Diode laser based ketone and aldehyde detection
An apparatus and method for quantifying ketone or alydehyde concentrations of gas. The invention includes passing a gas sample through a reactor and an optical cell and determining a concentration of a gaseous reaction product. Using the concentration of the gaseous reaction product and a predetermined reaction conversion efficiency, a ketone or aldehyde concentration is calculated. This invention can be used for diabetes screening, diabetes maintenance, identification and quantification of ketosis, explosives detection and formaldehyde detection.
1. A method of quantifying ketone or aldehyde concentrations in a gas, the method comprising the steps of:
passing the gas sample through a reactor comprising a solid hydroxylamine hydrogen halide material that reacts with ketones or aldehydes and flowing the gaseous reaction product of the ketone or aldehyde comprising a hydrogen halide into an optical cell;
employing spectroscopy of the gaseous reaction product in the optical cell to determine a hydrogen halide concentration of the gaseous reaction product of the ketone or aldehyde; and
calculating the ketone or aldehyde concentration from the hydrogen halide concentration of the gaseous reaction product and a predetermined reaction conversion efficiency.
2. The method of claim 1 additionally comprising the step of passing the gas sample through a desiccant.
3. The method of claim 1 wherein the ketone or aldehyde comprises acetone.
4. The method of claim 1 wherein the ketone or aldehyde comprises formaldehyde.
5. The method of claim 1 herein the hydroxylamine hydrogen halide material comprises one or more hydroxylamine hydrogen halides selected from the group consisting of hydrogen halide adducts of hydroxylamine (HA) and modified HA materials with oxygen bound substituents.
6. The method of claim 1 wherein the hydroxylamine hydrogen halide material comprises one or more hydroxylamine hydrogen halides selected from the group consisting of hydrogen halide adducts of hydroxylamine (HA) and modified HA materials with nitrogen bound substituents.
7. The method of claim 1 additionally comprising the step of determining the conversion efficiency by initially measuring the gaseous reaction product concentration of an acetone sample of known concentration.
8. The method of claim 1 additionally comprising the step of determining the correction for the sample oxygen content by employing a second desiccant.
9. The method of claim 8 wherein the second desiccant comprises calcium sulfate.
10. The method of claim 1 wherein the employing step comprises employing diode laser spectroscopy.
11. The method of claim 10 wherein the employing step detects HCl at an overtone vibrational transition.
12. The method of claim 11 wherein the employing step detects HCl at approximately 1742.4 nm.
13. The method of claim 1 wherein the method is employed to test for one or more of the items selected from the group consisting of diabetes screening, diabetes maintenance, identification and quantification of ketosis, explosives detection, and formaldehyde detection.
14. The method of claim 1 wherein the hydrogen halide comprises HCl.