CN113473907A

CN113473907A - Chewing gum and method for extracting chemicals from the mouth and breath

Info

Publication number: CN113473907A
Application number: CN201980079342.8A
Authority: CN
Inventors: R·A·巴兹莫尔; C·P·克里斯滕松; M·R·怀特
Original assignee: Volatil Analytics
Current assignee: Volatil Analytics
Priority date: 2018-10-17
Filing date: 2019-10-17
Publication date: 2021-10-01
Also published as: WO2020081832A1

Abstract

Chewing gum has an absorbent material, such as Polydimethylsiloxane (PDMS), for absorbing or adsorbing volatile and non-volatile chemicals from the mouth or breath of the user. While the chewing gum is being chewed, chemicals in the user's breath and saliva are absorbed or adsorbed into the absorbent material. The absorbent material is then analyzed to determine the amount of chemical substance absorbed or adsorbed into the absorbent material over time. Based on this analysis, various diseases or conditions can be detected or diagnosed.

Description

Chewing gum and method for extracting chemicals from the mouth and breath

Cross Reference to Related Applications

The present application claims priority from U.S. provisional application No. 62/747,087 entitled "chewing gum and method for extracting chemicals from the mouth and breath" and filed on 2018, 10, month 17, which is incorporated herein by reference.

RELATED ART

Advances in instrumentation have resulted in a new generation of reliable, accurate and accurate tools for scientists (analytical chemists, food scientists, biochemists, biologists). Technological advances have opened new research areas for the study of disease-related metabolites produced in the body, including the field of metabolomics. Metabolomics is a rapidly evolving field of research and holds promise to make disease detection and diagnosis less traumatic and much faster. The current difficult and time consuming procedure of collecting samples requiring blood, feces, urine or even more invasive tissues will be less frequently required, or will not be required at all. Sources of metabolites include blood, urine, feces, sweat, and breath. Breath analysis is challenging because the compounds present are smaller (lower molecular weight, typically less than 300 g/mole), volatile (preferentially present in the gaseous state), and reactive. Trace levels of metabolites in the breath add another dimension of difficulty because the amount of breath required to extract sufficient amounts of compounds to allow detection is relatively large.

Current methods for breath collection for subsequent analysis include directly exhaling one or two breaths into the instrument, or collecting 2 or 3 to more breaths (0.6 to 250L) into a Tedlar bag, an air tight bag made of teflon, plastic or other inert material. However, problems with these approaches limit their utility. For example, very low levels present in the analyzed respiratory volume, e.g., less than one part per trillion metabolites, are often inadequate for detection, or are difficult to detect by the most sensitive instruments. Moreover, the method for breathing directly into the instrument is cumbersome, inconvenient, and requires the user and the instrument to be present at the same site.

For example, researchers in Menssana Research have developed Breathscanner 2.5, an instrument that incorporates gas chromatography and a detector to identify volatiles from the breath of a user (e.g., a patient) that breathes directly to the instrument interface. The device is cumbersome and the result depends on the amount of substance present in the breath collected in a short time by the user who breathes into the device. U.S. patent No. 5,465,728 describes a hand-held device to measure respiratory components. Although portable, the device appears to lack trace level detection capability. Other methods for measuring respiration include U.S. patent publication No. 2008/0008666a1, which describes methods for monitoring the efficacy of oral malodor treatments by measuring specific chemicals listed. It does not seem to allow new extraction and detection modes. Finally, the main drawback associated with the collection of large volumes of breath with Tedlar bags is the transfer of large volumes of metabolites present in the air to the instrument while eliminating the problem of dilution effects. This method does not provide a means for concentrating the metabolites. Moreover, with the bag, some volatile metabolites are absorbed into the bag construction material, or adhered (adsorbed) to the side, and thus cannot be used for detection and measurement.

