Abstract
A simple and rapid method for measuring tar inriver sediment has been developed. Two grams of a dried sample passed through a screen of 28 mesh was extracted with a mixed solution of ethanol and benzene (1 : 4, v/v) for 10 min by using a ultrasonic apparatus. After centrifugation, a known volume of the extract was transferred into a short-neck kjeldahl flask, and the extract was evaporated to less than one ml under a reduced pressure. The concentrate was transferred to a test tube of a known weight, evaporated near dryness under a reduced pressure, and dried up by standing it in room temperature. After standing the test tube in a desiccator for 24 hrs, the residue was weighed on a balance. Tar contents of 25 river sediments obtained by this method were in good agreement with those by a soxhlet extraction method. Coefficient of variation of tar contents in this method was from 1.3 % to 4.7 %. This method shows the following advantages over a soxhlet extraction method : extraction time is short; tar is extracted with a small volume of solvent; and many samples can be treated simultaneously.
