Spectroscopic breath detector

A replaceable spectroscopic detector used in volatile organic compounds testing devices, such as a portable breath testing device for roadside drug testing or a testing device for any air handling systems, such as those used for indoor agriculture, which reversibly sorb compounds and prepare a concentrated sample in a single gas cell configured for performing spectroscopy of the contents within the cell.The disclosed invention comprising; one or more check valves, a source of electromagnetic radiation and an electromagnetic receiver that releasably connects to a volatile organic compounds testing device such that it is replaceable and is configured for performing spectroscopy and passing exhaled breath and/or airflow through a disposable and replaceable reversibly engaging cartridge comprising a reversible sorbent and a gas cell configured for spectroscopy. The invention further comprises a heater that preferably is included in the cartridge for heating the cell and desorbing the sorbed compounds preparing a concentrated sample inside the gas cell.

CROSS REFERENCE TO RELATED APPLICATION

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

REFERENCE TO SEQUENCE LISTING

Not applicable

BACKGROUND OF THE INVENTION

For simplicity, this document primarily describes the invention as it relates to a breath volatile organic compounds testing device for roadside cannabis testing, but the invention is usable in other manners. One example is a volatile organic compounds testing device for any air handling system, especially those systems containing volatile organic compounds resulting from second hand smoke and/or indoor agricultural.

Current volatile organic compounds testing devices reversibly sorb and thermally desorb volatile organic compounds in exhaled breath and/or airflow to prepare a concentrated sample using a pre-concentrator or similar apparatus. The concentrated sample is transported into a separate gas cell where spectroscopy is performed. In such devices sequential desorption is commonly used to target selected compounds by purging the pre-concentrator of non-targeted compounds using heating and venting. These devices require a complex gas handling system, such as a vacuum pump or gas pump and switches.

It is advantageous to use a detector with replaceable parts to reduce contamination and a disposable pre-concentrator has been proposed. Yet, a replaceable spectroscopic detector that reversibly sorbs volatile organic compounds contained in exhaled breath and/or airflow and prepares a concentrated sample within a heated and disposable gas cell configured for spectroscopy has not been proposed.

BRIEF SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a replaceable spectroscopic detector that releasably connects to a volatile organic compounds testing device for detecting and/or quantifying one or more volatile organic compounds in exhaled breath and/or airflow. For example, a breath volatile organic compounds testing device targeting compounds exhaled in breath a resulting from smoking any smokables and/or inhaling any vaporized substances, especially cannabis and other inhalants containing cannabinoids including tetrahydrocannabinol. The invention is further configured to reversibly engage a cartridge such that a gas cell configured for spectroscopy and reversible sorbent are disposable and replaceable. A method for using the invention is disclosed.

The invention is tubular in external appearance comprising a source of electromagnetic radiation and an electromagnetic receiver for performing spectroscopy of the contents within a reversibly engaging cartridge that is disposable and replaceable.

The cartridge forms a gas cell configured for spectroscopy and further comprises a reversible sorbent for reversibly sorbing volatile organic compounds exhaled in breath and/or airflow passing through the cartridge. The reversible sorbent is in fluid communication with the gas cell. The detector further comprises a heater for heating the gas cell and desorbing compounds from the reversible sorbent as a concentrated sample inside the same cell the compounds were sorbed.

The disposable and replaceable cartridge provides a means for fast sample turnaround. Directly following an analysis the hot and used cartridge is replaced with a fresh cartridge and another analysis may be performed. This eliminates the burn off time and cool down times required by systems using a non-replaceable pre-concentrator.

Currently proposed testing devices using a disposable reversible sorbent do so using a pre-concentrator and a separate spectroscopy cell. These are different from the disclosed invention because the disclosed invention does not transport a concentrated sample from one apparatus to another. That is volatile organic compounds are reversibly sorbed and a concentrated sample is prepared inside the gas cell configured for spectroscopy.

Performing spectroscopy of the concentrated sample inside the same cell it was formed in reduces concern of sample loss from transporting it from a pre-concentrator to a spectroscopy cell and provides a means to decrease the complexity of a gas handling system. To maintain sequential release of captured compounds, exhaled breath and/or airflow may be used to purge the cell.

