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Storage for the determination of trace elements

In contrast to the major components and nutrients, trace elements in seawater are extremely dilute analytes. Even minor absolute losses or sample contamination in the ultratrace range may significantly influence the results. In fact, the surface area of a container can be large enough to remove a trace element from solution completely by adsorption. Therefore, if possible, determination of trace elements should be performed on board ship within a few hours after collection. Relatively simple and fast electrochemical methods are now available for reliable on-board determinations of a number of trace elements if special conditions are met (see Chapter 12). [Pg.38]

If the speciation of trace elements is to be studied, measurements must be performed immediately after sampling. If for some elements minor changes in original speciation are acceptable, then the samples should be stored unacidified but frozen (see also the storage of As, Sb and Ge outlined in Chapter 12) to preserve as much as possible the original distribution of species. A few studies indicate, however, that some metal associations with humic substances might be stable even down to pH 2.3 (e.g., Helmers, 1994). [Pg.39]

An alternative storage procedure for a number of elements is their separation from seawater by ion-exchange resins e.g., Chelex 100) on-board, with subsequent elution in onshore laboratories (see Chapter 12). This procedure has the advantage of small sample quantities to be stored and can be carried out on board smaller vessels if a clean bench is available to reduce contamination risks. [Pg.39]

Helmers, E., Mart, L., Schrems, O. (1991), FreseniusJ. Anal Chem., 340,580. [Pg.39]

Howard, A.G., Statham, P.J. (1993), Inorganic Trace Analysis. Chichester John Wiley Sons, 1993. Hurd, D.C., Spencer, D.W., (Eds.) (1991), Marine particles Analysis and characterization. Washington American Geophysical Union, Geophysical Monograph 63. [Pg.39]


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