Abstract:
An automated computer controlled ground water system for monitoring and analysis for an analyte, has a sampling device in a well casing with a valve and sensor to provide a predetermined sample volume, a treatment assembly to prepare a calibration standard, a calibration assembly to provide a standard of known concentration and volume, an analytical assembly to analyze for analyte concentration, and a communication system to receive analysis data and transmit it to a cognizant agency.

Description:
RELATED APPLICATIONS  
       [0001]    Reference is made to our Provisional Application No. 60/228,312, filed Aug. 28, 2000, entitled “Ground-Water Monitoring System”. 
     
    
     
       BACKGROUND AND SUMMARY OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to analysis systems for determining the presence and concentrations of hazardous, carcinogenic, etc., chemicals in ground water. In particular, the invention relates to an automated system for operation on site to automatically and independently assay concentrations of analytes of interest, and to communicate analysis data to agencies concerned with health and safety.  
           [0004]    2. The Prior Art  
           [0005]    Analysis of ground water for analytes of interest has become progressively more important because of concern regarding soil and ground water contamination by industrial chemicals and the like, and by nuclear waste.  
           [0006]    The prior art comprises a wide assortment of liquid sampling systems and devices. These fall into three general categories:  
           [0007]    (a) devices lowered into a liquid to collect a sample;  
           [0008]    (b) devices lowered into a liquid and which pump the liquid to the surface for analysis; and  
           [0009]    (c) devices lowered into the liquid and which embody self-contained means for analysis of the liquid and the transmitting of analysis data to a processing station.  
           [0010]    Among the prior art patents relative to such liquid sampling devices are the following: U.S. Pat. No. 5,293,934 to Burge et al, U.S. Pat. No. 5,033,551 to C. Grantom, and U.S. Pat. No. 5,708,220 to R. Burge.  
           [0011]    Liquid sampling devices of the prior art involve certain disadvantages and shortcomings, which it is the purpose of the present invention to overcome.  
           [0012]    Devices which obtain samples by lowering a device into the liquid to be sampled, withdrawing the sample from the liquid, and retrieving and collecting samples, involve time-consumption, tedious processes and expense. A primary disadvantage is that contamination of the sample analyzing means within a submersible sampling device necessarily restricts the accuracy of sample analyses which may be performed, expose the instrumentation to risk of damage, unnecessarily increase the cost and complexity of sampling devices, and preclude utilizing such instrumentation for other purposes, as in laboratories.  
           [0013]    Devices lifting a column of water equal in height to the distance from the submerged sample collection device to the surface require very high pump outlet pressure, particularly when a sampling device is a substantial distance below ground surface, such as 1,000 ft. or much more.  
           [0014]    There has existed substantial and increasing need for an improved water sampling system and method which provides a complete automatic procedure from sampling through analysis, and under computer program control from sampling to disposal of waste samples and communicating the analysis results automatically to provide an assay for use by appropriate agencies.  
         THE PRESENT INVENTION  
         [0015]    The present invention provides an automatic computerized system, apparatus and method for the provision of analyses to identify specific elements and compounds as analytes in a sample automatically provided. The system prepares and standardizes a sample for presentation to an analysis assembly to process a sample by instrumentation to arrive at an assay of the sample. Assay data is sensed and processed for computer print-out and communication via a communication link to inform cognizant agencies. A computer and a control module  120  controls operation and sequencing of the system.  
           [0016]    The present ground water monitoring system of the present invention comprises, in a sampling module, a water treatment module, a calibration module, an analytical module, a communication/data logging module, and a waste module. There are embodiments wherein a particular module may not be used, or where the components of two or more modules are combined to form a combination module, which by the operation of this single module can perform the functions of one or more separate modules. The ground water monitoring system may be used without the water treatment module in certain embodiments.  
           [0017]    The purpose of the sampling module is to collect ground water samples from a monitoring well. The ground water sample collected within the sampling module may be analyzed within the body of the sampling module or transported to an analytical module located inside or outside of the monitoring well. The water treatment module serves to remove the analyte of interest from the water to be monitored. Alternatively, the water treatment module can be replaced by a reservoir of distilled water or water not containing the analytes of interest. The water treatment module is used to prepare blanks and standards for calibrating a sensor. The advantage of the water treatment module is that it allows water of the same ion strength, temperature, pH and other factors, to be used to calibrate the sensor.  
