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A Turbidimetric Potassium Determination Affected Little by Temperature
Author(s) -
Olson R. V.
Publication year - 1953
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1953.03615995001700010004x
Subject(s) - potassium , sodium , photometer , chemistry , blank , chromatography , analytical chemistry (journal) , materials science , optics , composite material , organic chemistry , physics
A modification of the turbidimetric cobaltinitrite method for determining potassium is presented. The method is applicable to use in routine soil testing laboratories and has been in use for 3 years in Kansas county laboratories. The method is not appreciably affected by temperature changes over the temperature range of 15° to 35° C but is subject to errors at temperatures greater than this. Comparisons of the effect of temperature on this method with two methods now in common use showed it to be subject to less error. The effects of temperature have been minimized by modifying the usual techniques in two ways: (1) by selecting the proper wave length and adjusting the photometer with a blank solution to prevent measurement of the amount of color in the solution phase, and (2) by introducing sodium cobaltinitrite powder directly into the potassium solution‐alcohol mixture, resulting in slow formation of the potassium precipitate.