Abstract:
A cooling apparatus for a radiant energy heated oven is disclosed, where the cooling apparatus cools the oven by directing a flow of coolant through a chamber in thermal communication with the oven resulting in sub-ambient cooling, sub-ambient holds, and in chromatography instruments, higher sample throughput by reducing cycle time or column cool down time.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a cooling system or apparatus in the field of liquid and gas chromatography instruments heated by radiant energy such as microwave or radiowave radiant energy and to methods for making and using same. 
         [0003]    More particularly, the present invention relates to a cooling system or apparatus in the field of liquid and gas chromatography instruments heated by radiant energy such as microwave or radiowave radiant energy and to methods for making and using same. The cooling system includes a cooling apparatus having an coolant inlet and a coolant outlet, a supply of a coolant, a conduit connecting the cooling apparatus to the coolant supply, where the cooling system is adapted to permit lower start temperatures and faster post run cool down resulting in faster cycling between samples or shorter sample cycle times. The present invention also relates to a microwave oven for use in liquid and gas chromatography instruments including a microwave oven having such a cooling apparatus and to methods for making and using same. 
         [0004]    2. Description of the Related Art 
         [0005]    Gas and liquid chromatography are physical methods for the separation, identification, and quantification of chemical compounds. These methods are used extensively for applications that include the measurement of product purity in analytical chemistry, the determination of environmental contamination, the characterization of natural substances, and the development of pharmaceuticals. 
         [0006]    The fundamental methods used in gas and liquid chromatography instruments to separate chemical constituents are similar. A sample mixture is injected into a flowing neutral carrier stream and the combination then flows through a tube or chromatographic column. The inner surface of the column is coated or the tube is packed with a material called the stationary phase. As the sample mixture and carrier stream flow through the column, the components within the mixture are retained by the stationary phase to a greater or lesser degree depending on the relative volatility (in the case of gas chromatography) or the relative solubility (in the case of liquid chromatography) of the individual components and/or on their respective affinities for the stationary phase. When the individual mixture components are released into the carrier stream by the stationary phase, they are swept towards the column outlet. As the combined flow exits the column outlet, the flow is forwarded to a detector, where the separated components are detected and measured. Different chemical components or compounds in the sample are retained for different times by the stationary phase or spend different amounts of time in the moving phase. By measuring the retention times, the specific compounds or components in the sample can be identified. The relative concentration of the components compounds is determined by comparing peak amplitudes measured with the detector for each compound or component in the sample. The peak amplitude are generally compared to peak heights for that component of know concentrations of the component or are derived from instrument calibration. 
         [0007]    The primary difference between gas chromatography (GC) and liquid chromatography (LC) is the mode of separation. In gas chromatography, the sample is volatilized and propelled down the analytical column by a moving stream of gas. In liquid chromatography, the sample is dissolved and propelled down the analytical column in a moving stream of liquid. Another difference between gas and liquid chromatography is that the columns used in liquid chromatography have stationary phases that fill or are packed into the tube; while those used in gas chromatography can be packed, but generally the stationary phase is coated or bonded to the interior wall, instead. 
         [0008]    GC and LC measurements are facilitated by the application of heat to the chromatographic column to change its temperature. The use of a heated column oven in gas chromatographic systems greatly increases the number of compounds that can be analyzed and speeds up the time required for each analysis by increasing the volatility of higher molecular weight compounds. Heating an LC column affects the relative solubility of the mixture&#39;s components in the two phases and can enhance the separation as well as improve the repeatability of the elution times of the component chemicals. 
         [0009]    Many methods have been described for heating chromatographic columns. The simplest and most commonly used method utilizes resistive heating elements to heat air which is in turn circulated through an insulated oven in which the column is placed. For example, U.S. Pat. No. 3,527,567 to Philyaw et al. describes a GC oven heated with resistive elements. 
         [0010]    The resistive element heating method has several limitations. To achieve even heating of the column, a large volume of air is rapidly circulated around the chromatographic column. In addition to heating the column, the air heats the oven itself. Because the thermal mass of the oven is much larger than that of the column, the rate at which the column can be heated is commensurately reduced. A related problem is cooling time. After heating the oven to a high temperature during an analysis, it takes significantly longer to cool the oven plus the column to their initial temperature so that the next sample may be analyzed than it would to cool the column alone. Together, these limitations reduce the throughput of the chromatography instruments. 
         [0011]    Attempts to localize the resistive heat element onto the column itself so as to reduce or eliminate peripheral heating of the “oven” are described in U.S. Pat. No. 3,169,389 to Green et al., U.S. Pat. No. 3,232,093 to Burow et al., and in U.S. Pat. No. 5,005,399 to Holtzclaw et al. Each of these patents describe methods for directly wrapping or cladding the chromatographic column with a resistive heating element. Methods are also described for positioning the resulting metal clad column adjacent to a cooling source to decrease cooling times. This method of heating can be difficult to implement in practice because of uneven heating of the column due to local hot or cold spots in the resistive heating element surrounding the column. Uneven heating of the column in turn compromises the quality of the analysis. 
         [0012]    Yet another limitation of all resistively heated chromatographic devices is that if operated improperly, they can be driven to temperatures higher than the maximum tolerated by a given column resulting in damage to or destruction of the column. 
