Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Fixing by Filtration

Abstract:
New testing strips for detecting heavy metals

Fixing by Filtration

Posted on January 03, 2006

Many heavy meals are toxic to the environment or to humans. Legal limits for these pollutants in drinking water and run-off are thus correspondingly low. Rapid on-the-spot analysis and routine water quality tests demand a rapid, cost-effective method that doesn’t require complex instruments. Test strips that indicate the presence and concentration of a heavy metal when simply dipped into the water are ideal. Commercially available strips are currently not sufficiently reliable or sensitive. Japanese researchers have now developed a new generation of test strips that meet these high demands. Their secret is pigment nanocrystals that are fixed to a membrane filter by means of simple filtration.

One of the main problems of current testing strips for heavy metals is that the reagents can be washed out, which significantly reduces their effectiveness. A truly satisfactory process for the fixation of pigments was previously unknown. A research team headed by Toshishige M. Suzuki has now discovered a very simple method for fixing the heavy-metal-specific color reagents to the test strips so that they can neither be washed away by the test solution nor rubbed off. They were thus able to produce testing strips that react specifically to divalent zinc, mercury, and iron.

The color reagent must first be formed into nanoscopic particles. The pigment is thus dissolved in an organic solvent and then sprayed into vigorously stirred water. Because the pigment is not water-soluble, it crystallizes out, and under these conditions it crystallizes in the form of nanocrystals that are finely dispersed in the solution. When filtered through a cellulose membrane, 99.5 % of the nanoparticles stick to the membrane surface in a fine, dense, even layer. This precise control of the amount of pigment applied is an important requirement for testing strips that give reproducible results. The continuous layer of the color reagent makes the strips highly sensitive, allowing the detection of zinc ions at concentrations as low as 65 ppb (parts per billion). Lower detection limits can be achieved by the filtration of larger amounts of the test solution through the reagent-coated membrane.

This new method for the production of testing strips can be used for many water-insoluble color reagents, allowing for the development of a large family of metal-specific testing strips.

####


Author: Toshishige M. Suzuki, AIST Tohoku (Japan), unit.aist.go.jp/lmc/english/staff/staff_01.htm

Title: Test Strips for Heavy-Metal Ions Fabricated from Nanosized Dye Compounds

Angewandte Chemie International Edition, doi: 10.1002/anie.200503015

Contact:
Editorial office:
angewandte@wiley-vch.de

or David Greenberg (US)
dgreenbe@wiley.com

or Julia Lampam (UK)
jlampam@wiley.co.uk

Copyright © Angewandte Chemie

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Materials/Metamaterials

Sustainable nanotechnology center September 1st, 2015

Using ultrathin sheets to discover new class of wrapped shapes: UMass Amherst materials researchers describe a new regime of wrapped shapes August 31st, 2015

An engineered surface unsticks sticky water droplets August 31st, 2015

New material science research may advance tech tools August 31st, 2015

Announcements

Making nanowires from protein and DNA September 3rd, 2015

Making fuel from light: Argonne research sheds light on photosynthesis and creation of solar fuel September 3rd, 2015

Reversible Writing with Light: Self-assembling nanoparticles take their cues from their surroundings September 3rd, 2015

A marine creature's magic trick explained: Crystal structures on the sea sapphire's back appear differently depending on the angle of reflection September 2nd, 2015

Water

Reversible Writing with Light: Self-assembling nanoparticles take their cues from their surroundings September 3rd, 2015

An engineered surface unsticks sticky water droplets August 31st, 2015

Southampton scientists find new way to detect ortho-para conversion in water August 25th, 2015

Iranian Scientists Utilize Nanomembranes to Purify Wastewater of Olive Oil Plants August 20th, 2015

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic