First the mercury contained in the sample is stripped with an air stream and sucked into an optical cell made of fused silica. There the quantitative determination of mercury is obtained by measuring UV absoption at a wavelength of 254 nm. This method is commonly known as the "cold vapor atomic absorption spectroscopy

(CVAAS)" method.

In contrast to a typical multielement AAS the LabAnalyzer 254 is specially designed for elemental mercury. This allows top performance in analytical appliacations. The use of a specially developed highly stable mercury lamp in connection with thermostat-controlled UV sensors results in a detection limit of a few ppt of mercury.

Memory effects are minimized and a high sample throughput is possible thanks to specially selected materials for sample gas conducting components and heating of the optical bench.

The LabAnalyzers 254 is operated with a waterproof membrane keypad and a graphic LCD. Handling is extremely easy. The LabAnalyzer 254 does not require auxiliary gases. The carrier gas flow required for the analysis is generated by a built-in membrane pump which is maintenance-free and has a long service life.

The sample is pipetted into an extractor and mixed with 0.5 ml of reducing agent, for example tin-II-chloride solution. The extractor is then connected to the LabAnalyzer 254 and the measurement is started by pressing a button. After 60 to 90 sec the result appears on the display and the device is ready for the next analysis. The system does not need to be purged, and the zero point is calibrated automatically before every measurement (auto zero).

The mercury cannot escape into the working environment, as any free mercury is collected in a sulfurized activated carbon cartridge. If the cartridge needs replacement a message appears on the control panel. The analyzed sample no longer contains any mercury.

Even with high concentrations no lengthy purging time is required. After every measurement a zero calibration is carried out automatically (auto zero). The typical duration of a measurement including purging is 60 to 100 sec. over the entire measuring range.

During the entire measurement the measuring signal is continuously displayed on the graphic display. An acoustic alarm is sounded to indicate the end of the measurement. In addition to the measurement signal curve over time, the peak value and the mercury concentration are indicated.

Together with the data necessary for quality assurance the results of the analyses are stored in the RAM of the built-in computer. They are available at any time, and an automatic print-out of this data is also possible.