Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Fluorobenzenes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1995

Studies on new phosphodiesterase inhibitors. I. Synthesis of 1-(2,3-epoxypropoxy)-2(4)-fluorobenzenes and 1-(2-hydroxy-3-morpholinopropoxy and piperazino)fluorobenzene derivatives.

A series of 1-(2,3-epoxypropoxy)-2(4)-fluorobenzenes and their corresponding 1-(2-hydroxy-3-morpholinopropoxy and piperazino)fluorobenzene derivatives (8a--f) were synthesised via a short synthetic route in good chemical yields and were evaluated for inotropic and chronotropic activity in isolated guinea-pig atria preparation. The compounds act as potential phosphodiesterase (PDE) inhibitors with desirable biological activity and have considerable promise in heart therapy.

Animals↗
PubMed1997

Influence of substituents in fluorobenzene derivatives on the cytochrome P450-catalyzed hydroxylation at the adjacent ortho aromatic carbon center.

In a previous study, the in vivo cytochrome P450-catalyzed regioselectivity of aromatic ring hydroxylation for a series of (poly)fluorobenzenes could be quantitatively predicted by the calculated frontier orbital density distribution in the aromatic ring [Rietjens et al. (1993) Biochemistry 32, 4801-4812]. However, the relative small fluorine, its size almost comparable to a hydrogen, is not expected to influence the regioselectivity of aromatic hydroxylation due to steric hindrance. The aim of the present study was to investigate the influence of substituents larger than a hydrogen or fluorine on the possibilities for hydroxylation at the adjacent carbon center. First, the in vivo regioselectivity of aromatic ring hydroxylation of a series of C4-substituted fluorobenzenes was investigated. The results obtained demonstrate that a chlorine and cyano C4 substituent do not hamper hydroxylation at the positions ortho to the C4 carbon atom. For 4-chloro- and 4-cyanofluorobenzene, the observed regioselectivity of aromatic hydroxylation correlated with the regioselectivity predicted on the basis of the frontier orbital density distribution. In contrast, a bromine and iodine substituent affected the hydroxylation at the adjacent ortho carbon centers, reducing it to respectively 40 and 6% of the calculated intrinsic reactivity of the carbon centers. Additional experiments were performed to investigate whether the regioselectivity of the aromatic hydroxylation of the C4-substituted fluorobenzene model compounds was influenced by changes in the cytochrome P450 enzyme pattern. Results obtained demonstrate that for these relatively small substrates the regioselectivity of their hydroxylation was not significantly influenced by several cytochrome P450 inducers. This suggests that the active sites of the cytochromes P450 catalyzing the aromatic hydroxylation do not impose a stereoselective orientation of the aromatic rings with respect to the iron-oxo porphyrin reaction center. Thus, the working hypothesis for additional experiments was that the deviations for the regioselectivity of aromatic hydroxylation observed for 4-bromo- and 4-iodofluorobenzene may be ascribed to steric hindrance by the bromine and iodine substituents hampering the attack of the cytochrome P450 iron-oxo species on the adjacent carbon centers in the benzene derivative. This working hypothesis was further tested by investigating whether useful steric correction factors could be derived from the results obtained with the series C4-substituted fluorobenzenes. These correction factors should make it possible to correct calculated relative reactivities of carbon sites for steric hindrance by substituents positioned ortho with respect to the carbon to be hydroxylated. This will make it possible to better explain and predict the regioselectivities for other chlorine-, bromine-, iodine-, and cyano-containing fluorobenzenes. The in vivo regioselectivity of aromatic ring hydroxylation of a series of five chlorine-, bromine-, iodine-, or cyano-containing fluorobenzenes did not correlate with the noncorrected calculated reactivities (r = 0.49). However, upon correction of the calculated reactivity values by using the steric correction factors, a correlation between the observed and calculated regioselectivity for the substrates of the present study was obtained (r = 0.91). Together these results strongly indicate that for the fluorobenzenes studied the main factors directing the regioselectivity of their aromatic hydroxylation are (i) the nucleophilic chemical reactivity of the site to be hydroxylated and (ii) the steric influence of the substituent ortho with respect to the site of hydroxylation. This latter effect appears to be negligible for a fluorine, chlorine, and cyano substituent but significant for a bromine and iodine substituent.

