Time-integrated methods for autonomous, in situ sampling of dissolved trace materials in open ocean, coastal and inland waters
article
A preconcentration step is usually required for the determination of organic and inorganic microcontaminants in natural seawater. Due to the low concentrations of these contaminants large sample volumes have to be used, which usually represent a single point in time and space. There is an urgent need for time-integrated in situ sampling methods to yield information on trends in changes of the level of microcontaminants. Methods have recently been described by which the sample is passed first through a filter and subsequently through an adsorption column. In situ samples of dissolved metals may be taken over a period of several hours using a battery operated instrument. A serious disadvantage of this approach is the filtration step, which may influence the composition of the sample. Other drawbacks are the risk of blockage of filter and column, and the limited operating time (several hours) as a result of the large amount of energy consumed by the pump equipment due to the large pressure drop over the column. An entirely new concept of trace enrichment is applied in the approach presented here. The preconcentration is realized on an adsorbent operated as a fluidized bed (patent pending) instead of on a normally packed adsorption column. In this system the dissolved contaminants are adsorbed by the bed while the particulate matter present in the sample is transported through the column without interaction with the adsorbens. Hence, no filtration of the seawater is needed before preconcentration. The transportation of the sample through the fluidized bed is almost without restriction. Therefore even a battery operated instrument can collect samples over a period of several weeks.
Topics
TNO Identifier
231659
ISSN
02731223
Source
Water Science & Technology, 24(10), pp. 283-284.
Pages
283-284
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