Sequential injection standard addition for on-line measurement of mercury in the river Elbe

The improvement of reliability by a sequential injection procedure for on-l ine standard addition is described. This procedure is applied to a monitor for on-line determination of mercury in river water at concentrations from 20 to 1000 ng/l. The flow injection cold vapour atomic absorption spectrome try measurement include an on-line digestion by BrCl and UV-irradiation. Th e instrumental arrangement is controlled by the home-made software "FIMS-Ma ster" (programmed based on LabView((R))). During standard addition period, a selector valve is switched that alternately for 1 s standard (500 and 100 0 ng/l, respectively) and for 9 s sample is transported to the injection va lve. Standard acid sample are mixed on the way to the injection valve by di spersion. The instrument has been tested at the German monitoring stations of Schnack enburg and Schmilka at 474.5 and 4.0 km from Czech border, respectively. De tails are published at the web: http//www.rzbd. fh-hamburg.de/similar to pr mercol. (C) 2001 Elsevier Science B.V. All rights reserved.