Animals↗
PubMed1993

Regioselectivity of cytochrome P-450 catalyzed hydroxylation of fluorobenzenes predicted by calculated frontier orbital substrate characteristics.

In the present study, a hypothesis is presented for the prediction of the regioselectivity of cytochrome P-450 catalyzed hydroxylation of fluorobenzenes. The regioselectivity of the in vivo hydroxylation of fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,2,3-triluorobenzene, and 1,2,4-triflurobenzene could be predicted within 6% accuracy on the basis of the substrate's frontier orbital characteristics for electrophilic attack. The in vivo regioselectivity of the hydroxylation of fluorobenzene was not significantly influenced by changes in the cytochrome P-450 enzyme pattern. This implies that the regioselectivity is not predominantly determined by the juxtaposition of the relatively small substrates in the active sites of the cytochrome P-450s catalyzing the reaction. Additional in vitro experiments using 1,2-difluorobenzene as the model substrate demonstrated that minor factors influencing the regioselectivity and possibly responsible for the 6% deviation from the calculated values in in vivo experiments might be (i) the influence of biotransformation routes occurring in vivo but not of importance in in vitro microsomal incubations and (ii) a small variation due to influences of the contribution of various cytochrome P-450 enzymes. On the basis of the results obtained, it is concluded that the aromatic hydroxylation of fluorobenzenes proceeds through an initial electrophilic attack of (FeO)3+ on the aromatic substrate, and not through initial electron abstraction followed by attack of the (FeO)2+ species on the substrate radical cation. The fact that the regioselectivity observed could be predicted and/or explained by the site of initial (FeO)3+ attack also argues against epoxides as important intermediates in the formation of phenol metabolites from fluorobenzenes.

Animals↗
PubMed2006

Degradation of fluorobenzene by Rhizobiales strain F11 via ortho cleavage of 4-fluorocatechol and catechol.

The aerobic metabolism of fluorobenzene by Rhizobiales sp. strain F11 was investigated. Liquid chromatography-mass spectrometry analysis showed that 4-fluorocatechol and catechol were formed as intermediates during fluorobenzene degradation by cell suspensions. Both these compounds, unlike 3-fluorocatechol, supported growth and oxygen uptake. Cells grown on fluorobenzene contained enzymes for the ortho pathway but not for meta ring cleavage of catechols. The results suggest that fluorobenzene is predominantly degraded via 4-fluorocatechol with subsequent ortho cleavage and also partially via catechol.

Alphaproteobacteria↗
PubMed2006

Molecular pair analysis: C-H...F interactions in the crystal structure of fluorobenzene? And related matters.

The crystal structure of fluorobenzene is compared with isomorphous crystal structures of molecules of roughly similar shape. The lowest-energy fluorobenzene dimers are identified by theoretical calculations. Molecular pair analysis of the crystal structure of fluorobenzene and of an isomorphous virtual low-energy polymorph of benzene suggests that the important intermolecular interactions in the two structures are closely similar. In particular, the intermolecular C-H...F interactions in the fluorobenzene crystal have approximately the same structure-directing ability and influence on the intermolecular energy as the corresponding C-H...H interactions in benzene. Molecular pair analysis of the isomorphous crystal structures of benzonitrile, alloxan, and cyclopentene-1,2,3-trione indicates that essentially the same crystal structure can be adopted with quite different patterns of pair energies and atom-atom interactions. The question as to whether the packing radius of organic fluorine is larger or smaller than that of hydrogen, is addressed, but not answered.

