Apr 26 2005
It's ‘plastic please' when it comes to scientists' choice of pesticide-water sampling devices in field crops.
Wide acceptance has been building for the compact plastic disks over glass containers which are used to collect water samples and determine threatening levels of pesticide runoff.
Experts say the glass containers were prone to break during transit from field to the laboratory, and have allowed chemicals to degrade prior to being analyzed.
The disks are used extensively as part of water quality research involving atrazine with the Texas Agricultural Experiment Station and Texas Cooperative Extension. Atrazine is a herbicide used to control broadleaf and grassy weeds.
The plastic round disks, known as "Solid Phase Extraction Disks," fit in the palm of your hand and filter water and other chemical compounds. Although the disks have made transit of water samples easier, Dr. Scott Senseman and a group of fellow southern region scientists are trying to determine if air temperature impacts samples on the plastic disks during transit.
"We're trying to determine if variations in heat cause differences in chemical stability," said Senseman, an Experiment Station scientist who also heads the Texas A&M University Pesticide Fate Research Laboratory.
"We can send samples in the mail with trace amounts of pesticides, and the temperature could be substantially high anywhere during the trip," he said. "We already know that several compounds are stable when attached to these disks when refrigerated, but what we don't know is how stable they are at higher temperatures like 40 or 50 degrees Celcius ."
Research has proven that pesticides attached to the disks are stable when testing a variety of compounds used as common crop protection chemicals, Senseman said. And the disks are easier to handle than glass containers.
"Usually, in pesticide water monitoring, we have to go and collect samples in glass jars, put them in a cooler filled with ice and hope that the samples don't degrade from the time the sample was collected to the time it gets back to the lab for analysis," Senseman said.
Since the disks act as filters, they also have been an effective storage medium for pesticide samples than glass containers, Senseman noted.
"Most compounds monitored in our studies could be filtered through the disks and temporarily stored there until transported back to the laboratory for analysis. The disks are unbreakable and smaller, therefore, providing a potentially better transportation vehicle for chemical analytes."
Another benefit is some of the samples may take an hour or two to filter in the laboratory. The plastic disks can be used in the field to extract samples during transport from one collection site to the next, Senseman noted.
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