Abstract: A method and apparatus for improving signal to noise in an electropherogram acquired by electrophoresis. The migration time is remapped by binning the data with respect to migration time to improve signal to noise and peak resolution. The data points of the electropherogram are pooled into variable size bins, each corresponding to a number of time intervals. The sizes of the bins increase with migration time. To further improve signal to noise and peak resolution, the binned data is filtered by Fourier transformation. The present invention allows for accurate determinatiion of DNA sequences.

Abstract: A electrophoretic system in which nonconductive members are strategically positioned in the electrolyte tank to selectively affect the electric field of electrodes so as to obtain a desired electric field for efficient separation. The size, shape and location of the nonconductive members are selected using a electric potential analysis.

Abstract: A centrifuge rotor and method for gradient density separation which supports a generally cylindrical volume of sample solution with its axis inclined to the spin axis at an angle which is optimized for maximum separation efficiency while reducing contamination by undesirable centrifugates upon reorientation of the desirable centrifugates. The optimum angle is determined based on the relationship .theta.=Tan.sup.-1 (D/15L).sup.0.5 where D and L are respectively the diameter and length of the cylindrical volume of the sample solution and .theta. is the angle of inclination.

Abstract: An automated chemical conversion unit for use in a peptide/protein sequencing process. The improved conversion methodology decreases the time necessary for the conversion reaction chemistry of the specific derivative of the sequenced amino acid to a more stable form. The conversion reaction is designed to be performed directly in a fraction collector tube which operates in one embodiment in conjunction with a thermoelectric temperature element to allow utilization of different temperature levels for different amino acid derivatives.

Abstract: Solid phases such as capillary tubes or solid supports used in chromatography, and in particular electrophoresis, are treated with oxidizing or reducing agents as needed to maintain or restore surface electrical charges or the lack thereof, which become modified during electrophoresis as a result of action by system components in the separation medium or the solutes themselves. The treatment is used as a means of achieving reproducible electroosmotic bulk flow when desired or suppressing unwanted electroosmotic flow arising due to the accumulation of charges on the surface. The result is improved reproducibility of retention times and component separation.

Abstract: A check valve cartridge insertable into a valve housing which is adapted to couple to a pump fluid head. The check valve cartridge has a fluid pathway therethrough with a desired direction for fluid flow. The cartridge utilizes a ball-seat assembly to control the direction of fluid flowing through the cartridge to the desired direction. The ball-seat assembly includes a rigid seat which is compliantly supported within the cartridge by thin compliant spacers. The check valve cartridge further has deformable seals which partially fit within the opposed ends of a cartridge body and are adapted to cold flow and seal to a surface when subjected to a force. One of the deformable seals is adapted to seal against a surface of the pump fluid head and has slidably mounted over its end a rigid ring which constrains the cold flow of the end of the seal that seals to the pump fluid head. The check valve cartridge may be designed to be used for inlet and outlet check valves.

Abstract: Aqueous buffer solutions for use in an ion exchange amino acid analysis system compounded so that it is non-corrosive to the stainless steel components of such a system while achieving high resolution and short analysis times in separation of the various amino acids in a sample mixture. The aqueous buffer preferably comprising a mixture of salts free of halogen ions but containing nitrate ions which tend to passivate stainless steel preventing corrosion.

Abstract: A process and apparatus for predicting the time and position dependent concentration of macromolecules of differing species in a gradient forming solution during centrifugation is disclosed. A mathematical model of the time dependent behavior of gradient forming solutes in a centrifugal field, based upon the underlying physical principles governing sedimentation and diffusion is formulated. The simplifying approximation is made that the wall effects may be ignored, and that the transport of solute may be treated as a one dimensional process with forces dependent only upon the radial distance. A sedimentation diffusion (Lamm) equation in one dimension is numerically integrated. The sedimentation diffusion equation (Lamm equation) for each macrosolute is solved concurrently with that for the gradient forming solute, utilizing the experimentally based density dependent sedimentation coefficient. The equations are solved for incremental time periods for the centrifuged samples in successive radial segments.

Abstract: A detector for detecting the presence of an electrically conductive sample solution in a sample injection metering valve by electrical sensing the leading edge of the sample solution, wherein the amount of sample solution in excess of the metered amount required to cause detection is minimized. A conductive probe is positioned on the valve body just downstream of the sample metering passage of the valve, the probe being electrically insulated from the valve body. The probe and valve body form electrodes which will detect the arrival of the leading edge of a conductive sample solution which completes a conductive circuit between the electrodes.

