TECHNICAL FIELD

[0001] This disclosure relates to fluid mixers and to fluid mixers used as a part of a chromatography system.

BACKGROUND

[0002] Chromatography can be an analytical or a preparative technique for separating a mixture into its constituents. The mixture containing compounds can be moved through a stationary phase, sometimes referred to as a medium, a resin or a gel. The compounds can exhibit different relative affinity for the stationary phase and the mobile phase. The compounds can be retained or allowed to pass at different rates as the mobile phase moves through the stationary phase and can result in bands or peaks of concentrations of the different compounds exiting the column at different times.

SUMMARY

[0003] In a first aspect disclosed herein a mixer is provided, the mixer comprising: a chamber comprising: an annular cavity; a first inlet; a second inlet; and an outlet; wherein the first and second inlets are located spaced apart from one another on the annular cavity, and the first and second inlets are configured to direct a first and a second fluid, respectively, into the annular cavity and the outlet is positioned to discharge a combination of the first and the second fluids from the chamber. [0004] In a second aspect disclosed herein, a chromatography system is provided, the chromatography system comprising a mixer, the mixer comprising: a chamber comprising: an annular cavity; a first inlet; a second inlet; and an outlet; wherein the first and second inlets are located spaced apart from one another on the annular cavity, and the first and second inlets are configured to direct a first and a second fluid, respectively, into the annular cavity and the outlet is positioned to discharge a combination of the first and the second fluids from the chamber; the chamber further comprises an end space, the end space located downstream of the annular cavity and the outlet is positioned and configured to discharge a combination of the first and second fluids from the end space; the mixer further comprises: a body comprising a wall, the wall surrounding the chamber; and an inner body having an outer surface comprising an end surface and the inner wall is positioned in the body, wherein a gap between the inner wall of the inner body and the body define the annular cavity and a second gap between the end surface of the and the body defines the end space; and the inner body comprises a pressure transducer and the mixer is configured to transmit a signal related to a pressure on an inlet of a chromatographic column.

[0005] In a third aspect disclosed herein, a method of using a mixer is provided, the mixer comprising: a chamber comprising: an annular cavity; a first inlet; a second inlet; and an outlet; wherein the first and second inlets are located spaced apart from one another on the annular cavity, and the first and second inlets are configured to direct a first and a second fluid, respectively, into the annular cavity and the outlet is positioned to discharge a combination of the first and the second fluids from the chamber, and the method comprising: injecting a first fluid at a first rate and a second fluid at a second rate into the first and second inlets, respectively, of the mixer; combining the first and second fluids in the mixer into a combination of the first and the second fluids; directing the combination of the first and the second fluids from the outlet to a chromatography column. [0006] In a fourth aspect disclosed herein, a chromatography system is provided, the chromatography system comprising: a chromatography column; a first fluid pump; a second fluid pump; a pressure sensor comprising: a pressure transducer; a body comprising: a chamber; a first inlet; a· second inlet; an outlet; and an outlet channel configured to carry fluid out of the chamber to the outlet; wherein the pressure transducer is present in the chamber and the first and second inlets are configured to direct a first and a second fluid, respectively, into the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. la shows an embodiment of a fluid system component.

[0008] FIG. lb shows an embodiment of a fluid system component that is a mixer.

[0009] FIG. lc shown an embodiment of a fluid system component that is a pressure sensor.

[0010] FIG. 2 shows a sectional view of FIG. la.

[0011] FIG. 3 shows an embodiment of an inner body comprising a pressure transducer.

[0012] FIG. 4 shows an embodiment of a chromatography system.

[0013] FIGS. 5-8 are response curves for testing embodiments of a fluid system component.

DETAILED DESCRIPTION

[0014] In the following description, numerous specific details are set forth to clearly describe various specific embodiments disclosed herein. One skilled in the art, however, will understand that the presently claimed invention may be practiced without all of the specific details discussed below. In other instances, well known features have not been described so as not to obscure the invention.

[0015] Some forms of chromatography can be classified as gas or liquid chromatography based upon the mobile phase passing through the chromatography column, and as analytical or preparatory chromatography based upon the scale of the separation and whether analytical data or samples/product are the goal. Gas chromatography can use one or more gaseous components as the fluid of the mobile phase to carry sample compounds to be separated through the column. Liquid chromatography uses a liquid as the fluid of the mobile phase and can comprise one or more components. Supercritical fluid chromatography uses one or more supercritical fluids as the fluid of the mobile phase operating under supercritical conditions in at least a portion of the stationary phase. As used herein, a "fluid" can be a gas, a liquid, a supercritical fluid and mixtures thereof.

[0016] Liquid chromatography can be categorized by pressure, such as low- pressure, medium-pressure and high-pressure. One common form of liquid chromatography, high-performance liquid chromatography (HPLC, previously referred to as high-pressure liquid chromatography), uses high pressure to propel liquids through the stationary phase.

