Method of discriminating breath contaminants and apparatus therefor

• US 5,048,321 A
• Filed: 05/11/1990
• Issued: 09/17/1991
• Est. Priority Date: 05/11/1990
• Status: Expired due to Term

• Current Assignee: Intoximeters, Inc.
• Original Assignee: Intoximeters, Inc.
• Inventors: Chow, G. Daniel
• Primary Examiner(s): Raevis, Robert
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/522,313
• Time in Patent Office: 494 Days
• Field of Search: 73/23.3, 73/23.2, 422/84
• US Class Current: 73/23.3
• CPC Class Codes: G01N 33/4972 Determining alcohol content for vehicle safety devices B60K28/06

Abstract

A method of discriminating alcohols different from ethanol in breath samples includes sampling voltages from a fuel cell at a rapid rate to establish a curve rising, upon introduction of a sample containing a known amount of ethanol without interferants, from an initial base line to a peak; determining a peak voltage; establishing an end point; determining the area under the curve from the introduction of the sample to the end point, and determing at least two other areas under the curve between the peak and the end point, a peak area, between the peak and a point on the curve relatively near the peak, and a trail area, between the end point and a point nearer the end point than the peak area; introducing to the fuel cell a breath sample that may contain an interferant in the form of an alcohol different from ethanol, and determining the peak voltage, end point, total area, peak area and trail area using the same criteria as were used in determining those pieces of information in connection with the sample containing only ethanol, and comparing the pieces of information electronically.

Claims

1. A method of discriminating alcohols different from ethanol in breath samples comprising sampling voltages from a fuel cell at a rapid rate to establish a curve rising, upon introduction of standard samples containing a known amount of ethanol without interferants, from an initial base line to a peak;

establishing an end point;

determining the area under the curve from the introduction of the sample to said end point, and establishing at least two other areas under the curve between the peak and the end point, a peak area, between the peak and a point on the curve relatively near the peak, and a trail area, between the end point and a point nearer the end point than the peak area;

introducing a sample containing interferants in the form of alcohols different from ethanol and detecting said interferants by establishing differences between the values calculated based on total areas and the peak and trail areas of curves generated in response to said sample containing said interferants and those of said standard sample containing ethanol alone.

2. The method of claim 1 wherein the end point is determined as a function of the voltage rise from the time of introduction of the sample, and the peak and trail area points are determined as functions of the time elapsing between the peak and the end point.

3. The method of claim 1 wherein said rate of sampling is on the order of twenty-five hundred times a second.

4. A method of discriminating breath contaminant in a breath alcohol detecting and measuring device comprising providing a fuel cell and an infra-red cell and means for supplying a breath sample to both, producing and measuring an output from said infra-red cell to establish an apparent breath alcohol measure;

defining a curve of the voltage output of said fuel cell against time, determining the height and position of the peak voltage of said fuel cell output, establishing an end point, measuring a first selected area under said curve from said peak to a first point that is a function of time or voltage following the peak, measuring a second area under said curve from a second point that is a function of time or voltage following the peak, determining the total area under said curve to said end point, and comparing electronically the position of said peak, the total area, the said first area and the said second area with those elements of a curve produced by a known standard sample containing only ethanol in a concentration of a magnitude with that indicated by the output of said infra-red cell.

5. The method of claim 4 wherein the end point is determined as a function of the voltage rise from the time of introduction of the sample, and the peak and trail area points are determined as functions of the time elapsing between the peak and the end point.

6. The method of claim 4 wherein said rate of sampling of the fuel cell is on the order of twenty-five hundred times a second.

7. The method of claim 5 wherein said rate of sampling is on the order of twenty-five hundred times a second.