Accordingly, there is a need to extract low levels (trace levels) of volatile, semi-volatile, and non-volatile compounds from respiratory devices for the purpose of developing the respiratory metabolomics field. Such devices will also be used in various applications such as disease detection, and in dentistry, food and flavor science. For example, in dental science, oral hygiene can be assessed by sampling metabolites present in saliva and breath. Common diseases, such as gum health, can be diagnosed based on the presence and concentration of known metabolites produced by infection, including odor-related compounds, such as carbon disulfide, methyl mercaptan, and dimethyl sulfide. In food and flavor science, flavor and taste, referred to as chemical sensation, means the sensation of taste and odor (flavor, taste and aroma) is the interpretation by the brain of signals generated by the interaction of chemicals (from food and spices) with receptors in the mouth and nose. By detecting and measuring these chemicals in the oral cavity, improvements in flavor and aroma technology, duration and efficacy can be successfully measured at levels that have not been achieved to date. For example, it can be more accurately assessed how long the product freshened your breath, or how pleasantly the product provides, by measuring the time that the breath freshening chemical remains in the mouth before rinsing out in saliva or exhaling through the air.

Drawings

The disclosure may be better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, like reference numerals designate corresponding parts throughout the several views.

Fig. 1 illustrates an exemplary chewing gum for extracting chemicals from the mouth and breath according to an exemplary embodiment of the present disclosure.

Fig. 2 illustrates a top view of the chewing gum depicted in fig. 1.

Fig. 3 illustrates a side view of the chewing gum depicted in fig. 1.

Fig. 4 is a flow chart illustrating an exemplary process for purifying an absorbent material, such as Polydimethylsiloxane (PDMS).

Detailed Description

The present disclosure relates generally to chewing gum and methods for extracting volatile, semi-volatile, and non-volatile chemicals from the mouth and breath. In one exemplary embodiment, the chewing gum used to extract the chemicals is portable, convenient, and designed to be easily adapted to the oral cavity. It consists of an absorbent material intended to remain in the oral cavity for a period ranging from a few minutes to a few hours, but other periods are also possible. With each breath, air flows over the absorbent and a large amount of the chemicals present in the breath are absorbed and/or adsorbed. As many (e.g., thousands) of breaths flow over the absorbent material, the chemicals present in the breath and saliva are retained. Even trace levels of volatile chemicals present in breath and saliva, over time, are sufficiently concentrated in the absorbent material to enable detection of these small amounts of chemicals via known analytical techniques. After a period of time, the chewing gum is removed from the oral cavity and the absorbent material is analyzed by a suitable analytical instrument to determine the chemical compounds absorbed from the breath and oral cavity (e.g., saliva).

Various types of materials may be used to absorb and/or adsorb chemicals from the breath and mouth. Such materials include, but are not limited to, Polydimethylsiloxane (PDMS), polyvinyl acetate, polyisoprene, styrene-butadiene rubber (SBR), polybutylene, polyacrylate, and other polymers known in the art or that may become known in the art to be safe for use in oral cavities. Such materials may be used in combination with each other in different proportions or they may be used alone. Softeners, such as microcrystalline waxes, may also be used to provide softer, easily moldable polymers. Additional absorbent materials that may be incorporated into chewing gum as described herein include all forms of activated carbon having engineered pore sizes, such as CarboPack or Carboxen materials, structures known as zeolites, absorbent materials known as Tenax, and cyclodextrins.

Note that PDMS alone may be used as the absorbing material. One characteristic of PDMS is that it is hydrophobic. It does not bind water significantly, but by absorption into the polymer liquid phase it does extract other volatile components present in the sample matrix (immersed in the liquid or from the headspace), making it ideal for use in an oral environment.

Moreover, regardless of the type of absorbent material used, the absorbent extracts and retains volatile, semi-volatile, and non-volatile components from the breath and oral cavity by absorption and adsorption. The forces and mechanisms responsible for absorption and/or adsorption include van der waals forces, polarity, and hydrophobicity or hydrophilicity.

