Beckman Instruments, Inc.

Beckman Coulter, Inc.

Chandra P Jain

Frank R Shu

Xihai Mu

A lithium ion-selective membrane that favors the bonding of lithium and depresses sodium interference is invented by a charge balance approach. A lithium ion-selective electrode (Li-ISE) having the membrane of this invention demonstrates a fast kinetic response, good precision and reproducibility, high sensitivity and the ability to retain the sensitivity after a long-term contact with biological samples. The sensor shows Nernst linearity with a slope of 55.4 mV for lithium ion concentrations between 0.5 &mgr;mol/L and 10 mmol/L. The membrane includes at least about 2% by weight of 6,6-dibenzyl-1,4,8,11 tetraoxacyclotetradecane ionophore; from about 0.025% to about 1% by weight of potassium tetrakis(4-chlorophenyl)borate additive; a plasticizer; and a polymeric material.

Lithium ion-selective electrode for clinical applications

An improved reagent combination of the type comprising a first solution comprising an aryl amine and an acid; and a second solution comprising a nitrite compound. The regent combination is characterized in that is further comprises a salt, wherein the salt is present in any preselected distribution in the solutions. Also, an improved method for colorimetrically determining bilirubin in a sample comprising mixing an aliquot of the above first solution with an aliquot of the above second solution to form a stable diazo reagent; contacting a sample to be assayed with a total bilirubin accelerator buffer system to form a prereaction medium; contacting the prereaction medium with the stable diazo reagent; and measuring the color of the azobilirubin formed form the coupling reaction of the stable diazo reagent with the bilirubin present in said sample. In addition, an improved method for producing a diazo reagent of the type comprising reacting an aryl amine with a nitrite compound in the presence of an acid. The method is characterized in that the reaction also takes place in the presence of a salt.

Method and stable diazo reagent for detecting bilirubin

An albumin reagent of the type comprising bromcresol green, a buffering agent having a buffering capacity in the pH range of about 4 to about 4.2, and polyoxyethylene(23) lauryl ether. The albumin reagent is characterized in that it contains from about 0.18 to about 0.22 gm/l bromcresol green and has a polyoxyethylene(23) lauryl ether:bromcresol green weight ratio of from about 10:1 to about 12:1.

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Placentia, CA, United States of America

Chandra P Jain