Rapid micro determination of sulfur in organic compounds

Abstract

Samples were decomposed by the flask-combustion method and the obtained sulfate was conductometrically titrated. Barium acetate was recommended as the titrant, whereby the appropriate concentration of iso-propyl alcohol in the titrant was 45% with optimum pH of 6∼7. The lower limit of determination under these circumstances was 504 μg sulfate with its lowest concentration of 16.8 μg/ml. Na+, Fe2+, Cl- and NO3- in their amounts usually met in the micro-elemental analysis did not interfere with the titration. Ca2+ was removed by the cation exchange resin treatment, and the interference of phosphate was eliminated by the treatment with silver nitrate, unless its amount was too large. In the actual titration, an automatic titrator (Potentiograph E-336 with Conductoscope E-165) was utilized, and the sulfur was determined in only 20 min. with an error of ±0.3%. © 1964, The Japan Society for Analytical Chemistry. All rights reserved.