Abstract:
A sample device and method for analyzing a sample are claimed. The sample device is a flat disc containing channels and wells for directing a sample to reagents located in the disc and for mixing the sample with the reagents. The disc is mounted on an analyzer and the sample is pumped into the disc, divided into a plurality of sub-sample, and at least some of the sub-samples are mixed with a number of reagents. The resultant analytes are analyzed spectrophotometrically for a determination of the concentration of various substances in the sample. The present invention permits multiple tests to be performed quickly and automatically with minimal operator involvement.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 60/906,369, filed Mar. 12, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    a. Field of the Invention 
         [0003]    The present invention relates generally to the field of chemical testing of a sample. More particularly, the invention provides a system and method for rapid testing of water quality via a small device that permits multiple tests to be performed simultaneously and automatically from a single sample. 
         [0004]    b. Description of the Related Art 
         [0005]    The process of preparing water for consumption in this country is highly regulated—nationally by the Environmental Protection Agency, and locally by state environmental agencies. Although the water treatment process is fairly straightforward, documenting that all proper precautions have been taken to protect the consumer can be a tedious and time-consuming process. In many other countries, resources are not as readily available to test water quality and, unfortunately, water is distributed for consumption containing many dangerous mineral and biological contaminants. The present invention is intended to simplify and expedite the analytical aspect of water treatment. 
       Overview of the Water Process  
       [0006]    Utilities may obtain water from rain water runoff collected in rivers, lakes, and streams, or from wells. Fresh, untreated water is referred to as “raw” water. The raw water is pumped to a water treatment plant, where analytical tests are performed to determine the quality of the raw water. The water is then filtered to remove debris and other turbid materials, and chemicals are added to improve the quality of the water. The water is then referred to as “finished” water. The finished water must be tested and held to regulated standards before being released to the distribution system. If the finished water passes all tests, it is pumped to water tanks where it is held in waiting for the consumer. 
         [0007]    Almost all water systems currently employ at least one operator who is responsible for laboratory procedures. Small labs are kept in-house in order to maintain the water system in compliance with certain mandatory tests that must be performed frequently. In fact, many tests are required to be performed every hour, a laborious and time-consuming undertaking. 
         [0008]    The water quality tests generally consist of a spectrophotometric analysis on 10-25 milliliter water samples of both raw and finished water. The water samples are mixed with chemical reagents and analyzed at a reagent-specific wavelength in order to determine the concentration of certain components in the water samples. Most analytes requires their own specific reagent and each test must be run independently from the other tests. For tests that are required frequently, this requires a series of analyses to be performed hourly. 
         [0009]    Although this manual method of testing is the standard across the industry, it is not without problems. The series of tests that must be performed is slow and tedious. Operators spend, on average, approximately twenty minutes of each hour performing simple analyses, and often more complex tests are left undone just because there is not enough time or man-power to do them. In some cases, multiple analytical devices must be purchased to increase the testing capacity of the water system. 
         [0010]    Sample size is an issue as well, not in that a water plant cannot spare a few milliliters-of water to run these tests, but because the actual sample being analyzed is not truly indicative of the entire water sample. A spectrophotometer works by shooting a beam of electromagnetic radiation at a particular wavelength through a sample and measuring the amount of electromagnetic radiation absorbed by the sample. One form of electromagnetic radiation is light, as from a light bulb. This beam of electromagnetic is, at most, 10 millimeters in diameter. When considering the size of a 25 milliliter sample vial, the test actually sees less than 10% of the total sample volume. If the sample is not 100% homogenous, the test results can be inaccurate. By the reagent manufacturer&#39;s own standards, a 100% homogenous mixture may not be achieved on most reagent-sample mixtures unless constantly stirred for more than one hour, which is not practical in this situation. Other tests which involve shooting a beam of electromagnetic radiation at a particular wavelength through a sample and measuring the amount of electromagnetic radiation coming from the sample are also possible, such as fluorescence testing. 
         [0011]    Also, repetitive testing by humans is inefficient. Tedious analytical tests such as these lead to increased user error and careless mistakes. Many test operators are not trained as laboratory technicians, but are expected to perform as such and are held responsible for laboratory practices. 