[0017] Some of the terminology for chromatography is provided in terms of an embodiment of HPLC as follows. In a one embodiment of an HPLC operation, a solvent (mobile phase) is forced (e.g. pumped) through a column having a solid porous material (stationary phase). A sample can be injected into the solvent and compounds in the sample can be adsorbed on the stationary phase or can interact with the stationary phase to different degrees. This step of placing the sample in the stationary phase can be referred to as "loading." Each compound can exhibit different relative affinity to the stationary phase versus the mobile phase so that during

"elution", they exit the column separated in time. The step or process of compounds leaving the stationary phase (and exiting the column) can be referred to as "elution", and the materials leaving the column (mobile phase and/or sample compounds, as context indicates) are referred to as the "eluent." A detector can interact with the eluent and generate an electrical signal indicative of the presence of compounds in the sample. Other types of chromatography, such as gas, low pressure, medium pressure and supercritical fluid chromatography can operate similarly with similar

terminology.

[0018] A mass spectrometer can be used as a detector as well as other types of detectors, such as those based on or utilizing UV detection, thermal conductivity, fluorescence, electron capture, conductivity, photoionization, refractive index, radiation detection, polarization or optical angle of rotation, aerosol detection

(including charged aerosol detectors), flame ionization, flame photometric properties, atomic-emission, thermionic specific detectors, evaporative light scattering, electrolytic conductivity, summon detectors, mira detectors, etc. Some detectors can be used to provide information about the chemical identity of the compounds.

[0019] It can be desirable to reduce the time taken for a separation and the materials consumed and to increase the degree of separation or sharpness of peaks of the separation. In some cases, one or more of these parameters can be improved by using "gradient" elution, wherein a mixture of two or more fluids can be used as the mobile phase. During gradient elution, the proportions of the two or more fluids can be varied as the separation proceeds. In some cases, the proportions can be changed to change the polarity of the mobile phase or to otherwise change the interaction of the compounds with the stationary phase. A change of the proportions of the two or more fluids can result in one or more compounds to elute more quickly and thereby shorten the retention time for such compounds.

[0020] In some cases, the gradient can be changed continuously, and in some cases the gradient can be changed by stepwise changes in the relative proportions of the two or more fluids used for the mobile phase. In some operations, a combination of continuous change and stepwise change can be used. Suitable method of performing a gradient elution can include the use of separate pumps for different fluids (or combinations of fluids) where the relative pump rates are varied during operation. Other suitable methods can include varying the concentration of a fluid that is supplied to a pump or by changing a fluid being supplied to a pump or a column.

[0021] Some chromatography operations can utilize small diameter columns and some operations can utilize resins (or other stationary phase material) having small particle sizes. Some operations require pumps (or feed systems) capable of producing stable flows at appropriate pressures for the stationary phase particle size and the column design. In some embodiments, a very stable flow at very high pressures is required, such as at 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000 psig or higher. Some operations can require pressures that are much lower, such as 10-200 psig, depending upon the column design and the specific stationary phase that is used.

[0022] Some operations require pumps (or feed systems) that are capable of operation in the liters per minute range for preparative operations, while analytical system require pumps (or feed systems) capable of operation in the ml/minute or nl/minute range, such as 0.02-0.05 or 0.05-0.1 or 0.1 -0.2 or 0.2-0.4 or 0.4-0.7 or 0.7- 1.0 or 1.0-1.5 or 1.5-2.0 or 2.0 or 2.0-3.0 or 3.0-4.0 or 4.0-5.0 ml/min.

[0023] When gradient elution is performed where two or more fluids are mixed in-line on the way to the chromatography column, rapid and complete mixing is desirable. If the mixing is not rapid and complete, various defects can occur such as where the concentration varies with time, exhibiting a noise ripple in a plot of concentration vs. time (See Figures 5-8), or overly gradual change from one concentration to another, such as after a stepwise change, exhibiting a sloped line (as opposed to a more vertical, ideal, line) transition from one concentration to another (See Figures 5-8.) If large mixing devices are used, then there is the further undesirable complication of an increased delay between when a change in concentration is initiated at the pump and when the change reaches the column. Large mixing devices can also in some cases result in the sloped transition line discussed above, such as where the mixing device leads to back-mixing of the fluids within the device, such as where some packets of fluid take longer to traverse the mixing device than other packets of fluid.

[0024] In-line mixing of fluids at low flow rates can be difficult. For example, with low flow rates it can be difficult or impossible to achieve turbulent flow which can aid in mixing the fluids.

Fluid System Component

[0025] A fluid system component 3, an embodiment of which is shown in

Figure la can comprise a body 14, a chamber 6 within the body 14, one or more inlets 7 to the chamber 6 and an outlet 9. In some embodiments, an outlet channel 43 can be located between the chamber 6 and the outlet 9 such that a fluid after exiting the chamber 6 can pass through the outlet channel 43 and then through the outlet 9. In some embodiments, the fluid system component 3 can be a mixer 5 or a pressure sensor 4 or a combination of a mixer 5 and a pressure sensor 4. In some particular embodiments, the mixer 5 and/or the pressure sensor 4 can be an in-line mixer 5 and/or pressure sensor 4, such as where the mixer 5 and/or pressure sensor 4 has a stream of fluid flowing through the fluid system component 3 during operation. In some embodiments, an inner body 16 can be at least partially present within the chamber 6, wherein the inner body 16 can in some embodiments form an annular cavity 10 and/or an end space 1 1 within the chamber 6.

