Abstract:
A novel method for testing if smoking has occurred within a space. Smoking is determined to have happened by testing for and confirming the presence of nicotine using a lateral flow test strip. The nicotine may be captured from secondhand smoke by exposing the condensing pad of the lateral flow tester to air within the space prior to activating the test strip. The nicotine may also be captured as part of thirdhand smoke residue on a surface within the space. A prior art commercially available lateral flow test strip used to test for the presence of cotinine within a biological sample, is used in novel ways for detecting for the past presence of nicotine smoke within a space. Improvements to the test apparatus are also disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    There are no related applications. 
       STATEMENT REGARDING FEDERALLY SPONSORED R&amp;D 
       [0002]    Not related to this application. 
       TECHNICAL FIELD 
       [0003]    This invention relates to chemical test technologies to detect both airborne secondhand tobacco smoke, and surface-borne thirdhand tobacco smoke. 
       BACKGROUND OF THE INVENTION 
       [0004]    The health dangers of smoking tobacco are well known. Firsthand smoke is purposefully inhaled by a smoker through well-known devices such as but not limited to, pipes, cigarettes and cigars. In addition to the user&#39;s desired nicotine from smoking, other chemicals, including but not limited to heavy metals and poisons, are also brought into the body. Some users enjoy smoking and don&#39;t want to quit, while many others continue to succumb to the addictive nature of nicotine by smoking when they wish not to. These users often feel ashamed and fear others knowing they smoke. As a result many smokers often use hidden locations such as bathrooms, hotel rooms and cars for smoking. 
         [0005]    The dangers of second hand smoke are also fairly well understood by the general public. Very much similar to smoking firsthand, second hand smoke causes someone not smoking to also inhale potentially toxic chemicals. The unfortunate thing about second hand smoke is that the person receiving the damage to their body has no desire for nicotine and the chemicals that come with smoking. Public awareness of the dangers of second hand smoke has swung the voters in many states to pass legislation restricting smoking in public locations. Many states force smokers to move outdoors and a certain distance from building entrances. These laws protect the non-smoking public from second hand smoke and further force smokers to undesirable locations. For many smokers, they are even further habitualized to smoke in locations away from public visibility. 
         [0006]    Unlike firsthand and secondhand smoke, the dangers of thirdhand smoke is not well known by the general public. Thirdhand smoke is the residue that remains on surfaces and objects as a result of smoking. Long after a smoker finishes a cigarette, a surface may include deposits of nicotine and the toxic chemicals that come along with cigarette smoke. Even worse, residue from the smoke can react with other environmental substances creating even more dangerous substances on surfaces. Thirdhand smoke residue, for example, can be in contact with cooking surfaces getting into food, or on bathroom counters getting into peoples&#39; eyes and mouths. Thirdhand smoke is likely to be the greatest risk to kids and infants as they spend a significant amount of time in contact with floors and living surfaces. Kids and infants are likely to make oral contact with surfaces and are less likely to wash their hands prior to eating or touching other surfaces of their body. 
         [0007]    In addition to the damages of smoke on the body, smoke also damages property. With the high level of public awareness on the dangers of smoking, smoked in dwellings and objects generally have less resell value than pristine versions. Business owners that rent spaces to the general public can very much be negatively financially impacted by smokers. Rental owners often require renters to sign a contract that they will not smoke in the owner&#39;s rental property. Car rental companies and hotels make customers sign contracts and install reminder signs not to smoke. Many businesses use fines as deterrents. 
         [0008]    With smokers increasingly being forced to smoke in hidden non-public places to maintain their addictions and with many smokers being ashamed of smoking, the problem of enforcing non-smoking contracts is very challenging. To catch a smoker in the act of smoking, the business owner either has to invade the smoker&#39;s privacy or use expensive electronic smoke detectors. Without a low cost method for detecting thirdhand smoke available today, owners are left with the subjective method of smelling thirdhand smoke. With smokers not wanting to get publicly humiliated for smoking and having an addiction overriding their better judgment, many smokers will lie about smoking. Even without lying, many long term smokers are desensitized from chronic exposure, and are unable to smell smoke and distinguish thirdhand contaminated spaces from pristine ones. Accusations from business owners wanting to protect their investments leads to relationship and business damaging disagreements with customers. Often the cost of losing a customer is more expensive than the immediate smoke damage, so the smell is covered up with fragrances and such. At some point, the repeated cover-ups no longer work which impacts non-smoking customers and property values. There is a need for business owners to protect their property without invading a customer&#39;s privacy, damaging the relationship with the customer by relying on subjective evidence, or having to spend significant amounts of money on highly scientific forensic analysis of evidence. For business owners, the goal is to change habits with credible data and not to take customers to court. 