Following absorption and/or adsorption, the chemical components can be released, analyzed, and measured by any of a variety of types of analytical procedures and tools. Such methods include, but are not limited to, thermal desorption and chemical desorption by exposure to a solvent, such as High Performance Liquid Chromatography (HPLC). For thermal desorption, the absorbent is placed in a thermal desorption unit or heating chamber equipped with inert gas flushing and temperature control. Once the chamber is heated, volatiles are released from the absorbent material, purged with an inert gas (e.g., helium, nitrogen, argon) to a capture mechanism (e.g., a liquid nitrogen cooled cryotrap, absorbent material, or a combination thereof). The capture mechanism can be rapidly heated to release the components and they are deposited as a dense band on a capillary column for separation by Gas Chromatography (GC) and detection and measurement by a detector (e.g., Mass Spectrometer (MS), flame ionization, or flame photometer). Alternatively, volatiles may be liberated by the solvent and analyzed by GC, as previously described, or by HPLC. HPLC may utilize various detectors such as MS, infrared, ultraviolet, diode arrays, and/or other wavelengths of electromagnetic radiation.

The data from the analysis may be used in various ways. As an example, it may be determined that the presence of certain chemicals in certain amounts and/or patterns of certain chemicals over time in the mouth and/or breath may indicate the presence of certain diseases or conditions. Thus, the data may be analyzed to predict or diagnose whether a user, which may be a human or an animal, has or will have certain diseases or conditions. By maintaining the absorbent in the oral cavity for an extended period of time (e.g., minutes or hours), even trace levels of chemicals may be concentrated in the absorbent, allowing such trace levels to be detected by conventional analytical equipment.

In one application, the absorbed chemical is analyzed to determine if the user has been exposed to (e.g., inhaled or otherwise consumed) certain chemicals. By way of example only, a sample from a soldier may be analyzed to determine whether the soldier has been exposed to a chemical weapon and, if so, to identify the type of chemical he or she has been exposed to. Various other types of conditions may be detected in other applications.

U.S. patent No. 9,480,461, published on 11/1/2016 and entitled "method for extracting chemicals from the nasal cavity and breath," describes exemplary embodiments of devices and methods that can be used to extract chemicals from the oral cavity and breath, which are incorporated herein by reference. U.S. patent No. 9,480,461 describes an embodiment in which chewing gum is used to extract chemicals from the mouth and breath of a user. In this regard, the chewing gum is composed of an absorbent material and is chewable so that a user may place the chewing gum into his or her mouth and chew the chewing gum. During chewing, the gum deforms and stimulates saliva flow. Chemicals present in saliva, mouth and breath are extracted and absorbed or adsorbed into the absorbent material. After chewing for a desired period of time sufficient to extract chemicals from breath and saliva, the chewing gum is then removed from the oral cavity and analyzed. If desired, the chewing gum may be cut or otherwise reshaped or arranged to facilitate analysis.

Chewing gum may be composed of heat resistant polymers including different combinations of Polydimethylsiloxane (PDMS), polyvinyl acetate, polyisoprene, styrene-butadiene rubber (SBR), and polybutylene. Additionally, microcrystalline waxes may be used as softeners. Various known materials commonly used in conventional chewing gum may be used to manufacture the chewing gum. Further, as with other conventional chewing gum products, the chewing gum may have many different sizes and shapes, and it may be manufactured using other known techniques for manufacturing conventional chewing gum.

PDMS may be incorporated into chewing gum by placing it and other polymers or other types of materials in a mixer capable of providing sufficient shear, such as a heated Z-blade mixer. In other embodiments, other types of absorbent materials may be used. The contents are blended for a period of time (e.g., about 15 to 30 minutes) to provide a homogeneous product and heated to a temperature ranging from about 50 degrees celsius (C) to about 200 degrees celsius. Mixing is carried out until the formulation produces a chewing gum that is sufficiently malleable so that it can be chewed by most healthy individuals. Edible waxes may be added to increase the softness of the chewing gum. The hydrophobic and hydrophilic properties of the chewing gum can be adjusted by selecting and concentrating the copolymer used. Other ingredients that may be added to the chewing gum-like products of the present disclosure include other absorbents such as activated carbon, Carbopack, carboxen, edible waxes for softening.

