Determination of strongly reducing substances in sediment.
Reducing substances in sediments play an important role in regulating the chemical and biological status of the sediment. Strongly reducing substances are the most active part of them, and are difficult to measure directly. In this work, we have developed a method for their determination based on the oxidation by Fe(III). Then, the produced Fe(II) was determined by colorimetry, using 2,2'-bipyridine as the chelating agent. Prior to determination, these substances were extracted from the sediment by M acetic acid. The whole process was carried out in a closed system, so that oxidation of Fe(II) and reducing substances by atmospheric oxygen could be avoided. The calibration curve between absorbance and Fe(II)-chelate concentration in extract was linear. When ascorbic acid was added to the extract, the recovery was larger than 94.0%. The effect of surplus Fe(III) on the result was discussed. With the proposed method, the concentration of strongly reducing substances in sediment samples from Dianchi Lake of China was measured with good reproducibility.
Li
Qingman
Q
Department of Chemistry, Nanjing University, Nanjing 210093, PR China. liqm@nju.edu.cn
Bi
Shuping
S
Ji
Guoliang
G
D002614:Chelating Agents / Q000032:analysis / Q000737:chemistry; D002681:China; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000032:analysis* / Q000737:chemistry; D010084:Oxidation-Reduction; D015203:Reproducibility of Results
D002614:Chelating Agents; D007501:Iron