Journal Article↗
PubMed1998

Contributions of dipole moments, quadrupole moments, and molecular polarizabilities to the anesthetic potency of fluorobenzenes.

Previous studies have emphasized the role of molecular polarizability and electric moments, especially dipole and quadrupole moments, in binding of drugs to sites of action. A recent publication of ED50s that prevent response to a noxious stimulus for eight fluorobenzenes has made it possible to compare anesthetic potency with ab initio Hartree-Fock calculations of molecular polarizability as well as dipole and quadrupole moments. Fluorobenzenes provide a stringent test of the role of electric moments in anesthetic potency because individual dipole moments range from 0 to 2.84 debye (D) while the quadrupole moment of benzene is large and negative (-30 x 10(-40) C m(2)), that of hexafluorobenzene is large and positive (30 x 10(-40) C m(2)), and that of 1,3,5-trifluorobenzene is nearly zero. We found that anesthetic potency of fluorobenzenes was not affected by the presence of either dipole or quadrupole moments. This result is surprising because fluoroalkanes and fluorocycloalkanes are most potent when half fluorinated and are usually not anesthetics when perfluorinated. The results suggest that electrostatic interactions are not important for binding of fluorobenzenes at sites of anesthetic action and that these sites are different from those that bind conventional anesthetics.

Journal Article↗
PubMed2004

Fluorobenzene-argon ground-state intermolecular potential energy surface.

The ground-state intermolecular potential energy surface for the fluorobenzene-argon van der Waals complex is evaluated using the coupled-cluster singles and doubles including connected triple excitations model, with the augmented correlation consistent polarized valence double-zeta basis set extended with a set of 3s3p2d1f1g midbond functions. In the surface minima the Ar atom is located above and below the fluorobenzene plane at a distance of 3.562 A from the fluorobenzene center of mass and at an angle of 6.33 degrees with respect to the axis perpendicular to the fluorobenzene plane. The corresponding binding energy is 391.1 cm(-1). Both these results and the eigenvalues obtained from the potential compare well with the experimental data available.

Journal Article↗
PubMed2006

Fluorobenzene-nucleobase interactions: hydrogen bonding or pi-stacking?

Studies on modified DNA oligomers and polymerase reactions have previously demonstrated that canonical nucleobases can exhibit stable and even selective pairing with shape-complementary fluorobenzene nucleotides. Because of the fluorination of the pairing edges, hydrogen bonds are believed to be absent, and the local DNA stability has been attributed to pi-stacking and shape complementarity. Using two-color resonant two-photon ionization and fluorescence emission spectroscopies, we show here that supersonically cooled complexes of the nucleobase analogue 2-pyridone with seven substituted fluorobenzenes (1-fluorobenzene, 1,2- and 1,4-difluorobenzene, 1,3,5- and 1,2,3-trifluorobenzene, 1,2,4,5- and 1,2,3,4-tetrafluorobenzene) are hydrogen-bonded and not pi-stacked. The S1 <--> S0 vibronic spectra show intermolecular vibrational frequencies that are characteristic for doubly hydrogen bonded complexes. The bands shift to the blue with increasing hydrogen-bond strength; the measured spectral blue shifts deltanu are in excellent agreement with the ab initio calculated shifts. The spectral shifts are also linearly correlated with the calculated hydrogen-bond dissociation energies D0, published in a companion paper (Frey, J. A.; Leist, R.; Leutwyler, S. J. Phys. Chem. A 2006, 110, 4188). This correlation allows us to reliably estimate the ground-state dissociation energies as D0 approximately 6 kcal/mol of the 2-pyridone.fluorobenzene complexes from the observed spectral shifts.

Fluorobenzenes↗
PubMed2003

Protonation of gas-phase aromatic molecules: IR spectrum of the fluoronium isomer of protonated fluorobenzene.

