as may be seen in fig1 and 2 , an assay device is indicated generally at 10 and comprises a cup - like transparent test container 11 having a cylindrical side wall 12 , a closed bottom 13 and an open top 14 . the cylindrical wall 12 may have a slight taper or be straight . the open end 14 of the test cup 11 is provided with external threads 15 upon which is seated an outer closure cover or cap 16 provided with corresponding internal threads which are not shown in the drawing . the cover 16 has a circular top surface 17 from the periphery of which depends a cylindrical wall 18 on the inner surface of which there are provided the internal threads . positioned within the container 11 is an assay assembly indicated at 19 which is partially shown in fig2 and is completely shown in a flattened position in fig3 . the assay assembly comprises a flexible backing member 20 of a plastic material which is preferably liquid impermeable and not reactive with any of the components of fluids which might be tested for drugs of abuse . the backing member 20 may be of an opaque plastic material , for example , white in color , or a transparent plastic material . the backing member has a front surface 21 upon which is attached a substantially rigid but flexible transparent cover sheet 22 which has molded therein a plurality of parallel elongated pockets 23 each of which is shaped to retain closely therein an immunoassay test strip 24 . the pockets 23 are positioned such that they extend longitudinally or vertically within the container when the assay assembly is mounted within the container as seen in fig1 . each pocket 23 has its top 25 and longitudinal sides 26 closed or sealed against the body portion of the cover sheet , but the bottom ends 27 of the pockets are open . the test strips 24 each have bottom portions 28 which extend outwardly of the pockets through these open bottom ends 27 and extreme ends 29 of the bottom portions 28 coincide with a bottom edge 30 of the backing member 20 . the test strips 24 are thus retained in their vertical positions which are axially of the container by being closely enclosed within the pockets 23 . the bottom portion 28 of each test strip functions as a sample receiving area . each test strip also has a test area 31 and a control area 32 . the test strips 24 may be attached or adhered directly to the front surface 21 of the backing member 20 such that retaining pockets 23 or similar retaining structures are no longer necessary . the height of the backing member 20 is substantially equal to the inner height of the container such that , when assembled within the container , the bottom edge 30 of the backing member rests on the bottom of the container and a top edge 33 of the backing member is flush with the top edge 14 of the container . top edge 34 of the cover sheet is spaced downwardly from the top edge 33 of the backing member as may be seen in fig3 . the cover sheet member 22 has a length , when flattened as shown in fig3 , which is substantially equal to the inner periphery of the container such that its ends 22 a and 22 b meet in abutting relation as shown in fig5 . however , the length of the cover sheet member may be increased such that the ends 22 a and 22 b will overlap . these overlapping ends may be provided with a registering depression and protuberance such that they can be snapped together to maintain the cover sheet member in a cylindrical shape which fits closely within the container . other forms of snaps or clips can be provided to lock abutting or overlapping ends into position . these particular test strips 24 indicate the presence or absence of the following specific drugs of abuse : pcp , cocaine , amphetamines ( amp ), marijuana ( thc ) and opiates . test strips 24 may be of the type as made by phamatech of san diego , calif . and arista biological of bethlehem , pa . such test strips are characterized as immunoassay assay strips and employ colloidal gold chemistry . in addition to immunoassay test strips 24 in the pockets 23 , a test strip similar in size and shape to the test strips 24 but having adulterant detection means may be placed in a pocket 23 . such an adulterant strip is capable of determining whether a sample of urine has been tampered with by administering either chemical analysis to ensure that the chemical composition of the sample is consistent with that of standard , non adulterated human urine and / or temperature analysis to ensure that the sample has been recently excreted from the donor and has not been brought to the test site by the donor from an earlier excretion . such adulterant strips are known in the art . each of the test strips 24 is a one - step immunoassay in which a specially treated drug , ( drug conjugate ) competes with a drug which may be present in the sample specimen for the limited number of binding sites on an antibody . the test strip consists of a membrane strip onto which a drug conjugate has been immobolized . a colloidal gold - antibody complex is dried at one end of the membrane . in the absence of any drug in the urine sample , the colloidal gold - antibody complex moves with the urine sample by capillary action to contact the immobilized drug conjugate . an antibody - antigen reaction occurs forming a visible line in the test area 31 of the test strip . the formation of a visible line occurs when the test is negative for the drug . when a drug is present in the urine sample , the drug or its metabolite will compete with the immobolized drug congate in the test area for the limited antibody sites on the colloidal gold - labeled antibody complex . if a sufficient amount of drug is present , it will fail all of the available binding sites , thus preventing attachment of the label antibody to the drug congate . an absence of a color line or band in the test area is indicative of a positive result . a control zone 32 or line comprised of a different antibody / antigen reaction is present on the membrane strip . the control line is not influenced by the presence or absence of drug in the urine and therefore should be present in all reactions . in summary , if a single band appears in the control zone 32 , then the results are “ positive ” which indicates that that particular drug is present above a predetermined level which is usually around 50 ng / ml . if two color bands appear , one in the control region and the other in the test region , then the rest of the results are “ negative ” which indicates that the level of that particular drug is below the predetermined detection of sensitivity . in the event there are no distinct color bands visible in both the test zone and the control zone or if there is a visible band in the test zone but not in the control zone , then the result is invalid and testing of the specimen is recommended with another test card . the quantity of liquid sample should be below a “ maximum ” line 36 which is shown on the container . if the quantity of the sample is above “ maximum ”, the test will not be affected since only a sufficient amount of liquid to conduct the test will flow into the open bottom end of a pocket . this quantity of liquid is limited by the air pressure built up in the closed pocket . the liquid sample contacting the bottom end of each test strip will wick up the test strip by capillary action to reach the chemical agents contained within the test strip to give positive , negative or inconclusive test results . any excess sample liquid may enter the open end of a pocket but only to a limited degree as described above . however this entering would be after the wicking of the sample has already begun when the sample contacted the bottom portions of the test strips resting on the bottom of the container . these results will be visible in the test area 31 of the strip and can also be seen through the transparent wall of the container . thus , this assay device enables one to obtain rapidly a visual , qualitative result which is very advantageous for forensic purposes but is not limited to such purposes . thus , it can be seen that the present invention discloses a novel and improved assay device for testing of liquid samples for drugs of abuse . this assay device could be modified to test for other substances by utilizing other agents and chemicals on the test strips . this assay device has a simplified but reliable structure which integrates the assay or test elements within the container in which the liquid sample to be tested is collected . this assay device does not require any pipetting of the liquid sample or specimen , adding or mixing of reagents or other manipulation of the device by the user . this device is particularly suitable for the immediate , point of collection screening for drugs of abuse and offers health care , law enforcement , government , industrial safety and educational professionals a self - contained , one - step screening device capable of identifying illicit drug use within minutes . it will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions , and accordingly , it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims .
an assay device for testing of liquid samples for drugs of abuse has a transparent container for retaining a liquid sample . a backing member is within the container and is curved so that its front surface corresponds to the curvature of the container wall . immunoassay test strips are on the front face of the backing and are visible through the container wall . each test strip is enclosed in a transparent pocket which has a bottom opening through which the bottom portion of the test strip protrudes to contact the liquid sample within the container . the liquid then flows upwardly through the test strip to react with reagents within the test strip .