# US 9,435,745 B2 · Measuring the rate of release of metal ions

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- Number: US 9,435,745 B2
- Document ID: US9435745B2
- Status: Granted
- Kind: B2
- Application number: 14/580,510
- Filed: 2014-12-23
- Published: 2016-06-23
- Granted: 2016-09-06
- Earliest claimed: 2014-12-23
- Assignees: Colgate-Palmolive Company
- Applicants: Colgate-Palmolive Company
- Inventors: Stanislav Jaracz; Ravi Subramanyam; Michael Prencipe
- Web page: https://patentgrep.com/patent/US9435745B2

## CPC

- G01N 21/78: producing a change of colour
- A61K 8/466: {containing sulfonic acid derivatives; Salts}
- A61Q 11/00: Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
- G01N 21/77: by observing the effect on a chemical indicator
- G01N 21/79: Photometric titration
- A61K 2800/45: Colour indicators, e.g. pH- or Redox indicators
- 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)
- A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D)
- A61Q: SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS

## Abstract

A method of measuring the relative rates of release of a target metal ion from two or more samples includes: (i) providing at least two aliquots of a solution including an indicator, the indicator having a color; (ii) dispersing a sample into each aliquot; and (iii) during step (ii), monitoring the color of the indicator in situ to determine the rates of release of the target metal ions from the samples relative to one another. Each sample includes at least one source of the target metal ion. The indicator contains zincon. The samples are oral care compositions selected from a toothpaste, a tooth gel, and a tooth powder. The target metal ion is selected from the stannous and zinc (II).

## Claims

### Claim 1

A method of measuring the relative rates of release of a target metal ion from two or more samples, each sample comprising at least one source of the target metal ion, which method comprises:
(i) providing at least two aliquots of a solution including an indicator, the indicator having a colour;
(ii) dispersing each sample into one of the aliquots; and
(iii) during step (ii), monitoring the colour of the indicator in situ to determine the rates of release of the target metal ion from the samples relative to one another;
wherein the indicator comprises zincon;
wherein each sample is an oral care composition selected from a toothpaste, a tooth gel, and a tooth powder; and
wherein the target metal ion is selected from stannous or stannous and zinc (II) in combination.

### Claim 2 (depends on 1)

The method of claim 1, wherein the solution has a pH in the range of 7 to 10.

### Claim 3 (depends on 2)

The method of claim 2, wherein the solution has a pH in the range 9 to 9.5.

### Claim 4 (depends on 1)

The method of claim 1, wherein the solution comprises a buffer.

### Claim 5 (depends on 1)

The method of claim 1, wherein the zincon is present in the solution in an amount in the range 10 to 100 ppm.

### Claim 6 (depends on 1)

The method of claim 1, wherein the temperature of the solution is in the range 21 ° C. to 27 ° C.

### Claim 7 (depends on 1)

The method of claim 1, wherein step (iii) comprises recording a video of the aliquots.

### Claim 8 (depends on 1)

The method of claim 1, wherein each sample further comprises a source of zinc ions.

### Claim 9 (depends on 1)

The method of claim 1, wherein step (ii) comprises agitating the aliquots in the presence of oxygen, the agitation being intermittent so as to allow oxidation of stannous ions to be detected using the indicator.

### Claim 10 (depends on 1)

The method of claim 1, wherein the target metal ion is zinc (II), wherein each sample further comprises a source of stannous ions, and wherein the solution includes an oxidizing agent for oxidizing the stannous ions to stannic ions.