Abstract
It is known that Cl ion in sea water diminishes the phospho-molybdenum blue on the phosphate determination by ATKINS∋method, so the correction must be made on the value obtained. These correction factors are varied by the authors from 1.00 to 1.35. This variation shows that there might be some other substances which disturb the colorimetry. It has already been pointed out by some investigators that these substances are colloidal iron, cupper and colloidal parts of mud. Some experiments were made on this problem, and it was found that nitrite in the water, too, diminishes the phosphomolybdenum blue and disturbs the determination.
It is often observed that the phosphate content of the water added with preservatives increases in the time of storage since bottled to analysis. Phosphomonoesterase, which liberates ortho-phosphate from organic phospho-rous compounds, is detected in the sea water and plankton tow water. The action of that enzymes in the water containing plankton or other organisms, is suggested one of the reasons of this phenomenon.
