# US 8,784,748 B2 · Dry test strip for measuring calcium

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- Number: US 8,784,748 B2
- Document ID: US8784748B2
- Status: Granted
- Kind: B2
- Application number: 13/457,291
- Filed: 2012-04-26
- Published: 2012-11-01
- Granted: 2014-07-22
- Earliest claimed: 2011-04-28
- Assignees: ARKRAY, Inc.
- Applicants: Tsutomu Nakamura
- Inventors: Tsutomu Nakamura
- Web page: https://patentgrep.com/patent/US8784748B2

## CPC

- G01N 33/526: {the element being adapted for a specific analyte}
- G01N 33/523: {the element being adapted for a specific analyte}
- G01N 33/84: involving inorganic compounds or pH
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A dry test strip for measuring calcium is comprising a support, a reagent layer provided on the support, and a reagent holding layer provided on the reagent layer, and containing, as reagents, o-cresolphthalene complexone, a magnesium selective masking agent, and a pH buffer for adjusting the pH of the environment for reaction of the o-cresolphthalene complexone with calcium to 10.0-11.0, wherein such reagents are present in either the reagent layer or the reagent holding layer or the both layers.

## Claims

### Claim 1

A dry test strip for measuring calcium which is comprising:
o-cresolphthalene complexone,
a magnesium selective masking agent, and
a pH buffer for adjusting the pH of the environment for reaction of the o-cresolphthalene complexone with calcium to 10.0-11.0,
wherein the pH buffer is at least one selected from the group consisting of N-methyl-D-glucamine alone and N-methyl-D-glucamine in combination with N-cyclohexyl-3-aminopropanesulfonic acid.

### Claim 2 (depends on 1)

The dry test strip for measuring calcium according to claim 1, wherein the pH buffer is a 9:1 mixture of N-cyclohexyl-3-aminopropanesulfonic acid and N-methyl-D-glucamine.

### Claim 3 (depends on 1)

The dry test strip for measuring calcium according to claim 1, wherein the magnesium selective masking agent is 8-hydroxyquinoline.

### Claim 4 (depends on 2)

The dry test strip for measuring calcium according to claim 2, wherein the magnesium selective masking agent is 8-hydroxyquinoline.

### Claim 5 (depends on 1)

The dry test strip for measuring calcium according to claim 1, said dry test strip further comprising a surfactant.

### Claim 6 (depends on 2)

The dry test strip for measuring calcium according to claim 2, said dry test strip further comprising a surfactant.

### Claim 7 (depends on 3)

The dry test strip for measuring calcium according to claim 3, said dry test strip further comprising a surfactant.

### Claim 8 (depends on 5)

The dry test strip for measuring calcium according to claim 5, wherein the surfactant is p-t-octyl phenol polyoxyethylene.

### Claim 9 (depends on 6)

The dry test strip for measuring calcium according to claim 6, wherein the surfactant is p-t-octyl phenol polyoxyethylene.

### Claim 10 (depends on 7)

The dry test strip for measuring calcium according to claim 7, wherein the surfactant is p-t-octyl phenol polyoxyethylene.

### Claim 11 (depends on 1)

The dry test strip for measuring calcium according to claim 1 further comprising:
a support,
a reagent layer provided on the support, and
a reagent holding layer provided on the reagent layer,
wherein the o-cresolphthalene complexone and the magnesium selective masking agent are contained in the reagent layer, and the pH buffer is contained in the reagent holding layer.

### Claim 12 (depends on 2)

The dry test strip for measuring calcium according to claim 2 further comprising:
a support,
a reagent layer provided on the support, and
a reagent holding layer provided on the reagent layer,
wherein the o-cresolphthalene complexone and the magnesium selective masking agent are contained in the reagent layer, and the pH buffer is contained in the reagent holding layer.

### Claim 13 (depends on 3)

The dry test strip for measuring calcium according to claim 3 further comprising:
a support,
a reagent layer provided on the support, and
a reagent holding layer provided on the reagent layer,
wherein the o-cresolphthalene complexone and the magnesium selective masking agent are contained in the reagent layer, and the pH buffer is contained in the reagent holding layer.

### Claim 14 (depends on 5)

The dry test strip for measuring calcium according to claim 5 further comprising:
a support,
a reagent layer provided on the support, and
a reagent holding layer provided on the reagent layer,
wherein the o-cresolphthalene complexone and the magnesium selective masking agent are contained in the reagent layer, and the pH buffer is contained in the reagent holding layer.

### Claim 15 (depends on 8)

The dry test strip for measuring calcium according to claim 8 further comprising:
a support,
a reagent layer provided on the support, and
a reagent holding layer provided on the reagent layer,
wherein the o-cresolphthalene complexone and the magnesium selective masking agent are contained in the reagent layer, and the pH buffer is contained in the reagent holding layer.