         [0013]    An alternative method for heating chromatographic columns is microwave heating as described in U.S. Pat. No. 4,204,423 or radio frequency heating described in U.S. Pat. No. 3,023,835. Additional background information on microwave heating instruments can be found in U.S. Pat. Nos. 6,514,316, 6,316,759, 6,182,504, 6,093,921, 6,029,498, and 5,939,614, incorporated herein by reference. 
         [0014]    Although the microwave heated chromatography instruments have been disclosed, these units are not well equipped for low temperature starts or for fast sample cycling. Thus, there is a need in the art for microwave heated chromatography instruments including a cooling apparatus that permits lower temperatures starts and faster sample cycling, i.e., reduced time between sample injections. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention provides a cooling apparatus for a radiant energy heated chromatography oven, such as a microwave or radiowave oven, including a coolant chamber, in thermal contact with a radiant energy heated oven, a coolant inlet and a coolant outlet, where the inlet directs coolant into the chamber and the outlet directs spent coolant out of the member. The apparatus can include a closed-loop coolant assembly, where the spent coolant is returned to the coolant supply or reservoir. The radiant energy heated oven includes a chromatography column and is designed to heat the column to a desired temperature at a desired rate or to heat the column according to an temperature programmed heating profile. The cooling apparatus is designed to decrease the sample cycle time of an analytical instrument including such a cooled radiant energy heated oven. In certain embodiments, the cooling member includes a radiator with or without radiant fins, where the radiator is in direct thermal contact with the oven. The radiator and/or fins are designed to radiate heat away from the oven and the coolant is designed to absorb the heat from the radiator and/or fins resulting in cooling of the oven, rapid and/or controlled. In other embodiments, the cooling chamber comprises a flow channel associated with a top or bottom of the oven with or without a radiator, where the coolant flows through the channel resulting in oven cooling. Of course, the rate of cooling depends on the temperature of the coolant, the flow rate of the coolant, and the material out of which the radiator or flow chamber is made. By adjusting the coolant temperature, flow rate and material, the cooling apparatus can cool the oven at a desired and controlled rate. The cooling can also be used to hold the oven at a sub-ambient temperature at cycle start or during an analytical protocol. The cooling can be used for decreasing sample cycle times, i.e., the time between sample runs. 
         [0016]    The present invention also provides a radiant energy or light heated oven apparatus for use in chromatography instruments including a housing having a radiant energy or light heated oven including a chromatographic column and cooling apparatus. In certain embodiments, the light or radiant energy is microwave radiation, while in other embodiments, the light or radiant energy is radiowave radiation. Of course, any frequency of light can be used provided that the light results in column heating in a controlled and repeatable manner. The cooling apparatus includes a coolant chamber, in thermal contact with the oven, a coolant inlet designed to direct coolant into the chamber and a coolant outlet designed to direct spent coolant out of the chamber. The apparatus can include a closed-loop coolant assembly, where the spent coolant is returned to the coolant supply or reservoir. The radiant energy heated oven includes a chromatography column and is designed to heat the column to a desired temperature at a desired rate or to heat the column according to an temperature programmed profile. The cooling apparatus is designed to decrease the sample cycle time of an analytical instrument including such a cooled radiant energy heated oven. In certain embodiments, the cooling member includes a radiator with or without radiant fins, where the radiator is in direct thermal contact with the oven. The radiator and/or fins are designed to radiate heat away from the oven and the coolant is designed to absorb the heat from the radiator and/or fins resulting in cooling of the oven, rapid and/or controlled. In other embodiments, the cooling chamber comprises a flow channel associated with a top or bottom of the oven with or without a radiator, where the coolant flows through the channel resulting in oven cooling. Of course, the rate of cooling depends on the temperature of the coolant, the flow rate of the coolant, and the material out of which the radiator or flow chamber is made. By adjusting the coolant temperature, flow rate and material, the cooling apparatus can cool the oven at a desired and controlled rate. The cooling can also be used to hold the oven at a sub-ambient temperature at cycle start or during an analytical protocol. The cooling can be used for decreasing sample cycle times, i.e., the time between sample runs. The cooling apparatus also includes a vortex cooler including a vortex inlet and a vortex outlet. The vortex outlet is connected to or integral with the coolant inlet and the vortex inlet is connect to a coolant supply. The cooling apparatus can also include flow controllers controlling an amount of coolant entering the chamber and an amount of coolant being feed to the vortex cooler. 
         [0017]    The present invention also provides a light heated chromatography instrument including a sample delivery assembly. The instrument also includes a light heated oven apparatus of this invention. In certain embodiments, the light is microwave radiation, while in other embodiments, the light is radiowave radiation. The instrument also includes a detector/analyzer assembly. The instrument may also include oxidation subassemblies and/or reduction subassemblies. 
         [0018]    The present invention also provides a method for cooling a light heated chromatography oven including the step of directing a coolant stream from a vortex cooler into a cooling chamber having a surface in thermal contact with the oven, where the chamber can comprise a flow channel or include a heat sink or radiator. In certain embodiments, the radiator can include fins. The coolant is supplied to the chamber at a rate and at a temperature sufficient to lower start temperatures and/or reduce cycle time, i.e., reduce a cool down time between sample runs. 
