Patent Publication Number: US-2022229022-A1

Title: Autosampler seal pack for reducing a carryover percentage

Description:
RELATED APPLICATIONS 
     This application is a division of U.S. patent application Ser. No. 16/368,402, filed on Mar. 28, 2019, entitled “Autosampler Seal Pack for Reducing a Carryover Percentage,” which is a non-provisional patent application claiming priority to U.S. Provisional Patent Application No. 62/650,140, filed Mar. 29, 2018, entitled “Autosampler Seal Pack for Reducing a Carryover Percentage,” which is incorporated herein by reference. 
    
    
     FIELD OF TECHNOLOGY 
     The following relates to embodiments of a seal pack, and more specifically to embodiments of a seal pack of an autosampler for liquid chromatography systems having an improved carryover percentage. 
     BACKGROUND 
     Liquid chromatography is a technique in analytic chemistry where distinct components of a mixture are identified by separating the individual components by passing the mixture through an adsorbent medium using fluid flow so that the components elute at different rates. Liquid chromatography systems are typically comprised of a solvent delivery pump, an autosampler, a column, and a detector. The solvent delivery pump pumps mobile phase fluid through the system, the autosampler introduces the sample to be analyzed to the analytic flow path, the column contains the adsorbent packing material used to effect separation, and the detector detects the separated components as they elute out of the column. 
     In certain liquid chromatography systems, seal packs are a part of the autosampler that is responsible for making a high-pressure seal with the outer diameter of the sample needle to allow for injection of a sample into an analytic flow stream. Further, the seal pack is responsible for washing the sample needle with a solvent from a wash reservoir. The sample needle is washed to remove/clean remaining sample from a previous run. Sample leftover on the sample needle may increase a carryover percentage, which is the presence of an analyte after a blank having no sample is injected into the analytic flow path. A carryover percentage above certain limits can adversely affect the analytical data obtained from the liquid chromatography run. 
     Thus, a need exists for improving a washing of the sample needle to reduce a carryover percentage. 
     SUMMARY 
     A first aspect relates generally to a seal pack of a sample manager of a liquid chromatography system, the seal pack comprising: a plurality of wash flow pathways fluidically connected to a central pathway that accommodates a sample needle, wherein a first wash flow pathway is vertically offset from a second wash flow pathway, such that a wash solution flows axially along an exterior surface of the sample needle in a vertical direction to wash the sample needle when flowing from the first wash flow pathway to the vertically offset second wash flow pathway. 
     In addition or alternatively, the wash solution flows within the central pathway between the first wash flow pathway and the second wash flow pathway. 
     In addition or alternatively, the wash solution washes the sample needle as the sample needle moves vertically within the seal pack. 
     In addition or alternatively, the seal pack includes an upper body portion, a middle portion, and a lower body portion, which form a general body structure of the seal pack. 
     In addition or alternatively, the first wash flow pathway and the second wash flow pathway are both disposed within the upper body portion. 
     In addition or alternatively, the first wash flow pathway includes a wash inlet fluidically connected to an external wash reservoir of the liquid chromatography system. 
     In addition or alternatively, the exterior surface of the sample needle is simultaneously cleaned by the wash solution at two different subsections of the exterior surface of the surface needle. 
     In addition or alternatively, the two different subsections of the exterior surface of the sample needle being simultaneously cleaned are located above and below a high-pressure seal arrangement within the seal pack, respectively. 
     In addition or alternatively, a carryover percentage is equal to or less than 0.0025%. 
     A second aspect relates generally to a seal pack of a sample manager of a liquid chromatography system, the seal pack having an upper body portion, a middle body portion, and a lower body portion, which forms a general body structure of the seal pack, the seal pack comprising: a central flow path extending vertically through the seal pack, the central flow path accommodating a sample needle, a wash inlet disposed in the upper body portion, configured to receive a wash solution, the wash inlet connecting to the central flow path, a first wash path disposed in the upper body portion and connected to the central flow path, the first wash path being vertically offset from the wash inlet, a connecting wash path extending through the upper body portion, the middle body portion, and the lower body portion, the connecting wash path connecting the first wash path to a second wash path disposed in the lower body portion, wherein the second wash path is connected to the central flow path, a third wash path disposed in the lower body portion, the third wash path being vertically offset from the second wash path, and a wash outlet disposed in the middle body portion, the wash outlet being fluidically connected to a suction pump for drawing the wash solution through the seal pack. 
     In addition or alternatively, when the wash solution flows from the wash inlet to the first wash path, the wash solution flows axially along the sample needle in a vertical direction to directly wash the sample needle. 
     In addition or alternatively, when the wash solution flows from the second wash path to the third wash path, the wash solution flows axially along the sample needle in a vertical direction to directly wash the sample needle. 
     In addition or alternatively, the seal pack does not include a lower wash frit. 
     In addition or alternatively, the seal pack includes an upper wash frit retainer and an upper wash frit, wherein the sample needle passes through the upper wash frit. 
     In addition or alternatively, the seal pack includes a bushing disposed within the lower body portion, the bushing having a central bore for receiving the sample needle as the sample needle moves toward a sample source. 
     In addition or alternatively, the bushing is comprised of a non-metal material and prevents damage to the sample needle from contacting a metal surface of the seal pack as the sample needle moves towards and away from the sample source. 
     In addition or alternatively, the wash solution is flowing through the seal pack as the sample needle is moving within the seal pack. 
     In addition or alternatively, the seal pack includes a first high-pressure seal and a second high-pressure seal, the first high-pressure seal and the second high-pressure seal are disposed within the middle body portion, and form a seal around the sample needle at a point where a sample is injected into an analytic flow path. 
