Comparison of the different methods for the recovery of suspended matter from estuarine waters: Deposition, filtration and centrifugation; Consequences for the determination of some heavy metals

Suspended materials are the main scavengers of particulate metal elements in estuaries. Because metal content evolves extensively in time and space, many samples are required to gain an understanding of this problem. The recovery of suspended matter raises many difficulties according to the environment and to the nature of the analysis to be made.

The authors have compared the advantages and disadvantages of the three most common methods of recovery: deposition, filtration and centrifugation used on samples from the Gironde estuary.

It appears that filtration is not the only usable method, in spite of the certainty that recovery is best by this method. On the one hand, recovery by deposition is satisfactory in cases of floculation and high turbidity; on the other hand, in zones of low turbidity, centrifugation—because of rapid functioning and good recovery rate—is reliable enough for the determination of several elements.