         [0019]    The present invention also provides a method for performing chromatographic analyses including the step of providing an instrument of this invention. The method also includes the step of injecting a sample from a sample delivery system into the chromatographic column in a heating zone of a light heated oven apparatus. The method may also include cooling the oven to a sub-ambient start temperature. The method may also include the step of maintaining the sub-ambient temperature or a different sub-ambient temperature for a first time period after the injection step, but prior to the heating step. The method also includes the step of heating the column under conditions to affect a given separation of the components in the sample. After separation, the sample components can be forwarded to the detector/analyzer assembly. The method may also include the steps of oxidizing the sample components in an oxidation subassembly and/or reducing the sample components in a reduction subassembly prior to forwarding the resulting oxidized, reduced, or oxidized and reduced components to the detector/analyzer assembly. After forwarding the sample components to the detector/analyzer assembly, the oven is cooled using the cooling assembly to shorten a duration between subsequent sample injections, i.e., to increase a number of samples that can be processed in a given period of time or to decrease the instrument cycle time. 
       DEFINITIONS USED IN THE INVENTION 
       [0020]    The term “temperature programmed heating profile” means a chromatography heating profile designed to achieve a desired analytical separation of components of a sample. In certain embodiments, the profiles is designed to maximize component separation. Profiles generally including at least one temperature ramp, positive or negative. The profiles can including one or a plurality of temperature holds. In certain embodiments, the temperature profile can include a sub-ambient start temperature, a sub-ambient hold temperature, or both. In other embodiments, the temperature profile can include an ambient start temperature, an ambient temperature hold or both. In other embodiments, the temperature profile can include an elevated start temperature, an elevated temperature hold or both. Thus, the profile can include a combination of start temperatures, holds, and negative and/or positive temperature ramps. 
         [0021]    The term “positive temperature ramp” means changing a temperature from a lower temperature to a higher temperature at a desired rate. The rate can be single valued or complex meaning that the temperature can be increase at a linear rate, a combination of linear rates or a non-linear rate, where the rate is designed to achieve a given component separation. 
         [0022]    The term “negative temperature ramp” means changing a temperature from a higher temperature to a lower temperature at a desired rate. The rate can be single valued or complex meaning that the temperature can be increase at a linear rate, a combination of linear rates or a non-linear rate, where the rate is designed to achieve a given component separation. 
         [0023]    The term “hold” means that the column is heated to a desired temperature and held at that temperature for a desired period of time. Each hold can be held for a different period of time, where the hold times are designed to achieve a given component separation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0024]    The invention can be better understood with reference to the following detailed description together with the appended illustrative drawings in which like elements are numbered the same: 
           [0025]      FIG. 1  depict a top view a generalized embodiment of a microwave oven apparatus including a cooling system of this invention. 
           [0026]      FIG. 2  depict a top view another embodiment of a microwave oven apparatus including a cooling system of this invention having a radiator or heat sink. 
           [0027]      FIG. 3A  depict a top view of another embodiments of a microwave heated oven apparatus including a cooling system of this invention having a radiator or heat sink. 
           [0028]      FIG. 3B  depict a front view of the heat sink of  FIG. 3A . 
           [0029]      FIG. 3C  depict a front view of a first embodiment of the cooler outlet of  FIG. 3A . 
           [0030]      FIG. 3D  depict a front view of a second embodiment of the cooler outlet of  FIG. 3A . 
           [0031]      FIG. 3E  depict a front view of a third embodiment of the cooler outlet of  FIG. 3A . 
           [0032]      FIG. 3F  depict a front view of a fourth embodiment of the cooler outlet of  FIG. 3A . 
           [0033]      FIG. 3G  depict a front view of a fourth embodiment of the cooler outlet of  FIG. 3A . 
           [0034]      FIG. 4A  depict a top view of another embodiments of a microwave heated oven apparatus of this invention including a cooling system. 
           [0035]      FIG. 4B  depict an expanded view of the embodiment of  FIG. 4A  for the oval shaped region of  FIG. 4A . 
           [0036]      FIGS. 5A  &amp; B depict two alternate designs of radiators or heat sinks for use in the microwave ovens of this invention. 
           [0037]      FIG. 6A  depicts an analytical instrument including a microwave oven apparatus of this invention. 
           [0038]      FIG. 6B  depicts another analytical instrument including a microwave oven apparatus of this invention. 
           [0039]      FIG. 6C  depicts another analytical instrument including a microwave oven apparatus of this invention. 
           [0040]      FIG. 7A  depicts a top view of another embodiments of a microwave heated oven apparatus including a cooling system of this invention. 
           [0041]      FIG. 7B  depicts a front view of the heat sink of  FIG. 7A . 
           [0042]      FIG. 7B  depicts a top view of another embodiments of a microwave heated oven apparatus including a cooling system of this invention. 
           [0043]      FIG. 8A  depicts an analytical instrument including a microwave oven apparatus of this invention. 
           [0044]      FIG. 8B  depicts another analytical instrument including a microwave oven apparatus of this invention. 