     In addition or alternatively, a carryover percentage is equal to or less than 0.0025%. 
     A third aspect relates generally to an autosampler of a liquid chromatography system, comprising: a sample needle, the sample needle configured to aspirate a sample from at least one sample source and inject the sample into an analytic flow path of the liquid chromatography system, a seal pack, the seal pack comprising a plurality of wash flow pathways fluidically connected to a central pathway that accommodates the sample needle, wherein a first wash flow pathway is vertically offset from a second wash flow pathway, a pump delivering a mobile phase to the seal pack, and a needle wash pump fluidically connected to the seal pack to draw a wash solution through the plurality of wash flow pathways of the seal pack and into a waste reservoir, wherein, when the needle wash pump draws the wash solution through the plurality of wash flow pathways, a wash solution flows axially along an exterior surface of the sample needle in a vertical direction to wash the sample needle when flowing from the first wash flow pathway to the vertically offset second wash flow pathway. 
     In addition or alternatively, the wash solution flows within the central pathway between the first wash flow pathway and the second wash flow pathway. 
     In addition or alternatively, the first wash flow pathway and the second wash flow pathway are both disposed within an upper body portion of the seal pack. 
     In addition or alternatively, the first wash flow pathway includes a wash inlet fluidically connected to the wash reservoir. 
     In addition or alternatively, the exterior surface of the sample needle is simultaneously cleaned by the wash solution at two different subsections of the exterior surface of the surface needle. 
     In addition or alternatively, the two different subsections of the exterior surface of the sample needle being simultaneously cleaned are located above and below a high-seal arrangement within the seal pack, respectively. 
     A fourth aspect relates generally to a method of washing a sample needle of a liquid chromatography system, the method comprising: directing a wash fluid axially along an exterior surface of a sample needle contained within a central pathway of a seal pack, the central pathway guiding the sample needle in a vertical only direction, wherein the directing the wash solution axially along the exterior surface of the needle includes: connecting a wash fluid inlet flow path located in an upper body portion of the seal back to the central pathway, and vertically offsetting a wash flow path located within the upper body portion from the wash fluid inlet flow path along the central pathway, wherein a needle wash pump fluidically connected to a wash flow outlet disposed within the seal pack is configured to draw the wash solution from the wash fluid inlet flow path through the central pathway against the exterior surface of the sample needle to the wash flow path. 
     In addition or alternatively, the directing the wash solution axially along the exterior surface of the needle further includes: interconnecting the wash flow path located in the upper body portion of the seal pack with a first wash flow path located in a lower body portion of the seal pack; connecting the first wash flow path to the central pathway; and vertically offsetting a second wash flow path located in the lower body portion of the seal pack from the first wash flow path along the central pathway. 
     In addition or alternatively, the wash fluid washes the sample needle as the sample needle moves vertically within the central pathway. 
     In addition or alternatively, the wash fluid outlet is located in a middle portion of the seal pack. 
     In addition or alternatively, the method further includes drawing air through a bushing disposed in the lower body portion of the seal pack as the wash fluid is drawn through the seal pack to reduce an overall solvent consumption rate as a needle wash pump is turned on. 
     In addition or alternatively, the method further includes disposing a bushing having a bore for receiving the sample needle in the lower body portion of the seal pack, the bushing preventing the sample needle from contacting a surface of the lower body portion of the seal pack as the sample needle moves vertically in and out of the seal pack to aspirate a sample. 
     In addition or alternatively, a carryover percentage is equal to or less than 0.0025%. 
     A fifth aspect relates to a wash sequence for washing a sample needle of an autosampler of a liquid chromatography system, the wash sequence comprising: continuously washing an exterior surface of the sample needle contained within a seal pack of the autosampler as the sample needle moves toward a sample source located proximate the seal pack, for a predetermined amount of time. 
     In addition or alternatively, the exterior surface of the sample needle is washed as the sample needle moves up and away from the sample source. 
     In addition or alternatively, in a first sequence, the predetermined amount of time is between 3-4 seconds, as the sample needle moves from inside the seal pack to the sample source. 
     In addition or alternatively, in a second sequence, the predetermined amount of time is between 14-16 seconds, as the sample needle moves towards the sample source. 
     In addition or alternatively, in the second sequence, a movement speed of the sample needle from inside the seal pack to the sample source is reduced to extend the predetermined amount of time, as compared to a movement speed of the sample needle in the first sequence. 
     In addition or alternatively, in a third sequence, the predetermined amount of time is equivalent to the second sequence, and also includes an additional washing step for a predetermined amount of time as the sample needle moves away from the sample source. 
     In addition or alternatively, the predetermined amount of time of the additional washing step is equivalent to the predetermined amount of time for the second sequence. 
     In addition or alternatively, the continuous washing of the exterior surface of the sample needle occurs axially along the sample needle in a vertical direction, within a central pathway of the seal pack. 
     In addition or alternatively, a wash fluid directly contacts the exterior surface of the sample needle during the continuous washing. 
     In addition or alternatively, the sample needle only moves up and down within the seal pack during the continuous washing. 
     In addition or alternatively, the sample needle is not relocated to a separate component for washing, and remains within a central pathway of the seal pack. 
     In addition or alternatively, a carryover percentage is equal to or less than 0.0025%. 
