Mechanism of porous core electroosmotic pump flow injection system and its application to determination of chromium(VI) in waste-water.

An electroosmotic pump flow injection system is introduced in this paper. According to electroosmotic theory, the pump's properties were described. A large flow range (mul min(-1)-ml min(-1)), moderate carrier pressure (0.15 MPa), reduced performance voltage (500 V) and stable flow rate (RSD3.0% in 4 h) are the main properties of the pump. NH(4)OH (0.35 mM) was used as carrier for improving the pump's flow stability. The electroosmotic efficiency of the pump's medium, porous core, can be recovered and regenerated. A sandwich zone was used for sample and reagent introduction in order to adapt to the pump performance. Flow injection-spectrophotometry was employed for the determination of Cr(V…

Synaptic release of zinc from brain slices: factors governing release, imaging, and accurate calculation of concentration.

Cerebrocortical neurons that store and release zinc synaptically are widely recognized as critical in maintenance of cortical excitability and in certain forms of brain injury and disease. Through the last 20 years, this synaptic release has been observed directly or indirectly and reported in more than a score of publications from over a dozen laboratories in eight countries. However, the concentration of zinc released synaptically has not been established with final certainty. In the present work we have considered six aspects of the methods for studying release that can affect the magnitude of zinc release, the imaging of the release, and the calculated concentration of released zinc. We…

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