           [0045]      FIG. 8C  depicts another analytical instrument including a microwave oven apparatus of this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0046]    The inventors have found that a microwave oven can be constructed with a cooling system making sub-ambient start temperatures and faster cycle times possible in microwave heated GC and LC instruments or to hold the column at a sub-ambient temperature during a microwave heated GC and LC instrument analysis. The inventors note that a key variable operators of chromatography instruments utilize in GC or LC analyses is the start temperature of the sample upon being introduced into the chromatographic column. Generally, a lower start temperature yields superior separation of low boiling components such as so-called light hydrocarbons. In practice, many operators resort to cooling the column with liquid nitrogen in order to achieve a low start temperature. In a microwave heated unit, due to the complicated nature of the thermal system, a number of constraints exist for cooling. The cooling system must be able to cool an environment around the microwave oven without disturbing the heated zones of the oven. The inventors have found that an effective and efficient cooling apparatus for a microwave oven can be constructed using a vortex cooled gas such as an inert gas, air, nitrogen or mixtures or combinations thereof. A fully pressurized vortex cooler provides sufficient cooled or cold coolant flow to keep a microwave heated analytical chromatographic column chamber at a desired sub ambient temperature. In certain applications, the sub ambient temperature is about 10° C. The inventors have also found that sub-ambient start temperatures make it easier for the heated zones to compensate and maintain their own temperature set points, with the oven body coming to equilibrium at or near the new ambient conditions. This effect translates into lower start of run temperature capabilities. The inventors have also found that cooling a microwave chamber give rises to a second and equally important benefit. Because the cooling apparatus forces coolant, a cooling fluid, across a heat sink on the back of or associated with the microwave oven, a much greater heat flux out can be used than would be possible with ambient temperature gas. The inventors have found that both benefits also serve to greatly reduce the cool down time or cycle time between runs and to assure that the system will be able to come back to its start of run temperature with greater repeatability. Thus, the present invention affords both benefits: lower start of run temperatures and faster cool down times or faster sample cycle times—reduced time between sample injections. 
       Suitable Reagents and Devices 
       [0047]    Suitable coolants include, without limitation, gas and liquid coolants or mixtures or combinations thereof. Exemplary gas coolants include air, He, Ne, Ar, Xe, Kr, oxygen, nitrogen, CO 2 , CO, ammonia, hydrocarbons, such as methane, ethane, propane, butane, or mixtures or combinations thereof. Exemplary liquids include water, liquid CO 2 , liquid nitrogen, chlorocarbons, fluorochlorocarbons and other refrigerants, and mixtures thereof. 
         [0048]    Suitable coolers include, without limitation, any refrigeration system of cooling a fluid, be it gas or liquid or a combination thereof. Exemplary gas coolers include Vortex® type coolers, liquidified gas coolers which provide a cooled stream of a gas, or any other type of gas refrigeration system. Exemplary liquid coolers include, without limitation, liquidified gas refrigeration and circulation system, liquid refrigeration and circulation system or the other similar refrigeration and circulation systems. 
       A General Cooling System Embodiment 
       [0049]    Referring now to  FIG. 1 , a generalized embodiment of a cooled microwave oven apparatus of this invention, generally  100 , is shown to include a housing  102 . The housing  102  includes a microwave heated zone  104  including a chromatographic column  106 . The housing  102  also includes a cooling system  108 . The cooling system  108  includes a cooling chamber  110  having a chamber inlet  112  and a chamber outlet  114 . The cooling system  108  also includes a vortex cooler  116  having a coolant inlet  118  and a cooled coolant outlet  120 , where the coolant inlet  118  is connected to a source of a coolant or coolant reservoir  122  via a coolant conduit  124  and the cooled coolant outlet  120  is connected to the chamber inlet  112  via a cooled coolant conduit  126 . The cooled coolant passes through the chamber  110  removing heat from the heated zone  104 . The chamber outlet  114  is connected to an exhaust conduit  128 . The chamber outlet  114  can also be connected to the coolant reservoir  122  for recycling of coolant is the coolant is to be recycled via a recycle conduit  130 . 
         [0000]    Cooling System Embodiments with Radiators 
         [0050]    Referring now to  FIG. 2 , an embodiment of a cooled microwave oven apparatus of this invention, generally  200 , is shown to include a housing  202 . The housing  202  includes a microwave heated zone  204  including a chromatographic column  206 . The housing  202  also includes a cooling system  208 . The cooling system  208  includes a cooling chamber  210  having a chamber inlet  212  and a chamber outlet  214 . The cooling system  208  also includes a vortex cooler  216  having a coolant inlet  218  and a cooled coolant outlet  220 , where the coolant inlet  218  is connected to a source of a coolant or coolant reservoir (not shown) via a coolant conduit  224  and the cooled coolant outlet  220  is connected to the chamber inlet  212  via a cooled coolant conduit  226 . The chamber outlet  214  is connected to an exhaust conduit  228 . The cooling system  208  also includes a radiator or heat sink  230  having a back side or face  232  in thermal contact with the heated zone  204  along an edge  234  thereof and a front face  236  and sides  238 . The front face  236  and sides  238  are exposed to the coolant passing through the chamber  210  resulting in thermal energy being absorbed by the coolant from the front face  236  and sides  238  of the heat sink or radiator  230 . 
