Patent Publication Number: US-11376557-B1

Title: Sample introduction system with mixing

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No. 15/838,673, filed Dec. 12, 2017, and titled “SAMPLE INTRODUCTION SYSTEM WITH MIXING,” which itself is a continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No. 14/461,588, filed Aug. 18, 2014, and titled “SAMPLE INTRODUCTION SYSTEM WITH MIXING,” which itself is a continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No. 13/868,300, filed Apr. 23, 2013, and titled “SAMPLE INTRODUCTION SYSTEM WITH MIXING,” and U.S. patent application Ser. No. 12/881,906, filed Sep. 14, 2010, and titled “SAMPLE INTRODUCTION SYSTEM WITH MIXING,” which itself claims priority under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 61/242,217, filed Sep. 14, 2009, and titled “SAMPLE INTRODUCTION SYSTEM WITH MIXING.” U.S. patent application Ser. Nos. 15/838,673; 14/461,588; 13/868,300; and 12/881,906 and U.S. Provisional Application Ser. No. 61/242,217 are herein incorporated by reference in their entireties. 
    
    
     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 mixing of a sample and a diluent within the container via gas injection. In one or more implementations, the sample introduction system causes a probe, such as the probe of an autosampler, to be inserted into a container containing a sample and a diluent so that an end of the probe is submerged beneath a surface of the diluent and the sample. Gas is then injected through the probe to mix the sample and the diluent within the container. An aliquot of the mixed sample and diluent is then withdrawn through the probe. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different instances in the description and the figures may indicate similar or identical items. 
         FIGS. 1A, 1B, and 1C  are illustrations of an environment in an example implementation that employs a sample introduction system that provides mixing using gas injection. 
         FIG. 2  is a flow diagram illustrating a procedure that may be employed by a sample introduction system such as the sample introduction system of the environment shown in  FIGS. 1A, 1B, and 1C  to mix a sample and diluent using gas injection and withdraw an aliquot of the mixed sample and diluent. 
         FIGS. 3A, 3B, 3C, and 3D  are illustrations depicting an example container containing a sample and diluent during mixing of the sample and diluent using gas injection and withdrawal of a aliquot of mixed sample and diluent in accordance with the procedure of  FIG. 2 . 
         FIGS. 4A and 4B  are illustrations depicting cleaning of the screen of a screened probe using gas injection. 
         FIG. 5  is a flow diagram illustrating a procedure in an example implementation to add a diluent to a sample and insert the sample and diluent into a container. 
         FIG. 6  is an illustration depicting the addition of a diluent to a sample in accordance with the procedure of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     ICP mass spectroscopy may be used in the analysis of oil samples. For example, ICP mass spectroscopy analysis of motor oil is often used by enterprises that maintain a large number of vehicles. Parts that wear in an engine will deposit trace metals in the engine&#39;s oil. Analysis of the used motor oil of an engine provides information about how the engine is operating by identifying worn parts within the engine. In addition, ICP mass spectometry analysis can determine the amounts of the original oil additives remain within the oil after a period of use, thus providing an indication of the amount service life the oil has remaining. 
     When samples of oil are analyzed, a diluent such as kerosene may be added to reduce the viscosity of the oil allowing an aliquot of the sample to be withdrawn for analysis. Generally, the oil sample and the diluent are provided in a container in an unmixed state. Consequently, prior to taking an aliquot of the sample for ICP mass spectrometry analysis, the sample and diluent are first mixed. 
     Accordingly, a sample introduction system is described that provides mixing of a sample and a diluent within the container via gas injection. The sample introduction system includes an auto sampler configured to insert a probe into a container holding a sample and a diluent so that an end of the probe is submerged beneath the surface of the sample and the diluent. A valve assembly is configured to cause gas to be injected into the container through the probe to mix the sample and the diluent within the container via bubbling. For example, in one or more implementations, the gas is injected in a series of short bursts to mix the sample and diluent. The valve assembly may then be configured to cause a vacuum to be applied to the probe to withdraw an aliquot of the mixed sample and diluent through the probe into a sample loop. By mixing the oil with the same probe that withdraws the aliquot through gas injection, the throughput of the sample introduction system is increased in comparison with sample introduction systems that use separate mixing apparatus. For example, in one implementation, the analysis time per sample of the sample introduction system may be reduced to less than about 24 seconds. Additionally, in implementations where a screened probe is used, the injection of gas through the probe may cause fibrous contaminants to be removed from the screen. 