In some embodiments, chewing gum may be formed by adding PDMS or other absorbent materials to conventional chewing gum. However, chewing gum is typically a composite material comprising a number of ingredients, including several different polymers, to provide the user with a desired texture and taste. Many of these components introduce impurities that interfere with the testing. In this regard, impurities may be released from the chewing gum when heated, and then mask chemicals from the mouth and breath of the user, making it particularly difficult to detect trace levels of certain chemicals. Further, during testing using certain techniques, such as gas chromatography or liquid chromatography, the material is typically heated to an elevated temperature, such as about 200 to 300 degrees celsius, and many of the polymers and other ingredients in conventional chewing gum degrade at such elevated temperatures. Therefore, chewing gum requires the absorption or adsorption of even trace levels of chemicals from the mouth and breath of the user without introducing significant impurities that cannot withstand high temperatures, such as between about 200 and 300 degrees celsius.

Fig. 1-3 depict a chemically extracted chewing gum 75 that is as chewable as a conventional chewing gum. The chewing gum 75 is composed of an absorbent material, such as PDMS or other material for absorbing and/or adsorbing chemicals from the mouth and breath, and has a texture conducive to chewing over an extended period of time, such as minutes or hours. While chewing gum 75 is chewed, it absorbs and/or adsorbs chemicals from the user's breath and mouth (e.g., saliva). After a desired period of exposure, such as minutes or hours, the chewing gum 75 is removed from the oral cavity and then analyzed to determine the chemicals and concentrations of chemicals absorbed and/or adsorbed by the chewing gum 75. The data from such analysis can then be used for various purposes, such as diagnosing a disease or condition of a user (e.g., a patient) or identifying markers or predictors of a disease or condition.

In some embodiments, the chewing gum 75 consists of a combination or mixture of the following: an absorbent material for absorbing or adsorbing chemicals, such as PDMS and another material, herein referred to as "filler", which when combined with the absorbent material imparts a texture similar to conventional chewing gum. PDMS is desirable for chewing gum 75 for various reasons. For example, PDMS (1) is a good absorbent for trace levels of chemicals typically found in the user's breath and saliva, (2) is stable at high temperatures above 200 degrees celsius, (3) is non-toxic, and (4) has a texture that can be chewed by the user, particularly when the PDMS is combined with certain fillers, as will be described in more detail below. In this regard, the filler preferably has a relatively high surface area and aspect ratio that modifies the rheology of the chewing gum 75 to help impart a texture similar to conventional chewing gum without having to use polymers or other materials that may otherwise introduce impurities or degrade at high temperatures. Activated carbon that has had acidity removed or reduced may be a suitable filler, but in other embodiments other types or combinations of fillers may be used. Activated carbon may also help absorb some chemicals that are not well absorbed by PDMS.

The texture of the chewing gum 75 may be controlled by selecting the viscosity of the absorbent material, such as PDMS, the aspect ratio of the filler, and the amount of filler added to the absorbent material. In some embodiments, the viscosity may be between about 20,000 centistokes (cSt) and 100,000,000 cSt. In other embodiments, other viscosities are possible. In general, higher viscosities are better, and viscosities greater than about 1,000,000cSt are preferred. Also, one or more fillers may be mixed with or otherwise added to the PDMS material until the chewing gum 75 achieves a desired texture.

PDMS is a very good absorber for non-polar molecules, but is not quite effective for absorbing polar molecules. In some embodiments, additional absorbent materials or fillers for absorbing or adsorbing chemical substances may be introduced. Examples of such additional absorbent materials may include materials that are good at absorbing or adsorbing polar molecules, such as activated carbon (including engineered activated carbon particles with specific pore sizes), zeolites, Tenax, beta cyclodextrin, and carbon nanoparticles. The use of a rheology-modifying filler material may include fired silica.