Previously proposed devices reuse a spectroscopic cell and do not have the ability to or are difficult to clean and/or replace in the field. The disclosed invention addresses this difficulty by incorporating a disposable and replaceable reversibly engaging cartridge that forms a gas cell configured for spectroscopy. In addition, the invention heats the cell where sample may condense causing gunk build-up and sample loss in the cell if not heated. Furthermore, the invention releasably connects to a testing device in such a manner that the detector and cartridge are not reversibly engaging and are replaceable, or the detector releasably connects to a testing device and reversibly engages the cartridge such that a selection may be made to replace the cartridge or detector and cartridge with a fresh corresponding unit to address sample carryover, contamination and reduction of electrical spectroscopy component performance.

In areas that require high integrity sampling, such as law enforcement, the possibility of a contaminated device, especially the gas cell configured to perform spectroscopy and reversible sorbent component; for example cartridge, pre-concentrator, etc. are problematic. Therefore, a volatile organic compounds testing device with a spectroscopic detector that reversibly sorbs volatile organic compounds preparing a concentrated sample inside the same gas cell spectroscopy is performed and allows expired, used and/or hot parts to be replaced is desirable.

DETAILED DESCRIPTION OF THE INVENTION

All components are constructed from materials capable of withstanding the operating temperature without denaturing or degrading.

The preferred spectroscopic breath detector embodiment is tubular in external appearance,FIG. 3, and releasably connects to and brings in electrical communication a volatile organic compounds testing device such that exhaled breath and/or airflow is accepted and electrical parts are powered.

The spectroscopic breath detector,FIG. 1, comprises an inlet check valve10for allowing exhaled breath and/or airflow to enter into a disposable and replaceable reversibly engaging cartridge11, the cartridge11is observed asFIG. 2. The cartridge11comprises a gas cell12configured for performing spectroscopy of the contents within and a reversible sorbent13in fluid communication with the gas cell12. The reversible sorbent13sorbs volatile organic compounds present in exhaled breath and/or airflow before the breath and/or airflow is expelled through the outlet check valve14. A heater15heats the gas cell12and desorbs the sorbed compounds forming a concentrated sample inside the gas cell12where the check valves10,14contain or reduce the loss of the sample by bracketing the cartridge11. The gas cell12volume is preferably less than 5 cm3.

The electrical spectroscopy components, source of electromagnetic radiation16and electromagnetic receiver17are configured for performing spectroscopy of the concentrated sample in the gas cell12by bracketing the cartridge11. The source of electromagnetic energy16and the electromagnetic receiver17are wired to separate releasable electrical connectors18,19. Still inFIG. 1, the heater15is a thin film heater is part of the cartridge11and the check valves10,14housing is extended for directing heat toward the gas cell12. The check valves10,14are electrically separated by a non-conductive material20. The check valves10,14are in-line check valves that also prevent the user from inhaling through the device. Check valve seals and springs not shown. The check valves10,14reversibly engage the cartridge11,FIG. 4, and releasably connect a testing device, perhaps using a squeezing mechanism, such that the detector as a whole, any part, parts, any combination of parts or any combinations of parts are replaceable.

Any parts can be combined. For example, as shown inFIG. 1, the inlet check valve10houses the source of electromagnetic radiation16and incorporates a connector18for releasably connecting a testing device.

FIG. 2is a proposed disposable and replaceable cartridge11wherein the reversible sorbent13is any substance or group of materials that filter, capture, collect, retain, extract, sorb, etc. at least one volatile organic compound, when present, and allows at least one of the sorbed compounds to thermally desorb, release, vaporize, volatilize, evaporate, burn, combust, etc. into the surrounding gaseous phase and is used throughout this document to mean such, as well as related terminology such as sorb and desorb, etc. The reversible sorbent13is preferably a chemically-selective substance that releases compounds sequentially or simultaneously, including but not limited to stationary phases used in gas chromatography columns, more preferably a retention material containing a glycol, and most preferably a material containing polyethylene glycol or propylene glycol.

In the preferred embodiment, the reversible sorbent13is supported by a non-conductive substrate21. The substrate21is preferably a low thermal expansion material, more preferably silica based, most preferably deactivated or fused silica.

InFIG. 1andFIG. 2the heater15is incorporated into the cartridge11. The heater15is any material that generates heat when current flows through it, for example a metal or metal alloy wire or a thin plate or a source of electromagnetic radiation. The preferred heater15is a resistive metal, more preferably a thin film heater. The preferred embodiment comprises a thin film heater in contact with the substrate21, but may be contained with or in the substrate21. Lead lines, not shown, are preferably of the same material as the heater15are used to electrically engage the heater15from both ends to the check valve10,14housings comprising an electrically conductive material in a reversible manner such that the heater15is capable of receiving powered. InFIG. 1, the check valves10,14are constructed from an electrically conductive material, preferably a metal, more preferably aluminum.