     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 Environment 
       FIGS. 1A, 1B, and 1C  illustrate an environment  100  in an example implementation that employs a sample introduction system  102  which provides mixing of samples with diluent using gas injection. As shown, the sample introduction system  102  includes a probe  104  that comprises a hollow tubular structure configured to be inserted into a container  106  that holds a sample to which a liquid diluent has been added. In the implementation illustrated, the probe  104  includes a single internal passageway through which gas is injected into the sample and diluent, and through which the aliquot of the mixed sample and diluent is withdrawn. In embodiments, the probe  104  may include an integral support formed of a generally rigid material such as carbon fiber, stainless steel, polyaryletheretherketone (PEEK), polyetherimide (PEI), or the like, encapsulated with polytetrafluoroethylene (PTFE). However, other probe structures are possible. Example probes  104  are shown in greater detail in  FIGS. 3B, 3C, 3D, 4A, 4B, and 6 . 
     The probe  104  may be coupled to an autosampler  110  that moves the probe  104  among a plurality of containers  106  in a tray or rack in a predetermined order. The autosampler  110  inserts the probe  104  into each of the containers  106  so that an aliquot of the diluted sample may be withdrawn for analysis. After the probe  104  is withdrawn from a container  106 , the autosampler  110  may rinse the probe  104  by inserting the probe  104  into a rinse station  112  containing a suitable rinse fluid, such as the diluent, or the like. 
     The autosampler  110  may provide functionality to control operation of other components of the sample introduction system  102 . Control of components of the sample introduction system  102  may also be provided by a separate control module, a general purpose computer, or the like. In the implementation shown, the autosampler  110  may be configured in accordance with one or both of U.S. Pat. Nos. 7,201,072 and 7,469,606, which are herein incorporated by reference in their entireties. However, autosamplers  110  having other configurations may be employed. 
     The sample introduction system  102  further includes a valve assembly  108  coupled to the probe  104  via a capillary  114 . The valve assembly  108  is configured to cause gas to be injected into a container  106  in which the probe  104  has been inserted, through the capillary  114  and probe  104  to mix the sample and the diluent within the container  106  via bubbling. The valve assembly  108  then causes a vacuum to be applied to the probe  104  via the capillary  114  to withdraw an aliquot of the mixed sample and diluent through the probe  104  and capillary  114  into a sample loop  116 , which temporarily holds the aliquot. 
     In the example implementation illustrated, the valve assembly  108  includes a first valve  118  and a second valve  120 . The first valve  118  comprises a six port valve that includes a first port  122 , a second port  124 , a third port  126 , a fourth port  128 , a fifth port  130 , and a sixth port  132 , while the second valve  120  comprises a four port valve that includes a first port  134 , a second port  136 , a third port  138 , and a fourth port  140 . 
     The first valve  118  may be actuated between a first state, shown in  FIGS. 1A and 1B  and a second state, shown in  FIG. 1C . When the first valve  118  is actuated to its first state, the first valve  118  connects the first port  122  with the sixth port  132 , the second port  124  with the third port  126 , and the fourth port  128  with the fifth port  130  to allow flow between the respective pairs of connected ports. Conversely, when the first valve  118  is actuated to its second state, the first valve  118  instead connects the first port  122  with the second port  124 , the third port  126  with the fourth port  128 , and the fifth port  130  with the sixth port  132  to allow flow between the respective pairs of connected ports. 
     The second valve  120  may similarly be actuated between a first state, shown in  FIGS. 1A and 1C , and a second state, shown in  FIG. 1B . When the second valve  120  is actuated to its first state, the second valve  120  connects the first port  134  with the fourth port  140  and the second port  136  with the third port  138  to allow flow between the respective pairs of connected ports. Conversely, when the second valve  120  is actuated to its second state, the second valve  120  instead connect the first port  134  with the second port  136  and the third port  138  with the fourth port  140  to allow flow between the respective pairs of connected ports. 