The IR spectrum of the fluoronium isomer of protonated fluorobenzene (F-C(6)H(6)F(+), phenylfluoronium) is recorded in the vicinity of the C-H and F-H stretch fundamentals to obtain the first structured spectrum of an isolated protonated aromatic molecule in the gas phase. Stable F-C(6)H(6)F(+) ions are produced via proton transfer from CH(5)(+) to fluorobenzene (C(6)H(5)F) in a supersonic plasma expansion. The F-C(6)H(6)F(+) spectrum recorded between 2,540 and 4,050 cm(-1) is consistent with a weakly bound ion-dipole complex composed of HF and the phenyl cation, HF-C(6)H(5)(+). The strongest transition occurs at 3,645 cm(-1) and is assigned to the F-H stretch (sigma(FH)). The antisymmetric C-H stretch of the two ortho hydrogen atoms, sigma(CH) = 3,125 cm(-1), is nearly unshifted from bare C(6)H(5)(+), indicating that HF complexation has little influence on the C-H bond strength of C(6)H(5)(+). Despite the simultaneous production of the more stable ring protonated carbenium isomers of C(6)H(6)F(+) (fluorobenzenium) in the electron ionization source, F-C(6)H(6)F(+) can selectively be photodissociated into C(6)H(5)(+) and HF under the present experimental conditions, because it has a much lower dissociation energy than all carbenium isomers. Quantum chemical calculations at the B3LYP and MP2 levels of theory using the 6-311G(2df,2pd) basis support the interpretation of the experimental data and provide further details on structural, energetic, and vibrational properties of F-C(6)H(6)F(+), the carbenium isomers of C(6)H(6)F(+), and other weakly bound HF-C(6)H(5)(+) ion-dipole complexes. The dissociation energy of F-C(6)H(6)F(+) with respect to dehydrofluorination is calculated as D(0) = 4521 cm(-1) (approximately 54 kJ/mol). Analysis of the charge distribution in F-C(6)H(6)F(+) supports the notation of a HF-C(6)H(5)(+) ion-dipole complex, with nearly the whole positive charge of the added proton distributed over the C(6)H(5)(+) ring. As a result, protonation at the F atom strongly destabilizes the C-F bond in C(6)H(5)F.

Fluorobenzenes↗
PubMed2006

Hydrogen bonding of the nucleobase mimic 2-pyridone to fluorobenzenes: an ab initio investigation.

The hydrogen-bonded complexes of the nucleobase mimic 2-pyridone (2PY) with seven different fluorinated benzenes (1-, 1,2-, 1,4-, 1,2,3-, 1,3,5-, 1,2,3,4-, and 1,2,4,5-fluorobenzene) are important model systems for investigating the relative importance of hydrogen bonding versus pi-stacking interactions in DNA. We have shown by supersonic-jet spectroscopy that these dimers are hydrogen bonded and not pi-stacked at low temperature (Leist, R.; Frey, J. A.; Leutwyler, S. J. Phys. Chem. A 2006, 110, 4180). Their geometries and binding energies D(e) were calculated using the resolution of identity (RI) Møller-Plesset second-order perturbation theory method (RIMP2). The most stable dimers are bound by antiparallel N-H...F-C and C-H...O=C hydrogen bonds. The binding energies are extrapolated to the complete basis set (CBS) limit, , using the aug-cc-pVXZ basis set series. The CBS binding energies range from -D(e,CBS) = 6.4-6.9 kcal/mol and the respective dissociation energies from -D(0,CBS) = 5.9-6.3 kcal/mol. In combination with experiment, the latter represent upper limits to the dissociation energies of the pi-stacked isomers (which are not observed experimentally). The individual C-H...O=C and N-H...F-C contributions to D(e) can be approximately separated. They are nearly equal for 2PY.fluorobenzene; each additional F atom strengthens the C-H...O=C hydrogen bond by approximately 0.5 kcal/mol and weakens the C-F...H-N hydrogen bond by approximately 0.3 kcal/mol. The single H-bond strengths and lengths correlate with the gas-phase acid-base properties of the C-H and C-F groups of the fluorobenzenes.

