“Do what you can, with what you have, where you are.”
As the seasons change, I’m reminded of this quote and its significance to the air, land and water that sustain us. As the weather gets warmer and winter transitions into spring, I love listening to the sound of birds chirping in the morning and watching new flowers blossom. I look forward to the coming weeks and months of picking strawberries, raspberries, cucumbers and a myriad of other fresh fruits and vegetables. There’s nothing like the feel of the warm sun and a gentle breeze as you pluck a fresh apple from a tree and bite into it.
It’s important to remember that there are a lot of components that contribute to the final produce we’re used to seeing in the grocery store. Fruits and vegetables grow on trees or vines, which need the right combination of soil, sun and water to successfully bear fruit. If pests or animals make a meal out of a growing plant, a field full of crops can quickly become useless as a food source. That’s where pesticides have been an agricultural asset.
Pesticide use goes back thousands of years, although early pesticides included salt or seawater, smoke (i.e. the smoke from burned crops/plants), or naturally-occurring, sulfur-based compounds. By the 1940s and 1950s, synthetic pesticides were starting to be developed and compounds that specifically targeted insects, disease and fungal pests were discovered. Organochlorine compounds were found to have activity across a broad spectrum of insects and diseases, so compounds such as dichlorodiphenyltrichloroethane (DDT), β-hexachlorocyclohexane (β-HCH) and Aldrin started being applied to farms and fields. The persistent nature of these compounds makes them great for long-term crop protection; however, it’s those same chemical properties that allow these compounds to accumulate in our environment – including our water sources.
Many of the pesticides that were used decades ago have now been banned, due to their known impact on the health of animals and humans. To ensure our continued safety, it’s important to be able to screen for pesticides in our food and water. The U.S. EPA has published several methods to outline the extraction and quantification of pesticides in water. Some of the methods cover a wide range of contaminants and include pesticide compounds – Methods 525.2, 525.3, 625.1, to name a few. Other methods are a bit more specific to pesticides. Method 549.2, for example, is specific to paraquat and diquat compounds (check out this blog post if you want to know more about those!), while Method 608.3 covers organochlorine pesticides. The extraction of pesticides can be challenging and processing samples by liquid-liquid extraction can result in poor accuracy and reproducibility. These challenges were taken into account for Method 608 and the latest revision (608.3) was published to formally allow the use of disk-based solid phase extraction (SPE) over liquid-liquid extraction (LLE). In addition to reducing solvent usage and streamlining the extraction process, SPE provides an opportunity to elute your target analytes directly into hexane. Want to see how? Check out this application note!