Chemistry: physical processes – Physical processes – Crystallization
Patent
1978-12-12
1981-02-03
Marcus, Michael S.
Chemistry: physical processes
Physical processes
Crystallization
116206, 422 56, 422 58, 422119, G01N 2106
Patent
active
042485975
ABSTRACT:
A novel depletion indicator (time watch) for removable substances containing acid or basic groups is disclosed, together with a novel method of use therefor. The removable substance of a predetermined concentration comes into contact with a suitable pH color indicator that can change color at a predetermined pH range within a much larger measurable pH range, which color change occurs as the concentration of the removable substance diminishes by passing through a permeable film containing both the removable substance and the pH color indicator.The color change occurs at a predetermined time, e.g., the same time that the active ingredient has diminished to the point it is determined to be inactive.
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patent: 4195058 (1980-03-01), Patel
Akzona Incorporated
Falk Robert H.
Marcus Michael S.
Wendel Charles A.
Young Francis W.
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