Briefly, liquid and solid fractions were separated via centrifugation. Solids were extracted with acetonitrile, and equal amounts of the liquid fraction and acetonitrile extract were combined and filtered (method and materials details and recovery information available in sections S.1.1, S.1.2, and S.2.1). This type of method leads to complex sample matrix that requires high analytical sensitivity and selectivity, which are provided by the chosen instrumentation.