Patent Publication Number: US-2021190808-A1

Title: Temperature-controlled sample introduction system for analysis of viscous samples

Description:
BACKGROUND 
     Inductively coupled plasma (ICP) mass spectroscopy is an analysis technique commonly used for the determination of trace element concentrations and isotope ratios in liquid samples. ICP mass spectroscopy employs electromagnetically generated partially ionized argon plasma which reaches a temperature of approximately 7000K. When a sample is introduced to the plasma, the high temperature causes sample atoms to become ionized or emit light. Since each chemical element produces a characteristic mass or emission spectrum, measuring said spectra allows the determination of the elemental composition of the original sample. 
     Sample introduction systems may be employed to introduce the liquid samples into the ICP mass spectroscopy instrumentation (e.g., an inductively coupled plasma mass spectrometer (ICP/ICPMS), an inductively coupled plasma atomic emission spectrometer (ICP-AES), or the like) for analysis. For example, a sample introduction system may withdraw an aliquot of a liquid sample from a container and thereafter transport the aliquot to a nebulizer that converts the aliquot into a polydisperse aerosol suitable for ionization in plasma by the ICP mass spectrometry instrumentation. The aerosol is then sorted in a spray chamber to remove the larger aerosol particles. Upon leaving the spray chamber, the aerosol is introduced to the ICPMS or ICPAES instruments for analysis. Often, the sample introduction is automated to allow a large number of samples to be introduced into the ICP mass spectroscopy instrumentation in an efficient manner. 
     SUMMARY 
     A sample introduction system is described that provides temperature-controlled handling and transfer of a sample from an autosampler, through a transfer line, to a heated environment proximate an analytical device. A system embodiment includes, but is not limited to, an autosampler including a temperature-controlled deck to support one or more sample containers; a heating unit including one or more heating elements to one or more fluids to be introduced to a sample removed from the one or more sample containers; a transfer line fluidically coupled with the autosampler and including a heating element configured to transfer heat to fluid flowing through the transfer line; and a sample handling system fluidically coupled with the transfer line and configured to fluidically couple with an analysis device, the sample handling system including a housing and a heating element configured to control a temperature of an environment defined by the housing. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       DRAWINGS 
       The Detailed Description is described with reference to the accompanying figures. 
         FIG. 1  is an illustration of a temperature-controlled system for handling and preparing samples for analysis in accordance with example implementations of the present disclosure. 
         FIG. 2A  is an exploded view of a temperature-controlled autosampler deck in accordance with example implementations of the present disclosure. 
         FIG. 2B  is an isometric view of a temperature-controlled autosampler with sample racks and containers supported on the deck in accordance with example implementations of the present disclosure. 
         FIG. 2C  is an exploded view of a portion of a temperature-controlled autosampler having heated fluid lines to introduce heated fluids to a sample in accordance with example implementations of the present disclosure. 
         FIG. 3A  is a side view of a temperature-controlled fluid transfer line in accordance with example implementations of the present disclosure. 
         FIG. 3B  is a partial view of an end of the temperature-controlled fluid transfer line of  FIG. 3A . 
         FIG. 3C  is a partial view of an end of the temperature-controlled fluid transfer line of  FIG. 3A . 
         FIG. 4  is an exploded view of a portion of an enclosed, temperature-controlled sample introduction system in accordance with example implementations of the present disclosure. 
         FIG. 5  is a view of an enclosed, temperature-controlled sample introduction system coupled with an analysis device in accordance with example implementations of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     ICP spectroscopy instrumentation may be used to analyze viscous samples, such as edible oils, hard fats, and the like. Viscous samples can present challenges for sample analysis, since many samples solidify or increase in viscosity at traditional room temperatures, causing the samples to become difficult to move or to become non-homogenized prior to analysis. For example, when multiple samples are available for analysis, an autosampling system (e.g., an autosampler) can be used to automatically draw samples from vials or other containers for transfer to an analysis system. As the samples are present at the autosampler, the likelihood that a given sample will solidify or increase in viscosity can increase over time. If samples that are later in a sample queue are permitted to partially solidify while waiting for the autosampler to remove the sample from the sample vial, the composition of the sample may not reflect the composition of the initial sample first presented to the sample vial. Additionally, samples that are initially in a liquid state may begin to solidify during transfer to a sample analysis device. The sample handling system may clog due to increased viscosity of samples, may decrease the flow rate of sample passed through sample tubing due to increased viscosity of samples resulting in lower throughput of sample analysis, or provide other challenges in handling and accurate sample analysis. 
