Abstract: The present disclosure relates to methodologies, systems and apparatus for controlling pressure in a CO2-based chromatography system. A first pressure control element is located downstream of a CO2-based chromatography system and is disposed to control pressure within the column. A split restrictor is located downstream of the primary pressure control element and is disposed to divert a portion of the mobile phase flow to a detector. A second pressure control element is located downstream of the split restrictor and is disposed to control pressure at the restrictor. While the first pressure control element executes a pressure-controlled gradient separation, the second pressure control element maintains a constant pressure at the restrictor. During a composition-programmed gradient separation, the second control element maintains a constant pressure at the split restrictor while the first pressure control element maintains a constant average density across the column.

Abstract: A passive pre-heater assembly includes a thermally conductive heat-spreading block and a plurality of passive pre-heaters in thermally conductive communication with the heat-spreading block. The plurality of the pre-heaters exchanges heat with the thermally conductive heat-spreading block. Each pre-heater includes a thermally conductive base in thermal communication with the heat-spreading block, and a plurality of thermally conductive fins is in thermal communication with the thermally conductive base. The plurality of fins of each pre-heater exchanges heat convectively with ambient air and conductively with the thermally conductive base of that pre-heater. A given one of the passive pre-heaters further comprises a tube in thermally conductive contact with the thermally conductive base of the given passive pre-heater. The thermally conductive heat-spreading block exchanges heat with a fluid passing through the tube of the given passive pre-heater.

Abstract: A thermal system for use in a column manager of a liquid chromatography system comprises a plurality of spatially separated individually controlled thermoelectric chips. A column module houses a plurality of thermally conductive troughs. Each trough resides in a separate thermal zone to be thermally conditioned individually by one of the individually controlled thermoelectric chips. Each trough is adapted to hold one or more liquid chromatography columns therein. A plurality of spatially separated thermal bridges includes a first thermal bridge thermally coupling one of the thermoelectric chips to a first one of the plurality of troughs and a second thermal bridge of the plurality of thermal bridges thermally coupling another of the thermoelectric chips to a second one of the plurality of troughs.

Abstract: A check valve comprises a valve seat element along a fluid path that is formed of a polymeric material and comprises a hole that extends from an input end of the valve seat element to an output end of the valve seat element. The valve seat element includes an inner taper that transitions the input end to the output end, the valve seat element including a sealing surface along the inner taper. A poppet body is formed of a polymeric material and configured to engage the internal tapered sealing surface of the valve seat element. The poppet body moves between a first position at which the poppet body sealingly engages the tapered sealing surface of the valve seat element and a second position at which the poppet body is separate from the inner taper of the valve seat member.

Abstract: A method of liquid chromatography includes providing one or more solvent reservoirs, providing a solvent pump, drawing one or more solvents into the pump in response to a pressure drop that promotes outgassing of the solvents, and dispersing outgassed bubbles into smaller bubbles to promote re-dissolution of the gas. A liquid-chromatography apparatus includes at least two solvent reservoirs, a pump, at least one bubble-dispersing unit that receives a pressurized flow of proportioned solvents from the pump, and a control unit. The control unit includes a processor and a memory that stores instructions; the control unit controls proportioning of solvents to obtain a preselected solvent composition, and pumping at flow rates to support preparative-scale or process-scale liquid chromatography.

Abstract: Low-pressure and high-pressure reciprocating and rotary applications use seal assemblies to prevent leakage. One embodiment of a seal assembly includes a major annular body having opposing spaced-apart annular lips extending from a heel portion. The major annular body has a bore extending through the heel portion. A first spring is disposed between the lips, biasing the lips apart. A minor annular body extends from one of the lips of the major annular body. The minor annular body has opposing spaced-apart walls that extend from a base region and form a pocket. A second spring is disposed in the pocket between the spaced-apart walls, biasing the walls apart. During actuator operation, pressurized fluid urges one wall of the minor annular body against a pump head surface to produce a face seal and one of the lips of the major annular body against a rod surface to produce a radial seal.

