Nitrooxy organosulfates derived from
terpenes (NOSTP) represent an important class of products
formed between anthropogenic
pollution (e.g., SO2 and NOx) and natural emissions. NOSTP compounds have been consistently
detected in atmospheric environments under varying urban influences.
Their chemical linkages to both anthroposphere and biosphere make
them valuable markers for tracking anthroposphere–biosphere
interactions. However, their quantification, formation, and transformation
kinetics in atmospheric aerosols are hindered due to the lack of NOSTP standards. In this work, we developed two routes for the
first concise chemical synthesis of eight NOSTP from terpenes
including α-pinene, β-pinene, limonene, limonaketone,
and β-caryophyllene. Subsequently, six of the synthesized NOSTP were for the first time positively identified in ambient
aerosol samples, clarifying certain misidentifications in previous
studies. More significantly, the availability of authentic standards
allows irrefutable observation of three carbon skeleton-rearranged
NOSTP, two derived from α-pinene, and one derived
from β-caryophyllene, revealing the occurrence of previously
unrecognized transformation pathways in the formation of NOSTP. Two synthesized NOSTP from β-pinene and limonene
could not be detected, likely due to rapid hydrolysis of their immediate
hydroxynitrate precursors outcompeting sulfation. Such mechanistic
evidence is valuable in understanding the atmospheric chemistry of
NOSTP and related compounds. This work demonstrates the
usefulness of authentic standards in probing the NOSTP formation
mechanisms in the atmosphere. Comparison of NOSTP ambient
samples collected from four Chinese cities in two winter months indicates
that anthropogenic chemical factors could outcompete terpene emissions
in the formation of NOSTP.