         [0012]    Unfortunately, the water treatment industry has been undeserved in the development of new technology to remedy these problems. Prior art devices have been designed to perform automated water quality testing, but the prior art devices require sophisticated manufacturing techniques. It would be desirable to have a system and method for rapid and repetitive testing of water quality that permits simple and economical testing of water samples. 
       SUMMARY OF THE INVENTION 
       [0013]    The current invention is a sample device where one sample is injected or input into the device one time, and a plurality of different chemical analyses are independently performed on the sample to provide several different test results. The sample is split into a plurality of different sub-samples, where each sub-sample is directed through a channel to an optical well. Electromagnetic radiation is transmitted through the optical well, and a detector detects how much electromagnetic radiation leaves the optical well. Light is frequently the preferred type of electromagnetic radiation used, and the amount of electromagnetic radiation leaving the optical well indicates the amount of a substance present in the sample. Before the sub-sample flows into the optical well, it can be directed through a reagent well containing a reagent specific to the chemical test to be performed. The reagent is then dissolved, and can react with specific compounds which may be in the sub-sample. The use of a specific reagent is required for many of the tests performed, and the reagent well and the channel between the reagent and optical well aid in dissolving the reagent in the sample. 
         [0014]    An analyzer is used in conjunction with the sample device to perform the chemical tests. The sample device is aligned on the analyzer, and different sources of electromagnetic radiation are transmitted through the different optical wells. The analyzer can be designed with fewer radiation sources than optical wells in the sample device, so the sample device can be automatically rotated so the radiation source is-transmitted through a second optical well after the first test is completed. This rotation and subsequent testing can be repeated as often as desired, so if the sample device had 16 optical wells, and the analyzer had 4 radiation sources, there could be 4 consecutive tests performed. 
         [0015]    In one embodiment, the sample device according to the present invention will allow users to monitor the quality of a water sample more quickly and more effectively than with conventional methods. Current testing is very time consuming, inefficient, and expensive. The sample device method will allow multiple tests to be run simultaneously and data to be automatically logged. Sample volumes will also be much reduced and the training needs for laboratory personnel will be simplified. The water system operator will simply have to load the water sample onto the disc and place it in the analytical device. The unit can be designed to automatically pump the water sample across several reagents simultaneously, take spectrophotometric readings, and generate a report showing the findings of each individual test. 
         [0016]    One objective of the present invention to provide a low cost, disposable device and analysis system to enable rapid and automatic water quality testing. 
         [0017]    Another objective of the present invention to provide for automatic uploading of water quality testing data. 
         [0018]    It is a further objective of the present invention to improve the mixing of the water sample with reagents for a more homogenized mixture when the sample is mixed. 
         [0019]    Another objective is to provide a simple to operate system for routine chemical analysis. 
         [0020]    Yet another objective is to improve lab safety by minimizing the number of operations and the amount and exposure to reagents for the laboratory technician. 
         [0021]    These and other objectives will be achieved by the device described in more detail in the detailed description. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a top view of the sample device according to one embodiment of the present invention. 
           [0023]      FIG. 2  is a cross-sectional representation of the sample device illustrated in  FIG. 1 , taken approximately along lines  2 - 2 . 
           [0024]      FIG. 3  is a cross-sectional representation of the sample device mounted on the analyzer according to one embodiment of the present invention. 
           [0025]      FIG. 4  is a top view of a sample device mounted on the analyzer, with the sample device shown in dotted lines. 
           [0026]      FIG. 5  is a cross-sectional representation of a sample device mounted on an analyzer according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The present invention can be used for a wide variety of sample testing applications, and this disclosure is not intended to limit the invention to any one particular embodiment. One potential use of the current invention is for the routine testing associated with water treatment facilities, and the current discussion is geared for this particular application. However, other possible uses also exist, and this discussion is not intended to limit the invention to this application. Those skilled in the art will recognize there are other uses and/or applications of the current invention which are intended to be included in this description. 