     As shown, the sample loop  116  is coupled to, and extends between, the first port  122  and the fourth port  128  of the first valve  118 . The sample loop  116  is comprised of a loop of tubing having a length sufficient to hold at least a portion of the aliquot of mixed sample and diluent withdrawn from a container  106 . In embodiments, the sample loop  116  is formed of a suitable material, such as PTFE, or the like. However, it is contemplated that the sample loop  116  may have other configurations. For example, the sample loop  116  may include a column, or like component, that is configured to further process (e.g., filter) the sample and diluent. 
     A diluent carrier is furnished via a line  142  coupled to the sixth port  132  of the first valve  118 . The diluent carrier may be supplied from a reservoir  144  of diluent by a pump (a peristaltic pump  146  is illustrated) at a predetermined flow rate. For example, in embodiments where the sample introduction system  102  is used in the analysis of oil samples, the diluent carrier may be kerosene supplied at a flow rate of at least about 2 mL/min. However, the use of other flow rates is contemplated. 
     In the example implementation shown, a nebulizer  148  is interconnected with the valve assembly  108  via a line  150  coupled to the fifth port  130  of the first valve  118 . As noted, the nebulizer  148  converts mixed sample and diluent received from the sample loop  116  into a polydisperse aerosol suitable for ionization in plasma by the ICP mass spectroscopy instrumentation  152  (e.g., ICPMS, ICPAES, or the like). The aerosol is then sorted in a spray chamber  154  to remove larger aerosol particles. Upon leaving the spray chamber  154 , the aerosol is introduced to the ICP mass spectroscopy instrumentation  152  for analysis. 
     The capillary  114  of the probe  104  is coupled to the third port  126  of the first valve  118 . In embodiments, the capillary  114  comprises a length of tubing formed of a suitable material, such as PTFE, or the like, which is sufficiently flexible to allow movement of the probe  104  by the autosampler  110 . 
     A second port  124  of the first valve  118  is coupled to the first port  134  of the second valve  120  via line  156 . A supply of gas is furnished via a line  158  coupled to the fourth port  140  of the second valve  120 . The gas supplied via line  158  may be any gas suitable for use with the sample and diluent. For example, in embodiments where the sample introduction system  102  is used in the analysis of oil samples, the gas supplied may be Argon (Ar) or Nitrogen (N 2 ). As shown, the gas may be supplied from a source  160  such as a pressurized tank, or the like. A regulator  162  regulates the pressure of the gas. For example, in embodiments where the sample introduction system  102  is used in the analysis of oil samples, the pressure may be regulated to about 0.25 bar by the regulator  162 . However, regulation of the pressure of the gas supplied to line  158  to other pressures is contemplated. 
     A vent line  164  may be connected to the third port  138  of the second valve  120 . In some embodiments, the vent line  164  may vent unused gas to atmosphere. In other embodiments, the vent line  164  may be coupled to a gas collection system to collect unused gas, for example, to be recycled. In further embodiments, vent line  164  may be capped so that unused gas does not vent. 
     A vacuum is supplied to the second port  136  of the second valve  120  via line  166 . In embodiments, the vacuum may be supplied by a vacuum pump  168  coupled to line  166 . In the implementation shown, the vacuum pump  168  is configured as a component of the autosampler  110 . However, it is contemplated that the vacuum pump  168  may also be a separate component of the sample introduction system  102 , may be combined with another component of the sample introduction system  102  such as a control module, or the like. 
     A first waste line  170  may be coupled to the vacuum pump  168  (e.g., the autosampler  110 ). Similarly, a second waste line  172  may be coupled to the spray chamber  154 . The waste lines  170 ,  172  receive excess sample and/or diluent from the autosampler  110  and/or the spray chamber  154 , respectively. In embodiments, a waste receptacle  176  may be coupled to the waste lines  170 ,  172  to receive the excess sample and/or diluent for disposal. A pump (a peristaltic pump  174  is shown) may be provided to draw the excess sample/diluent through the second waste line  172  from the spray chamber  154 . 