         [0009]    The problem of thirdhand smoke and the situation described above is not limited to business situations. It is not uncommon for kids to give into peer pressure and try smoking. Quickly they can become addicted. Similar to the situation previously described, parents will try to keep kids from smoking and kids will try to hide it. There is a need for a parent to test, or audit, if a child is smoking without damaging their relationship with subjective evidence or by forcing biological testing. 
         [0010]    It should be appreciated that there are methods today that can determine if firsthand, secondhand or thirdhand smoking contamination has occurred, or is occurring within a space. 
         [0011]    Firsthand smoking can be determined though video surveillance. Surveillance equipment is not only expensive, but it may be illegal in some situations. Even if legal, customers will be unlikely to sign a rental contract allowing an invasion of their personal privacy. Biological testing, that is testing urine and blood for cotinine, a byproduct of nicotine, is not a solution. Testing if someone has historically smoked by testing their blood or urine for cotinine does not provide a business owner the data to know if the customer has smoked in a rented space. 
         [0012]    Identifying secondhand smoke in a space can be done through the use of gas chromatography/mass spectrometry, as well as highly sensitive and expensive electronic smoke detectors. Air sampling and subsequent gas chromatography/mass spectrometry testing can provide very accurate results. This method of testing is slow and expensive, more suitable for forensic testing. Lower cost common commercial smoke detectors lack the sensitivity and selectivity needed for detecting secondhand cigarette smoke. In addition, smoke detectors are easily disabled. 
         [0013]    Currently, thirdhand smoke detection is limited to expensive and slow methods. A wipe of a surface and subsequent chromatographic or mass spectrometric testing of that wipe can provide accurate results, but the process is slow and expensive. Nicotine sensing films comprising conductive polymers linked with a reporting layer can record changes in chemiresistance due to absorption of nicotine, but to date the technologies are cost-prohibitive. 
         [0014]    In these respects, the device and methods for detecting secondhand and thirdhand smoke substantially depart from conventional concepts of the prior art, and in doing so provide an economical and quick method for testing for the presence of secondhand and thirdhand smoke in a space. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention therefore is directed at providing a test method for determining if smoking has occurred in a space. Smoking can be determined by the presence of secondhand smoke in the air or thirdhand smoke deposits on surfaces. The present invention uses lateral flow test apparatuses for economically and quickly absorbing smoke deposits and flowing them through a test structure using capillary action. The present invention also provides improvements to existing lateral flow cotinine test apparatuses by increasing their sensitivity above what is needed for cotinine testing of biological samples (e.g. blood, urine, saliva). There currently is not an economical, quick, or reliable method for determining if smoking has occurred in a space. 
         [0016]    One embodiment of the present invention collects nicotine via ambient contact with airborne secondhand smoke, where the sample collection pad acts as a nicotine condenser. After exposure to ambient secondhand smoke, the lateral flow assay is initiated by introduction of a suitable, often aqueous eluting solvent. The chemical interaction of nicotine with the test strip results in a visual change to the test trap. 
         [0017]    In another embodiment of the invention, sample residue is collected from a suspected thirdhand smoke surface via direct swabbing with the sample area of a test stick. The lateral flow assay is then initiated by introduction of a suitable, often aqueous eluting solvent. Alternatively, a suspected thirdhand smoke surface can be wet swabbed with a cotton ball, or similar tool, that has been wetted with a suitable solvent. After swabbing, the lateral flow assay is initiated with the introduction of liquid extracted or squeezed from the swabbing tool. Again, the chemical interaction of nicotine with the test strip results in a visual change of the test trap. 