Abstract: A composite rotor body has a drive hole insert attached. The drive hole insert seats along a conical surface. A disk spring bears against a washer, which in turn bears against the top surface of the composite material rotor body. The preloaded disk spring compresses the conic surface of the rotor body against the mating surface of the drive hole insert. The preload within the disk spring is activate by torquing centering nut until the disk spring is essentially flat. The centering nut captures and centers both the disk spring and washer within a counterbored recess on its bottom face. The contact surface is treated with a form of dry lubricant or release agent, typically particulate Teflon, such that axial translation is facilitated. The disk spring is sized such that the drive hole insert translates axially without rotation along the surface and, effectively, maintains constant in-plane orientation with respect to the rotor body.

Abstract: In an optical system for measuring sample absorption of light at a primary wavelength output from a monochromator, a method of subtracting the effect of secondary wavelength components of light from the monochromator. The sample absorption of light at the primary wavelength including the effect of the secondary wavelength components and at the secondary wavelength are determined. The results are used to obtain the sample absorption of light at the primary wavelength without the effect of the secondary wavelength components.

Abstract: A centrifuge sample is optically scanned during centrifuging. The sample, placed in a centrifuge rotor having a cell with top and bottom windows, is spun until stratification and discrete layering occurs within the sample. Such layering occurs on layers that are precisely normal to the radius of the centrifuge at the point of sample and parallel to the spin axis of the centrifuge. A slit scanner having a slit normal to the sample plane transverses the width of the sample below the cell to detect with precision the precise location of the strata in the cell. A light source is reflected by a toroidal mirror having two radius of curvature. One radius of curvature is selected to collimate rays of light parallel to the layer of the sample. The mirror is ruled with respect to the other radius of curvature to chromatically classify light to preselect band width. Rotation of the mirror preserved collimation but enables selected scanning light frequency.

Abstract: Method and apparatus for compensating for the deficiency in fluid flow occurring during the refill and piston chamber pump-up cycle of a single piston fluid pump are disclosed. The period of time during which the outlet valve is closed and no fluid is being delivered to the system is determined and the pump is driven at a speed greater than the normal delivery speed for a period of time such that the quantity of excess fluid delivered approximates the quantity of fluid that would have been delivered during the refill and pump-up period had the pump been delivering fluid at its normal delivery rate.

Abstract: A thermoelectric cooling design of the type having a nonconducting substrate mounting thermoelectric coolers is improved. Provisions for a flexible can and improved heat dissipation from the thermoelectric coolers are provided. For improved thermal response, the refrigerated vacuum can is provided with thin walls of high purity aluminum with the result that deformation of the wall surface, especially the bottom wall surface can occur both with respect to installation. A plurality of can heat sinks are placed on the walls of the can to form a unitary and locally rigid side wall to the can at the point of attachment. At least one thermoelectric cooler is communicated to the can heat sinks at a first side for receiving heat energy from the can. A second discharge heat sink is communicated to each thermoelectric cooler for dissipating heat energy from both the can and the thermoelectric cooler.

Abstract: A sample counting support for scintillation counting of a radioactive labeled sample comprises a base material covered with a thin layer of dry solid scintillator in a substantially permanent form so that the support may receive the sample and produce light emissions in response to particules emitted by a radioactive substance labelling said sample.

Abstract: A centrifuge hub-rotor drive is disclosed in which a rotor has an internal recess that fits over and interfaces with a hub. The hub has a skirt with a curved outer periphery that interfaces and contacts internal walls of the rotor which define a tapered section of the recess. The curved outer periphery of the skirt ideally meets the internal tapered walls of the rotor along a curved contact band. The outer periphery of the skirt is taken from a portion of a spheroid, regular, oblate or prolate.

Abstract: An efficiency extrapolation method is used in liquid scintillation counting for determining activity in an unknown sample. A dynamic and automatic determination of the range of the pulse height spectrum is used to permit a counting measurement in highly quenched samples, and with isotopes having low energy end points. A selected linear regression equation is extrapolated to provide the determination within a predetermined error established by a least squares condition.