     The foregoing and other features of construction and operation will be more readily understood and fully appreciated from the following detailed disclosure, taken in conjunction with accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein: 
         FIG. 1  depicts a fluidics diagram of an autosampler of a liquid chromatography system having a seal pack, in accordance with embodiments of the present invention; 
         FIG. 2  depicts a cross-section view of a conventional seal pack; 
         FIG. 3  depicts a wash cycle for the current seal pack of  FIG. 2 , when a sample needle is in a first position; 
         FIG. 4  depicts a wash cycle for the current seal pack of  FIG. 2 , when the sample needle is in a second position; 
         FIG. 5  depicts a cross-sectional-view of a seal pack  100 , in accordance with embodiments of the present invention; 
         FIG. 6  depicts a wash cycle through the seal pack of  FIG. 5 , when the sample needle is in a first position, in accordance with embodiments of the present invention; 
         FIG. 7  depicts a wash cycle through the seal pack of  FIG. 5 , when the sample needle is in a second position, in accordance with embodiments of the present invention; 
         FIG. 8  depicts a wash cycle through the seal pack of  FIG. 5 , when the sample needle has returned to the first position, in accordance with embodiments of the present invention; and 
         FIG. 9  depicts a graphical illustration of achieving a carryover percentage below 0.0025% using the seal pack of  FIG. 5 , in accordance with the embodiments of the present invention. 
     
    
    
     The cross-sectional views are composite images, as internal features may be in three different sectional planes. 
     DETAILED DESCRIPTION 
     A detailed description of the hereinafter described embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. Although certain embodiments are shown and described in detail, it should be understood that various changes and modifications may be made without departing from the scope of the appended claims. The scope of the present disclosure will in no way be limited to the number of constituting components, the materials thereof, the shapes thereof, the relative arrangement thereof, etc., and are disclosed simply as an example of embodiments of the present disclosure. 
     As a preface to the detailed description, it should be noted that, as used in this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise. 
     Referring to the drawings,  FIG. 1  depicts a fluidics diagram of an autosampler of a liquid chromatography system  10  having a seal pack  100 , in accordance with embodiments of the present invention. An entire liquid chromatography system may not be shown in  FIG. 1 , but system  10  may also include conventional components of a liquid chromatography system not shown, such as a column, detector, solvent reservoir, etc. Embodiments of the liquid chromatography system  10  may include a valve V 1  (e.g. high-pressure needle valve) fluidically connected to a pump, such as a solvent delivery pump, a valve V 2  (high-pressure needle valve), a valve V 3  (e.g. two-way solenoid valve) fluidically connected to the valve V 2 , a valve V 4  (e.g. three-way solenoid valve), a pressure transducer, a sample loop, a flow restrictor, a seal pack  100 , a sample needle  160 , a sample source (e.g. sample vial), a wash reservoir, a needle wash pump, one or more waste reservoirs, and a sample syringe In the system  10 , a movement of the sample needle  160  may be limited to vertical movement. For example, the sample needle  160  may not move in any other direction but up and down, to aspirate a sample from a sample source and inject the sample into an analytic flow path, within the seal pack  100 . Embodiments of system  10  may further include a carousel of sample vials that may rotate underneath the seal pack  100  to bring the proper sample source (e.g. sample vial) into alignment with the sample needle  160  of the seal pack  100 . Once aligned, the sample needle  160  may be dropped down through the seal pack  100  into the sample source to aspirate the sample into the sample needle  100  and into the sample loop. The sample is aspirated through a side port opening disposed a distance from the tip of the sample needle  160 , and when the sample needle  160  enters the sample source, some sample contacts and may remain on the exterior surface of the sample needle  160 , which may contaminate results or otherwise adversely affect a carryover percentage. After aspirating the sample, the sample needle  160  may then be pulled back up further into the seal pack  100  to inject the sample into a high-pressure analytic flow path. 
     The seal pack  100  shown in  FIG. 1  may include high-pressure seals (shown schematically as two rectangles in the seal pack). The high-pressure seals are arranged against an outer diameter of the sample needle  160  to allow the sample to be injected through a side port of the sample needle  160  into the high-pressure flow path. The high-pressure flow path comes into the seal pack  100  on side/point of the seal pack  100  (e.g. from pump and through flow restrictor) and exits another side/point of seal pack  100  to the column. The high-pressure flow path is fluidically connected to the seal pack  100  through a small chamber surrounded by the two high-pressure seals. After aspirating the sample from the sample source, the sample needle  160  may be brought back up so that the side port is positioned within the chamber surrounded by the high-pressure seals to inject the sample into the high-pressure analytic flow path. 
     Furthermore, when valve V 1  is closed, the high-pressure flow may be allowed to flow from the pump to the flow restrictor and into the seal pack  100 . When valve V 1  is open, the flow of the solvent/mobile phase may split such that a portion of the mobile phase is passing through to the flow restrictor and a portion is flowing towards valve V 2 . When valve V 2  is open, flow may continue towards the pressure transducer and to the sample loop, and may connect the sample syringe. To start the injection, the sample needle  160  is in the seal pack, V 2  is closed, and V 1  is opened. The flow coming from the pump now splits as valve V 1  is open, and small percentage of the flow will go through the flow restrictor and the rest of the flow will flow through valve V 2  and to the pressure transducer and to the sample loop and into the needle  160 , and leave the sample needle  160  through the side port of the sample needle  160  positioned between the two high-pressure seals, and then into the column. The flow of the mobile phase through the sample loop may push the sample in the sample loop and the sample needle out through the side port opening of the sample needle  160  and into the analytic flow path. 
     The seal pack  100  depicted schematically in  FIG. 1  may house, contain, or otherwise accommodate the sample needle  160  during the injection process. Embodiments of the seal pack  100  may also have a wash fluid pathway configuration that improves upon current sample needle washing to reduce a carryover percentage of the system  10 . Current sample needle washing fails to directly wash an exterior surface of the sample needle, among other things. 
