Analytical Services Tasmania (AST) has developed a method to detect certain pesticides at levels of only a few parts-per-trillion (ppt) and it is sharing the good news with the global science community.
The method uses a relatively new instrument at AST, the LC-MS/MS (liquid chromatograph tandem mass spectrometer). While it can easily detect pesticides in water at low levels (0.1 – 1 parts-per-billion, ppb) from the direct injection of samples, a method was developed in-house which lowered the detection limits to between 4–100 ppt, or about 10-25 times lower than previously.
The method uses a solid-phase to selectively remove the target pesticides from water samples. The pesticides are then collected and concentrated by an automated robot system requiring very little user input.
A research paper about the project was published recently in the international journal Analytical and Bioanalytical Chemistry (Vol 394, pp2257-2266) enabling other groups testing for similar suites of pesticides to easily adopt the automated sampler, saving time and resources.
Research Chemist in the Organic Section at the AST Dr Tim Jordan says the method was developed specifically for Tasmanian conditions, with the target pesticides being those commonly used in the state.
"The target pesticides vary widely in their chemical and physical properties which makes this type of method particularly difficult to develop," Tim says.
"A number of the pesticides are especially troublesome, and this is the first paper published in the scientific literature targeting a combination of these."
The method is awaiting NATA accreditation and will be adopted as soon as it has been accepted.
Future work planned for pesticide analysis at AST includes expanding the range of chemicals tested, and transferring other time-consuming methods to the automated sampler.