Abstract: Analytical-scale separation column assemblies include a tube with a bore packed with a stationary phase through which a mobile phase flows. In one embodiment, thermal elements are disposed remotely from and unattached to the tube. The thermal elements are in thermal communication with an external surface of the tube for producing a spatial thermal gradient outside of and along a length of the tube. In another embodiment, discrete, spatially separated strips of thermally conductive material are disposed on and wrapped around an external surface of the tube. Thermal elements are disposed remotely from the tube. Each thermal element is in thermal communication with one strip of thermally conductive material by a heat-transfer device. The thermal elements produce a spatial thermal gradient outside of and along a tube length by controlling temperature of each strip of thermally conductive material disposed on and wrapped around the external surface of the tube.

Abstract: The invention generally provides a static back pressure regulator. In exemplary embodiments, the static back pressure regulator includes a seat that defines part of a fluid pathway, a poppet, a spring arranged to bias the poppet toward the seat to restrict fluid flow through the fluid pathway, and a calibration element configured to adjust a force applied to the poppet by the spring. The calibration element can include a through hole that forms part of the fluid pathway. The poppet can include a first guiding portion that extends into the through hole of the calibration element and inhibits tipping of the poppet relative to the seat.

Abstract: Methods, systems and apparatus are provided for degassing a supersaturated solution. An example degasser is described having a continuous body of gas-permeable tubing to remove an amount of a gas from the supersaturated solution below the gas's saturation point in the supersaturated solution. The degasser can be connected to at least one of a fraction collector or a detector. The example degasser is sized and/or positioned to cause a change in pressure (?P) across the degasser to drive removal of a dissolved gas from a supersaturated solution passing through the degasser. As a result of the reduction of gas, efficiencies in system flow and fraction collection are achieved.

Abstract: Methods for transferring a separation procedure from a first chromatographic system to a second one are disclosed that involve substantially matching a pressure profile. In some such methods, a length, an area, and a particle size of a first column in the first system and a flow rate in the first separation procedure are identifiable. Some such methods also involve selecting a combination of a length, an area, and a particle size of a second column in the second system and a flow rate for the second separation procedure. These methods may involve calculating a target length, a target area, or a target particle size for the second column in the second system or a target flow rate for the second separation procedure.

Abstract: The present disclosure relates generally to a system and a method for improving performance of a chromatography system using a highly-compressible fluid based mobile phase (e.g., CO2). In particular, the present disclosure relates to a system that uses a conduit, such as a convergent-divergent nozzle, for reducing pressure noise in a chromatography system using a highly-compressible fluid based mobile phase. The chromatography system can include a conduit, such as a convergent-divergent nozzle, disposed downstream of the column to reduce or prevent the propagation of pressure or density pulses from a back pressure regulator.

Abstract: The present disclosure relates to methodologies, systems and apparatus for cooling pump heads and providing balanced cooling and heat transfer between multiple pump heads. Multi-pump systems that are used to pump fluids that vary greatly in density with minor changes in temperature, such as the mobile phase of a C02-based chromatography system, require highly stable temperature conditions. In order to achieve a substantially equal average heat transfer between multiple pump heads and a coolant fluid, coolant fluid may be flowed through coolant passageways within the pump heads in a recursive and/or parallel coolant flow patterns. Such recursive and/or parallel coolant fluid flow patterns provide increased stability in temperature, compressibility, and density of the fluids passing through a multi-pump system.

Abstract: Methods for transferring a carbon dioxide based separation procedure from a reference chromatographic system to a target chromatographic system involve alternative techniques for determining system pressure drops not attributable to the column. One technique involves leveraging experimental chromatography to develop a correction factor that is a function of at least one correction coefficient and at least one ratio of the differential analyte retention time to the retention time in the reference system. Another technique involves leveraging other experimental measurements of tubing pressure drops under various condition to develop a lookup table that can be used to identify likely tubing pressure drops in the target system. A third technique leverages knowledge of the separation procedure and the target system and the likely nature of the relevant flow to calculate tubing pressure drops in the target system.