       FIG. 2  depicts a cross-section view of current seal pack  1 . Seal pack  1  includes an upper body portion  10 , a middle body portion  20 , and a lower body portion  30 . The seal pack  1  may house, seal, accommodate, receive, etc. a sample needle  60 . The seal pack  1  may also include an upper frit  15  and a lower frit  35 .  FIG. 3  depicts a wash cycle for the current seal pack  1  of  FIG. 2 , when the sample needle  60  is in a first position. During a wash cycle, a wash fluid  5  enters the seal pack  1  via wash inlet  41  and flow through the wash inlet pathway and then through a connection pathway  42  to a wash outlet pathway and exits the seal pack  1  via wash outlet  43 . As the wash fluid  5  flows through the wash outlet pathway, the wash fluid  5  only cleans the lower frit  35 , and does not directly clean an exterior surface of the sample needle  60  as the sample needle  60  is held in the first position above the lower frit  35  for a predetermined amount of time. Thus, for a predetermined amount of time that the wash fluid  5  is flowing through the seal pack  1 , only the lower wash frit  35  is being contacted with wash fluid  5 . However, even when the sample needle  60  is lowered to a second position passing through the lower frit  35  to aspirate a sample, the sample needle  60  is not directly contacted with the wash fluid  5 .  FIG. 4  depicts a wash cycle for the current seal pack  1  of  FIG. 2 , when the sample needle  60  is in a second position. As shown in  FIG. 4 , with the current design of seal pack  1 , the wash fluid  5  flows around the lower frit  35  and into cavity  45  to exit the seal pack  1  via the wash outlet  43 , avoiding direct contact with a surface of the sample needle  60 . For instance, nothing is forcing the wash fluid  5  to flow through the lower wash frit  35 , but rather the wash fluid  5  flows around the circular lower wash frit  35  through the annular cavity or gap  45  formed between the lower wash frit  35  and/or a lower wash frit retainer surrounding or partially surrounding the lower wash frit  35  and the lower body portion  20 . As a result, the sample needle  60  may not be washed/cleaned well enough to remove sample residue left over from sample aspiration, thereby increasing a probability of carryover. 
     Referring still to the drawings,  FIG. 5  depicts a cross-sectional-view of a seal pack  100 , in accordance with embodiments of the present invention. Embodiments of the seal pack  100  may be a component in the liquid chromatography system depicted in  FIG. 1 . Embodiments of the seal pack  100  may include an upper frit retainer  116 , an upper frit  115 , an upper body portion  110 , a middle body portion  120 , a high-pressure seal arrangement  125  (e.g. an upper high-pressure seal and a lower high-pressure seal), a lower body portion  130 , and a bushing  135  disposed within the lower body portion  130 . Embodiments of the upper body portion  110 , the middle body portion  120 , and the lower body portion  130  may be operably coupled to each other to form a general body structure of the seal pack  100 . For example, the upper body portion  110 , the middle body portion  120 , and the lower body portion  130  may be fastened together, coupled together, attached together, adhered together, or in some embodiments, may be structurally integral. Embodiments of the upper body portion  110 , the middle body portion  120 , and the lower body portion  130  may be comprised of a metal, such as stainless steel. 
     Embodiments of the seal pack  100  may not include a lower wash frit, such as lower wash frit  35  of seal pack  1  shown in  FIGS. 2-4 . Embodiments of the seal pack  100  may include a bushing  135  pressed-in to a cavity of the lower body portion  130 . The bushing  135  may be a generally annular component made on a non-metal material, such as Teflon®. The bushing  135  may be disposed within the lower body portion, and have a central bore for receiving the sample needle  160  as the sample needle  160  moves toward a sample source. Because the bushing  135  may be comprised of a non-metal material, the bushing  145  may prevent damage to the sample needle  160  from contacting a metal surface of the seal pack  100  (i.e. lower body portion  130 ) as the sample needle  160  moves towards and away from the sample source. Additionally, air may be drawn through the bushing  135  disposed in the lower body portion  130  of the seal pack  100  as wash fluid  5  is drawn through the seal pack  100  to reduce an overall solvent consumption rate as a needle wash pump is turned on. Further, the seal arrangement  135  of the seal pack  100  may include a first high-pressure seal and a second high-pressure seal disposed within or proximate the middle body portion  120 , forming a seal around the sample needle  160  at a point where a sample is injected into an analytic flow path, as described above with respect to  FIG. 1 . 
     Moreover, embodiments of the seal pack  100  may include a plurality of wash flow pathways fluidically connected to a central pathway  165  that accommodates a sample needle  160 , wherein a first wash flow pathway is vertically offset from a second wash flow pathway, such that a wash solution flows axially along an exterior surface of the sample needle  160  in a vertical direction to wash the sample needle  160  when flowing from the first wash flow pathway to the vertically offset second wash flow pathway. In an exemplary embodiment, the seal pack  100  may have an upper body portion  110 , a middle body portion  120 , and a lower body portion  130 , which forms a general body structure of the seal pack  100 , the seal pack  100  including a central flow path  165  extending vertically through the seal pack  100 , the central flow path  165  accommodating the sample needle  160 , a wash inlet  141  disposed in the upper body portion  110 , configured to receive a wash solution  5 , the wash inlet  141  connecting to the central flow path  165  via flow path  142 , a first wash path  143  disposed in the upper body portion  120  and connected to the central flow path  165 , the first wash path  143  being vertically offset from the wash inlet  141 , a connecting wash path  144  extending through the upper body portion  110 , the middle body portion  120 , and the lower body portion  130 , the connecting wash path  144  connecting the first wash path  143  to a second wash path  145  disposed in the lower body portion  130 , wherein the second wash path  145  is connected to the central flow path  165 , a third wash path  146  disposed in the lower body portion  130 , the third wash path  146  being vertically offset from the second wash path  145 , and a wash outlet  149  disposed in the middle body portion  120 , the wash outlet  149  being fluidically connected to a suction pump for drawing the wash solution  5  through the seal pack  100 . Embodiments of the flow paths  141 ,  142 ,  143 ,  144 ,  145 ,  146 ,  147 ,  148 ,  149  may be paths, fluid pathways, pathways, bores, channels, tubes, connection lines, tunnels, and the like. 