Computer Simulation↗
PubMed1998

Occurrence of the NIH shift upon the cytochrome P450-catalyzed in vivo and in vitro aromatic ring hydroxylation of fluorobenzenes.

The in vivo cytochrome P450-catalyzed aromatic hydroxylation of a series of fluorobenzenes was investigated with special emphasis on the importance of the fluorine NIH shift. The results obtained demonstrate a minor role for the NIH shift in the metabolism of the fluorobenzenes to phenolic metabolites in control male Wistar rats. These in vivo results could indicate that (1) the NIH shift is an inherently minor process for fluorine substituents or (2) it is a potentially significant process but the presumed epoxide that leads to formation of the NIH-shifted metabolite is lost to an alternative metabolic pathway. In contrast to the in vivo data, in vitro experiments showed a significant amount of an NIH-shifted metabolite for 1,4-difluorobenzene. This result eliminates the explanation that the NIH shift is an inherently minor process for fluorine substituents. Results of additional experiments presented in this paper show that the reduced tendency of fluorine-substituted benzenes to undergo an NIH shift in vivo can-at least in part-be ascribed to the possible existence of alternative pathways for metabolism of the epoxide, such as, for example, GSH conjugation, being more efficient for fluorinated than chlorinated arene oxides.

Animals↗
PubMed1994

Influence of the type of halogen substituent on in vivo and in vitro phase II metabolism of 2-fluoro-4-halophenol metabolites formed from 3-halo-fluorobenzenes.

1. The influence of a change in the type of halogen substituent on phase II metabolism of 2-fluoro-4-halophenol metabolites formed from 3-halo-fluorobenzenes was studied in vivo and in vitro using 19F nmr and spectroscopic assays. 2. The ratio of sulphation to glucuronidation of 2-fluoro-4-halophenol metabolites formed from 3-halofluorobenzenes decreased from 48 to 13 to 6 when the halogen substituent varied from fluorine to chlorine to bromine. 3. When the 2-fluoro-4-halophenols themselves were administered to the rats, the ratio of sulphation to glucuronidation was not affected by the type of halogen substituent at C4 and at a constant value of 0.6, i.e. significantly lower. 4. Kinetic data for P450 catalysed hydroxylation of the 3-halo-fluorobenzenes and for sulphation and glucuronidation of their 2-fluoro-4-halophenol metabolites were obtained from in vitro microsomal and cytosolic incubations. These data demonstrate that the effects of varying the halogen substituent on phase II metabolism of the 2-fluoro-4-halophenol metabolites can be mainly ascribed to an apparently decreased Km for the glucuronidation of the 2-fluoro-4-halophenols with a change in the halo substituent from fluorine to chlorine to bromine. 5. Results from calculations on electronic and structural characteristics of the three 4-halo-2-fluorophenols demonstrate that the best explanation for the decrease in the apparent Km of the glucuronidation from 2,4-difluoro- to 4-chloro-2-fluoro- to 4-bromo-2-fluorophenol might be an increase in the hydrophobicity of the phenol. An increase in the hydrophobicity of the phenol would provide an increased possibility for substrate accumulation in the hydrophobic membrane environment of the UDP-glucuronyltransferases, resulting in an apparently decreased Km.

Animals↗
PubMed2005

Ortho effect in fluorobenzenes: cross-correlated relaxation and quantum chemical studies.

