Spectrophotometric Determination of Iron at Low Levels in Fresh and Saline Water. Determination of Chemical Oxygen Demand (COD) Employing Ceric Ion as Oxidant.

摘要

An accurate spectrophotometric method has been developed for determination of iron in fresh and saline waters. The method uses the purple-violet colored complex formed by Fe(II) and 3-(2-pyridyl)-5,6 diphenyl-1,2,4-triazine, PDT. It may be used for concentrations of iron as low as one part per billion (ppb). A progress report on the proposed modification of the standard method of determining Chemical Oxygen Demand (COD) using ceric ion as the oxidant indicates the efficacy of the modification for high level COD (>250 ppm) determinations with the saving of one and one-half hours in refluxing time and giving reliable values in saline waters as high as 12,500 ppm Cl(-) without using a conversion factor. Low level COD (5-50 ppm) determinations using ceric ion as the oxidant have not resulted so far in the precision and accuracy desired the saving time and the higher salinity of samples notwithstanding.