[0026] An in-line mixer 5, an embodiment of which is shown in Figure lb, can comprise an annular cavity 10 wherein two or more fluids are admitted, and an outlet 9 where the two fluids leave the mixer in a combined fluid. In some embodiments, the in-line mixer can also have an end space 1 1 located between the annular cavity 10 and the outlet 9. In various embodiments, the annular cavity 10 can be defined by a body 14 of the mixer and an inner body 16, wherein the inner body 16 is located within a chamber 6 of the body 14 with a gap 17 between the body 14 and inner body 16 forming an annular cavity. In some embodiments, the body 14 can have a wall 15 that surrounds the inner body 16, and the wall 15 can have a cylindrical shape, such as that shown in Figure 2. However, other shapes can be utilized for the wall 15 as well, such as ovalized, rounded, polygonal, hexagonal, heptagonal, rectangular, pentangular, triangular, and higher polygonal, etc.

[0027] The inner body 16 can have an outer surface 19 comprising an inner wall 12 where the inner wall 12 defines at least a portion of the inner surface of the annular cavity 10. In some embodiments, the inner body 16 can have a cylindrical shape or have a portion with a cylindrical shape, however other shapes can be utilized as well. In some embodiments, the inner wall 12 or a portion of the inner wall 12 can have a cylindrical shape, however, other shapes can be utilized as well. The inner body 16 can have a wetted portion 41 located within the chamber 6 and a dry portion 42 located outside of the chamber 6. The inner body 16 can be sealed to the body 14 at a location to separate the dry portion 42 from the wetted portion 41. In some embodiments, a seal 21 , such as an O-ring, gasket, or other sealing structure comprising, for example an elastomer, a polymer, or a metal, can be used for sealing the inner body 16 to the body 14.

[0028] The outer surface 19 of the inner body 16 can also comprise an end surface 20 position on the wetted portion 41 and distal the dry portion 42. End surface 20 can be flat or any other suitable shape, such as sloped, rounded, concave, convex, stepped, etc. The outer surface 19 can also include one or more recesses 13 located along the inner wall 12. In some embodiments, a recess 13 can be a groove that extends partway around inner body 16 or all the way around inner body 16 to form a ring. In some embodiments, recess 13 or groove can have a flat bottom and straight sides, such as a square channel encircling the inner body, or recess 13 or groove can be round, such as having an arcuate cross-section such as is used for some O-ring grooves. In some embodiments, recess 13 or groove can have some combination of flat and curved surfaces.

[0029] A first inlet 7 can be provided to direct fluid into the annular cavity 10.

In some embodiments, a second inlet 8 can also be provided to direct fluid into the annular cavity, however in some embodiments, a first fluid and a second fluid can be directed into the annular cavity through a single inlet. In further embodiments, more than two inlets can be provided to direct fluids into the annular cavity at different locations. In one embodiment, a second inlet 8 can be located a number of degrees around the periphery of the annular cavity 10 from the first inlet 7, such as at 90° or 180°. However, in some embodiments the first inlet 7 and second inlet 8 can be positioned at different relative positions such as at less than 5°, 5-10°, 10-20°, 20-30°, 30-40°, 40-50°, 50-60°, 60-70°, 70-80°, 80-90°, 90-100°, 100-1 10°, 1 10-120°, 120- 130°, 130-140°, 140-150°, 150-160°, 160-170° or 170-180°. When additional inlets are provided, such as a third, a fourth, or more, each can be placed at a suitable position such as those described for the second port. In some embodiments, a second port can be measured a number of degrees around the annular cavity 10, measuring in a first direction such as clockwise or counterclockwise and a third or higher numbered port can be measured a number of degrees around the annular cavity 10 measured in , the same direction or in a direction different from the first direction, such as counterclockwise or clockwise, respectively. In some embodiments, multiple inlets can be positioned at different locations along the length of the annular cavity 10 with some inlets being closer to end surface 20 and some inlets being closer to dry portion 42. In some embodiments, a second or higher numbered input can be positioned at a different location along the length of the annular cavity 10 and had a different location around the periphery of the annular cavity 10 as a first input. In some embodiments, a second or higher numbered input can be positioned at the same point along the periphery as the first input but at a different position along the length of the annular cavity 10. [0030] An outlet 9 from the chamber can be provided at any suitable location on the chamber. In one preferred embodiment, an outlet 9 can be provided adjacent end surface 20. In some embodiments, first inlet 7, second inlet, second inlet 8 as well as additional inlets can be arranged radially in relation to a central axis 23 of the annular cavity 10 with outlet 9 arranged axially in relation to the central axis 23 of the annular cavity 10. In some embodiments, an end space 1 1 can be located downstream of annular cavity 10 and between end surface 20 and body 14 with outlet 9 discharging the contents of end space 1 1.

