# US 2009/0260984 A1 · Ultra-Sensitive Simultaneous Electrochemical Determination of Arsenic, Mercury and Copper

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- Number: US 2009/0260984 A1
- Document ID: US20090260984A1
- Status: Published application
- Kind: A1
- Application number: 12/427,327
- Filed: 2009-04-21
- Published: 2009-10-22
- Earliest claimed: 2008-04-22
- Assignees: Indian Institute of Technology
- Inventors: C. Retna Raj; Bikash Kumar Jena
- Web page: https://patentgrep.com/patent/US20090260984A1

## CPC

- G01N 33/1813: {Specific cations in water, e.g. heavy metals}
- 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 sensor for the simultaneous detection of inorganic contaminants, As (III), Hg (II) and Cu (II) in water and having a limit of detection of 0.02 ppb, comprising a conducting support having a layer comprised of a three dimensional silicate network comprised of thiol tail groups immobilized with citrate stabilized gold nanoparticles, wherein the gold nanoparticles have a size in the range of 70 to 100 nm.

## Claims

### Claim at position 1

1-15. (canceled)

### Claim 16

A sensor for the simultaneous detection of inorganic contaminants, As (III), Hg (II) and Cu (II) in water, comprising:
a conducting support having a layer comprised of a three dimensional silicate network comprised of thiol tail groups immobilized with citrate stabilized gold nanoparticles, wherein the gold nanoparticles have a size in the range of 70 to 100 nm, and wherein the sensor has a limit of detection of 0.02 ppb.

### Claim 17 (depends on 16)

The sensor as claimed in claim 16, wherein the conducting support is an electrode having a surface comprising polycrystalline gold, coinage metal, platinum or palladium metal.

### Claim 18 (depends on 16)

The sensor as claimed in claim 16, wherein the silicate network is a three dimensional silicate derived from (3-mercaptopropyl)trimethoxysilane MPTS).

### Claim 19

A process for manufacturing a sensor for the simultaneous detection of inorganic contaminants of water comprising:
providing a conducting support;
adding a (3-mercaptopropyl)trimethoxysilane (MPTS) sol thereto;
forming a silicate network modified support from the MPTS;
preparing a mixture containing citrate stabilized gold nanoparticulates;
soaking the silicate network modified support in the mixture containing citrate stabilized gold nanoparticulates to immobilize the gold nanoparticulates on the silicate network modified support;
preparing a solution of hydroxylamine and chloroauric acid;
shaking the solution of hydroxylamine and chloroauric acid; and
placing the conducting support inside the solution of hydroxylamine and chloroauric acid, to obtain the sensor.

### Claim 20 (depends on 19)

The process as claimed in claim 19, wherein the conducting support is an electrode having a surface comprising polycrystalline gold, coinage metal, platinum or palladium.

### Claim 21 (depends on 19)

The process as claimed in claim 19, wherein the MPTS sol is prepared by dissolving MPTS, methanol and dilute hydrochloric acid into a mixture and stirring the mixture.

### Claim 22 (depends on 21)

The process as claimed in claim 21, wherein the MPTS, methanol and hydrochloric acid are present in a molar ratio of 1:3:3 to 2:10:10.

### Claim 23 (depends on 21)

The process as claimed in claim 21, wherein a 0.1 M hydrochloric acid is used.

### Claim 24 (depends on 21)

The process as claimed in claim 21, wherein the mixture is stirred for about 10 to 30 minutes.

### Claim 25 (depends on 19)

The process as claimed in claim 19, wherein the citrate stabilized gold nanoparticles are prepared by mixing trisodium citrate in 1-2% (weight/volume); HAuCl4 in 1 to 2% (weight/volume); and sodium borohydride in 0.08 to 0.1% (weight/volume), at room temperature and normal pressure.

### Claim 26 (depends on 19)

The process as claimed in claim 19, wherein the silicate network modified support is soaked in the mixture containing citrate stabilized gold nanoparticles for 12 to 18 hours at room temperature and normal pressure.

### Claim 27 (depends on 19)

The process as claimed in claim 19, wherein 0.01-5 mM of hydroxylamine hydrochloride is used.

### Claim 28 (depends on 19)

The process as claimed in claim 19, wherein 0.01 to 1 mM of chloroauric acid (HAuCl4) is used.

### Claim 29 (depends on 19)

The process as claimed in claim 19, wherein shaking the solution of hydroxylamine hydrochloride and HAuCl4 occurs at 200 to 500 rpm.