     In embodiments, lines  142 ,  150 ,  156 ,  158 ,  164 ,  166 ,  170 ,  172  may comprise lengths of flexible tubing formed of a suitable material, such as PTFE, or the like. However, other configurations are possible. 
       FIGS. 1A, 1B, and 1C  illustrate an example implementation of the sample introduction system  102  which provides mixing of samples with diluent using gas injection. However, it is contemplated that other implementations are possible. For example, a sample introduction system  102  in another implementation may employ a valve assembly that utilizes a single multiple-port valve, a valve assembly that utilizes three or more valves, and so on. Similarly, a sample introduction system  102  in another implementation may employ a separate control module in addition to the autosampler  110 . 
     Example Procedures 
       FIG. 2  illustrates an example procedure  200  suitable for use by the sample introduction system  102  in the environment  100  of  FIGS. 1A, 1B, and 1C  to mix a sample and diluent within a container  106  using gas injection and withdraw an aliquot of the mixed sample and diluent for analysis. As shown in  FIG. 2 , one or more containers that contain a sample and a diluent in an unmixed state are received for analysis (Block  202 ). For instance, as shown in  FIGS. 1A, 1B, and 1C , containers  106  containing various samples to which a diluent has been added may be received in a sample tray of the autosampler  110  in preparation for analysis of the samples by the ICP mass spectroscopy instrumentation  152 . 
       FIGS. 3A, 3B, 3C and 3D  illustrate an example container  106 , in this instance a sample vial  300 , that contains a sample  302  and diluent  304 .  FIG. 3A  shows the sample vial  300  while the sample  302  and diluent  304  are in an unmixed state. Because the sample  302  is normally denser than the diluent  304 , the sample  302  may tend to settle to the bottom surface  308  of the sample vial  300 , while the diluent  304  tends to float on top of the sample  302 . For example, in embodiments where the sample introduction system  102  is used in the analysis of oil samples, the sample  302  may comprise used engine oil, while the diluent  304  is comprised of kerosene which, being less dense tends to float on the surface of the oil. In one or more such embodiments in which the oil is diluted by a factor of ten (e.g., a 10× dilution), the sample vial  300  may be sized to contain approximately 1 ml of oil diluted with 9 ml of kerosene. 
     Referring again to  FIG. 2 , the probe  104  is then inserted into a first of the containers  106  (Block  204 ). In embodiments, the sample introduction system  102  may cause the autosampler  110  to insert the probe  104  into the container  106  until the end of the probe  104  is in a position proximal to a bottom surface of the container  106 . 
       FIG. 3B  illustrates the sample vial  300  containing a sample  302  and diluent  304  shown in  FIG. 3A , in which a probe  104  has been inserted. As shown, the probe  104  is inserted into the sample vial  300  until the end  306  of the probe  104  is in a position proximal to the bottom surface  308  of the container  106 . Thus, the end  306  of the probe  104  is generally submerged within the sample  302 . 
     The sample and diluent are next mixed (Block  206 ) by injecting gas into the container  106  through the probe  104  to cause bubbling of the sample and diluent. For example, as shown in  FIG. 1A , the first valve  118  is actuated to its first state so that the second port  124  of the first valve  118  is connected with the third port  126  to couple the capillary  114  to line  156 . The second valve  120  is also actuated to its first state so that the first port  134  of the second valve  120  is connected with the fourth port  140  to couple line  156  with line  158 . In this manner, gas is supplied to the probe  104  from the gas source  160  for injection into the container  106 . 
       FIG. 3C  illustrates injection of a gas  310  into the sample vial  300  by the probe  104  to mix the sample  302  and diluent  304  via bubbling. In one or more embodiments, gas may be injected in a series of short bursts to mix the sample  302  and diluent  304 . Use of short burst of gas provides efficient mixing of the sample  302  and diluent  304 , while preventing the sample  302  and diluent  304  from bubbling over the top  312  of the sample vial  300 . It is contemplated the length of each burst and/or the period separating successive bursts may be constant or may vary (e.g., increase or decrease, be randomly selected, and so on). Thus, the number and length of the bursts, and the period separating the bursts may be selected to maximize the efficiency of mixing of the sample  302  and diluent  304 . For instance, in embodiments where the sample introduction system  102  is used in the analysis of oil samples, gas  310  may be injected in three or more bursts having durations of about 0.1 seconds each, separated by periods between successive bursts of about 0.1 seconds in duration. 
