Wolfram Baumann

Polar drug residues in sewage and natural waters in the state of Rio de Janeiro, Brazil.

The drug residues of lipid regulators, anti-inflammatories and some drug metabolites have been detected in raw sewage, treated waste water and river water in the state of Rio de Janeiro, Brazil. These residues are mainly derived from humans via excretion. The median concentrations in the effluents of sewage treatment plants (STPs) of most drugs investigated in this study ranged from 0.1 to 1 microgram/l. The removal rates of individual drugs during passage through a Brazilian STP varied from 12 to 90%. As a consequence of the incomplete removal of these residues during passage through a STP, rivers were also found to be contaminated. Median concentrations ranged from between 0.02 and 0.04 microgram/l in river water, whereas the maximum values were observed to be up to 0.5 microgram/l.

UV-Filtersubstanzen in Wasser und Fischen

ZusammenfassungZur Erfassung der UV-Filtersubstanzen wird eine Methode vorgestellt, die die simultane Bestimmung dieser Verbindungen und von Organochlorverbindungen wie PCB und DDT in unterschiedlichen Fischkompartimenten bis in den ng/kg-Bereich ermöglicht. Die Nachweisgrenzen liegen zwischen 40 und 90 ng/kg Filet und die Wiederfindungsraten bewegen sich zwischen 78 und 104%.Die Belastung von Wasser und Fischen des Meerfelder Maares, Eifel, mit UV-Filtersubstanzen wurde 1991 und 1993 exemplarisch untersucht. Insgesamt konnten in den Fischen des Meerfelder Maares 6 UV-Filtersubstanzen identifiziert und quantifiziert werden. Die im Sommer 1991 gefangenen Barsche waren mit 2,0 mg/kg Fett (Summe nachgewiesener UV-Filtersubstanzen) und die Rotaugen von 1993 mit 0,50 mg/kg Fett belastet. In beiden Fischarten lag die Belastung in der gleichen Größenordnung wie die der Organochlorverbindungen PCB und DDT. In den Rotaugen aus drei weiteren deutschen Seen konnte im Filet Methylbenzylidencampher, eine lipophile UV-Filtersubstanz, nachgewiesen werden. Diese Befunde zeigen, daß UV-Filtersubstanzen in deutschen Seen weir verbreitet und vermutlich als relevante Umweltchemikalien zu betrachten sind. Da im Wasser der Seen die Konzentrationen der UV-Filter substanzen meistens unter der Bestimmungsgrenze lagen, können Fische für diese lipophilen Verbindungen als Expositionsmonitor verwendet werden. Eine ökotoxikologische Bewertung ist zum jetzigen Zeitpunkt nicht möglich, da die Datenlage völlig unzureichend ist.AbstractA method was developed for the analysis of fish samples to detect sunscreen agents (SSA) together with organochlorides (PCB, DDT) in different fish tissues. Detection limits of the compounds analyzed are in the range of ng/kg and vary between 40 and 90 ng/kg fillet. Recovery rates range from 78 to 104%.The contamination of water and fish with SSA in Meerfelder Maar lake, the Eifel, Germany was investigated in 1991 and 1993 and allowed the identification and quantification of six different SSA in the fish. The sum of SSA concentrations in perch taken in the summer of 1991 was 2.0 mg/kg lipid and 0.50 mg/kg lipid was found in roach sampled during the summer of 1993. Both species were contaminated with SSA and organochlorides to the same ranges as PCB and DDT. Even in the fillet of roach taken from three other lakes in Germany, methylbenzylidene camphor, a lipophilic SSA, was detected. These results indicate that SSA are wide-spread in German lakes. Therefore, they can be seen as a new group of relevant environmental chemicals. In the investigated lakes, the concentrations of the SSA in water were mostly below the detection limits. Thus, fish can be used as a biomonitor for these lipophilic compounds. Due to the lack of toxicological data for aquatic organisms, an ecotoxicological assessment is impossible at the moment.