       Sample Testing Background 
       [0028]    The principles and method of operation of the water quality analysis performed by the present invention are well known to persons of skill in the art. The method works on principles of light absorption; specifically, when an electromagnetic radiation beam crosses a substance, some of the radiation is absorbed by atoms, molecules or crystal lattices in the substance. Specific chemical compounds absorb specific wavelengths of electromagnetic radiation, so the concentration of these specific compounds can be determined by measuring how much electromagnetic radiation of a chosen specific wavelength is absorbed. Light is one form of electromagnetic radiation, and is the radiation source referenced in this discussion. Spectrophotometric chemical analysis can be based on the creation of an absorbing compound from a specific chemical reaction between a sample and a specific reagent. Beer&#39;s law states that when an absorbing compound absorbs light of a particular wavelength, the absorbance is directly proportional to the concentration of the absorbing compound in solution, as long as other factors are constant. The current system generally keeps the other factors constant, so the absorbance is proportional to the concentration of the absorbing compound. 
         [0029]    The analysis of the sample is accomplished by first mixing the sample with a reagent and then placing the mixed sample in between a light source and a detector which can measure the amount of light striking the detector. The amount of light passing through the sample (i.e., the radiation that is not absorbed by the sample) is detected by a detector or photometer which converts the light energy into a voltage signal. The photometer sends the voltage signal through an amplifier to a microprocessor which then correlates the voltage signal with the concentration of the absorbing atoms and molecules based upon the wavelengths which are absorbed and the amount of light which is absorbed. 
         [0030]    While the principles are well known in the art, the present invention enables the user to perform multiple tests simultaneously by providing a disposable sample device pre-loaded with multiple reagents. For example, if the sample device includes 16 different test sites, the following tests can be performed from a single sample injected into a single sample device. These tests are commonly required for water treatment facilities. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
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         [0031]    The sample device can be configured to support different types of water sample tests that may be needed for different water utilities, For example, a city using well water may need to perform different tests than a city using river water. The reagents in the sample device can be customized to support the type of water utility that will be using the sample device. The sample device can also be configured to support sampling applications other than testing water for utilities. 
         [0032]    Other tests which are more common in other industries include fluorescence testing and electrochemical testing. In fluorescence testing, one wavelength of electromagnetic radiation, often in the ultraviolet frequency, is transmitted into the sample, which absorbs energy from the radiation source. The sample material then re-transmits a longer wavelength of electromagnetic radiation, and the amount of the longer wavelength transmitted depends on the concentration of a particular molecule in the sample. 
         [0033]    In electrochemical testing, a probe is inserted into the sample, and the voltage, current, and/or resistance transmitted by the probe can be equated to a specific characteristic of the sample. For example, with a pH probe, the voltage potential between the probe and the hydrogen ions in the sample solution is measured, and in a conductivity probe, the electrical resistance of the sample solution is measured. 
       Sample Device 
       [0034]    The present invention and its advantages are best understood by referring to the drawings. The elements of the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. 
         [0035]    One embodiment of the present invention includes a sample device  10  for preparing fluid samples as shown in  FIGS. 1 and 2 . Reference to fluid samples is intended to include samples which are fluids as well as samples typically considered to be solids, but which are able to flow, such as sand. The sample device  10  is in the shape of a disc with wells for introducing the sample to various reagents, channels for mixing the sample with the reagents and directing the sample flow, and wells for analyzing the sample. The sample device  10  is also referred to as the disc  10  in this description. 
         [0036]    In this embodiment, the disc  10  is relatively thin and is fabricated from a transparent material such as a plastic material. The disc can also be fabricated from glass, quartz, or even photopolymers used in stereo lithography such as polydimethylsiloxane (PDMS.) The disc  10  has a body  12 , including a bottom plate  14  and a lid  16 . The lid  16  is generally a solid flat disc enclosing the top of the body  12 . The lid  16  is permanently affixed to the disc  10  by sonic welding, adhesive or other means such that a seal is formed between the lid  16  and the bottom plate  14 . A full surface bond between the lid  16  and the bottom plate  14  is desired. In one embodiment of the invention, the lid  16  is 1/16 inches thick, though other thicknesses are possible without departing from the scope of the invention. Generally, the cavities and paths defined in the body  12  are formed in the body bottom plate  14 , and the lid  16  is used to enclose and seal these paths and cavities. There can be a base (not shown) affixed to the bottom of the body bottom plate  14 , either in place of the lid  16  or in addition to the lid  16 . 
