Keeping Vegetables Safe for Salad Lovers

Summer or winter, spring or fall, salads are often the meal of choice for health-conscious eaters. To feed this demand, growers of lettuce, tomatoes and other popular vegetables often rely on pesticides to increase the yield of their crops. Unfortunately, these chemicals have the potential to harm humans and the environment.

To address the possible risks, many health agencies around the world have enacted regulations that affect the use of certain pesticides and limit the maximum residue level (MRL) permitted in salad vegetables. As part of these laws, authorizations for hundreds of existing pesticides have been withdrawn and hundreds more will follow between now and 2008. These older formulations are being replaced by new families of compounds such as polar and thermally unstable pesticides.

Facing new compounds and tougher environmental standards, many regulatory monitoring labs are looking for new analytical methods that offer superior identification and quantification of pesticides. One promising alternative combines liquid chromatography (LC) with time-of-flight mass spectrometry (TOF-MS).

Evaluating a new analysis alternative

To explore the feasibility of using LC/TOF-MS for pesticide analysis, Agilent worked with members of the Pesticide Residue Research Group at the University of Almeria in Spain. An initial study focused on three commonly used chloronicotinyl insecticides and measured their presence in tomatoes, peppers, lettuce and cucumbers.

The team's methods and results are presented in the Agilent application note "Determination of Chloronicotinyl Insecticides in Salad Vegetables by LC/MSD TOF and LC/MSD Trap." Measurements were made using an Agilent 1100 series LC and the Agilent LC/MSD TOF system, which delivers outstanding sensitivity, linearity and reproducibility. The TOF capability also provides excellent resolution and wide dynamic range.

In the study, the detected levels of chloronicotinyl pesticides in vegetable samples were equal to or better than the MRLs specified in European Directive 91/414/EEC. The LC/TOF-MS approach also enabled detection of trace residues: pesticide quantitation spanned two orders of magnitude with mass accuracy of less than 3 ppm (and typically better than 2 ppm). The authors conclude that LC/TOF-MS is both a powerful tool for the identification of pesticides in vegetables and a new tool for environmental food chemistry.

For consumers, this method can help provide assurance that the salads they eat are truly safe and healthy—whatever the season.

For more information

To learn more about related applications, please see the Foods & Flavors page. For additional information about these and other Agilent chemical analysis products and resources, please visit the Life Sciences/Chemical Analysis main page.