Considerations on the dipole moment of molecules forming the twisted intramolecular charge transfer state

Abstract Several derivatives of dual-fluorescing dimethylaminobenzonitrile (DMABN) are compared regarding their ground and excited-state dipole moments extracted from electro-optical emission and solvatochromic measurements. The comparison includes bridged model compounds as well as compounds with different degrees of steric hindrance to planarity, as well as ester and carbazolyl derivatives. The results are discussed on the basis of the twisted intramolecular charge transfer (TICT) model, the most widely accepted model. They show that (i) the dipole moment of the A (TICT) state (long-wavelength band) shows only little solvent sensitivity (polarizability), (ii) this observed small dependence of the dipole moment on solvent polarity can be considered as the result of overlap of two fluorescence bands or of solvent-induced changes in the mean deviation from the ideal TICT geometry (“atomic polarizability”), (iii) the dipole moment of the B state (short-wavelength band) is considerably smaller than that of the A band, (iv) the order of the dipole moment values obtained from solvatochromy is the same as from theoretical calculations: μ gp ep ( 1 L b ) ep ( 1 L a ) eT , (v) ester derivatives show a reduced dipole moment with respect to the corresponding nitriles and (vi) sterically crowded compounds seem to possess a reduced dipole moment. The possible reasons are discussed. The agreement and the differences between the two methods are discussed and compared with results from dielectric loss measurements and from quantum-chemical calculations.

Incomplete degradation of linear alkylbenzene sulfonate surfactants in Brazilian surface waters and pursuit of their polar metabolites in drinking waters.

In Brazil more than 90% of the population are not connected to municipal wastewater treatment plants. As a consequence, surface waters receive continuously considerable amounts of untreated domestic sewage containing surfactants as a major constituent. Such polluted waters gave rise to special interest if they are used as a source for the production of drinking water. In this work, the river Rio Macacu (State Rio de Janeiro, Brazil) was monitored for the occurrence of the most widely used anionic surfactant linear alkylbenzene sulfonate (LAS) together with its main degradative product, sulfophenyl carboxylates (SPC). In order to pursue the fate of both compounds after emission into the river, samples were collected at several locations along the river bank, and analyzed applying liquid chromatography-mass spectrometry after enrichment by solid-phase extraction. The LAS concentrations ranged between 14 and 155 microg l(-1) and the levels of their metabolic intermediates were found from 1.2 to 14 microg l(-1). The self-purification capacity of the water was impressively demonstrated in the upper course of the river downstream of a town considered as one major discharge point, whereas in the lower course the relative constant concentrations of both analytes were detected which was explained with an overall increasing level of pollution. Furthermore, a series of drinking water samples from Niterói and São Gonçalo, supplied by the same waterworks treating surface waters from the Rio Macacu, were taken during two sampling periods and examined for the presence of the strongly polar SPC which is suspected of by-passing the purification processes. The levels detected in the drinking water ranged between 1.6 and 3.3 microg l(-1). For the analyses of drinking and surface waters the peak pattern of a selected SPC homologue composed by several positional isomers served as an indicator to describe the progression of SPC degradation occurred in the river and could be used to distinguish drinking waters of different origins.

Gas-phase dipole moments of molecules in their fluorescent state

Abstract The effect of an external electric field on the fluorescence of molecules in the gas phase as well as in solutions is studied and the permanent dipole moments of 9-cyanoanthracene and 2,6-N,N-tetramethyl-4-cyanoaniline (TMCA) in their fluorescent states have been determined from such investigations. By comparison of the gas-phase and liquid-phase dipole moments, it could be shown that the Onsager model is adequate to describe the effective electric field, and the polarizability density related to the molecular volume could be determined. The values of the gas-phase and of the solution effective dipole moments of TMCA oppose the solute-solvent exciplex model and favour an emitting internal charge-transfer state.

Critical refinement of the theory of integral electro-optical emission measurements

Abstract A previously expounded theory of integral electro-optical emission measurements is extended by taking into account the electric field dependent spectral shift together with the inhomegeneous spectral sensitivity of the fluorescence channel of the fluoremeter. The revised theory is then checked by various experiments which demonstrate the power of the method

Ground and excited state dipole moments of coumarin laser dyes: Investigation by electro-optical absorption and emission methods

Abstract Modified electro-optical absorption and emission methods were used to measure the dipole moments of four efficient coumarin laser dyes (CU1, CU4, CU120, CU334) in the equilibrated ground, excited Franck-Condon and equilibrated excited states. The measurements were performed in cyclohexane (CU1, CU120, CU334) and dioxane (all CUs) at room temperature. Our results show that the charge distribution in CU4 differs substantially from that in the other CUs. The equilibrated ground and excited state dipole moments measured by electro-optical methods are compared with those derived from other measurement techniques and from semiempirical calculations. The possible role of twisted intermolecular charge transfer (TICT) state formation is discussed.