[0031] For some embodiments of a fluid system component 3, whether a mixer 5, a pressure sensor 4 or a combination of mixer and pressure sensor, an additional mixer, such as a static mixer can be used on one or both or all inlets, on the outlet, on a downstream port and/or downstream of the fluid system component 3. Static mixers are known in the art as are other types of in-line mixers.

[0032] Figure la shows an embodiment of a fluid mixer 5, which can in some embodiments, be used for chromatography systems, such as analytic chromatography systems. As shown in Figure 1, fluid mixer 5 can include a body 14 enclosing a chamber 6 comprising an annular cavity 10. In Figure 1 , the annular cavity 10 has an inner wall 12 which can be part of an inner body 16 present within chamber 6. Inner body 16 is sealingly connected to body 14 with seal 21. Any suitable retention means can be used for holding inner body 16 against seal 21 , such as a threaded nut, flange, sleeve with bolts or flange, and the like. In some embodiments, a sealing material can be located along the sides of inner body 16 to seal against body 14, such as with an O- ring, packing and the like at alternate sealing location 24. In some embodiments, a sealing material, such as an O-ring and the like can be used in the annular cavity 6 to seal between inner body 16 and body 14.

[0033] First inlet 7 and second inlet 8 are shown in Figure la in a 180° orientation. However, as shown in Figure 2 first inlet 7 and second inlet 8 can be located in a 180° or with alternate second inlet 25 oriented at 90° from first inlet 7. In further embodiments, first inlet 7 and second inlet 8 as well as additional inlets can be located at other positions around the periphery of annular cavity 10, as discussed above.

[0034] Also as shown in Figure la, first inlet 7 and second inlet 8 are located along the length of annular cavity 10 so as to correspond to groove 13. However one or both of first inlet 7 and second inlet 8 as well as other inlets can be located at different positions along the length of annular cavity 10, such as above, below or corresponding with groove 13, with each position independent of the other (such as one above and one below or both above for both below.) When additional inlets are also present, these two can be located above, below or corresponding to groove 13, with each position independent of the others.

[0035] As shown in Figure la, a first fluid and a second fluid can enter the annular cavity 10 through first inlet 7 and second inlet 8, respectively. These two fluids then flow through the annular cavity 10 to end space 1 1 and exit end space 1 1 through outlet 9. In some embodiments, a downstream port 26 can be located after end space 1 1 to provide an additional downstream inlet or an alternate outlet to outlet 9.

[0036] Also shown in Figure 1, the first inlet 7 and the second inlet 8 can provide a turn in the flow path for the fluid as the fluid enters the annular cavity 10.

In addition, a further turn in the flow path can occur at the transition between the annular cavity 10 and the end space 1 1. Changes to the geometry of the mixer 5 can vary these angles for one, or some or all to achieve 90°, more than 90 degrees or less than 90°. (In various embodiments, the angle can be 0-10°, 10-20°, 20-30°, 30-40°, 40-50°, 50-60°, 60-70°, 70-80°, 80-90°, 90-100°, 100-1 10°, 1 10-120°, 120-130°, HOMO ⁰ , 140-150°, 150-160°, 160-170° or 170-180°, with each angle determined independently.)

[0037] In various embodiments, the hold-up volume of fluid system component 3 or more specifically mixer 5 can be varied by changing various parameters such as the diameter inner wall 12, the shape of at least a portion of elongate structure 16 (e.g. circular, hexagonal, square, fluted, grooved, as well as any other shape), the width of gap 17 between inner wall 12 and body 14, the width of second gap 18 between end surface 20 and body 14, the presence/absence and dimensions of recesses 13 or groove, the length of annular cavity 10.

[0038] In operation, with fluids being provided to the annular cavity, such as through first inlet 7 and second inlet 8, the amount of time fluid is present in the mixer can be described in terms of a "residence time", defined as a volume of the mixer divided by the fluid flow rate, where the volume of mixer is the volume of the annular cavity 10 (including the volume of any recesses 13 or grooves present) plus the volume of end space 1 1. In some embodiments, it can be desirable to have a mixer volume of about 10-20 pL or 20-30 pL or 30-40 pL, 40-50 pL, 50-60 pL, 60-70 pL, 60-80 pL, 80-100 pL, 100-120 pL, 120-140 pL, 140-160 pL, 160-180 pL, or 180-200 pL, or larger. In preferred embodiments, the volume can be 40-80 or 50 - 70, or 65- 70 pL. In some embodiments, it can be desirable to have a residence time of about 0.5 sec, 1 sec, 1.5 sec, 2 sec or 2.5 sec, or from 0.5-1 , 1-1.5, 1.5-2, 2-2.5 sec or longer. In some embodiments, such as for example systems used in preparatory work, shorter residence times, such as 0.1 -0.2 or 0.2-0.3 or 0.3-0.4 or 0.4-0.5 sec can be used or in some embodiments, the residence time can be smaller or larger.

