Atmospheric Nanoparticles - Environmental and Human Health Impacts of Nanotechnology - page 185

Table 5.2 Instruments and techniques for monitoring nano-aerosol number, surface area
and mass concentrations (adapted from Mark, 2007).

Metric Devices Remarks

Number
directly

CPC CPCs provide real-time number concentration

measurements between their particle diameter
detection limits. Without a nanoparticle pre-
separator, they are not specifi c to the nanometre
size range. P-Trak has diffusion screen to limit
top size to 1 m.

Real-time size-selective (mobility diameter)
detection of number concentration, giving
number-based size distribution. Can select any
upper cut point size.
Off-line analysis of electron microscope samples
can provide information on size-specifi c aerosol
number concentration.
The UFP consists of a Corona charger, a DMA and
an electrometer. It provides real-time number
concentrations within six size classes 20-30,
30-50, 50-70, 70-100, 100-200,

µ

SMPS

Electron
microscopy

UFP 330

200 nm.
Real-time size-selective (aerodynamic diameter)
detection of active surface area concentration,
giving aerosol size distribution. Data may be
interpreted in terms of number concentration.
Size-selected samples may be further analysed
off-line.

>

Number by
calculation

ELPI

Surface area
directly

Diffusion charger Real-time measurement of aerosol active surface

area. Active surface area does not scale directly
with geometric surface area above 100 nm. Note
that not all commercially available diffusion
chargers have a response that scales with particle
active surface area below 100 nm. Diffusion
chargers are only specifi c to nanoparticles if used
with an appropriate inlet pre-separator.
Real-time measurements of active surface area. Not
specifi c to nanoparticles without an inlet
pre-separator.
Off-line analysis of electron microscope samples
can provide information on particle surface area
with respect to size. TEM analysis provides direct
information on the projected area of collected
particles, which may be related to geometric area
for some particle shapes.

Epiphaniometer

Surface area by
calculation

Electron
microscopy

SMPS Real-time size-selective (mobility diameter)

detection of number concentration. Data may be
interpreted in terms of aerosol surface area under
certain circumstances. For instance, the mobility
diameter of open agglomerates has been shown
to correlate well with projected surface area.

SMPS and ELPI
used in parallel

Differences in measured aerodynamic and mobility
can be used to infer particle fractal dimension,
which can be further used to estimate surface
area.