PH measurement utilizing a light source

• US 5,708,275 A
• Filed: 06/07/1996
• Issued: 01/13/1998
• Est. Priority Date: 06/07/1996
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Rhodes, Michael L.
• Primary Examiner(s): Porta, David P.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US08/660,140
• Time in Patent Office: 585 Days
• Field of Search: 250/461.1, 250/459.1, 250/252.1 A, 356/318, 356/317, 162/49
• US Class Current: 250/461.1
• CPC Class Codes: G01N 2021/6417 Spectrofluorimetric devices
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/64 Fluorescence; Phosphorescence
• CPC Class Codes: G01N 21/80 Indicating pH value

Abstract

The pH of a material containing lignin is determined by directing an ultraviolet light at the material. One of the characteristics of lignin is giving off a fluorescence in response to an ultraviolet light. A monochrometer is used to observe the fluorescence and produces a signal of the intensity of the fluorescent light at varying wavelengths. This signal is displayed on a display means such as a computer screen. Calibration occurs before the pH measurement of the material occurs. The calibration data along with information from the signal is used to calculate the pH of the material. No contact with the material is required in determining the pH of the material.

Claims

1. A method for determining the pH of a lignin containing substance comprising:

a) directing an ultraviolet light at the substance;

b) measuring the intensity of the fluorescence of the substance at particular wavelengths; and

c) determining the pH of the substance with information from a graph.

2. The method of claim 1 further including a step of calibrating a known value of pH prior to step a).

3. The step of calibrating of claim 2 wherein the step comprises:

a) taking a sample of the substance;

b) placing the sample in a solution of a known pH;

c) directing ultraviolet light at the sample in the solution of a known pH;

d) measuring the intensity of the fluorescence of the sample in the solution of a known pH at particular wavelengths;

e) recording information obtained from the intensity measurement;

f) repeating the steps from step b) for different pH values; and

g) using information from the intensity measurement for different pH values to create a graph.

4. The process for calibration of claim 3 wherein steps b) through d) are performed a plurality of times.

5. A method for determining the pH of a lignin containing material comprising:

a) directing an ultraviolet beam at the material;

b) measuring the intensity at particular wavelengths of a fluorescent light beam emitted from the material alter the ultraviolet light beam has hit the material; and

c) determining pH based on the measured intensity at said particular wavelengths.