           [0018]    The calibration module calibrates the sensor inside the analytical module. The communication/data logging module transmits or records the data for the user. The waste module may comprise a vessel for containing the waste water, or may include a small treatment unit. The waste treatment unit of the waste module may include cartridges filled with media which will remove specific contaminants or small chambers for removing contaminants, allowing the waste water to be cleaned to concentrations below the concerns of Federal or State regulations.  
           [0019]    Primary components of the analytical system are the sample vessel and the sensor therein. The enclosing of the sensor allows for the introduction of samples, standards, and other chemicals such as matrix modifiers. A sensor which is not enclosed inside the sample vessel cannot be interrogated and standardized. The chemical/physical sensor or other device capable of determining the concentration of the analyte in the ground water sample is placed inside this sample vessel. The analytical module may determine the species of interest, either directly in the water sample or by creating a head space over the sample for chemical/physical sensors which respond to the analyte in atmospheres in the head space. The sample vessel has water level sensors which allow predetermined volumes of standards or samples to be introduced into the sample vessel. The presence of two or more water level sensors allows for the dilution of samples or standards and/or adding special solutions to the sample vessel, such as matrix modifiers.  
           [0020]    It is feasible to combine the sampling and analytical modules into one unit for sensors fabricated to fit within the confines of a well casing.  
           [0021]    The water treatment unit allows for water from the monitoring well either to be introduced directly into the sample chamber or to pass through a media such as activated charcoal to remove the analyte of interest. Other media would include, but not be limited to, ion exchange resins, clays and zeolites. In some instances, the water treatment module may be replaced with a source of analyte free water.  
           [0022]    The calibration module may be located in or outside the monitoring well. If the calibration module is within the well, it contains the valving necessary to introduce liquid or gaseous standards to the analytical module. If the calibration module is located outside of the monitoring well, the module contains the valving necessary for the introduction of the samples (from the sampling module) and standards to the analytical module. The calibration standards can be presented to the sensor as a solution (aqueous or other solvent) or a gas. The type of standard depends upon the sensor and the physical attributes of the analyte to be measured, The calibration module allows for introduction of known concentrations of the analyte into the analytical module.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    [0023]FIG. 1 is a diagrammatic illustration of a preferred embodiment of the present invention;  
         [0024]    [0024]FIG. 2 is an enlarged view of the portion of FIG. 1 enclosed by circle  2  in FIG. 1;  
         [0025]    [0025]FIG. 3 is a schematic view of an embodiment wherein a sensor is deployed outside of a monitoring well;  
         [0026]    [0026]FIG. 4 is an embodiment of the invention wherein the sensor is deployed inside a well;  
         [0027]    [0027]FIG. 5 is a schematic illustration of an embodiment wherein a sensor is deployed in a separate well casing adjacent to a monitoring well for security and environmental control;  
         [0028]    [0028]FIG. 6 is a diagrammatic illustration of an embodiment wherein sampling, water treatment, and calibration modules, a sensor vessel, and analytic module for an optrode are deployed in an automated monitoring module;  
         [0029]    [0029]FIG. 7 is a diagrammatic view of an embodiment wherein a sensor is disposed in a monitoring well in a combined sampling and water treatment module; and  
         [0030]    [0030]FIG. 8 is a schematic illustration of a monitoring unit utilizing an ion-specific electrode.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    Referring to the drawings, FIGS.  1 - 3  show a basic ground-water monitoring system according to the invention. A sampling module  1  is disposed in a well casing  2  of a well to be monitored. A specimen or sample tube  3  conducts water from the well to a water treatment module  4 . The module source of analyte-free water is connected with a calibration module  5  which is attached to an analytical module  6 . The waste tube  7  connects the analytical module to a waste reservoir or module  8 . A source of electrical power, preferrably a solar cell  9 , is connected with an analytical module  6 . A communication module  10  is connected with the analytical module. Operation of the system and sequencing are controlled by a computer (not herein described) and a control module  120  (FIG. 1).  