Abstract: The present disclosure relates to methodologies, systems and apparatus for controlling pressure in a CO2-based chromatography system. A first pressure control element is located downstream of a CO2-based chromatography system and is disposed to control pressure within the column. A split restrictor is located downstream of the primary pressure control element and is disposed to divert a portion of the mobile phase flow to a detector. A second pressure control element is located downstream of the split restrictor and is disposed to control pressure at the restrictor. While the first pressure control element executes a pressure-controlled gradient separation, the second pressure control element maintains a constant pressure at the restrictor. During a composition-programmed gradient separation, the second control element maintains a constant pressure at the split restrictor while the first pressure control element maintains a constant average density across the column.

Abstract: The present disclosure relates to methodologies, systems and devices for controlling pressure of a mobile phase in a CO2-based chromatography system. A pump is used to pump a mobile phase containing CO2 and is located upstream of a chromatography column. A primary pressure control element is located downstream of the chromatography column and controls the pressure of the mobile phase within the column. A secondary pressure control element is located downstream of the primary pressure control element and maintains the pressure of the mobile phase above a threshold value between an outlet of the primary pressure control element and the point of detection within a detector. The detector is located downstream of both the primary pressure control element and the secondary pressure control element.

Abstract: Described is a method of generating a flow having a composition gradient such as a mobile phase gradient for liquid chromatography. A pair of pumps is operated such that the initiations of pump strokes for one pump are controlled to occur between the initiations of pump strokes for the other pump so that the sequences of pump strokes fort the two pumps are interspersed in time. Initiations of the pump strokes of the second pump are offset in time relative to initiations of the pump strokes of the first pump such that variations in the flow rates of the first and second pumps due to initiation do not overlap in time. The volume of liquid contributed by a pump stroke is controlled according to the relative contribution of the respective pump to the composition gradient.

Abstract: Exemplary embodiments of the present disclosure are directed to manipulating pressure-related hysteresis in a pressurized flow system by setting the pressure of the system to a predetermined location in the hysteresis band to advantageously minimize an effect of the pressure related hysteresis on the pressure of the system or to advantageously benefit from the effects of the hysteresis on the pressure of the system.

Abstract: Mixers in microfluidic separation systems comprise multiple fluidic paths that extend from a distribution well to a mixing well. An incoming flow of solvent composition splits at the distribution well into as many streams as fluidic paths. The streams recombine at the mixing well to produce an output stream. One embodiment has fluidic paths with different dwell volumes that determine a percentage of the incoming flow flowing through each path. These dwell volumes can be targeted to attenuate a known noise characteristic in the incoming compositional flow. Another embodiment of mixer has a contoured surface disposed between the distribution and mixing wells. The paths extend from the distribution well to the mixing well through this contoured surface, each path passing through a different valley defined by opposing upwardly sloping banks. The valleys can have different dwell volumes that determine a percentage of the incoming compositional flow flowing through each valley.

Abstract: Exemplary embodiments are directed to a gas liquid separator that includes a chamber, a fluid mixture inlet, a solvent outlet and a gas outlet. The gas liquid separator can include a phase-change inducing mechanism disposed in or proximate to the fluid mixture inlet. Exemplary methods of improving separation of a fluid mixture in a gas liquid separator and CO2-based chromatography flow systems including a gas liquid separator are also provided.

Abstract: The present disclosure relates to the regulation of carbon dioxide expansion in a carbon dioxide based chromatographic system. In particular, the present disclosure relates to minimizing or eliminating the deleterious effects of carbon dioxide expansion on one or more of the solvent, the analyte(s) of interest, the separation, the detection of the analyte(s) of interest, and other related aspects in a carbon dioxide based chromatographic system.