Figure 1.

Example NMR spectra of pollen extracts A) Birch, Betula pendula, representative of tree pollen extracts with the exception of B) Cypress, Cupresus arizonica representative of the Cupressaceae family of trees. C) Ragweed, Ambrosia artemisifolia similar to other weeds, and D) Timothy grass, Pheleum pretense, typical of other grasses. Isolated peaks of important compounds discussed in the text are annotated. DSS was added to all samples for standardization.