2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P69 ThE EPR STuDy OF PARTICuLATE MATTER
nADEŽDA ŠTEVULOVá, ADRIAnA EŠTOKOVá and
PAVeL STOPKA
Technical University of Košice, Civil Engineering Faculty,
Institute of Building and Environmental Engineering, Vysokoškolská
4, 042 00 Košice, Slovak Republic,
Nadezda.Stevulova@tuke.sk
Introduction
In recent years the role of particulate matter in environmental
and health areas has come under increased attention
of experts and public. The PM 10 and PM 2.5 (particle fractions
related to their size) concentrations show higher correlation to
the negative health effects in comparison to the total suspended
particulate matter 1 . Building constructions and materials
play an important role in indoor particulate matter contamination
due to particles infiltration through joint construction
leakages and material distribution and deposition processes 2 .
The dust particles are dangerous not only because of
their high concentrations in dependence on their particle size
but also because of their nature 3 . The surface of the inhaled
particles which determines the biological response is large.
The surface reactivity of particles depends on the number of
reactive spots on the dust particles surface and on the distribution
of various sites (free radicals and paramagnetic species)
at the surface 4 . It determines the pathogenic potential of
inhaled particles.
This work is concerned with the particulate matter reactivity
investigation by concentration of surface active centres.
Experimental
Both total suspended particles (TSP) and PM 10 measurement
includes integral sampling onto a collection material
(membrane filter Synpor 0.8 µm pore size, 35 mm in diameter)
by sampling equipment VPS 2000 (Envitech, Trenčín) at
flow rate of 960 dm 3 h –1 during sampling period of approximately
24 hours.
The surface reactive spots concentrations of suspended
particulate matter were detected on the spectrometer ERS
220 (GAS, Berlin) with a resonator RSX 216 at room temperature
under following conditions: the microwave power
10 mW, modulation amplitude 0.02 mT, time constant 0.5 s.
The relative intensity of the signals measured for investigated
dust samples was determined by comparing them with those
of Mn(II)/ZnS a Cr(III)/MgO as standard samples. The EPR
spectrum was recorded as the first derivation of the absorption
spectrum at the speed record 14.3 mT min –1 .
The quantitative and qualitative interpretation of obtained
spectra was performed by computer software Origin.
Results
Typical EPR spectra of investigated total suspended particulate
mater and PM 10 samples are illustrated in Figs. 1.–3.
s474
Fig. 1. EPR spectra of total suspended particulates
Fig. 2. EPR spectrum of PM 10
Fig. 3. Detail of PM 10 EPR spectrum
Wide singlet peak centered at g factor value was identified
in EPR spectra of particulates. The g factors range from
2.010 to 2.093 for measured particle samples as the Table I
shows.
Singlet peak superponed by triplet peak with factor
values g 1 = 2.1162, g 2 = 2.0700, g 3 = 2.0191 was identified
in EPR spectrum of total particulate matter in Fig. 1. It
could be an isotropic triplet (g = 2.07) with splitting constant
a = 7.6375 +/ 0.5495 mT.