A multi-ion sensor cell and data-acquisition system for flow injection analysis

The flow-injection system described is used for the determination of four ions simultaneously with detection by solid-contact polymer-membrane ion-selective electrodes. The construction of the flow cell and data-acquisition system are discussed. The programming language FORTH facilitates the fast data acquisition required for flow injection analysis. The utility of the system is demonstrated by applying it to the simultaneous determination of potassium, calcium, nitrated and chloride in soil extracts; the results are compared with standard procedures.     

Untersuchung von Mehl und Getreide

Ohne Zusammenfassung     

Hydrogen bonding control of molecular self-assembly

In this short review we describe approaches to the design and construction of synthetic molecules that mimic the process of self organization that is at the heart of biological complexity. Multi-subunit enzymes, viruses, and higher order DNA structures are formed by the non-covalent association of many smaller components. This self-assembly is controlled by the nature, number and orientation of interacting groups on the surface of the subunits. The central problem lies in overcoming the unfavorable entropy of multi-subunit association by significant enthalpic contribution from the binding of complementary regions on the subunits. We will place particular emphasis on the design of synthetic molecules that use hydrogen bonding interactions to control the formation of aggregates of well-defined structure.     

An automated system for the determination of fluoride

A procedure is reported for the automated determination of fluoride by the method of standard addition. Additions of standard are made via a peristaltic pump and the amounts of standard added are computed from the change in weight of the standard in its container on a digital electronic balance.