[0039] In some embodiments of a mixer 5, only one inlet, such as first inlet 7 can be present. In some suitable embodiments, a first and a second fluid can be combined upstream of mixer 5, whereupon when the combined fluid passes through the mixer 5, the first fluid and the second fluid present in the combined fluid are more intimately mixed together. In some embodiments, a third fluid or more fluids can be combined. In some embodiments, a greater degree of mixing (being more intimately mixed) can be evaluated by any appropriate method, such as be fluctuations in the response of an appropriate instrument, such as a pH meter, a spectrophotometer, a fluorescence detector, a refractance meter, an optical rotation meter, a conductivity meter, a particle/droplet size meter, etc., or by visual or microscopic inspection. [0040] In some embodiments of a fluid system component 3, such as a mixer

5 or a pressure sensor 4, the annular cavity can have a gap 17 between the body 14 and the inner wall 12 of about 0.009 inches, however, other gap sizes can also be used such as a gap of about 0.005-0.006, 0.006-0.007, 0.007-0.008, 0.008-0.009, 0.009- 0.010, 0.010-0.012, 0.012-0.014, 0.014-0.016, 0.016-0.018 or 0.018-0.020 inches or gaps that are larger or smaller can also be used. In some embodiments of a fluid system component 3, the outer diameter of the annular cavity 10 can be about 0.381 inches, however, other outer diameters can also be used such as diameters of 0.15- 0.20, 0.20-0.25, 0.25-0.30, 0.30-0.35, 0.35-0.40, 0.40-0.45, 0.45-0.50 inches or larger or smaller can also be used. In some embodiments, the length of the annular cavity (measured parallel to the central axis 23) can be about 0.227 inches, however annular cavity lengths of 0.15-0.20, 0.20-0.25, 0.25-0.30, 0.30-0.35, 0.35-0.40, 0.40-0.45, 0.45-0.50 inches or larger or smaller can also be used. In some embodiments, the recess 13 can be a groove having a length (parallel to the central axis 23) of about 0.030 inches and a depth of about 0.034 inches. However, lengths of 0.015-0.020, 0.020-0.025, 0.025-0.030, 0.030-0.035, 0.035-0.040, 0.040-0.045, 0.045-0.050 or larger or smaller can also effectively be used as can depths of 0.015-0.020, 0.020- 0.025, 0.025-0.030, 0.030-0.035, 0.035-0.040, 0.040-0.045, 0.045-0.050 or larger or smaller can also effectively be used.

[0041] In some embodiments of a fluid system component 3, such as a mixer

5 or a pressure sensor 4, the combined flow of the fluids passing through the chamber

6 can have a Reynolds number of about 50 using the smallest cross section of the inner body 16 or the pressure transducer diameter 22, such as in the annular cavity (e.g. where the fluidic initially meet inside the pressure transducer cavity) the combined flow is exposed to as the characteristic diameter. However, Reynolds numbers of about 20-25, 25-30, 30-35, 35-40, 40-45, 45-50, 50-55, 55-60, 60-65, 65- 70, 70-75 or higher or lower can also effectively be used. In some embodiments of a fluid system component 3, the combined flow of the fluids passing through the annular cavity 10 can have a Reynolds number of about 100. However, Reynolds number of about 50-75, 75-100, 10-125, 125-150, 150-175, 175-200, 200-225, 225- 250, 250-275, 275-300 or higher or lower can also effectively be used.

Combined Pressure Transducer and Mixer

[0042] In some embodiments, the fluid system component 3 can also be a pressure sensor 4, such as by inclusion of a pressure transducer 22 for sending a signal related to the fluid pressure at the fluid system component 3. In some embodiments, the pressure sensor 4 can also be a mixer 5. Suitable pressure transducers 22 can include any type which can be integrated with or connected to the body 14 or the inner body 16 of the fluid system component 3. In some embodiments, the inner body 16 can comprise a pressure transducer 22, such as where a diaphragm 27 is integrated into a surface of the wetted portion 41 of the inner body 16 and having electronic components, such as a strain gauge or piezo electric components present in the interior of inner body 16 and being in functional communication with the diaphragm. In some embodiments, the pressure transducer 22 can further comprise wires 28 for conducting a signal that is representative of the pressure being sensed by the pressure transducer away from the inner body. In some embodiments, methods of conducting a signal away from the pressure transducer 22, such as a wireless signal, can be used in addition to or in place of wires 28.

[0043] Figure 3 shows an embodiment of a pressure transducer integrated into an inner body 16. Here, an inner body 16 includes an end surface 20 which comprises a diaphragm 27, which is functionally connected to electronics (not shown) which convert strain/movement of the diaphragm 27 into electrical signals which are conveyed away from the inner body 16 via wire bundle 28.