         [0032]    In the operation of this embodiment, sampling module  1  collects a ground water sample which is transported via tube  3  to water treatment module  4  which is capable of passing the ground-water sample through the module without treatment or conducting the water through a filtering media to remove the analyte of interest. When water not containing the analyte is utilized, it can be supplied from an external source (not shown). The untreated sample passes to analytical module  6 . Treated water or analyte-free external water is passed through calibration module  5  for addition of a standard. Alternatively, the standard may be added directly to the sample container from the analytical module. Treated water, with standard added, can be passed to the analytical module for analysis. When the sample standards are analyzed, the sample or standard is transported by waste tube  7  to waste module  8 . Data generated by the analytical module by conventional means is relayed to communication module  10 , which transmits the data by radio or stores the data.  
         [0033]    Referring to FIG. 4, a ground water monitoring system is shown located within the monitoring well casing  11 . A sample inlet  12  and water treatment module  13  are attached to the bottom of the sampling/analytical module  14 . Alternatively, an external source of analyte free water may be supplied for performing the calibrations. The valving of the calibration module is attached to the sample vessel of the sampling/analytical module  14 . A gas line  16  conducts pressurized air, nitrogen or other gases, to the calibration module  15  and/or sampling/analytical module  14 . A waste tube  17  is attached to the sampling/analytical module  14 . A power/communication cable  18  attaches the communication module  19  to the sampling/analytical module  14 .  
         [0034]    The operation of the ground water monitoring system located within the well casing as illustrated in FIG. 4 is initiated by the ground water passing through either the sample inlet  12  or the water treatment module  13  into the sampling/analytical module  14 . Water conducted through the sample inlet  12  into the sampling/analytical module  14  is analyzed as the sample. After the sample is analyzed, the sample is transported out of the well casing  11 , using the waste tube  17 , to either a container or treatment unit. The water conducted through the water treatment module, or an external supply of water, is used to prepare the blanks and standards. The water may either be transported through a calibration module  15  for the addition of the standard, or the calibration module  15  adds the standard directly for use in a sampling/analytical module  14 . Alternatively, the water treatment module  13  may be deleted and water may be transported from the surface for the preparation of standards and blanks. The data generated from the sampling/analytical module  14  is relayed by the power/communications cable  18  to the communications module  19 .  
         [0035]    Referring to FIG. 5, an embodiment of the ground water monitoring system which disposes the analytical and calibration modules into a separate casing or enclosure adjacent to the monitoring well, is illustrated. The separate casing and enclosure allows for better environmental control, maintenance and security of the ground water monitoring system.  
         [0036]    A sampling module  20  is disposed in well casing  21 , and a sample tube  22  connects this module with water treatment module  23 , which is connected to a calibration module  24  or to a source of analyte-free water (not shown). Calibration module is attached to an analytical module  25 . The water treatment module, calibration module and analytical module are disposed in a separate casing  26 . Alternatively, a water treatment module may be disposed outside the enclosure or may be replaced by a source of water (not shown) not having the analyte of interest. The waste tube  27  connects analytical module  25  to a waste module  28 . Power cable  30  electrically connects the analytical module to a solar cell  29  (or other power source). Communication module  31  is attached to the analytical module  25 . Operation of the system of FIG. 5 is similar to that of the system of FIG. 1 except that the modules  24  and  25  are inside a protective casing  26 .  
         [0037]    Referring now to FIG. 6, an example of the sampling module, water treatment module, calibration module and the sensor vessel of the analytical module for an optrode deployed in the automated monitoring system is illustrated.  
         [0038]    The sampling module ( 33 - 38 ) is located in the well casing  32 , and comprises the several components  33  to  38 . Water inlet  33  is attached to sample chamber  35  through water inlet valve  34 . A gas valve  36  is connected to the sample chamber  35 . A vent tube  37  connects with the gas valve  36 . A water sensor  38  is located within the body of the sample chamber  35 . A pressurized gas tube  40  connects a source of pressurized gas  39  to a gas valve  36  and the sample chamber  35 . A sample tube  41  connects the sample chamber  35  to water treatment valve  42  of the water treatment module  42 - 44 . Alternatively, the sample module  33 - 38  may be replaced with commercially available pumps. The water treatment valve  42  is connected to the water treatment cartridge  43  and calibration valve  53 . The water treatment cartridge  43  is filled with sorbent media for removing and filtering out the analyte of interest. Water treatment cartridge  43  is connected with the standard valve  45  of the calibration module by a water tube  44 . Water diverted through treatment cartridge  43  removes the analyte of interest by passing the water through a sorbent media. Water exiting the treatment cartridge  43  is transported to valve  45  of the calibration module via a water tube  44 .  
