Continuous-flow system for the accurate determination of low concentrations of ammonium ions using a gas-permeable poly(tetrafluoroethylene) tube decontaminator and an ammonia gas-sensing membrane electrode
In the past decade, there have been extensive advancements in enzyme electrode technology. This paper reviews the technology, historical development and potential and current applications of enzyme electrodes in the food industry. Proper choice of enzyme, electrode and immobilization techniques are considered. An overview of potentiometric, polarographic and gas-sensing membrane electrode methods is provided. A discussion of the initial development of a variety of procedures for measuring glucose, using an assortment of electrodes and immobilization techniques is also included. Some electrodes for carbohydrate and amino acids analysis and other analytical applications for the food industry are listed as well as a number of commercially available techniques.
Abstract
An automated continuous flow procedure is described that improves the cost effectiveness and precision of AOAC methodology for multiresidue pesticide determinations in nonfatty foods. Individual modules capable of performing automated solvent partitioning and automated column chromatography were constructed and integrated into a continuous flow system. Data are presented comparing the recoveries and precision for the determination of 8 pesticides (aldrin, dieldrin, p,p’ - DDT, ethion, heptachlor epoxide, lindane, parathion, and ronnel) partitioned from 2 food crops (spinach and tomatoes) by both the manual and automated procedures.
Abstract
We describe routine methods for determining glucose in plasma with use of aldehyde dehydrogenase or glucose oxidase-aldehyde dehydrogenase immobilized in a nylon tube that is integrated into a continuous-flow system. Although the coupled-enzyme nylon-tube reactors require the presence of a third enzyme, catalase, in solution, the kinetics are not so complicated as to preclude reliable routine determination of glucose at very low cost. Precision is good, and results correlate well with those by the method involving glucose oxidase in solution. More than 3000 tests may be carried out with one reactor. The immobilized enzymes are stable for several months at 4 degrees C when not in use.
Determination of manganese at trace levels in natural waters with continuous flow system utilizing on-line cation-exchange separation and catalytic detection.