Constructed wetlands play a large role in the filtration of stormwater, contributing to reductions in nutrients and trace metals in the water body. Aquatic macrophytes have long been associated with this filtration process. However, a lack of consistent laboratory methods for the extraction of these chemicals from macrophytes has led to variable results and ongoing gaps in scientific knowledge. For some urban constructed wetlands, as in our study from Adelaide, South Australia, the outflow is pumped into the below ground aquifer and used for irrigation purposes by local councils for public amenities. In these cases, it is essential to accurately determine the efficiency of macrophytes at stormwater filtration. Before removal performance of nutrients and trace metals by aquatic macrophytes can be established it is imperative that standard, efficient protocols for isolating these chemicals be developed. The sedge species Schoenoplectus validus in the Cyperaceae family is commonly used for water filtration in constructed wetlands, yet currently there are no precise standard protocols for isolating nutrients and trace metals. In this study we tested multiple standards, including sorghum flour (Sorghum bicolor, Poaceae), corn meal (Zea mays, Poaceae) and tigernut flakes (Cyperus esculentus, Cyperaceae), to formulate a precise protocol suitable for isolating chemicals in S. Validus and other species of sedges. When compared to standards, our proposed nitrogen isolation protocol was 66% efficient for S. bicolor, 71% efficient for Z. mays, and 72% efficient for C. esculentus. This method will be further advanced to include trace metal isolation. The methodology formulated can be used to determine the nutrient and contaminant load in sedges from other constructed wetlands in future monitoring regimes.