| Abstract: | Flow-injection analysis is a precise, elegant, and economical technique, but its most troublesome feature is the mode of injection of the sample slug. We describe an alternative approach in which the sample is aspirated by the sample probe. In the simplest version the probe normally rests in reagent; when sampling is to take place, the pump is stopped and the probe is transferred to the sample container. The pump makes a predetermined angular movement, the probe is returned to reagent, and the pump is restarted. In more advanced versions the same approach is combined with the merging zone technique. The system is economical, precise, and capable of full automation in a multichannel discretionary analyzer. |
