Merlin detectors

The interface provides efficient transfer of samples into the Merlin, and, most importantly, a rapid flush-out there is no hold up of mercury (which is a feature of the commonly used atomic absorption techniques). To aid the transfer of mercury vapour, the tin(II) chloride regime is used, together with a gas/liquid separator designed for this task. Mercury is sparged from the reaction vessel into the Merlin Detector. Full automation is provided by using a simple standard DIO card fitted into an IBM compatible computer system with the PSA Touchstone software. This is an easy-to-use menu-driven system which controls the modules used in the instrumentation, calibrates the system, collects, collates and reprints the results, and which finks to host computer systems. 

Basically, these involve the addition of three electronically activated Teflon valves to direct the flow of gas from the gas-hquid separator and over the Galahad instrument. One valve is controlled directly from the vapour generator and this only diverts the argon containing mercury stream over the gold trap for a preset time. The additional two valves are controlled by the Galahad cycle so that the revaporized mercury can be directed to the Merlin detector for measurement. In this manner the flows for preconcentration and the flows for measurement can be optimized individually. The operation of these valves is shown schematically in Fig. 7. IS. 

Godden and Stockwell [11] have described a specific fluorescence detection system to provide fully supported analytical systems for routine analysis of mercury at low levels. The fluorescence approach provides a wide linear dynamic range and extremely low detection limits. P.S. Analytical s Merlin Plus System provides a fuUy automated system which will produce results at a rate of around 40 per hour. This is due to the optimization of the optical design of the detector, coupled to the inherent features of the fluorescence technique. 

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