Site selectivity in excited-state intramolecular proton transfer in flavonols

Abstract To investigate 4′-(diethylamino) (FET) and 4′-N-(15-azacrown-5) (FCR) derivatives of 3-hydroxyflavone in binary solvents and erythrocyte ghosts, we used the red-edge excitation spectroscopy (REES). The results obtained prove the existence of spectral heterogeneity of flavonols in the studied systems. The effect manifests itself in the dependence of the efficiency of excited-state intramolecular proton transfer (ESIPT) on the excitation frequency. The electro-optical absorption method (EOAM) was used to measure the dipole moments of the normal form of FET. The electric dipole moments in the ground (μg) and excited Franck–Condon ( μ e FC ) states have the values 22.7×10−30 and 53.3×10 −30 C m , respectively. On optical excitation, the electric dipole moment increases by 34×10 −30 C m , and the angle between μg and μ e FC is 25°. The results of the electro-optical and spectroscopic measurements enable us to describe more precisely the process of charge and proton transfer in 4′-amino-3-hydroxyflavones. Charge transfer and proton transfer occur alternately. The main stage of forward electron charge transfer takes place after excitation of the normal form (N∗) and partly after ESIPT. In the phototautomer (T), only partial reverse charge transfer happens after photon emission. The second, more efficient stage of reverse electron charge transfer occurs after radiationless conversion of phototautomer into the normal form.

Integral electrooptical emission measurements. A new method for the determination of dipole moments of molecules in fluorescent states

Abstract The influence of an external electric field on the total fluorescence intensity of molecules in solutions is investigated theoretically, using a well established model. From the experimental results on several solvent/solute systems, dipole moments of molecules in flucrescent states are determined using this theory. The values are compared with those from the literature and the new method is presented as an experimentally simplified excited states dipole meter.

Photoinduced charge transfer as revealed by ground and excited state dipole moments

As a measure of photoinduced charge transfer the excited state dipole moments of rigid molecules are detennined from the quantitatively observed effect of an external electric field on their fluorescence in various solvents. The observed solvent dependence of the excited state dipole moment is interpreted in terms of solvent induced moments which may be described by polarizabilities. The resulting excited state polarizability densities a,/a3 (a = Onsager’s interaction radius) are detennined to be around 0.1 to 0.2 CV-lm-l and do not add considerably to the excited state dipole moment in nonpolar solvents. I NTRODU CTl ON There are not many experimental methods available to study photoinduced charge transfer in molecules directly which means that the electric dipole moment of molecules before and after the absorption of a photon has to be measured. Usually, the solvent polarity induced shift of the absorption or fluorescence band is observed quantitatively from which excited state electric dipole moments can be derived. With a non-rigid compound the geometric and electronic structure may depend on the solvents dielectric constant E and therefore the resultant value for an excited state dipole moment can only be a poorly defined average value. This drawback is avoided by electrooptical measurements with which the effect of an external electric field on the absorption (ref. 1) or fluorescence intensity (ref. 2) of solute molecules is studied. Careful evaluation of the effects measured in a single solvent yield Franck Condon (FC) excited state dipole moments pFeC of the solute in this solvent from electrooptical absorption measurements (EOAM) and equilibrated excited state dipole moments pe from electrooptical emission measurements (EOEM). In this communication EOEM and its specialized version IEOEM (integral electrooptical emission measurements) (refs. 3 and 4) are used to show the effect of the solvent polarity on the electric dipole moment pLe of rigid compounds which are assumed not to undergo severe structural or electronic relaxation before fluorescence takes place to a considerable amount, as it is assumed with TICT fluorescence emitting compounds (ref. 5). From the solvent dependent excited state dipole moment the excited state polarizability can be determined. Such results are extremely useful for the discussion of TICT state dipole moments of non-rigid compounds.