         [0037]    The disc  10  has in its center an inlet port  18  in the form of a cylindrical through hole. Preferably, there is only one inlet port  18  per disc  10 . This inlet port  1 . 8  is defined in the body  12 , and passes into the body bottom plate  14 . In this embodiment, the sample enters the disc  10  through the inlet port  18  from a disc bottom surface  20 , though in other embodiments the sample is introduced from a disc top surface  22 . The inlet port  18  provides access and fluid communication from outside of the disc  10  to an inlet well  24  defined in the disc body  12 . Once the sample is introduced to the inlet well  24 , it is divided into sub-samples. The inlet well  24  can be concentric with the inlet port  18 , and is usually larger in diameter than the inlet port  18 . In one embodiment of the present invention, the inlet well  24  is ¼ inches deep, though other dimensions are possible within the scope of the invention. 
         [0038]    There are several features defined within the disc body  12  below the top surface  22 , and these features serve to contain, direct and mix the sample during the sample testing process. A plurality of channels  26  radiate from the inlet well  24 . The channels  26  include various channel sections, including a plurality of reagent channels  28  which connects the inlet well  24  to a plurality of reagent wells  30 . The reagent channels  28  provide fluid communication between the inlet port  18  and the reagent wells  30 . The reagent wells  30  can be generally cylindrically shaped, and are dimensioned with a sufficient depth to contain a reagent  32 . A plurality of reagents  32  can be pre-loaded into the reagent wells  30 . As is known by persons of skill in the art, some reagents  32  are in solid tablet form. Other reagents  32  are typically in liquid form, and may be loaded in the disc  10  in a semi-solid (e.g., “gel-cap”) form. 
         [0039]    For several tests, the reagents  32  need to be mixed and dissolved in the sample before the sample is tested. Typically the reagents  32  react with a particular component which may be in the sample, and the compound resulting from the reaction absorbs the light and is detected by the testing procedure. Therefore, the reagent should be thoroughly mixed with the sample for the most accurate test results. The reagent channel  28  can enter the reagent well  30  at close to a tangent of the reagent well  30  to help facilitate swirling and mixing within the reagent well. The dimensioning of the reagent well  30  and reagent channel  28  to facilitate swirling and agitation utilizes the fluid flow to aid in dissolving the reagent  32  in the sample. The reagent channels  28  can be similar in depth to the reagent well  30  to facilitate swirling and mixing in the reagent well  30  as the sample material enters. 
         [0040]    The channels  26  also include optical channels  34  which connect and provide fluid communication between the reagent wells  30  with a plurality of optical wells  36 . Preferably, the optical channels  34  are shallow, and serve as mixing channels to further mix the reagent  32  and the sample before the sample is spectrophotometrically tested. The optical channels  34  are dimensioned and sized so the fluid flowing through the channels  34  tends to agitate and mix the sample, and this enhances efficient mixing of the reagents  32  with the samples. The optical channels  34  can be more shallow than the optical wells  36  or the reagent wells  30  to reduce the cross sectional area of the optical channels  34  and therefore increase the Reynolds number in the optical channels  34 . This tends to enhance mixing by promoting turbulent flow in the sample. 
         [0041]    If a particular test or standard does not require a reagent  32 , the inlet well  24  can be directly connected to the optical well  36  by the optical channel  34 , with no reagent channel  28  or reagent well  30  between the inlet well  24  and the optical well  36 . As an alternative, the disc  10  can be designed with the reagent channel  28  and reagent well  30  between the inlet well  24  and the optical well  36 , but the reagent well  30  can be left empty with no reagent  32 . Either way, the sample can be directed to the optical well  36  without being mixed with a reagent  32 , if desired. 
