The naturally derived cyanotoxin, cylindrospermopsin (CYN), has been detected in freshwater systems worldwide and poses a threat to human health. The methods for the extraction and detection of this toxin in source water are well documented, but methods for CYN determination in exposed individuals have not been investigated. In this study, the extraction and detection of CYN from two different matrices, serum and urine, was explored. Both serum and urine matrices inherently produce interference with analytical analyses and require extensive clean-up. Methods for extraction of CYN from both matrices were developed and validated using fortified samples. Serum extraction included homogenization followed by protein precipitation and solid phase extraction (SPE). Urine samples were processed using filtration, pH manipulation, and SPE. Analyses using a commercially available enzyme-linked immunosorbent assay (ELISA) and liquid chromatography coupled with mass spectrometry (LC/MS/MS) were assessed. Matrix effects inhibited ELISA's use as a quantitative tool for both matrices. LC/MS/MS was determined to be the most effective and reproducible means to detect and quantify CYN. The method detection limits determined in this study using LC/MS/MS were 0.25 and 0.50 ng mL⁻¹ for serum and urine, respectively. This method can be used to test individuals exposed to blooms of cyanobacteria producing CYN.
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