Herbicides play a critical role in controlling undesired weed growth and are widely used in agricultural applications including pasture lands and against invasive species. Composting has been advocated as means to not only recycle waste, but also to capture carbon, reduce emission of greenhouse gases, improve soil quality and structure, reduce soil erosion, reduce chemical inputs, reduce requirement for landfills, and create jobs. Currently, cut grass hay is one of the common sources of compost feedstock. Herbicides present in cut grass hay may not be completely removed in the composting process, resulting in the presence of trace level of residues in the finished composts. In order to detect low level of herbicide residues in compost, an innovative analytical method was developed using picloram as an example. The primary issue with compost as a matrix when analysing for picloram in particular and herbicides in general is the matrix interference. Matrix interference may prevent accurate quantitation of picloram in compost, especially at very low levels (low ppb). We will discuss the sample clean-up options that were evaluated, and share information on the linearity, accuracy, and precision of the final method. In brief, we were able to obtain a lower limit of quantitation (LOQ) of 1 ppb with a linearity range from 1 ppb to 100 ppb of picloram in compost.

Method development for analysis of picloram in compost

256th National Meeting (2018)

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