Mixer in a chromatography system

[0044] As shown in Figure 4, a mixer 5 can be used in a chromatography system 31 , where multiple fluids are brought together, mixed in mixer 5, and the mixed fluid they passes through a chromatography column with eluent collected and/or analyzed. In some embodiments, a first pump 33 pumps a first fluid and a second pump 34 pumps a second fluid. The first and second fluids are mixed in the mixer 5 to produce a mixed fluid and are then routed to the chromatography column. In some embodiments, a sample, such as a sample for separation and/or analysis, can be injected into the first fluid, the second fluid or the mixed fluid and is loaded onto the chromatography column. In various embodiments, the composition of the mixed fluid can be varied, such as by changing the flowrate of the first fluid and/or the second fluid. In some embodiments, the flowrate of the first fluid and the second fluid can be changed such that the combined fluid flowrate can be constant. If additional fluids are present, such as a third or fourth fluid or higher fluid, the flow rate of any one or all or some combination of these can be changed, and in some specific embodiments, the flowrate of the combined fluid can be constant. The composition of the mixed fluid can be varied prior to injection of the sample, for example to stabilize the column, or during injection or after injection for example to better separate compounds or to more quickly elute a compound. In some embodiments, the flowrate of one or more of the fluids can be increased or decreased while increasing, decreasing or keeping constant the flowrate of the mixed fluid.

[0045] In some embodiments of a chromatography system 31 including a mixer 5, the mixer 5 can include a pressure transducer, and the chromatography system 31 can be configured so that the pressure transducer can send a signal representative of the pressure of the fluid sent to the chromatography column, such as the pressure at the inlet of the chromatography column.

[0046] In some embodiments, the chromatography system 31 can include additional features, such as a bypass tube or passage which can route at least a portion of the fluid around the injection valve such as to prevent temporal pressure increases or“shocks” as the valve is moved between positions.

[0047] In some embodiments, the chromatography system 31 can include a system that uses a pressure signal from a pressure sensor to control one or more pump drives. In some such embodiments, a pressure sensor can be used to provide a pressure signal to a control system such as a feedback control system for example to control the pump drive. In some such embodiments, the feedback control system can send a signal to increase the pump rate when the pressure signal decreases and/or to send a signal to decrease the pump rate when the pressure signal decreases.

[0048] In various embodiments, the chromatography system can also include additional instrumentation, such as flow meter(s), pH meter(s), additional pressure transducers, temperature transducers (thermocouple, resistance temperature devices, thermistors, etc.) or analyzers and combinations thereof. Suitable analyzers can include any analyzer used with a chromatography system, such as those discussed above.

Examples Example 1.

[00491 A pressure sensor and housing (Bio-Rad part no. 12000330, Bio-Rad,

Hercules, CA, USA) was configured to receive and combine a first fluid of D- 100™ HbAi _c Elution Buffer A (Bio-Rad part no. 290-2010) and a second fluid of D- 100™ HbAi _c Elution Buffer B (Bio-Rad part no. 290-201 1) into a mixed fluid. The mixed fluid was analyzed with a Bio-Rad D-100™ Detector Bio-Rad part no. 12000153 (Bio-Rad, Hercules, CA, USA) to evaluate the stability of the concentration. The pressure sensor and housing were configured similar to that shown in Figure 1 , where the inner body 16 comprised the pressure transducer, first inlet 7 was used for introduction of the first fluid, second inlet 8 was not present, and downstream port 26 was used for introduction of the second fluid.

[0050] During the test, flow of the first fluid was initiated at 2.6 ml/min and the flow of the second fluid was 0.0 ml/min. After the system stabilized, the flows were changed in a step-wise fashion to 20%, then 40%, then 80% then 100% second fluid on a vol/vol basis, each time maintaining the total flow at 2.6 ml/min. The system was allowed to stabilize after each change in flow.

[0051] Different system configurations were also tested as follows:

Table 1.

*See note for Table 2, below, regarding dilution and scaling. [0052] Figure 5 is a graph of the detector response for the control case showing the stepwise change in the intended composition of the mixed fluid, where component B is the second fluid, and the detector response vs. time. Figure 6 is a similar graph for Test 1 and Figure 7 is a similar graph for Test 2. Variability in concentration at each step was determined as a noise value by determining the RMS (root-mean-square) value for the readings at each concentration as follows:

[0053] A pre-selected number of equally spaced data points over the 20 second interval at a response level were selected (for example, 100 points), and their decimal points were shifted six places to the right for convenience, and the root-mean- square of these shifted data points was calculated as the mean over the interval. The standard deviation of the shifted data points was then calculated over the interval using this mean as the“noise” value shown in Table 2. The standard deviation of noise levels for five replicate runs was then calculated and reported as the standard deviation of the noise in Table 2. (Noise values for only one replicate are shown in Table 2; results for only one of the replicate runs are shown in Figure 5 through Figure 7 for each test in sequence (Control, Test 1, and Test 2.)

[0054] Other related methods can also be used to evaluate the noise and variability in the noise, such as by following a method substantially related to that describe above, but by varying the duration of the interval and/or the number of data points for a given interval, selecting peak values (high and low) instead of equally spaced data points, etc. Alternative methods can also be used, such as the method described in ASTM E685-93 (Reapproved 2005) and methods related to or derived from this ASTM method, as well as other segmented methods and methods that are a combination of the method described above and the ASTM method, as well as others.