     Embodiments of the seal pack  100  may include a central pathway  165 . Embodiments of the central pathway  165  may be a channel, a tube, a path, a pathway, a fluid path, a fluid pathway, bore, tunnel, and the like, which may extend vertically along vertical axis  3 . The central pathway  165  may be positioned at a center location of the seal pack  100 . Further, embodiments of the central pathway  165  may receive, accommodate, contain, guide, hold, etc. the sample needle  160 , as shown in  FIGS. 6-7 . For instance, the sample needle  160  may move up and down within the central pathway  165  along the vertical axis  3 . In an exemplary embodiment, the sample needle  160  may only move vertically along vertical axis  3  to aspirate and inject the sample, and during wash cycles. The sample needle  160  may be washed without having to move the sample needle  160  to another physical location outside of the seal pack  100 . Embodiments of the seal pack  100  may include a wash inlet  141 . Additionally, the central pathway  165  may extend through the upper body portion  110 , the middle body portion  120 , the lower body portion  130 , and the bushing  135 . An end of the central pathway  165  proximate or otherwise near an end face of the busing  135  may include an opening that allows the sample needle  160  to exit the seal pack  100  for sample aspiration. 
     Embodiments of the seal pack  100  may include a wash inlet  141 . Embodiments of the wash inlet  141  may be an inlet or opening proximate or at an external surface of the seal pack  100 , which may be in fluid communication with a wash fluid or wash reservoir or wash source. The wash inlet  141  may be disposed within the upper body portion  110 , configured to allow a wash solution or wash fluid to enter the interior of the seal pack  100 . In alternative embodiments, the wash inlet  141  may be disposed in the lower body portion  130  or the middle body portion  120 . The wash inlet  141  may also include a wash inlet flow path  142  that may extend within the seal pack  100  to fluidically and physically connect the wash inlet  141  to the central pathway  165 . Furthermore, embodiments of the seal pack  100  may include a wash flow path  143  (e.g. a first wash flow path). Embodiments of the wash flow path  143  may be disposed within the same body portion of the seal pack  100  (e.g. upper body portion  110 ) as the wash inlet  141  and wash inlet flow path  142 . The wash flow path  143  may be fluidically and physically connected to the central pathway  165 , extending from the central pathway  165 . For instance, the wash flow path  143  may extend horizontally from the central pathway  165 . The wash flow path  143  may be in fluid communication or fluidically connected to the wash inlet flow path  142 , via the central pathway  165 . In an exemplary embodiment, the wash flow path  143  may be vertically offset from the wash inlet flow path  142  and/or wash inlet  141 . For example, the flow path  143  may be interconnected with the central pathway  165  at a different point along the central pathway  165  than the wash inlet flow path  142  and/or wash inlet  141 , such that a vertical distance of the central pathway  165  separates the flow path  143  and the wash inlet flow path  142 /wash inlet  141 . The offsetting of the flow paths creates a section of the central pathway  165  that wash fluid may travel through to get from the wash inlet flow path  142  to the wash flow path  143 . As the wash fluid travels through the central pathway  165  between the flow paths  143 ,  142 , the wash fluid washes the sample needle axially across the exterior surface of the sample needle  160 , above the high-pressure seal arrangement  125 . 
     Referring still to  FIG. 1 , embodiments of the seal pack  100  may include a connecting wash path  144 . Embodiments of the connecting wash path  144  may interconnect physically and fluidically the wash flow path  143  and the wash flow path  145  (e.g. a second wash flow path). Embodiments of the connecting wash path  144  may be a connection path, a connector, a wash tube, a connection tube, an interconnection, and the like, configured to provide a fluid flow path between the wash flow path  143  and wash flow path  145 . The connecting wash path  144  may extend in a vertical direction, parallel to vertical axis  3  through the upper body portion  110 , the middle body portion  120 , and the lower body portion  130 . In an exemplary embodiment, the connecting wash path  144  may be a straight pathway extending parallel to the vertical axis  3 . In other embodiments, the connecting path  144  may be curved or otherwise include a stepped configuration between the wash flow path  143  and the wash flow path  145 . Further, a seal or washer may be disposed between the upper body portion  110  and the middle body portion  120  at a point where the connecting wash path  144  extends therethrough, and likewise between the middle body portion  120  and the lower body portion  130  where the connecting wash path  144  extends therethrough. Moreover, the wash flow path  145  may be fluidically and physically connected to the central pathway  165 . The wash flow path  145  may be disposed in the lower body portion  130  of the seal pack  100 . 