         [0042]    Optical wells  36  can be generally cylindrical wells defined in the body  12  to permit light to shine from beneath the disc  10  through the optical well  36  containing the sample to detectors received above the optical wells  36 , or vice versa. Therefore, the optical well bottom surface  38  and the optical well top surface  40  should be transparent to the wavelength of light used, and the top and bottom surfaces  38 ,  40  should be smooth to minimize diffraction and scattering of the light signal. It is acceptable for the top and bottom surfaces  38 ,  40  to absorb some of the light, as long as enough light is allowed to pass for an accurate test of the sample to be performed. In one embodiment of the invention, the reagent wells  30  and optical wells  36  are 30 inches deep, though other dimensions are possible. 
         [0043]    Waste channels  42  are sized to permit excess sample to exit the optical wells  36  and be received in an exterior waste well  44 , which can follow the perimeter of the disc  10 . Therefore, the waste channels  42  connect and provide fluid communication between the optical wells  36  and the waste well  44 . The waste well  44  is sufficiently deep to contain excess water or sample material. The waste channels  42 , which are another part of the channels  26 , can narrow at their entrance to the waste well  44  in order to reduce the possibility of backflow of sample material from the waste well  44  into the waste channels  42 . 
         [0044]    The lid  16  can include one or more vent holes  46 , and the vent hole  46  can be positioned over the waste well  44 . The channels  26  include the reagent channel  28 , the optical channel  34 , and the waste channel  42 . These channels  26  provide fluid communication between the inlet port  18 , the inlet well  24 , the reagent wells  30 , the optical wells  36 , and the waste well  44 , so a vent hole  46  in fluid communication with the waste well  44  is also in fluid communication with the other wells  24 ,  30 ,  36  and channels  26 ,  28 ,  34 . Therefore, a vent hole  46  in fluid communication with the waste well  44  allows for trapped gases and vapors to be vented throughout the disc  10 , and liquid flow is facilitated because the liquids are not forcing gases into confined areas, which would develop a resisting back pressure. 
         [0045]    Although the illustrated embodiment is fabricated from a transparent medium, in other embodiments the disc  10  could be fabricated from a non-transparent medium, with the limitation that the path light takes through the optical well  36  is relatively transparent to the wavelength of light used. Generally, this means the optical well bottom and top surfaces  38 ,  40  should be relatively transparent to the wavelength of light used. The material has to be transparent enough to the wavelength of light used to allow for enough light to determine the concentration of the compound being tested for. The intensity of the light source can affect the degree of transparency required for the material around the optical well  36 . 
         [0046]    The disc  10  can include a source indicator  48  received on the body  12 , such as a bar code. The source indicator  48  can be received on any body surface, including the disc top or bottom surface  20 ,  22  or a body outer edge  53 . Positioning the source indicator  48  on the disc top surface  22  may provide less resistance to movement and/or abrasion or wear on the source indicator  48  than either the bottom surface  20  or the body outer edge  53 . The source indicator can utilize a wide variety of indicators which can be read, including variations in depth, magnetism, color, shape, size, or position of marks. Any variation which can be read and interpreted can be utilized to indicate source, and the source indicator  48  can be used to indicate which type of tests are to be performed with a particular sample device  10 . 
         [0047]    The disc  10  can also be used for electrochemical testing. An electrochemical probe  47  can be positioned in an optical well  36 , a reagent well  30 , or even the waste well  44 , with sample device contact points  49  connected to the electrochemical probe  47 . When the sample contacts the probe  47  received in the well  30 ,  36 ,  44 , the probe  47  interacts with the sample, and an electrical signal indicates some characteristic of the sample material. A signal is transmitted from the probe  47  to the sample device contact points  49 , which can then be measured to calculate the sample characteristic. The electrical signal can be a measurement of voltage potential, resistance, or current, depending on the type of electrochemical probe  47  utilized. For example, voltage potential is measured when a pH probe is used, and resistance is measured when a conductivity probe is used. 
         [0048]    The disc  10  can be fabricated from a number of techniques, such as injection molding, etching, or machining, and can be made from a number of materials, such as acrylic, plastic, glass, quartz, photopolymers, or composite materials. Injection molding of the lid  16  and the bottom plate  14  allows rapid, affordable production of the sample device body  12 , and can include formation of the source indicator  48 . In one embodiment, the disc  10  is approximately five (5) inches in diameter and approximately ⅜ inches thick, but other sizes are possible without departing from the scope of the present invention. 
