The Determination of Nitrate in the Sea by Means of Reduced Strychnine

Abstract

The recent criticism of Thompson and Johnson (7) of the method of determining nitrate in the sea by means of reduced strychnine is held to be unsound. Preparation of the reagent given due care and pure materials has offered little difficulty. A possible method for the preparation of nitrate-free sulphuric acid is outlined. The effect of iodate in concentrations likely to be met in the sea is negligible. Interference by organic material has been avoided by first centrifuging all samples obtained during periods of plankton activity. The relative intensity of colour given by nitrate and by nitrite nitrogen is discussed.