     Embodiments of the seal pack  100  may further include a wash flow path  146  (e.g. a third wash flow path). Embodiments of the wash flow path  146  may be disposed within the same body portion of the seal pack  100  (e.g. lower body portion  130 ) as the wash flow path  145 . The wash flow path  146  may be fluidically and physically connected to the central pathway  165 , extending from the central pathway  165 . For instance, the wash flow path  146  may extend horizontally from the central pathway  165 . The wash flow path  146  may be in fluid communication or fluidically connected to the wash flow path  145 , via the central pathway  165 . In an exemplary embodiment, the wash flow path  146  may be vertically offset from the wash inlet path  145 . For example, the flow path  146  may be interconnected with the central pathway  165  at a different point along the central pathway  165  than the wash flow path  145 , such that a vertical distance of the central pathway  165  separates the flow path  146  and the wash flow path  145 . The offsetting of the flow paths creates a section of the central pathway  165 , which may be discrete and distinct from the section of the central pathway  165  between path  142  and  143 , that wash fluid may travel through to get from the wash flow path  145  to the wash flow path  146 . As the wash fluid travels through the central pathway  165  between the flow paths  145 ,  146 , the wash fluid washes the sample needle axially across the exterior surface of the sample needle  160 , below the high-pressure seal arrangement  125 . 
     Additionally, embodiments of the seal pack  100  may include wash outlet  149 . Embodiments of the wash outlet  149  may be an outlet or opening proximate or at an external surface of the seal pack  100 , which may be in fluid communication with a needle wash pump and a waste wash reservoir. For instance, a needle wash pump, which may be one or more pumps, may be connected to the wash outlet  149 , and create a suction force sufficient to create a vacuum within the seal pack  100  and to draw the wash fluid from the needle wash reservoir and into the wash inlet  141 , as schematically depicted in  FIG. 1 . The wash outlet  149  may be disposed within the middle body portion  120 , configured to allow a wash solution or wash fluid to exit the interior of the seal pack  100 . In alternative embodiments, the wash outlet  149  may be disposed in the lower body portion  130  or the upper body portion  110 . The wash outlet  149  may also include a wash outlet flow path  148  that may extend within the seal pack  100  to fluidically and physically connect the wash outlet  149  to an intermediate wash flow path  147 . The intermediate wash flow path  147  may connect the wash flow path  146  to the wash outlet flow path  147  and ultimately the wash outlet  149 . The intermediate flow path  147  may extend across multiple body portions of the seal pack  100 , such as the lower body portion  130  and the middle body portion  120 . At these points where the intermediate flow path  147  extends across the body portions of the seal pack  100 , a washer or seal may be disposed. 
     Accordingly, embodiments of the seal pack  100  may include a wash fluid flow path configuration that promotes direct contact between the wash fluid  5  and the sample needle  160 , such that the wash fluid  5  flows axially along a length of the exterior surface of the sample needle  160  simultaneously or otherwise at one or more locations (e.g. above and below high-pressure seal arrangement  125 ).  FIG. 6  depicts a wash cycle through the seal pack  100  when the sample needle  160  is in a first position, in accordance with embodiments of the present invention. In the first position, a tip of the sample needle  160  is positioned above the bushing  135  of the lower body portion  130 , within the central pathway  165  of the lower body portion  130 . If a wash cycle is initiated while the sample needle  160  is in the first position shown in  FIG. 6 , the sample needle  160  may still be washed by the wash fluid  5 , axially along the exterior surface of the sample needle  160 . A wash fluid  5  may be drawn in to the wash inlet  141  by suction forces created when the needle wash pump is activated and the valve V 4  associated with the needle wash reservoir is in a position to allow flow of the wash fluid  5  from the wash reservoir. The wash fluid  5  may flow through the wash inlet  141  and through the wash inlet flow path  142  to the central pathway  165  where the wash inlet flow path  142  intersections or connects with the central pathway  165 . The wash fluid  5  may thus flow axially along and against a length of the exterior surface of the sample needle  160  through the central pathway  165  in a vertical direction (e.g. up) along axis  3  to the wash flow path  143 . The flow of the wash fluid  5  axially across the sample needle  160  may act to clean and/or wash the sample needle  160  to help remove unwanted sample from previous runs that may have contacted the sample needle  160 . The wash fluid  5  may continue flowing through the wash flow path  143  and through the connecting wash path  144  to reach the wash flow path  145 . Because there is no lower wash frit, the wash fluid  5  continues through wash flow path  145  and may flow axially along and against a length of the exterior surface of the sample needle  160  through the central pathway  165  in a vertical direction (e.g. down) along axis  3  to the wash flow path  146 . The flow of the wash fluid  5  axially across the sample needle  160  may act to clean and/or wash the sample needle  160  to help remove unwanted sample from previous runs that may have contacted the sample needle  160 . The wash fluid may then flow through the wash flow path  146  and exit via the wash outlet  149 . In an exemplary embodiment, the wash fluid  5  may flow through the intermediate wash flow path  147  to the wash outlet flow path  148  and out through the outlet  149  to a wash waste reservoir. Thus, when the sample needle  160  is in the first position, prior to aspirating a sample from a sample source, the wash fluid  5  may be directly contacting the surface of the sample needle  160  to provide washing/cleaning benefits. 
       FIG. 7  depicts a wash cycle through the seal pack of  FIG. 5 , when the sample needle is in a second position, in accordance with embodiments of the present invention. The flow path of the wash fluid  5  may be the same or substantially the same as when the sample needle  160  is in the first position. However, the wash fluid  5  may be flowing through the seal pack  100  as the sample needle moves from the first position shown in  FIG. 6  to the second position shown in  FIG. 7 . To achieve the second position, the sample needle  160  is lowered or otherwise moved in a direction D (e.g. vertically along axis  3 ) towards a sample source, and eventually into a sample source (e.g. sample vial) to aspirate the sample. Thus, in exemplary embodiments, the sample needle  160  is being directly contacted with the wash fluid  5  axially along a length of the exterior surface of the sample needle  160  to remove sample from the exterior surface of the sample needle  160  and ultimately reduce a carryover percentage. Because the sample needle  160  is moving in direction D from the first position to the second position, and the wash fluid  5  flows axially along the sample needle  160  through sections of the central pathway  165 , a surface area of the exterior surface of the sample needle  160  being cleaned is increased and overall exposure of the sample needle  160  to the wash fluid  5  is increased throughout the wash cycle. 
