Abstract: An apparatus for correcting an initial measurement of the concentration of a first water soluble species dissolved in a water-based component of a biological fluid that also includes a second water soluble species and a volume occupying component, the initial measurement having been taken using an original sample of the fluid that had been diluted by an amount of additional aqueous solution to form a diluted sample is disclosed; the concentration of the second water soluble species is measured in an undiluted sample of the biological fluid to obtain a direct concentration and is measured using a diluted sample of the fluid to obtain an indirect concentration, and the initial measurement of concentration of the first species is adjusted based on a combination of the direct and indirect concentration determination of the second species.

Abstract: The occurrence of physical contact between a conductive probe and a surface of a liquid held in a container is detected as the probe is moved toward and eventually touches the liquid surface; a conductor is disposed on the other side of the container from the probe; an electrical signal is sent through the liquid between the conductive probe and the conductor, and the time when physical contact has occurred is determined based on when the resulting electrical signal which has passed through the liquid exceeds a threshold; and the threshold is determined based on the resulting electrical signal. In another aspect, the electrical signal is pulsed, and the resulting electrical signal is synchronously detected as the basis for determining when the physical contact has occurred.

Abstract: Correcting an initial measurement of the concentration of a first water soluble species dissolved in a water-based component of a biological fluid that also includes a second water soluble species and a volume occupying component, the initial measurement having been taken using an original sample of the fluid that had been diluted by an amount of additional aqueous solution to form a diluted sample is disclosed; the concentration of the second water soluble species is measured in an undiluted sample of the biological fluid to obtain a direct concentration and is measured using a diluted sample of the fluid to obtain an indirect concentration, and the initial measurement of concentration of the first species is adjusted based on a combination of the direct and indirect concentration determinations of the second species.

Abstract: Apparatus for removing fluid residue from an outer surface of a probe after it has been exposed to a fluid sample; the apparatus includes a wiper having a contact surface for wiping the residue from the outer surface of the probe, and a fluid flow path that cooperates with the contact surface for withdrawing wiped residue away from the contact surface and the probe; and a mechanism is provided for causing the contact surface to be swept along the outer surface of the probe. An apparatus for cleaning the outer surface of a probe after it is exposed to a fluid sample including a wiper for contacting the outer surface of the probe and a mechanism for causing relative motion between the wiper and the probe to wipe fluid from the outer surface.

Abstract: Apparatus for controlling the use of consumable accessory units with machines where a memory device associated with each accessory unit holds information concerning the accessory unit, and circuitry in the machine acts in response to the information.

Abstract: A two electrode assembly in a polarographic cell includes a sensor electrode and a silver/silver chloride reference electrode in which silver metal is in contact with a substantial reservoir of silver chloride.

Abstract: A clamping device for controlling liquid flow in a length of flexible tubing; the device includes a generally planar support having a keyhole, an annular flexible sleeve seated in the keyhole for receiving the tubing in an orientation generally perpendicular to the planar support, and a mechanism for moving the flexible sleeve between the larger side of the keyhole and the smaller side of the keyhole to cause pinching of the tubing to control liquid flow.

Abstract: An electrode for determining the lithium content of a liquid sample to be tested, has a membrane containing a lithium ion selective compound and a plasticizer, the improvement wherein the plasticizer is a liquid, lipophilic dialkyl phthalate compound or a liquid phenyl phenyl ether compound that has a strong electron withdrawing group at an ortho position on one of the phenyl rings. The ion selective compound has the formula: ##STR1## wherein A is an alkyl group having between 8 and 16 carbon atoms, B is an alkyl group having between 1 and 4 carbon atoms, and each C and D is, independently, a hydrogen atom or an alkyl group having between 1 and 16 carbon atoms, provided that both C and D are not alkyl groups having greater than 4 carbon atoms.

Abstract: An electrode assembly for polarographic assay of glucose in solution having a laminated membrane, the outer membrane being from 1 to 20 .mu.m thick and having a pore size of 10 to 125 .ANG., the inner membrane having a thickness of 2 to 4 .mu.m, and bonded to the outer membrane with immobilized glucose oxidase. Rapid assays are carried out by measuring the current difference before equilibrium is attained and at least 5 seconds after initial contact of sample with the outer membrane.

Abstract: A releasing reagent for releasing, as ionized calcium, protein-bound calcium in a biological sample for measurement of the ionized calcium, together with any ionized calcium originally present in the sample, using a calcium ion specific electrode, the releasing reagent including monochlorocoacetate salt, formate salt, and formic acid, in concentrations sufficient to render the pH of the sample, when mixed with the reagent, in the range of 4.0 to 5.5. Also disclosed is a method of measuring calcium in a liquid sample using such a releasing reagent.

Abstract: In an electrode for determining the potassium ion content of a liquid sample to be tested, the electrode including a membrane having incorporated therein an ion selective component, the improvement in which the ion specific component is a compound of the formula: ##STR1## wherein each R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, and R.sub.8 is hydrogen or an alkyl group containing between one and about 20 carbon atoms, p is 0 or 1, n is one or more, and, each s and r, independently, is 1, 2, or 3, provided that, when p is 1, n is 8 or more.

Abstract: An electrode assembly comprising an organic plastic sample flow-through tube, a portion of the wall of which comprises a membrane, the membrane comprising a matrix of an organic plastic material containing a non-volatile solvent-plasticizer and an ion exchange material dissolved in the solvent plasticizer, the membrane chemically bonded to and integral with said tube. The method of forming the membrane to the tube comprises dissolving the matrix material, the ion exchange material and the non-volatile solvent plasticizer in a volatile solvent, placing the resulting solution on a surface and evaporating the volatile solvent to form the membrane, contacting an edge of the tube to the membrane material, contacting the tube edge with said volatile solvent and allowing the solvent to evaporate.

Abstract: An electrode assembly comprising an organic plastic sample flow-through tube, a portion of the wall of which comprises a membrane, the membrane comprising a matrix of an organic plastic material containing a non-volatile solvent-plasticizer and an ion exchange material dissolved in the solvent plasticizer, the membrane chemically bonded to and integral with said tube. The method of forming the membrane to the tube comprises dissolving the matrix material, the ion exchange material and the non-volatile plasticizer in a volatile solvent, placing the resulting solution on a surface and evaporating the volatile solvent to form the membrane, contacting an edge of the tube to the membrane material, contacting the tube edge with said volatile solvent and allowing the solvent to evaporate.