If desired, chewing gum flavors that do not unacceptably interfere with analytical measurements of chemicals may be added. Flavoring agents may include less volatile materials such as those that impart sweetness, sourness, pungency (capsaicin), saltiness, bitterness, astringents, and the like. To help avoid interference with testing, it may be desirable to use flavors that quickly chew out of the chewing gum 75, or that come out of the chewing gum 75, and dissolve in saliva and swallow. The use of added flavor components can also be used as an analytical internal standard for quantitative measurement of various compounds.

Additionally, chewing gum 75 may contain chemical compounds or functionalities that derivatize or slightly modify the chemical structure of or bind to target biomarkers or difficult to capture metabolites important in disease and enhance analytical detection and measurement. Chewing gum 75 may contain chemicals that, when interacting with specific compounds present in the oral cavity, enhance the detection of a target disease.

The chewing gum 75 may also have additives that may affect the pH level of the chewing gum 75 or the oral cavity as may be desired. As an example, the chewing gum 75 may adjust/buffer the pH of the oral cavity when chewing to enhance metabolite collection, and/or reduce interference. Chewing gum 75 may enhance the collection of a class of chemicals called "amines" by modifying the pH to acidic levels, and using a basic pH to release amines after capture. Chewing gum 75 may also enhance the collection of a class of chemicals called "volatile acids" by modifying the pH to an alkaline level, and using an acidic pH to release the acid after capture. The oral pH can also be adjusted by using an acidic or basic rinse to enhance the collection of amines or volatile acids. Some additives, such as citric acid, may be added to the chewing gum 75 to modify the pH of the chewing gum 75 while also providing a flavor that stimulates saliva production in the oral cavity. This stimulation by saliva may provide greater absorption or adsorption of trace levels of chemicals into the chewing gum 75.

At high temperatures, PDMS materials may release relatively large amounts of impurities, such as siloxanes, which can unacceptably interfere with the detection of trace amounts of certain chemicals. In some embodiments, the purified PDMS is then mixed or otherwise combined with filler materials in order to remove various impurities, including siloxanes. An exemplary process for purifying PDMS to remove substantial amounts of siloxane and other impurities from the PDMS is described in more detail below.

PDMS was completely dissolved in a solvent as shown in block 100 of fig. 4. In one embodiment, a dichloromethane or DCM (also known as dichloromethane) solvent is used, but in other embodiments other types of solvents may be used. Note that it is desirable to use HPLC grade solvent purity in order to limit the amount of impurities in the solution. A ratio of about 1:5 weight/weight (PDMS: DCM) may be used, but other ratios are possible in other embodiments. The solution was mixed well and a reagent to precipitate PDMS was added. Ethanol or methanol, which introduces relatively small amounts of impurities, may be used as such an agent. In one embodiment, methanol is used and about twice the initial weight of the DCM solution relative to the PDMS is added. However, in other embodiments other agents may be added.

In response to the addition of the reagent, the PDMS precipitates from the solution as a gel, as shown in block 105 of fig. 4, and a percentage of impurities remains in the solution, effectively removing such impurities from the PDMS gel precipitate. Excess solvent (e.g., DCM) and reagents (e.g., methanol) were poured and removed, leaving only the PDMS gel precipitate. The above process of dissolving and then precipitating PDMS may be repeated one or more times to help further remove impurities remaining in the PDMS.

The PDMS gel resulting from the above process is baked at high temperature (e.g., over 200 degrees celsius) for greater than 2 hours in an inert atmosphere, such as ultra-high purity (UHP) nitrogen, to remove residual solvent and additional PDMS impurities, as shown in block 110 of fig. 4. A vacuum oven may be used for the baking.

