Liquid Chromatography - The Fixed Wavelength Detector 1

The 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 17.

 

Figure 17. The Fixed Wavelength UV Detector

The detector consists of a small cylindrical cell (2.0 to 10.0 ml 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 photo electric cell. In the fixed wavelength detector the wavelength of the light depend on the type of lamp that is used. There are a number of lamps available the at provide of wavelengths ranging from about 210 nm to 280 nm. The lamps that are commercially available at the time of writing this book are as follows:-

Lamp Type

Emission Wavelengths

Mercury Vapor Lamp

253.7 nm

Zinc Vapor Lamp

2123.9 nm and 307.6 nm

Cadmium Vapor Lamp

228.8, 326.1,340.3, and 346.6 nm