Michal Oravec


Chiral pollutants


Masaryk University, Faculty of Science,

Research Centre for Toxic Compounds in the Environment (RECETOX)

Brno, Czech Republic, 2010


Abstract


Changes of enantiomeric fraction (EF) of chiral compounds interacting with components of soil and
the effect of amount of soil components on EF value were investigated. Soil components (humic acid
and ash) were isolated from soil using method recommended by the International Humic Substance
Society (IHSS). Dichloromethane was used as an extraction solvent for extraction of enantiomers of
polychlorinated biphenyls (PCBs), mecoprop and its methyl ester from humic acid (HA) and ash
sample. The extracts were analyzed by a high performance liquid chromatography (HPLC). HPLC columns
filled with silica gel modified by permethylated cyclodextrine acting as a chiral selector were
used for analytical separation of enantiomers. The results confirm the stereoselective effect of
soil components on extractable amount of individual enantiomers. Significant changes of EF of
chiral pollutants were observed for investigated PCBs enantiomers (HA 0.49–0.45, ash 0.50–0.58) and
for mecoprop-methyl ester (HA 0.55–0.59, ash 0.49–0.34), smaller changes of EF were observed for
mecoprop (HA 0.52–0.50, ash 0.49–0.50). The changes of EF were dependent on
an amount of humic acid and ash. Inverse trends of EF changes of humic acid were obtained comparing
to trends of EF changes of ash.

Changes of enantiomeric fraction (EF) of chiral environmental pollutants, polychlorinated biphenyls
(PCBs 84, 135, 175), mecoprop and mecoprop-methyl ester, were investigated as a soil pH function.
Suitable method enabling adjustment of a stable soil pH in the range of pH 4–7 was used. Addition
of phosphate buffer and direct soil pH measurement was used for the study of soil pH effect on EF
changes during 40–55 days incubation. Monitoring of EF changes (0.45–0.56) was feasible in the
whole incubation interval according to the properties of pollutants. Changes of EF were
quantitatively and qualitatively dependent on the soil pH. Different trends of EF changes were
recorded for different soil pH. The most significant changes of enantiomeric fraction (EF) were
observed in the beginning of all experiments. Differences in adsorption rate and extent of
enantioselective sorption of enantiomers on soil components can be used for explanation of obtained
results.


Second part will be focused on development and optimization of LC/MS/MS method for analysis of
polycyclic aromatic nitrogen heterocycles (PANHs), Cylindrospermopsin and Microcystins (MCs) in
environmental samples.