         [0039]    The calibration module comprises a source  49  of low pressure gas attached to a valve  50  connected with a bottle  51 , which is connected by a tube  52  to the valve  45 . This valve is connected to a calibrated loop  46  containing a known volume of standard.  
         [0040]    A loop valve  47  is connected to calibrated loop  46  opposite from valve  45 . A waste tube  48  is attached to a third port of loop valve  47 , as shown. Calibration valve  53  is connected to water treatment valve  42  and loop valve  47 . A third port of calibration valve  53  is connected to a diversion valve  55  which is connected to a waste tube  56  and a sample vessel valve  58  which is connected to waste tube  60  and a sample vessel  59  of the analytical module.  
         [0041]    In the analytical module, the sample vessel  59  is attached to a sample vessel cap  61  which houses the sensor  62 . A port of gas valve  63  is connected to a vent  64  and a pressurized gas tube  65 . Water level sensors  66 ,  67  serve to monitor height of the water column in the sample vessel.  
         [0042]    Introduction of the calibration standards is effected by low pressure gas source  49  which gas is conducted by valve  50  to head space of standard bottle  51 , which head space is pressurized, transporting the standard through the standard tube  52  into standard valve  45  and calibrated loop  46  into loop valve  47  into the waste tube  48 . Thereafter, calibrated loop  46  is filled with a precise volume of standard, which is flushed from calibrated loop  46  by the water from the treatment cartridge  43  via loop valve  47 , calibration valve  53 , diversion valve  55 , sample vessel  58  and into sample vessel  59 . Filling of the calibrated loop  46  may be done several times during the filling of sample vessel  59  to create one to several concentrations of standards. Water flows into the sample vessel  59  until water sensor  66 ,  67  is activated. After analysis of the standard, water in sample vessel  59  is transported through the valve  58  into waste tube  60 . Purging of the sample vessel is facilitated by the gas valve  63  which is connected with a source of pressurized gas  65 .  
         [0043]    The procedure in introducing a sample to the analytical module includes passing the water through water treatment valve  42 , calibration valve  53 , diversion valve  55 , sample valve  58  and sample vessel  59 . The filling and emptying of the sample vessel is similar to the filling cycle for the calibration solutions.  
         [0044]    Dilution of a sample is accomplished by introducing a sample until lower water level sensor  67  is activated. The remaining water or solution moves through the treatment cartridge  43  or an external source of analyte-free water until upper water level sensor  66  is satisfied. It is thus possible to dilute the sample to allow the sample outside the analytical range of sensor  62  utilized in the ground-water monitoring system.  
         [0045]    Operation of this embodiment begins with the water being transported through the water inlet  33  and water inlet valve  34  into the sample chamber  35 . Water continues to be conducted into the sample chamber  35  until the water level sensor  38  is satisfied. The gas valve  36  opens the port to the pressurized gas at  39 ,  40  which pressurizes the head air space in the sample chamber  35 . The water is evacuated from the sample chamber  35  by a sample tube  41  and is transported to the water treatment valve  42  of the water treatment module  42 - 44 . Alternatively, this may be replaced with a commercial ground-water pump.  
         [0046]    The water treatment valve  42  diverts the ground water through the water treatment cartridge  43  or to the calibration valve  53 . Water conducted to the water treatment cartridge  43  is used to prepare the standards. Water transported to the calibration valve  53  is used as the sample. Water diverted through the water treatment cartridge  43  removes the analyte of interest by passing through a sorbent media. Water exiting the water treatment cartridge  43  is transported to the standard valve  45  of the calibration module via a water tube  44 .  
