WATER-SOLUBLE ORGANICS IN ATMOSPHERIC PARTICLES - A CRITICAL-REVIEW OF THE LITERATURE AND APPLICATION OF THERMODYNAMICS TO IDENTIFY CANDIDATE COMPOUNDS
P. Saxena et Lm. Hildemann, WATER-SOLUBLE ORGANICS IN ATMOSPHERIC PARTICLES - A CRITICAL-REVIEW OF THE LITERATURE AND APPLICATION OF THERMODYNAMICS TO IDENTIFY CANDIDATE COMPOUNDS, Journal of atmospheric chemistry, 24(1), 1996, pp. 57-109
Although organic compounds typically constitute a substantial fraction
of the fine particulate matter (PM) in the atmosphere, their molecula
r composition remains poorly characterized. This is largely because at
mospheric particles contain a myriad of diverse organic compounds, not
all of which extract in a single solvent or elute through a gas chrom
atograph; therefore, a substantial portion typically remains unanalyze
d. Most often the chemical analysis is pet-formed on a fraction that e
xtracts in organic solvents such as benzene, ether or hexane; conseque
ntly, information on the molecular composition of the water-soluble fr
action is particularly sparse and incomplete. This paper investigates
theoretically the characteristics of the water-soluble fraction by spl
icing together various strands of information from the literature. We
identify specific compounds that are likely to contribute to the water
-soluble fraction by juxtaposing observations regarding the extraction
characteristics and the molecular composition of atmospheric particul
ate organics with compound-specific solubility and condensibility for
a wide variety of organics. The results show that water-soluble organi
cs, which constitute a substantial fraction of the total organic mass,
include CZ to C7 multifunctional compounds (e.g., diacids, polyols, a
mino acids). The importance of diacids is already recognized; our resu
lts provide an impetus for new experiments to establish the atmospheri
c concentrations and sources of polyols, amino acids and other oxygena
ted multifunctional compounds.