         [0051]    Referring now to  FIG. 3A , another embodiment of a cooled microwave oven apparatus of this invention, generally  300 , is shown to include a housing  302 . The housing  302  includes a microwave heated zone  304  including a chromatographic column  306 . The housing  302  also includes a cooling system  308 . The cooling system  308  includes a cooling chamber  310  having a chamber inlet  312  and a chamber outlet  314 . The cooling system  308  also includes a vortex cooler  316  having a coolant inlet  318  and a cooled coolant outlet  320 , where the coolant inlet  318  is connected to a source of a coolant or coolant reservoir (not shown) via a coolant conduit  324  and the cooled coolant outlet  320  is connected to the chamber inlet  312  via a cooled coolant conduit  326 . The chamber outlet  314  is connected to an exhaust conduit  328 . The cooling system  308  also includes a radiator or heat sink  330  having a back side or face  332  in thermal contact with the heated zone  304  along an edge  334  thereof and a front face  336  and sides  338 . The front face  336  and sides  338  are exposed to the coolant passing through the chamber  310  resulting in thermal energy being absorbed by the coolant from the front face  336  and sides  338  of the heat sink or radiator  330 . 
         [0052]    Referring now to  FIG. 3B , a front view the radiator or heat sink  330  is shown to include fins  340  and valleys  342  designed to increase a surface area over which the coolant exiting the outlet  314  flows to improve cooling of the heated zone  304 . 
         [0053]    Referring now to  FIG. 3C , a front view a first embodiment of the chamber inlet  312  is shown connected to the cooled coolant conduit  326  and includes a front plate  344 . The front plate  344  includes aligned rows  346  of apertures  348 , where the apertures  348  are designed to more uniformly direct the coolant flows onto heat sink  330 . 
         [0054]    Referring now to  FIG. 3D , a front view a second embodiment of the chamber inlet  312  is shown connected to the cooled coolant conduit  326  and includes a front plate  344 . The front plate  344  includes aligned rows  346  of apertures  348 , where the apertures  348  are designed to more uniformly direct the coolant flows onto heat sink  330 . 
         [0055]    Referring now to  FIG. 3E , a front view a third embodiment of the chamber inlet  312  is shown connected to the cooled coolant conduit  326  and includes a front plate  344 . The front plate  344  includes a screen  352 , where the screen  352  is designed to more uniformly direct the coolant flows onto heat sink  330 . 
         [0056]    Referring now to  FIG. 3F , a front view a fourth embodiment of the chamber inlet  312  is shown connected to the cooled coolant conduit  326  and includes a front plate  344 . The front plate  344  includes a plurality of slots  354 , where the slots  354  is designed to more uniformly direct the coolant flows onto heat sink  330 . 
         [0057]    Referring now to  FIG. 3G , a front view a fifth embodiment of the chamber inlet  312  is shown connected to the cooled coolant conduit  326  and including a front plate  344 . The front plate  346  includes aligned rows  356  of square apertures  358 , where the apertures  358  are designed to more uniformly direct the coolant flows onto heat sink  330 . 
         [0058]    Referring now to  FIG. 4A , another embodiment of a cooled microwave oven apparatus of this invention, generally  400 , is shown to include a housing  402 . The housing  402  includes a microwave heated zone  404  including a chromatographic column  406 . The housing  402  also includes a cooling system  408 . The cooling system  408  includes a cooling chamber  410  having a chamber inlet  412  and a chamber outlet  414 . The cooling system  408  also includes a vortex cooler  416  having a coolant inlet  418  and a cooled coolant outlet  420 , where the coolant inlet  418  is connected to a source of a coolant or coolant reservoir (not shown) via a coolant conduit  424  and the cooled coolant outlet  420  is connected to the chamber inlet  412  via a cooled coolant conduit  426 . The chamber outlet  414  is connected to an exhaust conduit  428 . The cooling system  408  also includes a radiator or heat sink  430  having a back side or face  432  in thermal contact with the heated zone  404  along an edge  434  thereof and a front face  436  and sides  438 . The front face  436  and sides  438  are exposed to the coolant passing through the chamber  410  resulting in thermal energy being absorbed by the coolant from the front face  436  and sides  438  of the heat sink or radiator  430 . 
         [0059]    Referring now to  FIG. 4B , a view looking down the cooled coolant conduit  426  in transparency at the heat sink  430 . The heat sink  430  includes fins  440  and valleys  442  designed to increase a surface area over which the coolant exiting the chamber inlet  412  flows to improve cooling of the heated zone  404 . The chamber inlet  412  includes a plurality of slotted apertures  444 , where each aperture  444  directs a coolant flow into a valley  442  of the heat sink  430 . 
         [0060]    Referring now to  FIG. 5A , another embodiment of a heat sink of this invention, generally  500 , is shown to include tapered fins  502  and associated tapered valleys  504 . 
         [0061]    Referring now to  FIG. 5B , another embodiment of a heat sink of this invention, generally  500 , is shown to include triangle tipped rectangular fins  502  and associated valleys  504 . 