         [0047]    [0047]FIG. 7 shows a sensor deployed in a monitoring well in combination with a sampling/water treatment/calibration analytical module. The analytical/calibration water treatment module is contained within a well casing  68  under the static water level  69 . A water inlet  70  is attached to a water inlet valve  71  which is attached to sample chamber  72 . A third port (not shown) of inlet valve  71  is connected to a waste tube  88 . One or more water level sensors  73 ,  74  monitor the water level in sample chamber  72 . A gas valve  75  is connected with sample chamber  72 . The gas valve is connected to a vent  77  and pressurized gas tube  76 . A water treatment inlet  78  is connected with water treatment cartridge  79 . Water treatment valve  80  is connected atop the treatment cartridge  79 , tube  81  and the bottom of chamber  72 . Tube  81  is connected to standard valve  82 . Gas valve  83  is connected with pressurized gas tube  76  and standard bottle  84 . A tube  85  connects standard bottle  84  to standard valve  82 . A calibrated loop  86  is attached to valve  82  and loop valve  87  which is connected with waste tube  88  and the top of sample chamber  72 . A chemical/physical sensor  89  is disposed in sample chamber  72 . A stirring bead  90  is inside sample bottle  72 .  
         [0048]    If analysis requires sample dilution, lower water sensor  74  controls sample introduction. If dilution is not required, upper sensor  73  terminates sample introduction. These level sensors control the creation and volume of a headspace in the chamber. Certain embodiments (not shown) require no level sensor, and water is introduced into the sample chamber until reaching static water level  69 , or by a timer (not shown) connected to stop water introduction into the chamber.  
         [0049]    A water sample collected in chamber  72  is analyzed by chemical/physical sensor  89  which may be placed either into the head space above the water sample, or may be inserted into the water. After analysis, a gas valve  75  pressurizes the head space in chamber  72 , while water is conducted from inlet valve  71  and via waste tube  88 .  
         [0050]    If the sensor  89  is to be calibrated with a blank, the water treatment valve  80  is activated, thus to cause ground water to flow via the water treatment inlet  78  and water treatment cartridge  79 . Alternatively, a source of analyte-free water may be used. The analyte of interest is removed from the water and the water is passed via water treatment valve  80  into sample chamber  72 . The water level rises in the chamber until the water level sensor is activated. In combination with the sample introduction, this allows for dilution of the sample. The water flow into the sample chamber is terminated by the water treatment valve  80  and the analysis initiated. The sample chamber is emptied in a similar method as outlined above.  
         [0051]    The operation of the monitoring system with the water treatment/calibration/analytical modules located within a monitoring well is initiated by activating the water inlet valve  71 . The hydrostatic pressure causes ground water to fill the sample chamber  72  through the water inlet  70 . The water fills the sample chamber until one of the water level sensors  73 ,  74  de-activates the water inlet valve  71 .  
         [0052]    If sensor  89  is to be calibrated with a standard containing the analyte of interest, water treatment valve is activated and ground water is passed via water inlet  78 , treatment cartridge  79 , inlet valve  80  and water tube  81  to standard valve  82 . The standard is introduced by activating gas valve  83  to pressurize head space in standard bottle  84  conducting the standard via standard tube  85  to standard valve  82 . Standard is then conducted via standard valve  82  through calibrated loop  86  into loop valve  87  and into waste tube  88 . Such procedure causes the calibrated loop  86  to be filled with a precise volume of standard. The standard is flushed from loop  86  when the treated water is introduced to standard valve  82 , and the treated water transports the standard via loop valve  87  into sample chamber  72 . A stirrer motor  91  and stirring bead  90  agitate water in the sample chamber  72 .  
         [0053]    [0053]FIG. 8 shows an embodiment of the invention wherein a preferred form of electrode which is pH or ion-specific is deployed in a monitoring well, although other types could be utilized, and is located inside a well casing  92  under the static water level  93 . A water inlet  94  is connected to an inlet valve  95  connected with matrix modifier loop valve  96 . As shown, a calibrated matrix loop  98  connects the matrix modifier loop valve  96 . The calibrated matrix loop  98  connects with a third port of the matrix modifier loop valve  96  to the matrix modifier valve  97 . The valve  97  is connected to matrix modifier tube  99  which is connected with a matrix modifier reservoir  100  which may be located on the surface of or within well casing  92 . As shown, a third port of the matrix modifier valve  97  is connected to the calibration valve  103 . A calibration loop  104  is connected with calibration valve  103  with calibration loop valve  105 . A third port of the calibration valve  103  is connected to standard tube  106  which is connected with standard reservoir  107  located at the surface or within well casing  92 . Calibration valve  105  is connected with a waste tube  101  and the bottom of a sample chamber  108 .  
