Abstract
A new type of automatic amperometric titrator was constructed altering the imput circuit of the automatic recording apparatus for potentiometric titration developed by S. Miyake (Hiranuma Type RAT-1).
Its usable conditions and precisions of analytical results were investigated by means of short-circuit amperometric argentometry of halides using a rotating platinum wire electrode (1000 rpm) and an SCE.
The titration curves obtained by the proposed apparatus were well defined, and it was found to be possible to titrate halides more rapidly, precisely and sensitively than potentiometric titration.
Chloride solution could be rapidly titrated using the proposed apparatus at the concentration range of 10-210-4N. It was determined by the stepwise addition method of titrant (silver nitrate solution) in 9 minutes at 10-2N chloride with the relative deviation (dev.) of + 0.10% and the coefficient of variation (c. v.) of 0.11%, in 5 minutes at 10-3N with +0.13% (dev.) and 0.12% (c. v.), and in 7 minutes at 10-4N with +0.85% (dev.) and 0.43% (c. v.).
On the other hand, it was determined by the continuous addition method of titrant in 2 minutes at 10-2N chloride with -0.05% (dev.) and 0.05% (c. v.), in 1 minute at 10-3N with + 0.06% (dev.) and 0.20% (c. v.), and in 1 minute at 10-4N with +2.36% (dev.) and 0.45% (c. v.).
Bromide, iodide and thiocyanate solutions were titrated respectively by the proposed stepwise addition method of titrant at the concentration range of 10-2 10-5N.
Bromide solution was determined in 6 minutes at 10-2N bromide with -0.01% (dev.) and 0.05% (c. v.), in 3 minutes at 10-3N with -0.05% (dev.) and 0.11% (c. v.), in 4 minutes at 10-4N with +0.27% (dev.) and 0.16% (c. v.), and in 5 minutes at 10-5N with -2.21% (dev.) and 0.87% (c. v.).
Iodide solution was determined in 9 minutes at 10-2N iodide with +0.05% (dev.) and 0.15% (c. v.), in 4 minutes at 10-3N with +0.05% (dev.) and 0.18% (c. v.), in 4 minutes at 10-4N with +0.18% (dev.) and 0.28% (c. v.), and in 5 minutes at 10-5N with + 3.40% (dev.) and 0.53% (c. v.).
Thiocyanate solution was determined in 7 minutes at 10-2N thiocyanate with +0.02% (dev.) and 0.06%(c. v.), in 3 minutes at 10-3N with +0.10% (dev.) and 0.13% (c. v.), in 4 minutes at 10-4N with -0.22% (dev.) and 0.21% (c. v.), and in 5 minutes at 10-5N with -3.13% (dev.) and 1.74% (c. v.).
