Dipstick Offers Smarter Detection of Pesticides in Foods
R. Colin Johnson | Date: 11-10-09 | Comments: 0
- A litmus-like paper "dipstick" simple enough for anyone to use changes colors if there is the presence of pesticides.
Consumers could soon be able
to test their own foods for the presence of pesticides with a simple
litmus-like paper "dipstick" that you merely dip into the food and
watch for a distinctive color change in less than 5 minutes.
Detecting pesticides in foods
today is a complicated process involving sophisticated test equipment that can
take hours to detect and measure the amount of contamination. Now a new paper
test strip method has been developed that permits consumers to test their own
foods for contamination by common pesticides, according to professor John
Brennan, who developed the new
test method with colleagues in the Department of Chemistry and
Chemical Biology at McMaster University (Hamilton, Ontario).
Consumers today must depend
upon testing labs to detect and measure how much contamination with pesticides
is contained in foods. Unfortunately, these tests can take hours to perform, and
even then there is no standardized method of presenting the results to
consumers. Some conscientious food store franchises take it upon themselves to
perform such tests and post "no detectable pesticides" on produce,
but today consumers are usually forced to choose more expensive
"organic" varieties of foods to avoid ingesting pesticides.
Particularly in developing
countries where the availability of organic foods is rare, and their expense
prohibitive, an inexpensive procedure is needed to enable consumers to test
their own foods for contamination by common pesticides. A recently
demonstration of the effectiveness of the new paper dipstick method showed how
they can be directly exposed to suspect foods, then read for level of
contamination by how much color change is observed.
In a recent test on
intentionally contaminated milk and apple juice samples, white paper dipsticks
were fabricated and impregnated with the chemicals that change color when
exposed to pesticides containing organophosphates. In the tests, the paper
dipsticks were able to detect the presence and display the amount of
contamination in the beverages. The tests took less that 5 minutes to perform,
but nevertheless displayed results that were consistent with laboratory testing
procedures that required hours to perform on expensive test equipment.
The scientists claim that
their new reagent-less bioactive paper-based solid-phase biosensor testing
method will be particularly appreciated in developing countries where the
quick, simple testing procedure by non-skilled personnel can substitute for a
lack of availability of expensive testing equipment and in some cases even the
electricity to run a lab. The dipstick testing method also displays its results
in an easy-to-read color-change format that can be interpreted by anyone,
regardless of their language skills. In addition, the low cost of the paper
dipsticks, which are prepared by inkjet printing of biocompatible sol-gel
derived silica layers onto paper, should make the method easy to widely
distribute, as well as eco-friendly and non-toxic.