[0055] Software packages are available to perform the calculations as well.

Using alternate methods can result in different values being determined for each test condition, but it is expected that the relative ranking of the variability for the different conditions would not change or would not change significantly. [0056] The noise results are shown below:

Table 2

[0057] * Control and Test 2 used Component B (second fluid) at the manufacturer’s concentration. Test 1 used a different concentration of Component B (second fluid) as compared to the Control and to Test 2 as discussed below. In the Control and Test 2, Component B concentration in achieved a response of 0.1745 AU as measured with a Bio-Rad D-100™ Detector Bio-Rad part no. 12000153. In test 1 , Component B was used at a lower concentration, diluted with deionized water to achieve a response of 0.1433 AU as measured with a Bio-Rad D-100™ Detector Bio- Rad part no. 12000153. The results for test 1 were then scaled for the change in concentration by multiplying the measured value by 0.1745 and divided by 0.1433. The figures provided above for noise are thus the scaled noise values.

Example 2

[0058] Additional fluid introduction and mixing configurations were tested as in Example 1 with the equipment configurations shown below:

Table 3.

[0059] Noise results for Tests 3-7 are shown below:

Table 4.

*See note for Table 2, above, regarding dilution and scaling.

[0060] Reviewing test configuration 2, this configuration of a mixer comprises an annular mixer as described herein. Comparing the results for test configuration 2 with the other configurations tested, test configuration 2 provides comparable mixing results to commercial static mixers. Further, test configuration 2 demonstrates a mixer that can be integrated with a pressure sensor, without the addition of external mixers. In addition, configuration 2 can, if desired, be used with external mixer(s), positioned upstream and/or downstream of the annular mixer if further mixing is desired. In various embodiments, the mixer can achieve standard deviations of noise values of less than 147, such as less than or equal to 120, 100, 80, 70, 60, 50 or 44. In some additional embodiments, the mixer can achieve standard deviations of noise values less than or equal to 44, 42, 40, 38, 36, 34, 32, 30, 28, 26, 24, 22, 20, 18, 16,

14, 12, 10, 8.8, 8, 6 or 5.6. In various embodiments, the mixer can achieve noise values of less than 1931 or less than 1612, such as less than or equal to 1400, 1200, 1000, 800, 700, 600, 500, 464 or 219 or lower. In some embodiments, a mixer can be combined with an external mixer.

Example 3.

[0061] Test configurations 2, 3, 4 and 7 were tested for delays in response of the detector and for changes in response time of the detector. The response curve for a step change from 0 to 100% of the second fluid for test configurations 2, 3, 4 and 7 is shown in Figure 8. The delay in the response is the time from when the step change in composition is made to when it is detected. The delay for each configuration is shown below:

Table 5.

[0062] Without wishing to be limited by theory, it is believed that the delay time can be caused by an increase in the volume of the system between the fluid inlet and the detector. Accordingly, the calculated volumes (dwell volume) for the different configurations is shown above in Table 5, above, for a 2.6 ml/min flowrate. In some embodiments of systems using a mixer, such as a chromatography system, it can be desirable for the delay time to be low, for example to facilitate rapid changes in concentration, continuous changes in concentration and to facilitate control strategies. [0063] In addition, the response time, which can be viewed as being related to the slope of the response vs. time curve, can be seen in Figure 8, with a steeper slope indicating a faster response time. In some methods, such as that of ASTM E685-93 (ASTM International, West Conshoken, PA, USA), the response time is defined as the time for the signal to rise from 10% to 90% of the new equilibrium value. Without wishing to be limited by theory, in some embodiments, changes in response time can be related to changes in the amount of back-mixing that occurs within the fluid system. In Figure 8, test configuration 3 has the steepest slope, and therefore the fastest response time, followed by test configuration 2, followed by test configuration 4 and then test configuration 7. In some embodiments of systems using a mixer, such as a chromatography system, it can be desirable for the response time to be low, for example to facilitate rapid changes in concentration, continuous changes in concentration and to facilitate control strategies.

[0064] Having now described the invention in accordance with the requirements of the patent statutes, those skilled in this art will understand how to make changes and modifications to the present invention to meet their specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention as disclosed herein.

[0065] The foregoing Detailed Description of exemplary and preferred embodiments are presented for purposes of illustration and disclosure in accordance with the requirements of the law. It is not intended to be exhaustive nor to limit the invention to the precise form(s) described, but only to enable others skilled in the art to understand how the invention may be suited for a particular use or implementation. The possibility of modifications and variations will be apparent to practitioners skilled in the art. No limitation is intended by the description of exemplary embodiments which may have included tolerances, feature dimensions, specific operating conditions, engineering specifications, or the like, and which may vary between implementations or with changes to the state of the art, and no limitation should be implied therefrom. Applicant has made this disclosure with respect to the current state of the art, but also contemplates advancements and that adaptations in the future may take into consideration of those advancements, namely in accordance with the then current state of the art. It is intended that the scope of the invention be defined by the Claims as written and equivalents as applicable. Reference to a claim element in the singular is not intended to mean "one and only one" unless explicitly so stated. Moreover, no element, component, nor method or process step in this disclosure is intended to be dedicated to the public regardless of whether the element, component, or step is explicitly recited in the Claims.