         [0018]    These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Preferred embodiments of the invention are described below with the reference to the following accompanying drawings: 
           [0020]      FIG. 1  is a front perspective view of a test apparatus according to the present invention where a moistened swab is used to gather smoke residue for testing; 
           [0021]      FIG. 2  is a front perspective view of an alternative embodiment according to the present invention, wherein a simplified test strip is used to directly swab a surface; 
           [0022]      FIG. 3  is a perspective view of a test unit for collecting test particles from air prior to being activated with liquid; 
           [0023]      FIG. 4  is perspective view of an alternative embodiment test strip where anti-radial chromatography is used to increase the sensitivity of the test. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Many of the fastening, connection, manufacturing and other means and components utilized in this invention are widely known and used in the field of the invention are described, and their exact nature or type is not necessary for a person of ordinary skill in the art or science to understand the invention; therefore they will not be discussed in detail. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered and anticipated by this invention and the practice of a specific application or embodiment of any element may already be widely known or used in the art, or persons skilled in the art or science; therefore, each will not be discussed in significant detail. 
         [0025]    The term “smoke” as used herein is intended to include any type of airborne byproduct created by a user smoking a device. That device may be, but is not limited to, a pipe, cigarette, or an electronic cigarette. The product creating the smoke is generally referred herein to tobacco smoke containing the drug nicotine, but the present invention should not be construed to be limited to tobacco smoke. The present invention applies to other types of substances that are smoked. 
         [0026]    Now referring to drawings.  FIG. 1  shows a preferred embodiment of the present invention. A preferred test device assembly  10  is a lateral flow test strip. Although pregnancy test kits are well known by the general public, few know how lateral flow testing technology works. Present day lateral flow cotinine test strips are designed and used to detect cotinine in a person&#39;s blood, saliva, or urine. Cotinine, the body&#39;s metabolite of nicotine, reacts with a test strip to show a person has recently used a nicotine product. A positive result from a prior art cotinine test only indicates that a person has consumed nicotine. Prior art test strips reveal neither the route of consumption nor the physical location where said nicotine was consumed. For example, nicotine from smokeless tobacco, or a smoking cessation aid such as a nicotine strip, could have created the cotinine in a person&#39;s blood or urine. Moreover, a prior art cotinine test strip does not indicate a person smoked in a given space. Therefore, prior art cotinine test strips used with individual&#39;s blood, saliva, and/or urine samples do not accomplish the desired results of the present invention. Prior art cotinine test strips can be purchased from the NyMox Corporation. 
         [0027]    In preferred test device assembly  10 , a base  11  is used as a support structure for other components and to provide rigidity to the assembly during use. Attached to base  11  is sample pad  12 . Sample pad  12  is made from an adsorbent material. Sample pad  12  adsorbs a liquid  18  dispensed from a moistened swab  19 . Swab  19  is shown as a common cotton or synthetic swab, but it could be a moistened cotton ball or fabric, or such. The present invention should not be construed to be limited to a particular type of swab  19 . Swab  19  provides the means for collecting particles from a test surface  21 . Swab  19  is pre-moistened with a suitable, often aqueous solvent. Testing has shown that using water as a solvent in combination with commercially available cotinine lateral flow test strips can indicate the presence of nicotine on surfaces. 
         [0028]    Swab  19  dispenses fluid  18  onto sample pad  12  via a squeeze or solvent extraction of the tip of swab  19 , or by direct contact of the two. By pre-moistening swab  19 , its tip more readily captures surface contaminants from surface  21  over that of a dry swab tip. The moisture of swab  19  provides the means for capillary action of lateral flow of test device assembly  10 . 
         [0029]    Once fluid  18  is dispensed onto sample pad  12 , capillary action takes fluid  18  towards a conjugate pad  13  which is connected to sample pad  12  and base  11 . Conjugate pad  13  contains-a colored or otherwise detectable antibody-label conjugate which binds with high affinity and selectivity to nicotine. Such conjugates maybe composed of, but are not limited to, antibody receptors deposited on gold nanoparticles. An optional control antibody, commonly Immunoglobulin G or other suitable protein complex, if present, also reacts with fluid  18 . Fluid  18  then becomes a mixture containing the original liquid of the swab, the test antibody, potentially a nicotine residue from surface  21 , and optionally the control antibody. Conjugate pad  13  provides the means for mixing test fluid  18  with the test antibody. The presence of nicotine analyte in a sample  18  results in irreversible formation of a nicotine-antibody-label ternary construct. This ternary construct is either immediately visually or photometrically detectable, or, more commonly, it travels along a porous medium  14  to where it can be visually or photometrically detected in a trap area  15 . 
         [0030]    Alternatively, the antibody can reside in trap area  15 , where the binding of nicotine analyte prevents the absorption of colored particles, resulting in a colorless positive test. Alternatively, the trap area can be populated with a release ligand, which only captures the labeled antibody in the absence of nicotine analyte, again resulting in a colorless positive test. In fluid connection with porous medium  14  is a wick pad  17 . Wick pad  17  provides the necessary capillary action to ensure proper flow of fluid. A more detailed discussion of the lateral flow test process may be found in U.S. Pat. No. 5,238,652 to Sun et al. and U.S. Pat. No. 6,121,008 to Fitzpatrick and Lenda, which are herein incorporated by this reference. 
         [0031]      FIG. 2  shows an alternative test strip and can be used to describe a second test method. A simplified test strip  20  is comprised of a sample pad  22  which is in contact and fluid connection with simplified reaction pad  23 . Similar to the preferred embodiment according the present invention, simplified test strip  20  uses an antibody for reacting with nicotine molecules to make the lateral flow test process work. Rather than having a second antibody as a control indicator, the alternative embodiment only uses a simplified test trap  24  and not a control trap. The resulting test strip is less expensive to manufacture and provides the desired test results. In this alternative embodiment, simplified sample pad  22  is rubbed against a suspected thirdhand smoke surface, directly capturing potential nicotine residue. The needed liquid for capillary flow of the test strip can be provided to surface  21  prior to contact with simplified pad  22 , or the liquid can be applied to simplified pad  22  after it has been rubbed against surface  21 . It should be appreciated that the use method of the alternative embodiment of  FIG. 2  could also apply to the preferred embodiment of  FIG. 1 , that is sample pad  11  could be directly applied to surface  21  regardless the addition of a control trap. 
         [0032]      FIG. 3  shows a smoke capturing test strip  30  which is another alternative embodiment of the present invention. This embodiment is similar to the preferred embodiment according to the present invention as it has similar structure to that of  FIG. 1 . Smoke capturing test strip  30  has a housing  32  for holding the lateral flow test strip. Housing  32  has an optional control trap window  34  and a test trap window  33 . A dry smoke capturing pad  31  is in fluid contact with an ambient airflow  35 . Smoke capturing test strip  30  is used as a passive smoke capturing device within a space. Consistent with known test design, maximum surface area per unit volume is likely desirable for sample pad  31 . Thus, dry smoke capturing pad  31  can be variably configured in a conical, cylindrical, pyramidal, helical, ridged, or otherwise corrugated design such that airborne smoke is efficiently collected. Airflow  35  continually flows over dry smoke capturing pad condenser  31 . When desired, a wetting fluid  36  is applied to dry capturing pad  31 , activating test strip  30 . The resulting test method is then the same as previously described for the preferred embodiment as shown in  FIG. 1 , wherein via capillary forces a fluid drives a color change of a test trap line. This embodiment can provide more efficient airborne sample collection than can be accomplished with a conventional fluid activated lateral flow test strip. 
         [0033]    Yet another embodiment of the present invention is an anti-radial flow device  40 , shown in  FIG. 4 . The surface area of an ambient smoke capture area  42  is enhanced relative to the lateral flow stick design. Functioning as a condenser, capture area  42  sensibly benefits from designs with increased surface area, such as those described in the previous section. After exposure to ambient smoke, capture area  42  is uniformly wetted with a suitable, often aqueous solvent. The resulting mixture then travels via capillary action across a membrane  43 , toward the center of the anti-radial flow device  40 . This capillary flow effectively concentrates the collected nicotine, thereby affording greater sensitivity over standard linear flow cotinine testing. The nicotine is then detected at a circular trap line  44 . An absorbent wick  45  ensures proper capillary flow. 
         [0034]    Further embodiments are possible without departing from the scope of the present invention. For instance, another embodiment may use the configuration and use of test devices previously described herein, but may include a nicotine hapten derived antibody optimized for testing smoke residuals, rather than cotinine hapten derived antibody optimized for bio-fluid testing, thereby affording greater sensitivity and selectivity to the test strip. 
         [0035]    While the device and methods for detecting secondhand and thirdhand smoke herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise form of assemblies, and that changes may be made therein without departing from the scope and spirit of the invention as defined in the appended claims.