The cartridge11includes a casing22forming a protective layer of non-conductive heat resistant material, preferably a polymer, more preferably polyimide, electrically separate the heater15from the check valve10,14housings so they may act as releasable electrical connectors18,19as is the matter inFIG. 1.

The cartridge11comprises a gas cell12where the energy travels from the source of electromagnetic radiation16into the cell12to interact with compounds desorbed from the reversible sorbent13before it encounters the electromagnetic receiver17. In the preferred embodiment,FIG. 1shows the source of electromagnetic radiation16and electromagnetic receiver17bracketing the cartridge11for performing spectroscopy.

The source of electromagnetic radiation16is any source that emits electromagnetic energy at any wavelengths, preferably a source providing a band or bands of light in the ultraviolet, visible and/or infrared regions, more preferably a light emitting diode or laser emitting diode. InFIG. 1, the source of electromagnetic radiation16is a light emitting diode.

The electromagnetic receiver17is any sensor that provides an output signal at a signal magnitude proportional to the intensity of electromagnetic energy received. The preferred electromagnetic receiver17is any photosensor including but are not limited to photoresistor, photomultiplier, phototransistor and photodiode, where the preferred sensor is a photodiode. InFIG. 1, the electromagnetic receiver17is a photodiode.

In this embodiment,FIG. 1, the source of electromagnetic radiation16and electromagnetic receiver17are wired to individual electrical connectors18,19that releasably connect to a testing device, perhaps using a squeezing mechanism, allowing the spectroscopic electric components16,17to be replaced. An optional optical band pass filter23for discriminating unwanted frequencies is place between the source of electromagnetic radiation16and electromagnetic receiver17.

Where the target analyte is one or more cannabinoids, such as tetrahydrocannabinol, cannabidiol, and/or cannabinol the source of electromagnetic radiation16is a light emitting diode emitting light at about 280 nm and may be combined with a 280 nm polarized band pass filter23. The electromagnetic receiver17is a photodiode, preferably an ultraviolet sensitive photodiode, more preferably an ultraviolet B only sensitive photodiode with a spectral range of 230-315 nm and a peak wavelength of 280 nm, one example of such a photodiode is a silicon carbide diode.

Operation

The invention may operate in any manner found suitable to sorb volatile organic compounds when exhaled breath and/or airflow passes through the invention, and thermally desorb compounds form a concentrated sample in a gas cell12configured for spectroscopy. Several manners for using the invention are proposed and not intended to be restrictive.

One manner of operation is now described. The invention reversibly engages to a volatile organic compounds testing device in a manner to accept exhaled breath and/or airflow and power electrical parts15,16,17. Forced breath or airflow opens the check valves10,14and the check valves10,14close when the breath is not being forced or airflow is not being directed through the invention. Volatile organic compounds pass through the cartridge11where the reversible sorbent13sorbs volatile organic compounds before the breath and/or airflow exits the invention. Next, using heat the sorbed compounds are thermally desorbed into the gaseous phase of the gas cell12. The closed check valves10,14contain or reduce the loss of the generated concentrated sample in the gas cell12.

Variations exist in the operation. One variation involves a means for reducing non-targeted compounds with low desorption temperatures. Before the invention accepts exhaled breath and/or airflow, the heater15is adjusted to a predetermined temperature above the ambient temperature and below the temperature the target compounds desorb, for example 50 degrees Celsius for cannabinoids. This allows some non-targeted compounds to pass through the cartridge11without being sorbed, while targeted compounds are reversibly sorbed.

Another variation involves another means for further removing non-targeted compounds from the gas cell12before performing spectroscopy and may be combined with the previous variation of operation. After exhaled breath and/or airflow has been accepted by the invention, heat is provided for desorbing non-targeted compounds with lower desorption temperatures than the target compounds and for retaining the targeted compounds, for example 100 degrees Celsius. The non-targeted compounds within the gaseous phase of the cell12may be expelled using exhaled breath and/or airflow. Finally, sufficient heat is provided to desorb the targeted compounds as a concentrated sample and spectroscopy may be performed.

Spectroscopic measurements may be performed of the gaseous phase contained in the gas cell12at any one time or a multitude of times anytime.

Lastly, the hot and used cartridge11or invention may be replaced with a fresh corresponding unit.