SOLVENT DISPLACEMENT OF SEDIMENT INTERSTITIAL WATERS BEFORE TRACE-METAL ANALYSIS

The use of an inert, dense fluorocarbon solvent, FC-78, has been examined for the displacement by centrifugation of sediment interstitial waters. This technique has been compared with centrifugation in the absence of solvent, using both conventional tubes and those with basal collection cups. While the latter are satisfactory for sandy sediments, and the former for fine sediments, solvent displacement offers advantages of increased recoveries after shorter times at low speeds (1600 RCF) with greater ease of operation. The effect of rotation speed on interstitial water recovery was studied. Detailed experiments showed that the solvent did not extract organic compounds or heavy metal species from the interstitial water sample. The method is therefore suitable for the separation of waters for heavy metal speciation studies in both aerobic and anaerobic samples. © 1979.