detection for some indole alkaloids for a fixed wavelength detector equipped for 254 and 280 nm detection. 

Fixed-wavelength detectors have disappeared almost completely from the... 

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