Results and Discussion
Analysis of SVOC Collected by a SIF. Since VOC has a great
potential to break through the denuder, the OC captured on
backup SIFs presumably contains the SVOC that evaporates
off the particles and possibly the VOC that breaks through
the denuder (15, 26). Such VOC should be differentiated from
SVOC during the analysis of total SVOC on the SIFs.
It should be pointed out that there is no specific definition
for semivolatile organics. They are often defined as compounds
captured by backup media such as a polyurethane
foam (PUF) placed downstream of a filter during conventional
FP sampling. England et al. defined the semivolatile volatile
organics to be those with vapor pressure between 10-1 and
10-7 mmHg (10-10-5 Pa) at 25 °C (27). Cui et al. postulate
that compounds with vapor pressure less than 3800 Pa at 25
°C should be considered semivolatile (8). These definitions
are inconsistent. In fact, the gas-particle partitioning of
organics depends not only on vapor pressure, which is
strongly influenced by the temperature, but also on the
physical characteristics of both the compound and the
particles (e.g., surface area, other organics associated with
the particles).