     Accordingly, in one aspect, the present disclosure is directed to systems and methods for controlling transfer of viscous fluid-containing samples, such as oils, hard fats, and the like, and preparation of the samples for introduction to an analysis device to determine analytic composition of the samples. For example, a system can include an autosampler with a temperature-controlled sample deck to support one or more sample containers configured to hold sample(s) in a fluid state while awaiting analysis, for example, by preventing significant increases in viscosity of the samples during sample pendency on the sample deck (e.g., waiting for the autosampler probe to remove individual samples from respective containers). A temperature-controlled sample transfer line is coupled between the autosampler and a sample introduction system (e.g., a sample handling system), and is configured to transfer heat to fluid flowing through the transfer line to maintain the sample in the fluid state. The sample introduction system conditions a sample prior to introduction to the analysis device, and can include a temperature-controlled environment for one or more pumps, spray chambers, nebulizers, valves, or other fluid-handling devices through which the sample passes before being introduced to the sample analysis device (e.g., introduced to an ICP torch of ICP spectroscopy instrumentation). In an implementation, the sample introduction system includes a housing with a pump, nebulizer, and valve supported therein and a blower system configured to introduce heated air within the housing to maintain a threshold temperature within the housing. 
     In another implementation, a method can include heating a sample held in a sample container positioned on a deck of an autosampler to maintain the sample in a fluid state, and removing, via a sample probe, the sample in the fluid state from the sample container. The sample is introduced in the fluid state to a transfer line in fluid communication with the sample probe, and transferred in the fluid state through the transfer line to a sample introduction system. The transfer line is heated during transfer of the sample to maintain the sample in the fluid state during transfer from the autosampler to the sample introduction system. An environment defined by a housing of the sample introduction system is heated while the sample is received from the transfer line in the fluid state, and the sample is transferred from the housing of the sample introduction system to a sample analysis device for analytic determination of one or more components in the sample. In an implementation, the temperature of another fluid(s) that are to be brought into contact with the sample is controlled to prevent a significant temperature gradient or gap between the fluid flow(s) and sample flow(s). For example, the fluid is heated prior to introduction of the fluid to the sample to form a mixed sample in the fluid state. Such fluids may be introduced to the sample in the sample container positioned on the deck of the autosampler, or subsequent to removing the sample from the sample container. 
     In the following discussion, an example environment is first described. Example functionality is then described that may be implemented by the sample introduction system in the exemplary environment, as well as in other environments without departing from the spirit and scope thereof. 
     Example Implementations 
     Referring generally to  FIGS. 1 through 5 , systems  100  are shown for controlling sample transfer and handling conditions from sample uptake through sample analysis at an analysis device. The system  100  can be utilized to facilitate transfer and handling of viscous samples by controlling the temperature of one or more components of the system  100 , which can maintain a substantially fluid state of the sample during transfer and handling. The system  100  shown in  FIG. 1  includes an autosampler  102 , a transfer line  104 , a sample introduction system  106 , and an analysis device  108  in a fluidically coupled arrangement and communicatively connected with a system controller  110 . In general, a plurality of fluid-containing samples are held in sample containers supported on a deck or surface of the autosampler  102 , where a probe of the autosampler  102  is positioned above respective sample containers to draw the samples into a fluid line coupled with the transfer line  104  through action of a pump, vacuum, or fluid moving device. The transfer line  104  is coupled between the autosampler  102  and the sample introduction system  106  to transfer the sample drawn from the sample container by the probe to the sample introduction system  106 , where the sample is conditioned for analysis prior to transfer to the analysis device  108 . In an implementation, each of the autosampler  102 , the transfer line  104 , and the sample introduction system  106  includes a heating element configured to control a temperature of the respective portion of the system  100  to facilitate transfer of viscous samples through the system  100  by, for example, maintaining the samples in a fluid state. The heating element of the respective portions of system  100  can be controlled by a controller local to the respective portions, by the system controller  110 , or combinations thereof. 