[0066] Use of language such as "about", "approximately", "substantially" are intended to carry the meaning as understood by a person of skill in the art in the context presented where small changes can occur to the numerical value so described which do not change the functioning of the device, unless the context implies a more specific value. In situations where a person of skill would require further guidance, a variation of 5% would be intended.

[0067] All elements, parts and steps described herein are preferably included.

It is to be understood that any of these elements, parts and steps may be replaced by other elements, parts and steps or deleted altogether as will be obvious to those skilled in the art.

[0068] Broadly, this writing discloses at least the following:

Fluid system components such as fluid mixers and pressure sensors are described.

The fluid system components can be used in chromatography systems, such as a chromatography system comprising: a chromatography column; a first fluid pump; a second fluid pump; a pressure sensor comprising: a pressure transducer; a body comprising: a chamber; a first inlet; a second inlet; an outlet; and an outlet channel configured to carry fluid out of the chamber to the outlet; wherein the pressure transducer is present in the chamber and the first and second inlets are configured to direct a first and a second fluid, respectively, into the chamber. CONCEPTS

Concept 1. A chromatography system comprising:

a chromatography column;

a first fluid pump;

a second fluid pump;

a pressure sensor comprising:

a pressure transducer;

a body comprising:

a chamber;

a first inlet;

a second inlet;

an outlet; and

an outlet channel configured to carry fluid out of the chamber to the outlet;

wherein the pressure transducer is present in the chamber and the first and second inlets are configured to direct a first and a second fluid, respectively, into the chamber.

Concept 2. The chromatography system of Concept 1 , wherein the pressure transducer divides the chamber into an annular cavity and an end chamber, wherein the first inlet is configured to direct the first fluid into the annular cavity and the outlet channel is configured to carry fluid out of the end chamber.

Concept 3. A mixer comprising:

a chamber comprising: an annular cavity;

a first inlet;

a second inlet; and

an outlet; wherein the first and second inlets are located spaced apart from one another on the annular cavity, and the first and second inlets are configured to direct a first and a second fluid, respectively, into the annular cavity and the outlet is positioned to discharge a combination of the first and the second fluids from the chamber.

Concept 4. The mixer of Concept 3, wherein the chamber further comprises an end space, the end space located downstream of the annular cavity and the outlet is positioned and configured to discharge a combination of the first and second fluids from the end space.

Concept 5. The mixer of Concept 3 or 4, wherein the first and the second inlets are spaced apart circumferentially about the annular cavity.

Concept 6. The mixer of any one of Concepts 3-5, wherein the annular cavity comprises an inner wall, and the inner wall comprises a groove open to the annular cavity and running around the inner wall to form a ring.

Concept 7. The mixer of Concept 5, wherein the annular cavity comprises an inner wall, and the inner wall comprises a groove open to the annular cavity and running around the inner wall to form a ring.

Concept 8. The mixer of Concept 7, wherein the first inlet is aligned with the groove.

Concept 9. The mixer of Concept 7, wherein the first and second inlets are aligned with the groove.

Concept 10. The mixer of Concept 4, wherein the mixer further comprises:

a body comprising a wall, the wall surrounding the chamber; and an inner body having an outer surface comprising an end surface and the inner wall is positioned in the body, wherein a gap between the inner wall of the inner body and the body define the annular cavity and a second gap between the end surface of the and the body defines the end space.

Concept 1 1. The mixer of Concept 10, wherein the inner body comprises a pressure transducer for a chromatography system.

Concept 12. The mixer of Concept 10 or 1 1 , wherein the inner body is sealingly connected to the body along the outer surface of the inner body.

Concept 13. The mixer of any one of Concepts 3-6, wherein the wherein the annular cavity is bounded by an inner wall, and the inner wall has a cylindrical shape.

Concept 14. The mixer of any one of Concepts 10-12, wherein the inner body has a cylindrical shape and the wall has a cylindrical shape.

Concept 15. A chromatography system comprising the mixer of Concept 1 1 , wherein the mixer is configured to transmit a signal related to a pressure on an inlet of a chromatographic column.

Concept 16. A method of using the mixer of any one of Concepts 3-6 and 13, the method comprising:

injecting a first fluid at a first rate and a second fluid at a second rate into the first and second inlets, respectively, of the mixer;

combining the first and second fluids in the mixer into a combination of the first and the second fluids;

directing the combination of the first and the second fluids from the outlet to a chromatography column. Concept 17. The method of Concept 16 further comprising:

increasing the flowrate of the first fluid to perform a portion of a gradient elution.