2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P86 ANTIbIOTICS IN ThE ENVIRONMENT
H. VíTEČKOVá, L. VYDROVá, D. VELEBOVá, M.
VáVROVá and L. MRAVCOVá
Brno University of Technology, Faculty of Chemistry, Purkyňova
118, Brno 612 00, Czech Republic,
viteckova@fch.vutbr.cz
Introduction
Tetracyclines (TC) present a class of antibacterial
drugs. Due to their broad antibacterial spectrum and economic
advantages, tetracyclines have been commonly used in
veterinary medicine and in human medicine for the purpose
of prevention and treatment of disease. However, their widespread
utilization could lead to TC residues in animal-originated
food and in the environment. The antibiotics in food
and water consumed for long periods can also cause problems
regarding the spread of drug-resistant microorganisms 1 .
It is well known that the principal pathway of antibiotics
into the aquatic environment is via wastewater systems following
consumption and excretion by humans, and via effluents
from landfills and farms 2 . Presently conventional wastewater
treatment plants (WWTPs) were designed without
consideration of antibiotics removal from wastewater. Many
previous studies have shown that, while some antibiotics
may be eliminated in the WWTPs, some other may be hardly
removed in the process, therefore they can reach the aquatic
environment 3,4 . Due to irremovable antibiotics, wastewater
treatment plants become an important point source of emissions
into the environmen 1,2,3 .
Experimental
To monitor the tetracycline residues a reliable method is
needed. SPE for purification and preconcentration of analytes
was used. Spectrophotometric method for antibiotic determination
was used.
S a m p l i n g
Waste water samples have been taken from the waste
water treatment plant (WWTP) in the University of Veterinary
and Pharmaceutical Sciences Brno campus in one-day
intervals into amber glass sampling bottles. In this WWTP,
we decided to deal with the antibiotics in particular because
these drugs samples were taken from the WWTP inlet and
compared with the samples taken from WWTP outlet.
The samples were processed immediately or stored
in a refrigerator till the following day.
R e a g e n t s
During the process, the following chemicals have been
used: oxalic acid, p.a. sulfuric acid p.a., dinatrium phosphate
dodecahydrate p.a., all from Lachema, CZ; acetonitrile for
HPLC, methanol for HPLC, from Riedel-de-Haen, SRn; citric
acid, p.a. Onex, CZ; Chelaton III, p.a. Penta,CZ;
Tetracycline, Chlorotetracycline and Oxytetracycline,
standards for HPLC, were from Sigma Aldrich, CZ.
s511
McIlvain buffer: citric acid (12.9 g dm –3 ), natrium salt of
ethylenediaminetetraacetate (37.2 g dm –3 ), dodecahydrate of
dinatrium phosphate (30.2 g dm –3 ) in deionized water
Elution mixture: 20 mmol dm –3 oxalic acid in methanol.
S a m p l e T r e a t m e n t
Samples were filtered using paper filters to remove particles.
Volume of 200 ml samples were extracted 20 minutes
with McIlvain buffer in an ultrasonic bath.
A Phenomenex Strata C18-E SPE column (55 μm,
500 mg 6 ml –1 ) was conditioned with 4 ml of methanol followed
by 3 ml of McIlvain buffer. After sample loading, the
column was washed with 3 ml deionized water. The column
was dried using the vacuum of the SPE manifold. Then the
tetracyclines were eluted with 10 ml of elution mixture.
S p e c t r o p h o t o m e t r i c A n a l y s i s
The analyses were carried out on UV-VIS spectrophotometer
Spectronic Helios (UK). Deuterium and wolfram lamp
was used for determination.
At first the absorption spectrum was measured in the
range 230–450 nm step by step 2 nm. Tetracyclines have two
absorption maximas as resulting from absorption spectrum
and with accordance to published data: 246 nm and 360 nm 4 .
Spectrophotometer was adjusted to zero value through the use
of elution reagent. Subsequently, real samples were measured
to determine the absorbance value at absorption maximum.
Quartz cuvette with optical path 1 cm was used.
Fig. 1. Absorption spectrum of tetracycline in various concentrations
[mg ml –1 ]
Fig. 2. Concentration of tetracycline in real samples