     The probe  104  may then be retracted (Block  208 ) by the autosampler  110 . For example, as shown in  FIG. 3D , the probe  104  may be withdrawn from the position shown in  FIG. 3C , wherein the end  306  of the probe  104  is proximal to the bottom surface  308  of the sample vial  300  following injection of the gas  310  and mixing of the sample  302  and diluent  304 . The probe  104  may be withdrawn until the end  306  of the probe  104  is spaced away from the bottom surface  308  but is held beneath the surface  314  of the mixed sample and diluent  316 . 
     An aliquot of the mixed sample and diluent is then withdrawn from the container  106  (Block  210 ). For example, as shown in  FIG. 1B , after injection of the gas, the first valve  118  is actuated to its second state so that the first port  122  of the first valve  118  is connected with the second port  124  and the third port  126  is connected with the fourth port  128  to couple the sample loop  116  between the capillary  114  and line  156 . The second valve  120  is also actuated to its second state so that the first port  134  of the second valve  120  is connected with the second port  136  to couple line  156  with line  166 . In this manner, a vacuum is applied to the probe  104  to draw the mixed sample and diluent through the probe  104  and capillary  114  into the sample loop  116 .  FIG. 3D  illustrates the position of the probe  104  within the sample vial  300  during withdrawal of the aliquot of the mixed sample and diluent  316 . 
     While the first and second valves  118 ,  120  are actuated to their second states as shown in  FIG. 1B , the fifth port  130  of the first valve  118  is coupled to the sixth port  132  to couple line  142  to line  150  so that carrier diluent may be supplied to the nebulizer  148  to rinse the injector of the nebulizer  148 . Moreover, the third port  138  of the second valve  120  is connected to the fourth port  140  so that excess mixed sample and diluent  316  may be ported to the waste receptacle  176  via vent line  164 . 
     Referring again to  FIG. 2 , the probe  104  is then removed from the container  106  (Block  212 ) by the autosampler  110  and rinsed (Block  214 ). In the implementation illustrated in  FIGS. 1A, 1B, and 1C , the autosampler  110  may cause the probe  104  to be moved to and inserted within the rinse station  112 . A rinse fluid (e.g., the diluent) may then be drawn through the probe  104 . Simultaneously, the aliquot of mixed sample and diluent that was drawn into the sample loop  116  may be provided to the nebulizer  148  for conversion into a polydisperse aerosol suitable for ionization in plasma by the ICP mass spectroscopy instrumentation  152 . 
     As shown in  FIG. 1C , the first valve  118  is actuated to its first state so that the second port  124  of the first valve  118  is connected with the third port  126  to couple the capillary  114  to line  156 . The second valve  120  is actuated to its second state so that the first port  134  of the second valve  120  is connected with the second port  136  to couple line  156  with line  166 . In this manner, a vacuum is applied to the capillary  114  to draw rinse fluid through the probe  104 , the capillary  114 , first valve  118 , line  156 , second valve  120 , and line  166 . The rinse fluid is then transported to the waste receptacle  176  via waste line  170 . 
     The first port  122  of the first valve  118  is also connected with the sixth port  132 , while the fourth port  128  of the first valve  118  is connected with the fifth port  130  to couple line  142  to line  150 . In this manner, diluent carrier supplied from the reservoir  144  of diluent by peristaltic pump  146  may be used to advance the aliquot of mixed sample and diluent that was drawn into the sample loop  116  into the nebulizer  148 . 
     If additional samples are to be analyzed (“Yes” from Decision Block  216 ), the probe  104  is inserted into the next container  106  containing a sample to be analyzed, and the procedure  200  (Blocks  204 - 216 ) is repeated. When no more samples remain to be analyzed (“No” from Decision Block  216 ), the procedure  200  may be halted or paused until additional containers  106  are received for analysis (Block  202 ). 