         [0054]    The matrix modifier loop  98  and two accompanying valves, matrix modifier valve  97  and matrix modifier loop valve  96 , may be disposed after admission of calibration loop  104 , calibration valve  103  and calibration loop valve  105 . The location of the matrix introduction, relative to standard introduction, is not important to the operation of the device. The top of sample chamber  108  is connected with a gas vent tube  109  connected to a valve  110  disposed above or below static water level  93  in casing  92 . An air tube  111  and vent tube  112  are connected to the gas vent valve  110 .  
         [0055]    An electrode  115  is connected with the interior of chamber  108 , and a stirring head  116  is disposed in the chamber, and a stirring motor  117  mounted beneath the chamber, as shown.  
         [0056]    A protective casing  119  encloses the entire assembly under static water level  93 , as shown in FIG. 8. One or more water level sensors  113 ,  114  may be disposed inside or outside of the sample chamber. Operation of the system of the invention allows a pH, ion-specific other type electrode to be deployed in a monitor well, requiring a water inlet valve  95  to be activated to cause water to pass through inlet  94 , and water flows into the device because of head pressure between inlet  94  and static water level  93 .  
         [0057]    The ground-water sample passes via inlet valve  95  and matrix modifier loop valve  96 , and is then conducted via the matrix modifier loop  98 , matrix modifier valve  97 , calibration water valve  103 , calibration loop  104 , calibration loop valve  105  and into sample chamber  108 .  
         [0058]    Addition of the matrix modifier may be accomplished using one of two methods now described. The amount of matrix modifier may be measured by modifier loop  98 . The procedure to add the matrix modifier is by activating matrix modifier loop  96  and matrix modifier valve  97 , thus causing matrix modifier solution in the matrix modifier reservoir  100  to pass via tube  99 , matrix modifier valve  97 , matrix modifier loop  98 , modifier loop valve  96 , and into waste tube  101 . After a short time, the program deactivates the matrix modifier loop  96  and matrix modifier valve  97 , thus causing an exact amount of matrix modifier solution to be contained in the matrix modifier loop  98  which is flushed into the sample chamber  108  by opening inlet valve  95 , modifier loop valve  96 , matrix modifier loop  98 , matrix modifier valve  97 , calibration valve  103 , calibration loop  104 , calibration loop valve  105 , and into the sample chamber  108 .  
         [0059]    The second method of producing the matrix modifier is to remove matrix modifier valve  96  and matrix modifier loop  98 , and allow the matrix modifier to be introduced via matrix modifier valve  97 , calibration valve  103 , calibration loop  104 , calibration loop valve  105  and into sample chamber  108 . The solution will rise into the sample chamber  108  until the lower water level sensor  113  or upper water level sensor  114  is activated. The procedure allows for a precise volume of matrix modifier to be introduced in the chamber  108 .  
         [0060]    To calibrate electrode  115 , calibration valve  103  and loop valve  105  are activated to pass the standard to the standard reservoir  107  via standard tube  106 , calibration valve  103 , calibration loop  104  and loop valve  105  to waste tube  101 . After a time, calibration valve  103  and calibration loop valve  105  will be activated, thus causing an exact amount of standard solution to be contained in the calibration loop  104 , which is flushed into the sample chamber by opening inlet valve  94 , matrix modifier loop  96 , matrix modifier loop  98 , matrix modifier valve  97 , calibration valve  103 , calibration loop  104 , calibration loop valve  105  and into sample chamber  108 . In one embodiment of the invention (earlier described), no matrix modifier loop valve and no matrix modifier loop are utilized.  
         [0061]    During the foregoing operation, gas vent valve  110  vents the head space in chamber  108  to atmosphere. The filling operation is halted when the water level in the chamber rises inside the gas/vent tube  109  to the static water level  93 , thus to initiate the analytic phase of operation. Stirring motor  117  is activated to agitate the sample in the chamber with the stirring bead  116 . Electrode  115  measures the concentration of the analyte of interest in either a sample or in a standard.  
         [0062]    Upon completion of an analysis, gas/vent valve  110  is activated to allow a source of compressed gas to pressurize the head space of the sample chamber and simultaneously, waste valve  102  is activated to drain the sample chamber via waste valve  102  and waste tube  118 .  
         [0063]    It will be understood that various changes and modifications may be made from the preferred embodiments discussed above without departing from the scope of the present invention, which is established by the following claims and equivalents thereof.