Title: Chemical analysis with coated, light waveguide under humidity control

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Claims: What is claimed is:

1. In a method for detecting a first material wherein there are the steps of

(a) exposing an elongated waveguide having on a longitudinal peripheral surface of said waveguide a second material providing for multiple internal reflections of light through said coating material, to an unknown material which may contain said first material, said second material upon being contacted with said first material selectively combines in in a water sensitive reaction with said first material to measurably change the light transmitting capabilities of said waveguide;

(b) transmitting light through said waveguide after exposure in step (a); and,

(c) detecting the light transmitted in step (b) as a measure of said first material, the improvement comprising increasing the sensitivity of detection in step (a) by maintaining said waveguide in an environment of substantially constant relative humidity at which said reaction is not appreciably affected by changes in ambient relative humidity.

2. A method according to claim 1 wherein said first material comprises gaseous ammonia.

Other info:

Inventors: David, Donald J. (Centerville, OH, US)
Willson, Michael C. (Waynesville, OH, US)

Application Number: 781596
Filing Date: 1977-03-28
Publication_date: 1978-08-15
Assignee: Monsanto Research Corporation (St. Louis, MO)
Primary Class(es): 436/113 422/83, 436/100, 436/121, 436/122, 436/133, 436/165
Other Classes:
US Patent Ref:

3704060	Nov, 1972	McNaney	350/336.
3904371	Sep, 1975	Neti	23/232.
3960495	Jun, 1976	Tantram	23/232.
4003707	Jan, 1977	Lubbers	23/232.

Other Refs:
Primary Examiner: Marantz, Sidney
Assistant Examiner:
Attorney: Stevens; Bruce