NOx monitor using differential mobility spectrometry

Abstract

System for detection and analysis of gas samples in fieldable real-time Differential Mobility Spectrometry (DMS) chemical sensor system which uses non-radioactive ion source for monitoring and detecting NOx emissions; provides reliable methods for detecting and monitoring of anthropogenic sources of NOx; also detection of NO in exhaled breath for patient health diagnosis.

Description

RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application Ser. No. 60 / 418,235, filed Oct. 12, 2002, entitled FAIMS METHOD AND APPARATUS FOR NOX DETECTION AND ANALYSIS, by Raanan A. Miller, Erkinjon G. Nazarov, and Muning Zhong. The entire teachings of the above application are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] The present invention relates to spectrometry, and more particularly, to spectrometer devices providing chemical analysis by aspects of ion mobility in an electric field. [0003] Chemical detection systems are used in a wide array of applications. These devices may take samples directly from the environment, or may incorporate a front end device to separate compounds in a sample before detection. There is particular interest in providing a chemical detection system capable of accurate compound detection and identification, and which may be deployed in various venues, whether in the lab, in the workplace or in ...

AI Technical Summary

Benefits of technology

[0018] The present invention achieves non-radioactive detection and identification of trace amounts of NOx species in a gas sample. In various embodiment of the invention, method and apparatus (i.e., systems) are provided for non-radioactive detection and quantification of NOx in a gas sample. Systems of the invention are compact, with fast response times (msec scale), high sensitivity and specificity, and low manufacturing cost. Devices of the invention are capable of being mass-produced with broad applicability.

[0020] In practice of the invention of preferred embodiments of the invention, it is possible to detect NOx constituents in a single analytical scheme. A simple, practice of the invention includes Differential Mobility Spectrometry (DMS) systems which operate rapidly and can provide analytical information in real-time. These systems preferably feature non-radioactive ionization, which may be by means of a UV lamp, by corona discharge, by plasma, or by other photon sources. Use of a non-radioactive ionization source reduces risk to users and avoids regulatory issues as well as reducing the ionization energy to a level that avoids fragmenting or otherwise damaging the sample analytes to be detected.

[0022] Still another illustrative application of the invention includes a system for non-radioactive detection of NO in exhaled breath. Such detection system enables non-invasive and real-time patient health evaluations, and can be provided in a compact and low-cost package.

[0023] It has also been found that DMS practices of the invention minimize the affect of moisture on analyte detection. In one practice of the invention, moisture in a NOx sample does not affect DMS response up to about 1000 ppm and above 1000 ppm the compensation voltage increases with increasing humidity. Quite advantageously, this results in an enhanced resolving ability of the DMS in with varying levels of moisture.

Problems solved by technology

Mass spectrometers are well known as the gold standard of laboratory-based systems operate at low pressures, resulting in complex systems, and the spectra output can be difficult to interpret, often requiring a highly trained operator.

But the GC-MS is not well-suited for small, low cost, fieldable instruments for real-time chemical detection.

These techniques, however, generally require sophisticated optical equipment, or suffer from significant drawbacks such as slow response times, or the detection of only certain NOx species, making them problematic for routine measurements.

However, a serious disadvantage is that its response is highly affected by the presence of moisture.

Widespread use, however, still remains a problem for TOF-IMS.

Among other things, TOF-IMS flow channels (also referred to as drift tubes) are still comparatively large and expensive and suffer from losses in detection limits when made small.

The device has been found to be complex, with many parts, and somewhat limited in utility.

Images