Abstract: Apparatus and methods are provided relating to evaporation of solvents from samples and to prolonging the time taken to carry out an evaporation procedure. A cap for engaging with an open end of a sample container comprises an engaging surface for engaging with the open end, and a body portion which extends over the open end. The body portion is preformed to define an opening which provides a fluid pathway between the open end of the container and the surroundings of the container, such that the cap impedes vapor flow from a sample in the container to the surroundings of the container. A holder for receiving a plurality of such caps is also provided and a method of evaporating a solvent from a sample in a sample container is described.

Abstract: A method and sample holding assembly are described for use in the preparation of samples for analysis. The method comprises the steps of collecting a sample in a concentration tube which is open at one end and closed at the other, the closed end being selectively openable. A vial is coupled to the open end, the tube is inverted, the closed end is opened, and then solvent is evaporated from the sample via the opened end until the concentrated sample is confined to the vial. A sample holding assembly for use in the present method is also described. It comprises a concentration tube, and an adaptor arrangement for coupling a vial to the open end of the tube and defining a fluid path between the tube and the vial.

Abstract: An evaporator is provided for evaporation of liquid from a solution or liquid mixtures, together with methods of operation of the evaporator. The evaporator comprises a chamber (1); a liquid reservoir (3) for holding a heat transfer liquid exposed to the interior of the chamber; a support (6) for supporting a container (8) in the chamber, such that the liquid sample in the container is exposed to a fluid path (15) for connection to a condenser (16), the fluid path being separated from the chamber interior, and at least a portion of the container is closely thermally coupled to the chamber interior; and means (4) for heating the heat transfer liquid in the reservoir to create heat transfer liquid vapor, which in use condenses and releases latent heat of vaporization to the liquid sample in the container. As the temperature of the sample is dependent on the saturated vapor temperature of the liquid in the reservoir, the temperature of the samples is reliably limited, thereby avoiding overheating.

Abstract: A method and sample holding assembly are described for use in the preparation of samples for analysis. In known techniques, following concentration of a sample using an evaporator, the concentrated solution is manually transferred to a smaller vial compatible with analysis apparatus using a pipette. This leads to loss of the sample and risks cross-contamination. Using the present method, a sample is concentrated directly into the vial. The method comprises the steps of collecting a sample in a concentration tube which is open at one end and closed at the other, the closed end being selectively openable. A vial is coupled to the open end, the tube is inverted, the closed end is opened, and then solvent is evaporated from the sample via the opened end until the concentrated sample is confined to the vial. A sample holding assembly for use in the present method is also described.

Abstract: An evaporator is provided for evaporation of liquid from a solution or liquid mixtures, together with methods of operation of the evaporator. The evaporator comprises a chamber (1); a liquid reservoir (3) for holding a heat transfer liquid exposed to the interior of the chamber; a support (6) for supporting a container (8) in the chamber, such that the liquid sample in the container is exposed to a fluid path (15) for connection to a condenser (16), the fluid path being separated from the chamber interior, and at least a portion of the container is closely thermally coupled to the chamber interior; and means (4) for heating the heat transfer liquid in the reservoir to create heat transfer liquid vapour, which in use condenses and releases latent heat of vaporisation to the liquid sample in the container. As the temperature of the sample is dependent on the saturated vapour temperature of the liquid in the reservoir, the temperature of the samples is reliably limited, thereby avoiding overheating.

Abstract: A method is described for evaporating liquid samples contained in sample holders mounted within a chamber and rotated by the rotor during an evaporation process in which the pressure in the chamber is reduced below atmospheric and the sample holders are rotated at high speed so as to exert centrifugal force on the contents of the holders. Heat is supplied to elevate the temperature of the liquid component of the samples to assist in the evaporation process. The temperature of the sample material is continuously or regularly monitored during the evaporation process and temperature signals are transmitted to a remote computing means which is programmed to generate a control signal for controlling the supply of heat to the samples and controlling the evaporation process. The temperature may be sensed by a probe in a sample holder containing an evaporating liquid sample, or in an adjoining sample holder containing a buffer liquid.

Abstract: A method of protectively heating a microtitre well plate from below using infra-red radiation in a centrifugal evaporator, wherein a barrier plate is placed in contact with and surrounding the lower ends of the wells. The barrier plate is adapted to convey heat energy to the wells and contents thereof and is selected to be substantially non-transmittive of radiation having wavelengths in the range 200 nm to 3000 nm, and the surface of the barrier plate which is to receive the wells includes a plurality of sockets in which the closed lower ends of the wells are a snug fit. The plate is adapted to fit between the underside of the wells and a swinging sample holder mount of a centrifugal evaporator, or a shelf of a swinging sample holder mount, having two or more shelves for stacking well plates one above the other in such an evaporator.

