An important atmospheric finding is the presence of an organosulfate that is related to methyl vinyl ketone, a major gas-phase oxidation product of isoprene.

Furthermore, several nitroxy-organosulfates originating from monoterpenes were found in the ambient samples.

Conclusions: A more complete structural characterization of polar organosulfates that originate from isoprene secondary organic aerosol was achieved.

These nitroxy-organosulfates were only detected in the nighttime samples, suggesting a role for nighttime chemistry in their formation.

One of the detected organosulfates also occurred in ambient aerosol samples that were collected at a forest site in northeastern Bavaria, Germany.

Rationale: A considerable fraction of atmospheric particulate fine matter consists of organosulfates, with some of the most polar ones originating from the oxidation of isoprene.