Calcium assay
AssigneeSherwood Medical Industries Inc.
InventorsLouis M. Mezei, Laurence N. Jacobs, Samuel C. Berry
Life of this patent
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Abstract
The stability of a reagent comprising an aqueous solution of a phenolsulphonephthalein dye is enhanced by the presence of a weak acid in the reagent.
Claims25
In a reagent comprising an aqueous solution of a dye which comprises a phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, the improvement wherein said reagent includes a stabilizing amount of a weak acid.
In a reagent for determination and demonstration of calcium in a liquid sample, said reagent comprising an aqueous solution of methylthymol blue dye and an amount of 8-hydroxyquinoline sufficient to sequester magnesium present in said sample, the improvement wherein said reagent further includes a weak acid in an amount sufficient to maintain said 8-hydroxyquinoline in solution and to stabilize said methylthymol blue dye, said reagent being substantially free of strong acids.
A method of stabilizing an aqueous solution of a dye which comprises phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, said method comprising the step of including a dye-stabilizing amount of a weak acid in said dye solution.
A method of stabilizing an aqueous solution of methylthymol blue dye and 8-hydroxyquinoline, said method comprising the step of including in said solution an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and to stabilize said methylthymol blue dye, said solution being substantially free of strong acids.
A reagent comprising an aqueous solution of:
- (a) a dye comprising phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof;
- and
- (b) a dye-stabilizing amount of a weak acid.
A reagent comprising an aqueous solution of methylthymol blue dye, 8-hydroxyquinoline, and an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and stabilize said methylthymol blue dye, said solution being substantially free of strong acids.
A method of determining calcium in a liquid sample, said method comprising the steps of:
- (a) mixing said sample with a reagent comprising an aqueous solution of a phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, and a dye stabilizing amount of a weak acid, to form a reaction mixture;
- (b) observing the color change of said reaction mixture;
- and
- (c) comparing said color change to calibration means.
A method of determining calcium in a liquid sample, said method comprising the steps of:
- (a) mixing said sample with a reagent comprising an aqueous solution of methylthymol blue dye, 8-hydroxyquinoline, and an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and stabilize said methylthymol blue dye to form a reaction mixture, said solution being substantially free of strong acids;
- (b) observing the color change of said reaction mixture;
- and,
- (c) comparing said color change to calibration means.
Dependencies are inferred from the claim text.