Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
1995-10-23
2003-02-18
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C422S082070, C436S172000
Reexamination Certificate
active
06521185
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to apparatus for and methods of rapidly and sensitively detecting and monitoring chemical and biological materials.
Recent developments in the world political situation, exemplified by the demise of the Soviet Union, continued geopolitical pressures in the Middle East and Eastern Europe and the proliferation of terrorist activities throughout the world, have raised increased concerns about the use of chemical and biological warfare materials in local conflicts. The defense against chemical and biological warfare agents includes detection of potential threats, development and use of protective equipment, development of vaccination post-exposure prophylaxis measures and fabrication of structures providing barriers to the toxic agents which are suitable for decontamination procedures. Threat identification is imperative prior to engagement, during battle and after battle during decontamination procedures. In addition, chemical sensors for detecting chemical warfare materials are needed for treaty verification, demilitarization, environmental monitoring and characterization of materials acting as barriers to agent diffusion.
Existing methods of detection have proven inadequate. Existing methods for long-range threat identification, such as light detection and ranging (LIDAR), and for laboratory analysis of chemical warfare agents using gas chromatography to provide a chemical agent monitor (miniCAMS), light addressable potentiometric sensor (LAPS) or ion mobility sensor (IMS) technology, have proven slow and cumbersome to carry out. Needs exist for lightweight, high-sensitivity sensors having rapid response times.
Existing sensors have proven capable of meeting the requirements of several applications but no sensor has provided the combined sensitivity and speed of response needed for each application. Needs exist for field-usable chemical and biological sensors for the detection of vapor and liquid dispersed chemical warfare agents, toxins of biological origin and aerosol dispersed pathogenic microorganisms. Existing instrumentation used in identifying chemical warfare agents rely on ion mobility spectroscopy or gas chromatography for detection. The Advanced Chemical Agent Detection/Alarm System (ACADA) uses ion-mobility spectroscopy to achieve sensitivities to Sarin and Soman on the order of 1 mg/m
3
(170 parts per billion (ppb)) in ten seconds and 0.1 mg/m
3
(17 ppb) in 30 seconds. In addition to the system's slow response and low sensitivity, the size and weight characteristics of the ACADA system (one cubic foot in volume and 25 pounds in weight) reduce the applicability of the system for distributed sensing or remote sensing applications. Sensors such as the miniCAMS system provide unparalleled sensitivity but require preconcentration times on the order of minutes. That response time is unsuitable for rapid detection of conditions that are immediately dangerous to life and health. Other existing methods use acoustic or optical/electrochemical methods of detection, such as surface acoustic wave (SAW)-based instruments and light addressable potentiometric sensors (LAPS). Neither method has proven effective in meeting the sensitivity and response times required. At best, the SAW instrument has demonstrated sensitivities to Sarin/Soman at 0.01 mg/m
3
(1.7 ppb), but requires preconcentration times ranging from 2 minutes to 14 minutes. Needs exist for field-usable sensors that provide for highly-sensitive, rapid response measurements of the concentration of analytes in solution or in air.
Previous efforts indicate that polymers can be used to improve the sensitivity of SAW devices to a range of analytes and that polymer coatings are effective in enhancing the concentrations of analyte detected by optical probes. Polymer-coated waveguides have been used to detect nerve agent simulants, such as dimethyl-methyl-phosphonate (DMMP), and polymeric materials having affinity for the nerve agent and exhibiting a change in refractive index upon absorption of the agent have been identified. Floropolyol was found to have a partition coefficient for vapor phase DMMP between one million and ten million, indicating that the concentration of DMMP in the fluoropolyol was up to ten million times that in the vapor phase. Fluoropolyol is strongly acidic, which may improve sensitivity to strongly basic vapors such as the organophosphorus compounds. No sensors have been developed, however, that have short response times and high sensitivity, that are low cost and that are easily and safely incorporated into small, portable packages for deployment in rugged domains. Needs exist for optical chemical and biological sensors having those characteristics for use in a network of point detectors for multiple applications, including monitoring decontamination of military field structures, detecting chemical and biological agents in chemical treaty verification, assisting in reconnaissance of battlefield and depot perimeters, demilitarization exercises and monitoring breakthrough times associated with polymeric or other complex structural materials.
The far-visible and near-infrared (IR) spectral regions (600-1000 nm) are areas of low interference, where only several classes of molecules exhibit significant absorption and fluorescence. The use of near-IR labels in sensor design is becoming increasingly important due to the advent of semiconductor-based light sources and detectors and the reduced interference in the near-IR wavelength range. Heptamethine cyanine dyes have been shown effective in labeling nucleic acid materials. For biomolecule labeling and for analytes containing primary amino functional groups, isothiocynate derivatives of those cyanine dyes are the most suitable labels because they form stable thioureas. Needs exist for sensors for use in biochemical applications that use near-IR fluorophores.
Needs exist for low-cost sensors exhibiting rapid response at very low concentrations of chemical warfare agent and simulant materials. Needs also exist for laser-based sensors that can be used commercially in biomedical, industrial and environmental applications requiring on-site, rapid and sensitive chemical and biological analysis. In the field of biomedical testing, there is great need for point-of-care monitoring of physiological conditions and disease producing microorganisms. In the food industry, there is a need for sensors for product quality control and distributed process control applications. Needs for rapid, sensitive, small, portable and inexpensive sensors are also needed in the chemical and pharmaceutical processing industries, and in the area of pollution monitoring. Needs exist for sensors that can meet the sensitivity and time response requirements dictated by each industry and that are of a reasonable size and cost.
SUMMARY OF THE INVENTION
A highly-sensitive, rapid response fluorescent probe is based on the affinity of a polymer matrix for an analyte of interest.
The polymer/fluorophore probes of the present invention have the sensitivity and rapid response needed for detection of chemical agent and biological materials. Sensors using the probes provide sensitivity to Sarin at several hundred parts per trillion without the need for preconcentration steps. The lack of necessity for preconcentration allows vapors to be detected in one second or less. That is a notable advance over state-of-the-art detectors that require preconcentration steps, which in turn restrict response times to one minute or more.
Fluorescent dyes showing little or no sensitivity to an analyte of interest provide significant sensitivity to that same analyte of interest as long as a polymer having affinity for the analyte is employed as the matrix. A wide-range of near-infrared excitable fluorophores are used as sensitive probes for analytes not detectable when the fluorophores are outside the polymer matrix. The present sensors provide early warning of the presence of toxic chemicals, provide for on-line analysis of trace materials in chemical and biologi
Churchill Russell J.
Groger Howard P.
Lo K. Peter
Luo Shufang
Sloan James M.
American Research Corporation of Virginia
Creighton Wray James
Narasimhan Meera P.
Warden Jill
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