Christiansen detector

This device has been manufactured by GOW-MAC Inc., who claimed it had a sensitivity of 1 x 10 refractive index units. This would be equivalent to a sensitivity of 9 x 10 g/ml of benzene (refractive index 1.501) eluted in w-heptane (refractive index 1.388). The cell volume was kept to 8 pi, a little large for modern sensors but small enough to work well with normal 4.6 mm I.D. columns. Different cells packed with appropriate materials were necessary to cover the refractive index range of 1.31 to 1.60. A diagram of the Christiansen detector is shown in figure 5. 

Gow-Mac has recently marketed a refractometer which is based on the Christiansen effect . The system consists of a sample flow cell which is packed with a solid material having the same refractive index as the mobile phase. Visible light is therefore transmitted directly through the cell. When a solute enters the cell, the refractive index of the mobile phase alters, causing a change in the quantity of transmitted light which reaches the detector. A variety of solid materials is available for use with a large number of solvent systems. 

Christiansen et al. developed an HPLC method of screening Norwegian mushrooms for the presence of psilocin and psilocybin. The alkaloids were extracted from powdered dried mushrooms with methanol which contained 10% IN ammonium nitrate (Christiansen et al. 1981). The recovery of psilocybin was at least 98%, whereas the recovery of psilocin was not reported. The analytes were separated on an unmodified silica column using an alkaline eluent (Christiansen and Rasmussen 1983). After separation, the effluent was split to UV and FL detectors, and an EC detector was connected downstream of the UV detector. Psilocybin was identified and determined by both UV and FL detection. EC was optimized for psilocin due to its low concentration in the mushroom. The detection limit of psilocin by EC was 100 and 250 times lower than by UV and FL, respectively. Psilocybin gave only a small response by EC, since it is optimally oxidized at a higher potential. By this method, it was found that Conocybe cyanopus and Pluteus salicinus also contained psilocin and psilocybin (Christiansen et al. 1984). 

Christiansen JA, Hevesy G, Lomholt S (1924) Recherches, par une m hode radiochimique, sur la circulation du bismuth dans Torganisme. Compt Rend 178 1324 Cleveland BT, Daily T, Davis R Jr et al (1998) Measurement of the solar electron neutrino flux with the Homestake chlorine detector. Astrophys 1496 505... 

Different cells packed with appropriate materials were necessary to cover the refractive index range of 1.31 to 1.60. A diagram of a Christiansen effect detector is shown in Figure 6. 

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