         [0000]    Analytical Instrument Embodiments with Radiators 
         [0062]    Referring now to  FIG. 6A , an embodiment of an instrument of this invention, generally  600 , is shown to include a sample supply assembly  602  and a microwave oven apparatus  604 , where the sample supply assembly  602  is adapted to forward a sample to the oven apparatus  604  via sample path  606 . The oven apparatus  604  includes a heating zone  608  with a chromatographic column  610  disposed inside the zone  608 . The oven apparatus  604  also includes a heat sink  612  attached to a backside of the heating zone  606 . The oven apparatus  604  also includes a cooling assembly  614 . The cooling assembly  614  includes a vortex cooler  616 , a coolant supply conduit  618  connected to a supply of coolant (not shown). The vortex cooler  616  also includes an outlet  620  adapted to direct coolant onto the heat sink  610 . 
         [0063]    The system  600  also includes a detection/analyzer assembly  622  connected to the oven apparatus  604  via a oven output path  624 . The sample supply assembly  602  can be a single port injector, a automated sample injector system, a sample loop, an in-line sample loop, an automated sample loop apparatus for forwarding numerous samples to the column, or any other sample supply assembly used in analytical instruments now or will be used in the future. The detector/analyzer assembly  622  can be any now know or yet to be developed oxide detection and analyzing system including, without limitation, IR spectrometers, FTIR spectrometers, MS spectrometers, UV spectrometers, UV fluorescence spectrometers, ICR spectrometers, any other spectrographic detection and analyzing system or mixtures or combinations thereof. 
         [0064]    Referring now to  FIG. 6B , another embodiment of an instrument of this invention, generally  600 , is shown to include a sample supply assembly  602  and a microwave oven apparatus  604 , where the sample supply assembly  602  is adapted to forward a sample to the oven apparatus  604  via sample path  606 . The oven apparatus  604  includes a heating zone  608  with a chromatographic column  610  disposed inside the zone  608 . The oven apparatus  604  also includes a heat sink  612  attached to a backside of the heating zone  606 . The oven apparatus  604  also includes a cooling assembly  614 . The cooling assembly  614  includes a vortex cooler  616 , a coolant supply conduit  618  connected to a supply of coolant (not shown). The vortex cooler  616  also includes an outlet  620  adapted to direct coolant onto the heat sink  610 . 
         [0065]    The system  600  also includes an oxidation unit  624 , where the oxidation unit  624  is connected to the oven apparatus  604  by an oven output path  626 . The oxidation unit  624  includes an oxidizing agent supply  628  and a conduit  630  connecting the oxidizing agent supply  628  to the oxidation unit  624 . The system  600  also includes a detection/analyzer assembly  622 , where the assembly  622  is connected to the oxidation unit  624  via an oxidation unit output path  632 . The oven output path  626  can include a mixing or nebulizing unit (not shown) immediately upstream of the oxidation or combustion unit  624  adapted to supply a thoroughly mixed sample and oxidizing agent mixture to the combustion unit  624  or an atomized sample and oxidizing agent mixture to the combustion unit  624 . The sample supply assembly  602  can be a single port injector, a automated sample injector system, a sample loop, an in-line sample loop, an automated sample loop apparatus for forwarding numerous samples to the column, or any other sample supply assembly used in analytical instruments now or will be used in the future. The detector/analyzer assembly  622  can be any now know or yet to be developed oxide detection and analyzing system including, without limitation, IR spectrometers, FTIR spectrometers, MS spectrometers, UV spectrometers, UV fluorescence spectrometers, chemiluminescence spectrometers, ICR spectrometers, any other spectrographic detection and analyzing system or mixtures or combinations thereof. If the detection system includes a chemiluminescent detector, then detector will also include a source of ozone and associated conduits between the ozone generator and the detector. 
         [0066]    Referring now to  FIG. 6C , another embodiment of an instrument of this invention, generally  600 , is shown to include a sample supply assembly  602  and a microwave oven apparatus  604 , where the sample supply assembly  602  is adapted to forward a sample to the oven apparatus  604  via sample path  606 . The oven apparatus  604  includes a heating zone  608  with a chromatographic column  610  disposed inside the zone  608 . The oven apparatus  604  also includes a heat sink  612  attached to a backside of the heating zone  606 . The oven apparatus  604  also includes a cooling assembly  614 . The cooling assembly  614  includes a vortex cooler  616 , a coolant supply conduit  618  connected to a supply of coolant (not shown). The vortex cooler  616  also includes an outlet  620  adapted to direct coolant onto the heat sink  610 . 
         [0067]    The system  600  also includes an oxidation unit  624 , where the oxidation unit  624  is connected to the oven apparatus  604  by an oven output path  626 . The oxidation unit  624  includes an oxidizing agent supply  628  and a conduit  630  connecting the oxidizing agent supply  628  to the oxidation unit  624 . The system  600  also includes a reduction unit  632 , where the reduction unit  632  is connected to the oxidation unit  624  via an oxidation unit output path  634 . The reduction unit  632  includes a reducing agent supply  636  and a conduit  638  connecting the reducing agent supply  636  to the reduction unit  632 . The system  600  also includes a detection/analyzer assembly  622 , where the assembly  622  is connected to the reduction unit  632  via a reduction unit output path  640 . The oven output path  626  can include a mixing or nebulizing unit (not shown) immediately upstream of the oxidation or combustion unit  624  adapted to supply a thoroughly mixed sample and oxidizing agent mixture to the combustion unit  624  or an atomized sample and oxidizing agent mixture to the combustion unit  624 . The sample supply assembly  602  can be a single port injector, a automated sample injector system, a sample loop, an in-line sample loop, an automated sample loop apparatus for forwarding numerous samples to the column, or any other sample supply assembly used in analytical instruments now or will be used in the future. The detector/analyzer assembly  614  can be any now know or yet to be developed oxide detection and analyzing system including, without limitation, IR spectrometers, FTIR spectrometers, MS spectrometers, UV spectrometers, UV fluorescence spectrometers, chemiluminescence spectrometers, ICR spectrometers, any other spectrographic detection and analyzing system or mixtures or combinations thereof. If the detection system includes a chemiluminescent detector, then detector will also include a source of ozone and associated conduits between the ozone generator and the detector. 