     It is contemplated that, in one or more embodiments, the probe  104  may be rinsed (Block  214 ) prior to initial insertion of the probe  104  into the first of the containers  106  (Block  204 ) as described above. Further, gas may be injected through the probe  104  while the probe  104  is rinsed (Block  214 ). For example, in some embodiments, the probe  104  may employ a screen member (e.g., a screen, a filter, or the like) to filter fibrous contaminants from the sample and diluent so that the contaminants do not enter the probe  104 . The injection of gas through the probe  104  may have the effect of causing the fibrous contaminants to be removed from the screen during rinsing and/or during mixing of the sample and diluent. 
     Injection of gas by the sample introduction system  102  may be accomplished by actuating the first and second valves  118 ,  120  to their first state while the probe  104  is inserted within the rinse station  112  by the autosampler  110 . As shown in  FIG. 1A , the second port  124  of the first valve  118  is thus connected with the third port  126  to couple the capillary  114  to line  156 , while the first port  134  of the second valve  120  is connected with the fourth port  140  to couple line  156  with line  158 , so that gas is supplied to the probe  104  from the gas source  160 . The second valve  120  may be actuated to its first state either before or after injection of the gas to draw the rinse solution through the probe  104  as described above. 
       FIGS. 4A and 4B  illustrate an example probe  104 , in this instance a screened probe  400 , that is cleaned using gas injection in accordance with the present disclosure. As shown, the probe  400  comprises a hollow tubular structure  402  having an end that includes a screen member  406 . As shown in  FIG. 4A , fibrous contaminants  408  filtered by the screen member  406  may tend to collect on the screen member  406 , possibly reducing the flow of sample and diluent into the probe  400 . As shown in  FIG. 4B , the injection of gas through the probe  400  may dislodge at least some of the fibrous contaminants  408  from the screen member  406  into the rinse fluid during rinsing and/or into the sample and diluent during mixing. 
       FIG. 5  illustrates a procedure  500  in an example implementation that is suitable for use by the sample introduction system  102  in the environment  100  of  FIGS. 1A, 1B, and 1C  to add a diluent to a sample. In the implementation illustrated, the probe  104  is first rinsed (Block  502 ) to avoid contamination of the sample. For example, as shown in  FIG. 1C , the autosampler  110  may cause the probe  104  to be moved to and inserted within the rinse station  112 . The first valve  118  is actuated to its first state so that the second port  124  of the first valve  118  is connected with the third port  126  to couple the capillary  114  to line  156 . The second valve  120  is actuated to its second state so that the first port  134  of the second valve  120  is connected with the second port  136  to couple line  156  with line  166 . In this manner, a vacuum is applied to capillary  114  to draw rinse fluid through the probe  104 , the capillary  114 , first valve  118 , line  156 , second valve  120 , and line  166 . The rinse fluid is then transported to the waste receptacle  176  via waste line  170 . 
     Gas may be injected through the probe  104  while the probe  104  is rinsed (Block  502 ). As shown in  FIG. 1A , injection of gas by the sample introduction system  102  may be accomplished by actuating the first and second valves  118 ,  120  to their first state while the probe  104  is inserted within the rinse station  112  by the autosampler  110 . The second port  124  of the first valve  118  is thus connected with the third port  126  to couple the capillary  114  to line  156 , while the first port  134  of the second valve  120  is connected with the fourth port  140  to couple line  156  with line  158  so that gas is supplied to the probe  104  from the gas source  160 . The second valve  120  may be actuated to its first state either before or after injection of the gas to draw the rinse solution through the probe  104  as described above. 
     Diluent may then be taken up into the probe  104  and/or the capillary  114  (Block  504 ). The autosampler  110  may cause the probe  104  to be inserted into a supply of diluent. The first valve  118  is actuated to its first state so that the second port  124  of the first valve  118  is connected with the third port  126  to couple the capillary  114  to line  156 . The second valve  120  is actuated to its second state so that the first port  134  of the second valve  120  is connected with the second port  136  to couple line  156  with line  166 . In this manner, a vacuum is applied to capillary  114  to draw the diluent into the probe  104  and capillary  114 . 
