Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

How a tetrahedral substance can be more symmetrical than a spherical atom: A new type of symmetry September 14th, 2018

Peering into private life of atomic clusters -- using the world's tiniest test tubes September 6th, 2018

Cannibalistic materials feed on themselves to grow new nanostructures September 1st, 2018

Environmentally friendly photoluminescent nanoparticles for more vivid display colors: Osaka University-led researchers created a new type of light-emitting nanoparticle that is made of ternary non-toxic semiconductors to help create displays and LED lighting with better colors t August 29th, 2018

Announcements

Nanobiotix: Update on Head and Neck Phase I/II Trial with NBTXR3 and Other program data presented at ImmunoRad 2018 September 20th, 2018

NUS researchers invent new test kit for quick, accurate and low-cost screening of diseases: Test results are denoted by a color change and could be further analyzed by a smartphone app, making it attractive as a point-of-care diagnostic device September 19th, 2018

Silver nanoparticles are toxic for aquatic organisms: A research team at the UPV/EHU-University of the Basque Country has analysed how zebrafish are affected in the long term by exposure to silver particles September 19th, 2018

Leti Announces EU Project to Develop Powerful, Inexpensive Sensors with Photonic Integrated Circuits: REDFINCH Members Initially Targeting Applications for Gas Detection and Analysis For Refineries & Petrochemical Industry and Protein Analysis for Dairy Industry September 19th, 2018

Water

Silver nanoparticles are toxic for aquatic organisms: A research team at the UPV/EHU-University of the Basque Country has analysed how zebrafish are affected in the long term by exposure to silver particles September 19th, 2018

Halas wins American Chemical Society Award in Colloid Chemistry: Rice University nanophotonics pioneer honored for colloid research September 18th, 2018

S, N co-doped carbon nanotube-encapsulated CoS2@Co: Efficient and stable catalysts for water splitting September 10th, 2018

Producing hydrogen from splitting water without splitting hairs: New model explains interactions between small copper clusters used as low-cost catalysts in the production of hydrogen by breaking down water molecules August 31st, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project