The increased availability and use of drugs of abuse along with the need for testing of other analytes, for example HIV or antibodies thereto, has caused employers, governmental agencies, sports groups, hospital emergency rooms and other organizations to utilize drug and analyte screening methods in a wide variety of situations such as in screening individuals for potential employment or purchasing insurance, or in order to maintain safety in the work place. In addition, in law enforcement, there is a constant need for providing improved on-the-spot testing for drugs of abuse or other analytes in a quick and simple manner since these tests will be far removed from the clinical setting. Screening tests for the detection of drugs of abuse and other analytes range in complexity from simple immunoassay tests to very complex analytical procedures.
Over the years the speed and specificity of immunoassays have made them one of the most accepted methods for screening for drugs of abuse in body fluids. Typical drug screening tests are performed for the purpose of quickly identifying on a qualitative basis, the presence of drugs in a body fluid which may be urine or saliva. A complete analysis of the sample may then be carried out in a laboratory only if the preliminary screening results are positive. More and more such drug screenings are taking place on site or at the work place, or during routine police stops or check points, and these are generally carried out by testing personnel who are generally not technically trained as would be a laboratory technician. It is thus important that the drug screening procedure is simple but yet reliable. Further, the test apparatus must be designed so as to enable the testing personnel to avoid all contact with the fluid specimen which is being tested.
While blood and urine samples have long been the primary fluids used for testing for disease as well as for evidence of substance abuse, there is increasing interest in testing regimens which can test a variety of body fluids including salivary specimens. Some advantages in a system that can test saliva in addition to bodily fluids such as blood and urine is that it is relatively easy to obtain a saliva sample and that a saliva sample obtained on the spot cannot be adulterated. Also, saliva testing is more suitable in testing of recent use since it does not maintain reactivity of the analyte after use for up to four to six weeks. Accordingly, testing of saliva gives a result in real time within a span of hours as compared to urine which gives a test result after-the-fact. In general, saliva and blood are useful to measure impairment, while urine tests generally are not suitable for this purpose.
However, the ability to collect and analyze saliva samples in addition to other bodily fluids using an immunoassay for diagnostic purposes is complicated by the relatively high viscosity of the fluid and the small volumes of salivary fluid secreted. In particular, saliva contains mucins which are a family of large, heavily glycosylated proteins which account for many of the properties of saliva. These mucins also act to disrupt or inhibit the lateral flow necessary to achieve a rapid and accurate test result and greatly restrict both the time it takes for a sample to travel through the immunoassay strip as well as the amount of the target compound in the sample which can travel up the strip and thus be determined by the immunoassay.
Because of the problems caused by mucins, certain testing systems had recommended long and elaborate procedures for removing mucins prior to testing the sample. These procedures include pre-treating a sample such as saliva with a diluent or other reagent which is capable of breaking down the interferants in a sample, e.g., mucins in saliva, so that these interferants do not restrict the capillary flow of the sample through the test strip, in order to try to achieve a rapid test of target compounds. However, these pre-treatment steps with specific reagents to dilute or denature interferants, modify analyte structure, or release analyte from binders, must generally be performed outside the confines of the test device, and this incurs additional steps and solutions which must be handled by the persons administering the test. For example, it is necessary to suitably collect the sample, have the sample expressed into a buffer solution, and then dispensed into a reaction well which generally contains a second reagent such as an identifying reagent, all before the testing solution including the sample is introduced onto an immunoassay test strip. All these steps necessitate the development of means and techniques for constructing self-contained devices which can test for saliva in addition to other body fluids in a manner that allows one to safely and efficiently control the test sample during pre-treatment and testing, but is still safe and simple to use and also able to obtain accurate results.
Previously, others have attempted to develop devices to test saliva, but none have provided a safe, quick and effective means for testing a variety of body fluids including saliva which can be used in a variety of settings including on-the-spot testing in addition to testing in the workplace setting by non-professional testing personnel. For example, U.S. Pat. No. 6,634,243 issued to Wickstead relates to a device which has an inadequate and ineffective provision for control of the test sample. Other art in this field includes U.S. Pat. Nos. 6,267,722 issued Anderson et al, 6,214,629 issued to Freitag et al., and 5,630,986 issued to Charlton et al. In addition, U.S. Pat. Nos. 6,464,939, 6,468,474 and 6,489,172, each issued to Bachand et al, disclose other saliva testing devices which also do not allow for quick and efficient break down of mucins so as to facilitate a highly sensitive test for a drug of abuse from a saliva sample. Finally, other devices are shown in U.S. Pat. No. 6,524,530 and in European Patent Application 520,408 A1, but once again these references do not disclose a flexible testing system which can suitably handle the problems associated with saliva testing and at the same time be able to readily test other bodily fluids for drugs of abuse and/or other analytes.
It thus remains a highly desirable object to develop methods and devices which allow for quick, safe and accurate testing of drugs of abuse or other analytes from a variety of body fluids including saliva, and which can be used conveniently and effectively in a wide variety of settings, including on-the-spot testing.