Spectrometer

摘要

A spectrometer includign a flame atomiser (7) is provided with a sample diluter comprising a mixing vessel (1) having a diluent supply channel (20) and a sample supply tube (10). The mixing vessel (1) has a converging lower portion (2) to which a outlet tube (5) is connected, the outlet tube feeding a mixture of sample and diluent to a nebuliser (47). The sample supply tube (10) is aligned with and spaced from the outlet tube (5). Sample liquid from the sample supply tube (10) passes into the outlet tube (5) as a central core (29) entrained in a sheath of diluent. The sample and diluent flow through the tube (5) with a laminar flow due to the profile of the mixing vessel (1) thus preventing the sample liquid from coming into contact with the wall of the outlet tube (5). Consequently memory effects are reduced. The rate of flow of sample may be controlled automatically by means of a processing and control circuit (40) which has an output (B) which controls the speed of a stepping motor (61) which is arranged to advance a plunger (13) in a syringe (15) containing the sample liquid. The processing and control circuit calculates the absorption or emission of the sample in the atomiser (7) and controls the stepping motor (61) to bring the calculated value within the most sensitive range of the instrument.