     Referring generally to  FIGS. 2A through 2C , portions of the autosampler  102  are described in accordance with example implementations.  FIG. 2A  shows a temperature-controlled deck  200  of the autosampler  102  upon which sample containers, sample racks, or the like are supported for access by a sample probe  202  (e.g., shown in  FIG. 2B ). The deck  200  is formed from a heat transfer material to facilitate heating samples directly or indirectly supported by the deck  200 . For example, the deck  200  can include materials including, but not necessarily limited to: aluminum, tungsten, nickel, titanium, metal alloys, graphite, heat resistant plastic, and so forth, and combinations thereof. The deck  200  is thermally coupled with one or more heating elements  204  that can regulate a temperature of the deck  200  and transfer heat to the samples supported by the deck  200 . The heating elements  204  can include, but are not limited to, electric cartridge heaters that generate heat in response to electrical resistance of the materials forming the cartridge heater. In an implementation, the deck  200  forms an aperture  206  into which the heating elements  204  are inserted to substantially enclose the heating elements  204  within the deck  200 . An end plate  208  covers the aperture  206  to provide an enclosed temperature regulation environment within the deck  200 , which can prevent direct contact of individuals or structures with the heating elements  204 , and the like. 
     The deck  200  can include one or more features to monitor and control the temperature of the deck  200 . For instance, the deck  200  can include one or more thermocouples  210  to monitor the temperature of the material of the deck  200 , the heating elements  204 , or another portion of the deck  200 . The thermocouples  210  or other temperature or heat sensor can be communicatively coupled with a controller to control the deck  200  to maintain the samples in the fluid state. For example, the output of the thermocouples  210  or other temperature or heat sensor can be transmitted to the controller  210  or another controller to coordinate operation of the heating elements  204  to provide a desired temperature of the deck  200 . 
     Referring to  FIG. 2B , the deck  200  is shown supporting heat-conductive sample holders  212  defining apertures  214  into which sample containers  216  (e.g., vials, tubes, etc.) are inserted for access by the sample probe  202 . The sample holders  212  can be formed from the same materials as the deck  200 , a different heat transfer material, or the like to transfer heat from the deck  200  to the sample containers  216  supported thereby. Samples, such as edible oils, hard fats, or the like, can be positioned within the sample containers  216 , where the deck  200  transfers heat from the heating elements  204  to maintain the samples in a substantially liquid state. 
     Referring to  FIG. 2C , the autosampler  102  or another portion of the system  100  can include a heating unit  218  to control the temperature of other fluids to be used by the system  100  to prepare a sample taken up by the probe  202  for analysis by the analysis device  108 . For instance, the heating unit  218  can control the temperature of fluids that are to be brought into contact with the sample to prevent a significant temperature gradient or gap between the fluid flow(s) and sample flow(s) that could cause the sample to increase in viscosity, solidify, etc. The heating unit  218  is shown including a housing  220  that supports one or more heating blocks  222  heated by one or more cartridge heaters  224 . The cartridge heaters  224  can include, but are not limited to, electric cartridge heaters that generate heat in response to electrical resistance of the materials forming the cartridge heater. The heating blocks  222  can transfer heat from the cartridge heaters  224  to fluids held in fluid lines  226  (e.g., tubing) passed by the heating blocks  222 . Two fluids lines  226  are shown to facilitate temperature control of two fluids simultaneously, however the system  100  is not limited to two fluid lines  226  and can include more than two fluid lines  226  or fewer than two fluid lines  226 . The fluids introduced to the fluid lines  226  can include fluids used in the system  100  to generate calibration curves at the analysis device  108 , to combine with or interact with samples taken by the probe  202 , or the like. For example, the fluids can include, but are not limited to, diluents, internal standards, chemical spikes, working fluids (e.g., to push a sample taken by the sample probe  202  through the system  100 ), etc. 
     The fluid lines  226  can be wound around or otherwise brought into proximity of the heating blocks  222  to control a temperature of fluid held by, or passed through, the fluid lines  226 . The fluid lines  226  are shown in  FIG. 2C  as being coils to be positioned around the heating blocks  222  (e.g., positioned about an exterior surface of the heating blocks  222 ). The heating blocks  222  can be supported within the housing  220  by a base  228  (e.g., secured by one or more mounts  232 ). The heating unit  218  can include one or more features to monitor and control the heat transferred to the fluid lines  226 . For instance, the heating unit  218  can include one or more thermocouples  230  to monitor the temperature of the material of the heating blocks  222 , the cartridge heaters  224 , or another portion of the heating unit  218 . The thermocouples  230  or other temperature or heat sensor can be communicatively coupled with a controller to control the temperature of the fluids within the fluid lines  226 . For example, the output of the thermocouples  230  or other temperature or heat sensor can be transmitted to the controller  210  or another controller to coordinate operation of the cartridge heaters  224  to provide a desired temperature of the fluid(s) within the fluid lines  226 . The heating unit  218  can be coupled with the autosampler  102  (e.g., positioned beneath or otherwise adjacent to the deck  200 ) or can be located remote from the autosampler  102 . 
