Abstract: A liquid coenzyme reagent comprises the coenzyme nicotinamide adenine dinucleotide (NAD), or nicotinamide adenine dinucleotide phosphate (NADP), and a sulfhydryl compound capable of counteracting the inhibitory effects of NAD (or NADP) degradation products on LD-L activity. The reagent is maintained at a pH of less than about 31/2. The liquid reagent has a shelf life of at least about 2 years, maintaining a LD-L activity of at least 90% that of the reagent when fresh, when stored at a temperature of from 2.degree.-8.degree. C.

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: A calibration method and apparatus for economical and rapid calibration of a scientific instrument utilizing a monochromator to generate monochromatic light utilizing controllable means for determining the angular position of a light dispersing element in the monochromator and a filter having a narrow absorption band(s) to determine a relationship between the wavelength of the monochromatic light generated by the monochromator and an angular position of the dispersing element so that the dispersing element can be rotated to an exact position for the monochromator to generate a selected wavelength of monochromatic light.

Abstract: A reagent cartridge for use in an automated clinical analyzer, the reagent cartridge including a plurality of storage compartments each including wall members. The reagent cartridge includes connecting members formed integrally with the storage compartments for holding the storage compartments in a fixed relationship with respect to each other and separating the wall members from each other to thus prevent reagent migration between adjacent reagent compartments. Each of the storage compartments includes an access opening and a neck formed about the opening, the neck including a collar that is spaced a predetermined distance from a bottom wall of the associated storage compartment, the predetermined distance adapted to accommodate an automatically controlled reagent transfer probe.

Abstract: A system of modular analyzers each adapted for independent operation and each possessing different operational characteristics adapted for particular applications. Such modular analyzers may be joined together with precise indexing means such that a single sample carousel may be accessed by fluid transfer probes from both of the analyzers to thus form a system which operates as a single analyzer of increased capacity and versatility.

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 liquid degassing system including a liquid reservoir having an inlet to receive a liquid to be degassed and an outlet through which degassed liquid may flow. A vacuum source is controllably connected through a valve to the reservoir to draw gas out of the liquid held within the reservoir. A valve in a liquid inlet conduit supplying the reservoir may interrupt flow to the reservoir while vacuum is applied thereto. A second valve in an outlet conduit connected to the reservoir may interrupt flow from the reservoir when vacuum is applied to the reservoir.

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 temperature control apparatus for controlling the temperature of a plurality of cuvettes consisting of an annular sealed chamber containing a refrigerant, means fixed to the sealed chamber for receiving the sample cuvettes, a heater in thermal contact with the sealed chamber, and a temperature sensor in thermal contact with the sealed chamber. The sealed chamber may include a plurality of thermally conductive posts fixed to the chamber, the spacing between adjacent ones of the posts being adapted to receive the sample cuvettes.

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: 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: 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 liquid degasser includes a debubbler chamber connected in a line from a reservoir. Degassed liquid is fed from the chamber via a sensing electrode back to the reservoir. Fluid is drawn into the debubbler chamber at a first volume of flow rate, and gas is removed at a second, slower volume of rate. Degassed liquid is pumped from the base of the chamber through the sensing electrode and fed back to the reservoir. The gases from the debubbler chamber are returned directly to the reservoir.