         [0000]    Cooling System Embodiments with Coolant Flow Channels 
         [0068]    Referring now to  FIG. 7A , another embodiment of a cooled microwave oven apparatus of this invention, generally  700 , is shown to include a housing  702 . The housing  702  includes a microwave heated zone  704  including a chromatographic column  706 . The housing  702  also includes a cooling system  708 . The cooling system  708  includes a vortex cooler  710  including a coolant inlet  712  connected to a coolant reservoir or a source of a coolant  714  via a conduit  716 . The vortex cooler  710  also includes a cooled coolant outlet  718 . The housing  702  includes a coolant chamber  720 . The coolant chamber  720  including a coolant inlet  722  connected to the cooled coolant outlet  718  of the vortex cooler  710  via a cooled coolant conduit  724 . The coolant chamber  720  also includes a flow channel  726  in thermal contact with the heated zone  704 . The coolant chamber  720  also includes an outlet (not shown, it is hidden by the inlet  722 ) connected to a vent  728  via an exhaust conduit  730 . The housing  702  is also shown with two transfer lines apparatuses  732  (only one shown) described herein. The apparatus  700  also includes an oven purge inlet  734  connected to an oven purge supply  736  via an oven purge supply conduit  738  and an oven purge outlet  740  connected to the vent  728  or the exhaust conduit  730  via a oven purge exhaust conduit  742 . 
         [0069]    Referring now to  FIG. 7B , a 3D rendering of the apparatus of  FIG. 7A  is shown with corresponding parts labeled accordingly and showing the coolant flow in the channel. 
         [0070]    Referring now to  FIG. 7C , another embodiment of a cooled microwave oven apparatus of this invention, generally  700 , is shown to include a housing  702 . The housing  702  includes a microwave heated zone  704  including a chromatographic column  706 . The housing  702  also includes a cooling system  708 . The cooling system  708  includes a vortex cooler  710  including a coolant inlet  712  connected to a coolant reservoir or a source of a coolant  714  via a conduit  716 . The vortex cooler  710  also includes a cooled coolant outlet  718 . The housing  702  includes a coolant chamber  720 . The coolant chamber  720  including a coolant inlet  722  connected to the cooled coolant outlet  718  of the vortex cooler  710  via a cooled coolant conduit  724 . The coolant chamber  720  also includes a flow channel  726  in thermal contact with the heated zone  704 . The coolant chamber  720  also includes an outlet (not shown, it is hidden by the inlet  722 ) connected to a vent  728  via an exhaust conduit  730 . The housing  702  is also shown with two transfer lines apparatuses  732  (only one shown) described herein. The apparatus  700  also includes an oven purge inlet  734  connected to an oven purge supply  736  via an oven purge supply conduit  738  and an oven purge outlet  740  connected to the vent  728  or the exhaust conduit  730  via a oven purge exhaust conduit  742 . The channel  726  includes a radiator  744  including fins  746 . The radiator  744  with fins  746  is shown in  FIGS. 7D  &amp; E. 
         [0000]    Analytical Instrument Embodiments with Coolant Flow Channels 
         [0071]    Referring now to  FIG. 8A , an embodiment of an instrument of this invention, generally  800 , is shown to include a sample supply assembly  802  and a microwave oven apparatus  804 , where the sample supply assembly  802  is adapted to forward a sample to the oven apparatus  804  via sample path  806 . The oven apparatus  804  includes a heating zone  808  with a chromatographic column  810  disposed inside the zone  808 . The oven apparatus  804  also includes a cooling assembly  812  having a coolant chamber  814  in thermal contact with the heating zone  808 . The chamber  814  includes a coolant flow channel  816  and a cooled coolant inlet  818  and a coolant exhaust output  820 . The cooling assembly  812  also includes a vortex cooler  822  having a coolant inlet  824  connected to a supply of coolant (not shown). The vortex cooler  822  also includes a cooled coolant outlet  826  connected to chamber inlet  818  via a coolant conduit  828 . 
         [0072]    The system  800  also includes a detection/analyzer assembly  830  connected to the oven apparatus  804  via an oven output path  832 . The sample supply assembly  802  can be a single port injector, a automated sample injector system, a sample loop, an in-line sample loop, an automated sample loop apparatus for forwarding numerous samples to the column, or any other sample supply assembly used in analytical instruments now or will be used in the future. The detector/analyzer assembly  830  can be any now know or yet to be developed oxide detection and analyzing system including, without limitation, IR spectrometers, FTIR spectrometers, MS spectrometers, UV spectrometers, UV fluorescence spectrometers, ICR spectrometers, any other spectrographic detection and analyzing system or mixtures or combinations thereof. 