When the PDMS gel is heated to high temperatures, the siloxane and other impurities are released in gaseous form, effectively removing such impurities from the PDMS gel. Without such a baking step, when the chewing gum has been chewed by a user and analyzed, impurities will be released at a later time when the PDMS is heated by the GC or other instrument, thereby adversely affecting the analysis performed by the GC or other instrument. In addition, the PDMS gel was baked in a UHP nitrogen atmosphere to prevent oxygen from contacting the PDMS gel. If oxygen contacts the PDMS gel at high temperatures, the PDMS will likely form a solid material with a texture that is not conducive to chewing. In other embodiments, other types of atmospheres for preventing oxygen from contacting the PDMS material during baking may be used.

It should be emphasized that the above-described processes for purifying absorbent materials are exemplary, and that various modifications and alterations to the purification processes will be apparent to those of ordinary skill in the art upon reading this disclosure. Further, other techniques for purifying the absorbent material are possible.

By selecting materials and purifying the absorbent material according to the techniques described herein, the resulting chewing gum may have various characteristics that make it desirable and advantageous for use in extracting chemicals from the mouth and breath. In this regard, the chewing gum 75 may be chewed and retained in the mouth, absorbing or adsorbing the chemicals for an extended period of time, such as many minutes or hours, to facilitate detection of trace levels of certain chemicals. The chewing gum 75 is substantially clean in that it introduces very small amounts of impurities that would otherwise be released at high temperatures and interfere with testing. Additionally, the chewing gum 75 exhibits the general texture (viscosity, rheology) of conventional chewing gums and retains elasticity and integrity (will not significantly break down, fragment into small pieces, dissolve or lose a large portion of the bulk in the user's mouth) while being chewed for an extended period of time, such as up to at least about 12 hours. The chewing gum 75 may also remain stable at elevated temperatures, such as at 200 degrees celsius or higher. As an example, the chewing gum 75 will not thermally degrade at a temperature of about 200 degrees for at least 30 minutes or more, thereby making the chewing gum 75 suitable for use with thermal desorption techniques utilized in analytical instruments, such as gas chromatography and liquid chromatography.

Reducing the amount of impurities to a level less than one thousandth should be sufficient for detecting trace levels of many target chemical species, but it is generally desirable to reduce the amount of impurities as much as possible. Using the techniques described herein for purifying PDMS, it is possible to reduce the total amount of impurities, including siloxanes, to levels of less than one part per million or even parts per billion.

For illustrative purposes, a detailed process for purifying PDMS will be described in more detail below. It should be emphasized that the detailed process described below is exemplary and that, as can be appreciated, various changes and modifications can be made to the process.

A mass of PDMS is initially dissolved in DCM or other solvent. In one embodiment, the amount of DCM used as solvent is about ten times the amount of PDMS. An amount of ethanol approximately four times the initial amount of PDMS was added to the precipitated PDMS from the DCM solution. In this embodiment, ethanol is used as a reagent prior to baking, as it is somewhat less effective in precipitating PDMS. That is, ethanol does not precipitate PDMS as readily as methanol does. This effect has the advantage of precipitating the PDMS material with the greatest tendency to precipitate so that slightly more PDMS material remains in the DCM solution, thereby helping to keep a larger amount of impurities in the DCM solution.

After the PDMS precipitates to form the PDMS gel, the process of dissolving the PDMS gel into a solvent, such as DCM, may be repeated any number of times. In one embodiment, the process is repeated twice, referred to as "second extraction" and "third extraction". In a second extraction, DCM was used as a solvent in an amount of about five times the mass of the original PDMS, and ethanol was added in an amount of about four times the mass of the original PDMS to precipitate the PDMS from the DCM solution. In a third extraction, DCM was used as a solvent in an amount of about four times the mass of the original PDMS, and ethanol was added in an amount of about four times the mass of the original PDMS to precipitate the PDMS from the DCM solution.

In this embodiment, after three extractions, the resulting PDMS gel is heated at low heat to drive off residual solvent. Next, the PDMS gel is heated in a furnace to a temperature above 200 degrees celsius under a nitrogen atmosphere for several hours (e.g., ten hours) to drive off impurities in the gel, as described above.