     Next, a segmentation bubble may be taken up by the probe  104  (Block  506 ). For example, the autosampler  110  may cause the probe  104  to be removed from the supply of diluent. The first valve  118  is again actuated to its second state, while the second valve  120  is actuated to its second state so that the vacuum is briefly applied to the capillary  114  to draw atmospheric gas (e.g., air) into the probe  104  to form the segmentation bubble. 
     The sample is then taken up by the probe  104  (Block  508 ). For example, the autosampler  110  may cause the probe  104  to be moved to and inserted within a container  106  that contains an undiluted sample. The first valve  118  is again actuated to its second state, while the second valve  120  is actuated to its second state so that a vacuum is applied to the capillary  114  to draw the sample into the probe  104 . It is contemplated that the segmentation bubble may be taken up by the probe as the autosampler  110  moves the probe from the supply of diluent to the container  106  that contains the sample to be taken up by the probe  104 . 
     A second bubble may then be taken up by the probe  104  (Block  510 ) behind the sample. For example, the autosampler  110  may cause the probe  104  to be removed from the container containing the sample. The first valve  118  is again actuated to its second state, while the second valve  120  is actuated to its second state so that a vacuum is briefly applied to the capillary  114  to draw atmospheric gas (e.g., air) into the probe  104  to form the second bubble. 
     The sample and diluent are then expelled into a mixing container  106  (Block  512 ). For example, the autosampler  110  may cause the probe  104  to be moved to and inserted within an empty container  106 . The first and second valves  118 ,  120  may then be actuated to their first state as shown in  FIG. 1A . Thus, the second port  124  of the first valve  118  is connected with the third port  126  to couple the capillary  114  to line  156 , while the first port  134  of the second valve  120  is connected with the fourth port  140  to couple line  156  with line  158  so that gas is supplied to the capillary  114  from the gas source  160 . The gas causes the sample and diluent to be expelled from the capillary  114  and probe  104  into the empty container  106 . It is contemplated that the second bubble may be taken up by the probe  104  as the autosampler  110  moves the probe  104  from the container  106  that contains the sample to the mixing container  106 . 
       FIG. 6  depicts the probe  104  and capillary  114  of the sample introduction system  102  after taking up the diluent  602  and sample  604 . Segmentation bubble  606  separates the diluent  602  and the sample  604 , while second bubble  608  prevents leakage of the sample  604  from the probe  104 . In one or more embodiments, about 9 mL of diluent  602  and about 1 mL of sample are taken up by the probe  104 . However, it is contemplated that amounts of diluent  602  and sample  604  may also be taken up by the probe  104 . 
     Referring again to  FIG. 5 , an aliquot of the mixed sample and diluent is then withdrawn from the mixing container  106  (Block  514 ). For example, as shown in  FIG. 1B , after expulsion of the sample and diluent, the first valve  118  is again actuated to its second state so that the first port  122  of the first valve  118  is connected with the second port  124  and the third port  126  is connected with the fourth port  128  to couple the sample loop  116  between the capillary  114  and line  156 . The second valve  120  is also actuated to its second state so that the first port  134  of the second valve  120  is connected with the second port  136  to couple line  156  with line  166 . In this manner, a vacuum is applied to the probe  104  to draw the mixed sample and diluent through the probe  104  and capillary  114  into the sample loop  116 . 
     In some applications, expulsion of the sample and diluent from the probe  104  (Block  512 ) may sufficiently mix the sample and diluent to allow withdrawal of an aliquot of mixed sample and diluent. However, in other applications, additional mixing of the sample may be provided. In such applications, additional mixing may be provided via additional gas injection, for example, in accordance with aspects of the procedure  200  of  FIG. 2 . 
     In the discussion above, reference has been made to an example implementation in which the sample introduction system  102  is used in the analysis of oil samples. However, it is contemplated that the sample introduction system  102  is not limited to this implementation, but instead may be used in the analysis of a variety of sample substances. For example, in other implementations, the sample introduction system  102  may be used in the analysis of blood samples, wherein the diluent supplied is water or another suitable liquid. 
     CONCLUSION 
     Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as example forms of implementing the claimed invention.