         [0073]    Referring now to  FIG. 8B , another embodiment of an instrument of this invention, generally  800 , is shown to include a sample supply assembly  802  and a microwave oven apparatus  804 , where the sample supply assembly  802  is adapted to forward a sample to the oven apparatus  804  via sample path  806 . The oven apparatus  804  includes a heating zone  808  with a chromatographic column  810  disposed inside the zone  808 . The oven apparatus  804  also includes a cooling assembly  812  having a coolant chamber  814  in thermal contact with the heating zone  808 . The chamber  814  includes a coolant flow channel  816  and a cooled coolant inlet  818  and a coolant exhaust output  820 . The cooling assembly  812  also includes a vortex cooler  822  having a coolant inlet  824  connected to a supply of coolant (not shown). The vortex cooler  822  also includes a cooled coolant outlet  826  connected to chamber inlet  818  via a coolant conduit  828 . 
         [0074]    The system  800  also includes an oxidation unit  834 , where the oxidation unit  834  is connected to the oven apparatus  804  by the oven output path  832 . The oxidation unit  834  also includes an oxidizing agent supply  836  and a conduit  838  connecting the oxidizing agent supply  836  to the oxidation unit  834 . The system  800  also includes a detection/analyzer assembly  830 , where the assembly  830  is connected to the oxidation unit  834  via an oxidation unit output path  840 . The oven output path  832  can include a mixing or nebulizing unit (not shown) immediately upstream of the oxidation or combustion unit  834  adapted to supply a thoroughly mixed sample and oxidizing agent mixture to the combustion unit  834  or an atomized sample and oxidizing agent mixture to the combustion unit  834 . The sample supply assembly  802  can be a single port injector, a automated sample injector system, a sample loop, an in-line sample loop, an automated sample loop apparatus for forwarding numerous samples to the column, or any other sample supply assembly used in analytical instruments now or will be used in the future. The detector/analyzer assembly  830  can be any now know or yet to be developed oxide detection and analyzing system including, without limitation, IR spectrometers, FTIR spectrometers, MS spectrometers, UV spectrometers, UV fluorescence spectrometers, chemiluminescence spectrometers, ICR spectrometers, any other spectrographic detection and analyzing system or mixtures or combinations thereof. If the detection system includes a chemiluminescent detector, then detector will also include a source of ozone and associated conduits between the ozone generator and the detector. 
         [0075]    Referring now to  FIG. 8C , another embodiment of an instrument of this invention, generally  800 , is shown to include a sample supply assembly  802  and a microwave oven apparatus  804 , where the sample supply assembly  802  is adapted to forward a sample to the oven apparatus  804  via sample path  806 . The oven apparatus  804  includes a heating zone  808  with a chromatographic column  810  disposed inside the zone  808 . The oven apparatus  804  also includes a cooling assembly  812  having a coolant chamber  814  in thermal contact with the heating zone  808 . The chamber  814  includes a coolant flow channel  816  and a cooled coolant inlet  818  and a coolant exhaust output  820 . The cooling assembly  812  also includes a vortex cooler  822  having a coolant inlet  824  connected to a supply of coolant (not shown). The vortex cooler  822  also includes a cooled coolant outlet  826  connected to chamber inlet  818  via a coolant conduit  828 . 
         [0076]    The system  800  also includes the oxidation unit  834 , where the oxidation unit  834  is connected to the oven apparatus  804  by the oven output path  832 . The oxidation unit  834  also includes the oxidizing agent supply  836  and the conduit  838  connecting the oxidizing agent supply  836  to the oxidation unit  834 . The system  800  also includes a reduction unit  842 , where the reduction unit  842  is connected to the oxidation unit  834  via the oxidation unit output path  840 . The reduction unit  842  includes a reducing agent supply  844  and a conduit  846  connecting the reducing agent supply  844  to the reduction unit  842 . The system  800  also includes a detection/analyzer assembly  830 , where the assembly  830  is connected to the reduction unit  842  via a reduction unit output path  848 . The oven output path  832  can include a mixing or nebulizing unit (not shown) immediately upstream of the oxidation or combustion unit  834  adapted to supply a thoroughly mixed sample and oxidizing agent mixture to the combustion unit  834  or an atomized sample and oxidizing agent mixture to the combustion unit  834 . The sample supply assembly  802  can be a single port injector, a automated sample injector system, a sample loop, an in-line sample loop, an automated sample loop apparatus for forwarding numerous samples to the column, or any other sample supply assembly used in analytical instruments now or will be used in the future. The detector/analyzer assembly  830  can be any now know or yet to be developed oxide detection and analyzing system including, without limitation, IR spectrometers, FTIR spectrometers, MS spectrometers, UV spectrometers, UV fluorescence spectrometers, chemiluminescence spectrometers, ICR spectrometers, any other spectrographic detection and analyzing system or mixtures or combinations thereof. If the detection system includes a chemiluminescent detector, then detector will also include a source of ozone and associated conduits between the ozone generator and the detector. 
         [0077]    All references cited herein are incorporated by reference. Although the invention has been disclosed with reference to its preferred embodiments, from reading this description those of skill in the art may appreciate changes and modification that may be made which do not depart from the scope and spirit of the invention as described above and claimed hereafter.