       The Analyzer and Testing 
       [0049]    A functional representation of one embodiment of the disc  10  mounted on the analyzer  50  is shown in  FIGS. 3 and 4 . In this embodiment, the disc  10  is mounted on the top of the analyzer  50  between rollers  52 . The purpose of the rollers  52  is to constrain and position the disc  10  while permitting it to rotate horizontally. The sample device body outer edge  53  contacts the rollers  52  such that the body outer edge  53  can rotate within the rollers, but the basic position of the outer edge  53  is controlled by the rollers  52 . A rotation pin  54  in the analyzer  50  fits into an alignment notch  56  defined in the disc body  12 , and can be used to rotate the disc  10  as needed between sample testings so different sub-samples can be sequentially tested. The rotation pin  54  and alignment notch  56  also serve to properly and consistently position and align the disc  10  on the analyzer  50 , so the position of each optical well  36  is set and known when an analysis is started. To enable consistent and unique alignment of the disc  10 , the alignment notch  56  should be positioned somewhere other than the center of the disc  10 . 
         [0050]    In the operation of the illustrated embodiment, the disc  10  is placed on the analyzer  50  and an opaque cover  58  is positioned over the disc  10  such that the disc  10  is encased before a test is started. The cover  58  is opened to insert or remove a sample device  10 , and the cover  58  on the analyzer  50  is closed during the testing to substantially block out ambient light from the sample device  10 . In this embodiment, the sample is injected into the inlet port  18  from the disc bottom surface  20  and is directed via sixteen (16) identical and equally-spaced channels  26  to sixteen (16) optical wells  36 . Air or another gas can be introduced into the inlet port  18  after the sample, to move the sample through the disc  10  and to maintain pressure on the sample material, thus helping to keep the optical wells  36  full. The air pressure can be maintained with a line using a valve (not shown) connected to the inlet port  18 . The sample could be injected through the same valve. If the inlet port  18  is on the disc bottom surface  20 , special fittings can be used to seal the inlet port  18  to the analyzer  50 . 
         [0051]    After the sample is introduced into the optical wells  36 , a source  60  of electromagnetic radiation is activated to transmit into the sample in the optical wells  36 , and detectors  62  are positioned to measure the amount of electromagnetic radiation emanating from the optical wells  36 . This is used to analyze the samples in the optical wells  36 . Generally, the detectors  62  are positioned on the opposite side of the optical wells  36  from the source  60 . However, for fluorescence testing, the source  60  and the detector  62  do not have to be aligned, so a wide variety of source  60  and detector  62  positions are possible. In this embodiment, LEDs are used as the radiation source  60 , and light is the radiation emitted by the LED source  60 , but lasers or other sources of electromagnetic radiation could also be used. 
         [0052]    Excess sample water drains into the waste well  44  via waste channels  42 . Excess air, forced out when the sample is introduced into the disc  10 , exits via the vent hole  46  in the lid  16 . The detectors  62  are connected to a microprocessor  66 , which performs the required calculations and records the test results. The term “microprocessor” includes any device or collection of devices capable of receiving signals and calculating concentrations or other sample characteristics based on the signals received. A greater concentration of the absorbing material in the optical well  36  results in more light from the LED source  60  being absorbed, and less light reaching the detector  62 . Therefore, after proper calibration, the amount of light being detected by the detector can be used to determine the concentration of the absorbing material in the optical well  36 . The disc  10  should be encased before the testing operation, or ambient light will reach the detector  62  and bias the test results. 
         [0053]    The analyzer  50  can also perform electrochemical analysis if properly configured. Analyzer contact points  68  can be provided on the analyzer  50 , with the analyzer contact points  68  positioned to contact the sample device contact points  49  when the sample device  10  is properly positioned on the analyzer  50 . The probe  47  in the disc  10  then sends an electronic signal to be read by the microprocessor  66  through the sample device contact points  49 , which are in electrical communication with the analyzer contact points  68 , which are connected to the microprocessor  66 . The analyzer and/or sample device contact points  49 ,  68  can be a printed board or some sort, a contact pin, contact plates, or any means of providing electrical communication when the analyzer and sample device contact points  49 ,  68  are aligned. The analyzer  50  can provide an electrical signal to the probe  47  to produce the probe signal, if necessary. It is also possible to include “+” and “−” nodes in a well  30 ,  36 ,  44  in place of the probe  47 , with the analyzer providing charge to the nodes for other tests such as DNA extraction. 