     Referring generally to  FIGS. 3A through 3C , portions of the transfer line  104  are described in accordance with example implementations. The transfer line  104  is configured to receive one or more fluids from the autosampler  102 , the heating unit  218 , or other portion(s) of the system  100  to transfer the fluids, under temperature control, to the sample introduction system  106 . For example, the transfer line  104  can include a heating element  300  in proximity with a fluid line  302  to transfer heat from the heating element  300  to fluid held by and transferred through the fluid line  302 . In an implementation, the transfer line  104  includes an outer tube  304  surrounding the fluid line  302  and wires of the heating element  300  to enclose components of the transfer line  104  and separate the components from the surrounding environment. For instance, the fluid line  302  and wires of the heating element  300  are disposed within an interior of the outer tube  304 . The heating element  300  can include a wire through which a voltage is applied to generate heat based on the resistive properties of the wire. For example, the heating element  300  can include a first wire  306  (e.g., a resistance wire) separated from a second wire  308  (e.g., a non-resistance wire) by an inner tube  310 , with terminal ends of the first wire  306  and the second wire  308  being connected (e.g., by solder  314  as shown in  FIG. 3C ) and opposing ends introduced to a voltage source (e.g., via connector  312 ). In an implementation, the first wire  306  is a resistive wire contained within the inner tube  310  and the second wire  308  is positioned within the outer tube  304  exterior to the inner tube  310 , such as adjacent the fluid line  302 , to position the inner tube  310  between the first wire  306  and the second wire  308 . The controller  110  or another controller can coordinate operation of the heating element  300  to apply a voltage to the first wire  306  suitable to achieve a threshold temperature of, or heat transfer to, fluid contained within the fluid line  302 . Fluid received at a first end of the transfer line  104  (e.g., into the fluid line  302 ) is transferred through the transfer line  104  to a second end of the transfer line  104  coupled with the sample introduction system  106  (e.g., through operation of one or more pumps, vacuum sources, or the like). 
     Referring generally to  FIGS. 4 and 5 , portions of the sample introduction system  106  are shown in accordance with example implementations. The sample introduction system  106  is configured to receive the fluid transferred through the transfer line  104  to prepare the fluid for introduction to the analysis device  108  (e.g., ICP spectroscopy instrumentation, such as ICPAES or ICPMS). The sample introduction system  106  maintains a temperature-controlled environment for the fluid preparation process and the components of the system  100  involved therein. For example, in an implementation, the sample introduction system  106  includes a housing  400  configured to support a heating element  402  which introduces heat into an environment formed by the housing  400 . The housing  400  can enclose a pump system (e.g., peristaltic pump  404 ), a spray chamber, a nebulizer, one or more valves, and associated fluid tubing to receive the fluid from the transfer line  104  and process the sample for introduction to the analysis device  108  through an aperture  406  in a top surface of the housing  400 . In an implementation, the heating element  402  includes one or more air intake fans to draw air into the heating element  402 , past one or more heating coils, and directed into housing  400  to control a temperature of the enclosed environment. The sample introduction system  106  can include one or more temperature sensors to measure a temperature of the heating element  402 , the environment of the housing, or the like, where the temperature sensor can be communicatively coupled with a controller to control operation of the heating element  402  to maintain the sample in the fluid state. For example, an output of the temperature sensor(s) can be transmitted to the controller  210  or another controller to coordinate operation of the heating element  402  to provide a desired temperature of the enclosed environment within the housing  400  and the components contained therein. In an implementation, the housing  400  is sized to provide a gap between the aperture  406  and an input of the analysis device  108  to facilitate gas flow between the sample introduction system  106  and the analysis device  108  (e.g., as shown in  FIG. 5 ). 
     CONCLUSION 
     Although the subject matter has been described in language specific to structural features and/or process operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.