After heating the PDMS gel as described above, another extraction was attempted to further remove impurities. In this regard, although ethanol is generally less effective at precipitating PDMS and, therefore, is used for earlier extractions, ethanol may introduce some impurities that are desired to be removed or reduced. In this final extraction, methanol was used as a reagent to precipitate PDMS instead of ethanol. In this regard, DCM was used as a solvent in an amount of about ten times the mass of the original PDMS to dissolve the PDMS, and methanol was added in an amount of about four times the original PDMS to precipitate the PDMS from the DCM solution. This final extraction is performed with methanol to help remove some of the impurities introduced by the ethanol in the earlier extractions.

After the purified PDMS is formed by the above-described process, it may be combined with one or more fillers to enhance the material for chewing (e.g., to alter the texture of the material or to add flavors) or to aid the material in absorbing or adsorbing certain compounds. Thereafter, the material can be used to absorb or adsorb volatile, semi-volatile, and non-volatile compounds from breath or saliva in accordance with the techniques described above.

Note that the techniques used to purify PDMS can be used to provide purified PDMS for absorbing or adsorbing volatile, semi-volatile, and non-volatile compounds from breath using devices of types other than chewing gum. As an example, us patent No. 9,480,461 describes the use of PDMS for absorbing or adsorbing compounds from the nasal cavity, and the techniques described herein are used to purify PDMS in such applications.

Claims

1. A chewing gum for extracting chemicals from the mouth or breath of a user, comprising:

purified Polydimethylsiloxane (PDMS) treated to reduce the total siloxane level to less than one in a thousand,

wherein the chewing gum has a viscosity of greater than twenty thousand (20,000) centistokes (cSt).

2. The chewing gum of claim 1 further comprising at least one filler in combination with the purified PDMS.

3. The chewing gum of claim 2 wherein the at least one filler comprises activated carbon.

4. The chewing gum of claim 1 wherein the viscosity is greater than one million (1,000,000) cSt.

5. The chewing gum of claim 1 wherein the purified PDMS is treated to reduce total siloxane levels to less than one part per million.

6. A method for extracting a chemical substance from the mouth or breath of a user, comprising:

inserting a chewing gum into a user's oral cavity, wherein the chewing gum comprises purified Polydimethylsiloxane (PDMS) treated to reduce a total siloxane level in the chewing gum to less than one thousandth, and wherein the chewing gum has a viscosity of greater than twenty thousand (20,000) centistokes (cSt);

chewing the chewing gum in the oral cavity such that chemicals from the user's breath or saliva are absorbed or adsorbed into the chewing gum; and is

Removing the chewing gum from the oral cavity.

7. The method of claim 6, wherein the chewing gum further comprises at least one filler in combination with the purified PDMS.

8. The method of claim 7, wherein the at least one filler comprises activated carbon.

9. The method of claim 6, wherein the viscosity is greater than one million (1,000,000) cSt.

10. The method of claim 6, wherein the purified PDMS is treated to reduce the total siloxane level to less than one part per million.

11. A method for purifying Polydimethylsiloxane (PDMS), comprising:

dissolving the PDMS in a solvent;

precipitating the PDMS from the solvent to form a PDMS gel, the precipitating comprising adding a reagent to the solvent for causing precipitation of the PDMS; and

heating the PDMS gel to a temperature greater than 200 degrees Celsius.

12. The method of claim 11, wherein the solvent is dichloromethane.

13. The method of claim 11, wherein the heating of the PDMS gel is performed in an atmosphere free of oxygen.

14. The method of claim 11, wherein the heating of the PDMS gel is performed in a nitrogen atmosphere.

15. The method of claim 11, wherein the reagent is methanol.

16. The method of claim 11, wherein the agent is ethanol.

17. The method of claim 16, further comprising:

dissolving the PDMS gel into a second solvent; and

precipitating PDMS from the second solvent to form a second PDMS gel, the precipitating comprising adding methanol to the second solvent.