         [0054]    The analyzer  50  can also be equipped with a device  70  for reading the source indicator  48 . This can be a bar code reading device  70 , but other devices can also be used depending on the type of source indicator  48  used. For example, lasers for detecting depth variation or lights and detectors for reading color variations could be used. 
         [0055]    The source indicator  48  could indicate which tests to perform, and the disc  10  could be customized for that pre-determined sample testing routine. The analyzer  50  could have a plurality of sample testing routines, such as one for well water supplies, one for river water supplies, and one for waste water treatment. Such things as the number of sub samples generated, the reagents  32  used, the position of the optical wells  36 , and probe  47  positions could be customized for each test routine, and the source indicator  48  allows the analyzer  50  to select the proper testing routine. 
         [0056]    In one embodiment of the invention, the analyzer  50  provides four (4) equally-spaced LED source&#39;s  60  and four (4) equally-spaced detectors  62  which are used to test sixteen (16) analytes in the sixteen (16) optical wells  36 . Each LED source  60  can be at a specific wavelength of light, so the reagents and tests would be grouped based on the required wavelength for the test. With this configuration, the analytes in four (4) optical wells  36  may be analyzed simultaneously. After analysis of four analytes, the analyzer  50  rotates the sample device  10  until the four (4) LED sources  60  underlie four different optical wells  36 , and the next four analytes are tested. This process is repeated until all sixteen (16) analytes have been tested. 
         [0057]    It may be desirable to leave at least one reagent well  30  empty, and use the associated optical well  36  as a blank for a baseline reading. This baseline can then be applied to other samples tested. The rotation is driven in the illustrated embodiment by the rotation pin  54  on the analyzer  50  that engages in the notch  56  in the disc bottom surface  20 . The disc  10  is held in position during the rotation by the rollers  52 , so the disc  10  rotates about its center axis. The rotation pin  54  allows the sample device  10  to be rotated between at least two analysis stages, which can be different tests or redundant tests, as desired. 
         [0058]    Another embodiment of the present invention is illustrated in  FIG. 5 . In this embodiment, the inlet port  18  is on the disc top surface  22 , and there is no central hole through the disc bottom surface  20 . The cover  58  of the analyzer  50  includes a seal  64  that seals against the disc  10  when the cover  58  is closed. Using this embodiment, the sample can be introduced into the disc  10  before the disc  10  is mounted on the analyzer  50 , or the sample can be introduced into the disc  10  after the disc  10  is mounted on the analyzer  50  with the cover  58  closed. This seal  64  may be accomplished by any number of methods well known by persons of skill in the art. The seal  64  should block light which can interfere with the optical testing, and the seal may be water-proof to minimize issues associated with leaks. 
         [0059]    The disc  10  and analyzer  50  in the illustrated embodiment include sixteen reagent wells  30  and sixteen optical wells  36 , and permit four tests to be performed at once. This configuration was chosen in order to permit multiple tests to be performed quickly while keeping the size of the analyzer  50  reasonably small, e.g., smaller than a breadbox. However, other configurations are possible without departing from the scope of the present invention. By way of example only, the analyzer  50  could be enlarged to perform sixteen tests at one time, and thus the rotation of the disc  10  would not be necessary. Further, the size of the disc  10  and the number of optical wells  36  could be varied. Thus, a wide variety of disc  10  and analyzer  50  configurations are possible, depending upon the number and nature of the tests desired to be performed and the size and space limitations of the analyzer  50 . 
         [0060]    In addition, although the illustrated embodiment of the disc  10  is generally symmetrical, some tests may require a different topography of channels  26  and wells  28 ,  34 ,  44 . Therefore other configurations and sizes of channels  26  and wells  28 ,  34 ,  44  are possible within the scope of the present invention. 
         [0061]    While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed here. Accordingly, the scope of the invention should be limited only by the attached claims.