Abstract: A sample holder is described, for use in centrifugal evaporators, which permits accelerated evaporation of solvents from samples while ensuring that samples from which evaporation is complete are not damaged by overheating. The sample holder is radiantly heated and has sample containers mounted either directly in it, or in intermediate holders themselves mounted in it. The sample holder imparts heat to the samples and has a cross-sectional area chosen such that no appreciable temperature gradient exists between the radiantly or otherwise heated surfaces of the holder and the sample containers. The sample containers are mounted in the holder at an angle between 35° and 65° to the vertical and orientated such that centrifugal force tends to retain the sample material in the containers. The sample holder may be combined with other holders in a stack, the joints between adjacent holders in the stack being adapted to minimize the temperature difference across them.

Abstract: A centrifugal evaporator is described having internally of a chamber a source of IR radiation which directs energy towards a sample support platform on which a microtitre plate is mounted in use, for rotation within the chamber. The wells of the microtitre plate will normally contain liquid samples which are to be evaporated whilst subjected to heat from the IR source and centrifugal force from the rotation of the platform. The swing characteristic of the latter allows the plate to be mounted and demounted with the plate generally horizontal, but as the support platform is rotated, it swings up through approximately 90° so that the wells are now substantially horizontal and the plate is now substantially vertical, so that centrifugal force pins the liquid at the bottom of the wells.

Abstract: A method of controlling the evaporation of liquid in samples in an evaporating centrifuge, by monitoring the centrifugal force exerted on a sample holder containing a liquid sample having solid material dissolved or otherwise mixed therein. The centrifugal force is determined using a load cell, a strain gauge or, where relative movement between sample holder and rotor is permitted albeit with resilient restraint, the centrifugal force signal may be generated by a position sensing transducer. The speed of rotation is sensed by a further transducer and both force and speed signals are conveyed to a computer programmed to generate a process control signal for controlling the evaporation process therefrom. A preferred method of control involves determining the rate of change of weight with time and terminating the evaporation process when the rate of change drops to zero.

Abstract: A centrifugal evaporator for evaporating a mixture of liquids having different volabilities and specific gravities, the mixture being contained in a test tube 14 pivotally mounted on a rotatable support arm 12 in a sealable vacuum chamber 16, the support arm is rotated up to a speed of the order of 2000 rpm before evaporation of the more volatile component occurs, and only then is the chamber progressively evacuated. The motor is preferably a three-phase induction motor connected to the electric supply in a frequency convertor.

Abstract: A method is described for evaporating liquid samples contained in sample holders mounted within a chamber and rotated by the rotor during an evaporation process in which the pressure in the chamber is reduced below atmospheric and the sample holders are rotated at high speed so as to exert centrifugal force on the contents of the holders. Heat is supplied to elevate the temperature of the liquid component of the samples to assist in the evaporation process. The temperature of the sample material is continuously or regularly monitored during the evaporation process and temperature signals are transmitted to a remote computing means which is programmed to generate a control signal for controlling the supply of heat to the samples and controlling the evaporation process. The temperature may be sensed by a probe in a sample holder containing an evaporating liquid sample, or in an adjoining sample holder containing a buffer liquid.

Abstract: A reduction of sample loss from a container open to atmosphere, and including liquid trifluoroacetic acid (TFA), is carried out by a variety of methods each of which reduces creep of TFA up the walls of the container. In one method, particularly applicable to microtitre plates, each container or well is sealed by a cap which is retained by a strap (FIGS. 4 and 5). In another method the top of the container is formed with a downwardly pointing entrance tube, in the form of an unspillable inkwell (FIG. 2), where the container is a screw top vial, the entrance tube is sealed around the top of the neck of the vial (FIG. 9b).

Abstract: A method of and apparatus for pumping fluids wherein a rotating ring of liquid traverses a hollow probe which has a surface aperture out of which the fluid to be pumped is sucked into the rotating liquid ring, wherein the fluid migrates to a collection region inside the rotating liquid ring, from where the fluid can pass to a fluid outlet, and wherein a gas which does not condense under the prevailing operating conditions is also fed to the collection region in order to assist throughput of the fluid being pumped.

Abstract: A fluid pump having an outer cylindrical housing (10) rotating relative to an inner hub (44) from which radially projects a probe (52) apertured in its external surface to be exposed to the flow therepast of an annulus of operational liquid (14) constrained in a circular path of motion by the rotating housing, the probe having an internal passage for communicating the aperture with a first external space and the inner liquid-free space in the housing having an outlet for communicating with a second external space. In use, fluid to be pumped is sucked out of the apertured probe to emerge as fluid bubbles which migrate through the rotating liquid annulus to the liquid-free center, then to pass to the outlet.