       FIG. 8  depicts a wash cycle through the seal pack of  FIG. 5 , when the sample needle has returned to the first position, in accordance with embodiments of the present invention. The flow path of the wash fluid  5  may be the same or substantially the same as when the sample needle  160  is in the first position and second position. However, the wash fluid  5  may be flowing through the seal pack  100  as the sample needle  160  moves from the second position shown in  FIG. 7  back to the second position shown in  FIG. 8 . To return to the first position from the second position, the sample needle  160  is raised or otherwise moved in a direction D (e.g. vertically along axis  3 ) away from a sample source to eventually inject the sample into the high-pressure analytic flow path flowing through the seal pack  100  and ultimately to the column of the liquid chromatography system. Thus, in exemplary embodiments, the sample needle  160  is being directly contacted with the wash fluid  5  axially along a length of the exterior surface of the sample needle  160  to remove sample from the exterior surface of the sample needle  160  and ultimately reduce a carryover percentage. Because the sample needle  160  is moving in direction D from the second position to the first position, and the wash fluid  5  flows axially along the sample needle  160  through sections of the central pathway  165 , a surface area of the exterior surface of the sample needle  160  being cleaned is increased and overall exposure of the sample needle  160  to the wash fluid  5  is increased throughout the wash cycle. 
     In alternative embodiments, the seal pack  100  may include one or more flow paths in addition to the flow paths shown in  FIGS. 5-8 . For example, embodiments of the seal pack  100  may have a wash flow path configuration that directs the wash fluid  5  to flow through the central pathway  165  at more than two distinct and discrete locations. Further, embodiments of the seal pack  100  may include a wash flow path configuration that only washes the sample needle  160  above the high-pressure seal arrangement  125  or only below the high-pressure seal arrangement  125 . 
     Referring now to  FIGS. 1 and 5-8 , embodiments of the seal pack  100  may be a part of an autosampler or sample manager of a liquid chromatography system  10 . In an exemplary embodiment, an autosampler of a liquid chromatography system may include a sample needle  160  configured to aspirate a sample from at least one sample source and inject the sample into an analytic flow path of the liquid chromatography system, and a seal pack  100  comprising a plurality of wash flow pathways fluidically connected to a central pathway that accommodates the sample needle, wherein a first wash flow pathway is vertically offset from a second wash flow pathway. Embodiments of the autosampler may also include a pump delivering a mobile phase to the seal pack  100 , and a needle wash pump fluidically connected to the seal pack  100  to draw a wash solution  5  through the plurality of wash flow pathways of the seal pack  100  and into a waste reservoir. In the autosampler of exemplary embodiments of the present invention, when the needle wash pump draws the wash solution through the plurality of wash flow pathways, a wash solution flows axially along an exterior surface of the sample needle in a vertical direction to wash the sample needle when flowing from the first wash flow pathway to the vertically offset second wash flow pathway. 
     Furthermore, a method of washing a sample needle  160  of a liquid chromatography system may include a step of directing a wash fluid  5  axially along an exterior surface of a sample needle  160  contained within a central pathway  165  of a seal pack  100 , the central pathway  165  guiding the sample needle  160  in a vertical only direction. Embodiments of the step of directing the wash solution  5  axially along the exterior surface of the needle  160  may include multiple steps. For instance, the step of directing the wash solution  5  axially along the sample needle  160  may include a step of connecting a wash fluid inlet flow path  142  located in an upper body portion  110  of the seal pack  100  to the central pathway  165 . The directing may also include a step of vertically offsetting a wash flow path  143  located within the upper body portion  110  from the wash fluid inlet flow path  142  along the central pathway  165 , and/or vertically offsetting a wash flow path  146  located within the lower body portion  130  from a wash flow path  145  also located in the lower body portion, along the central pathway  165 . The directing step may also include fluidically connecting a wash flow outlet disposed within the seal pack  100  to draw the wash solution  5  into the wash fluid inlet flow path  142 / 141  and through the central pathway against the exterior surface of the sample needle  160  to the wash flow paths of the seal pack  100 . The step of directing may also include the steps of interconnecting the wash flow path  143  located in the upper body portion  110  of the seal pack  100  with a first wash flow path  145  located in a lower body portion  130  of the seal pack  100 , connecting the first wash flow path  145  to the central pathway  165 , and vertically offsetting a second wash flow path  146  located in the lower body portion  130  of the seal pack  100  from the first wash flow path  145  along the central pathway  165 . Moreover, embodiments of the method of washing the sample needle  100  may also include a step of disposing a bushing  135  having a bore for receiving the sample needle  160  in the lower body portion  120  of the seal pack  100 , the bushing  135  preventing the sample needle  160  from contacting a surface of the lower body portion  130  of the seal pack  100  as the sample needle  160  moves vertically in and out of the seal pack  100  to aspirate a sample. The method may also include a step of drawing air through an opening in the bushing  135  disposed in the lower body portion  130  of the seal pack  100  as the wash fluid  5  is drawn through the seal pack  100  to reduce an overall solvent consumption rate as a needle wash pump is turned on. The method may achieve a carryover percentage equal to or less than 0.0025%. 
     Furthermore, seal pack  100  may be conducive to applying new wash sequences that can reduce a carryover percentage. An exemplary wash sequence for washing a sample needle of an autosampler of a liquid chromatography system may include continuously washing an exterior surface of the sample needle  160  contained within a seal pack  100  of the autosampler as the sample needle  160  moves toward a sample source located proximate the seal pack  100 , for a predetermined amount of time. During the wash sequence, the exterior surface of the sample needle  160  may be washed as the sample needle  160  moves up and away from the sample source. The wash sequence may include more than one modes or sequences. For example, the wash sequence may include a “normal” sequence, a “double” sequence, and an “extended” sequence. 
     In the normal sequence, the predetermined amount of time of washing the sample needle  160  may be between 3-4 seconds (e.g. 3.6 second), as the sample needle  160  moves from inside the seal pack towards the sample source and into the sample source to aspirate the sample. In the “double” sequence, the predetermined amount of time of washing the sample needle  160  may be between 14-16 seconds (e.g. 15 second), as the sample moves towards the sample source and into the sample source to aspirate the sample. The time for the washing cycle in the “double” sequence is approximately double or slightly more than double the time in the “normal” sequence. 
     In the “double” sequence, a movement speed of the sample needle  160  from inside the seal pack  100  to the sample source may be reduced, slowed, throttled, etc. to extend the predetermined amount of wash time from 3-6 seconds to 14-16, without pausing the movement of the needle  160 , as compared to a movement speed of the sample needle in the “normal” sequence. In previous, known wash sequences, a movement of the needle  160  would be paused for a predetermined amount of time (e.g. 14 seconds) while the sample needle  160  was in the position shown in  FIG. 3 , wherein the wash fluid was only contacting and moving around the wash frit  35 . Thus, by not pausing and continuously but controllably reducing a movement speed of the sample needle  160  as the sample needle  160  enters the sample source, a duration of direct exposure of the exterior surface of the sample needle  160  to a wash fluid  5  is thereby increased, which can reduce a carryover percentage. 
     In the “extended” sequence, the predetermined amount of wash time as the sample needle  160  moves towards the sample source to aspirate the sample may be equivalent to the “double” sequence, but may also include an additional washing step for a predetermined amount of time as the sample needle  160  moves away from the sample source and returns to an original position within the seal pack  100 . The predetermined amount of time of the additional washing step (e.g. 14-16 seconds) may be equivalent to the predetermined amount of time for the “double” sequence. In previous, known wash sequences, a movement of the needle  160  would be paused for a predetermined amount of time (e.g. 40 seconds) while the sample needle  160  was in the position shown in  FIG. 3 , wherein the wash fluid was only contacting and moving around the wash fit  35 . Thus, by not pausing and continuously but controllably reducing a movement speed of the sample needle  160  as the sample needle  160  enters the sample source and returns to the interior of the seal pack  100 , a duration of direct exposure of the exterior surface of the sample needle  160  to a wash fluid  5  is thereby further increased, which can reduce a carryover percentage. 
     During the wash sequence described herein, the continuous washing of the exterior surface of the sample needle  160  may occur axially along the sample needle  160  in a vertical direction, within a central pathway  165  of the seal pack  100 . For instance, a wash fluid  5  may directly contact the exterior surface of the sample needle  160  during the continuous washing. Furthermore, the sample needle  160  may only move up and down within the seal pack  100  during the continuous washing of the wash sequence, and the sample needle  160  may not be relocated to a separate component for washing, remaining within the central pathway  165  of the seal pack  100 . Using this wash sequence with the seal pack  100  may achieve a carryover percentage is equal to or less than 0.0025%. 
       FIG. 9  depicts a graphical illustration of achieving a carryover percentage below 0.0025% using the seal pack of  FIG. 5  and the “normal” wash sequence, in accordance with the embodiments of the present invention. The carryover percentage well below 0.0025% may be achieved using the seal pack  100  with the other wash sequences described above. Carryover percentage may refer to the presence of an analyte after a blank having no sample is injected into the analytic flow path. Systems Qualification Tests (SQT) may be performed to test a carryover percentage. To test for a carryover percentage, a blank having no sample and only mobile phase (e.g. solvent) is first injected into the analytic flow path to show that the sample needle  160  is clean. Then, a carryover standard  201  of sample is injected into the analytic flow path. In  FIG. 9 , the carryover standard injection was 0.0025%. Next, a challenge sample containing a sample is injected into the analytic flow path. After the challenge sample is injected, one or more blanks  202  (e.g. no sample, only mobile phase) may again be injected into the analytic flow path.  FIG. 9  indicates the peak carryover percentage for the carryover standard injection at  201   p,  and indicates the peak carryover percentage for two blanks after the challenge sample was injected at  202   p.  As can be seen graphically in  FIG. 9 , the peak carryover percentage after the challenge sample was injected was well below 0.0025% (i.e. 0%). The sample used in the SQT shown in  FIG. 9  is caffeine. However, the seal pack  100  using the “normal” wash sequence achieves a carryover percentage below 0.0025% and at 0 (i.e. carryover) for other samples, such as anthracene, diphenhydramine, oxybutynin, and sulfadimethoxine. Accordingly, the seal pack  100  may reduce or eliminate a carryover percentage as compared to previous, known seal packs. 
     While this disclosure has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the present disclosure as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention, as required by the following claims. The claims provide the scope of the coverage of the invention and should not be limited to the specific examples provided herein.