An early solid-state NMR study of the shielding tensors in substituted fluorobenzenes had indicated the presence of the 'ortho effect'. This was confirmed recently in the liquid state from a study of cross-correlated relaxation, which gives a handle on the shielding tensor. We report here a combined experimental and computational study on substituted fluorobenzenes where the ortho substituent is varied systematically. Experimental measurements of the longitudinal relaxation of 19F indicate the cross-correlation between the chemical shift anisotropy (CSA) of fluorine and its dipolar interaction with the ortho proton, and provide a measure of the CSA orientation parameter. This parameter is obtained also from quantum chemical calculations of the 19F CSA tensor. We establish a correlation between the CSA orientation parameter and linear free energy parameters by resorting to a multi-parameter regression analysis. Excellent correlation is obtained for most of these substituents only when a parameter for the ortho effect is included.

Journal Article↗
PubMed2003

Photodissociation dynamics of fluorobenzene.

Photodissociation of both fluorobenzene and d(5)-fluorobenzene at 193 nm under collision-free conditions has been studied in separate experiments using multimass ion imaging techniques. HF and DF eliminations were found to be the major dissociation channels. Small amounts of photofragments, C(6)H(4)F and C(6)D(4)F, corresponding to H and D atom eliminations were also observed. Dissociation rate and fragment translational energy distribution suggest that HF (DF) and H (D) atom elimination reactions occur in the ground electronic state. The potential energy surface obtained from ab initio calculations indicates that the four-center reaction in the ground electronic state is the major dissociation mechanism for the HF and DF eliminations. A comparison with photodissociation of benzene has been made.

Journal Article↗
PubMed1988

Soluble factors in tolerance and contact sensitivity to 2,4-dinitro-fluorobenzene in mice. IX. A monoclonal T cell suppressor molecule is structurally and serologically related to the alpha/beta T cell receptor.

Ts cells from mice tolerized with dinitrobenzene sulfonate produce a DNP-specific, MHC-restricted soluble suppressor factor (SSF) which regulates contact sensitivity to 2,4-dinitro-fluorobenzene. Previous studies have shown that the SSF-producing T cells and the soluble factor have the same hapten/MHC specificity suggesting that SSF may represent a secreted form of the Ts membrane receptor. The relationship between TCR proteins and SSF was investigated by examining the structural and serologic properties of a monoclonal DNP/H-2Kd-specific suppressor molecule produced by a Ts hybridoma. Reduction followed by alkylation abrogated the ability of the 3-10 molecule to inhibit transfer of contact sensitivity to 2,4-dinitro-fluorobenzene, indicating that intact disulfide bonds were a required structural property for suppression. Reduction of the 3-10 molecule followed by affinity chromatography on DNP-coupled Sepharose beads indicated that the 3-10 suppressor molecule is a dimer and that one of its chains binds to cell-free DNP. Serologic properties of the 3-10 molecule were examined by determining the ability of pan-reactive rabbit anti-TCR antibodies and anti-V beta 8 mAb KJ16.133 and F23.1 to adsorb suppressor activity from 3-10 culture supernatant and affinity purified 3-10 ascites material. All three reagents adsorbed the suppressor activity whereas control antibodies had no effect. When 3-10 material was passed through a F23.1-conjugated Sepharose affinity column, suppressor activity was recovered in the column eluate but not in the effluent fraction. When the 3-10 molecule was reduced and separated into its two chains (i.e., DNP-binding and non-DNP-binding chains), it was found that the anti-V beta 8 antibody F23.1-bound to the non-DNP-binding chain of the suppressor molecule. Collectively, these results indicate that the monoclonal 3-10 suppressor molecule is structurally similar to the alpha/beta TCR and suggest that the 3-10 molecule expresses a determinant encoded by the V beta 8 family of TCR genes. These results are consistent with our hypothesis that these suppressor molecules represent a secreted form of the TCR expressed on the surface of the DNP-specific Ts.

Animals↗
PubMed2005

Long-term performance and microbial dynamics of an up-flow fixed bed reactor established for the biodegradation of fluorobenzene.

An up-flow fixed bed reactor (UFBR) was established to investigate the biodegradation of fluorobenzene (FB) under a number of operating conditions, which included variation in the concentration of FB in the feed stream (up to 180 mg l(-1)) and temporary suspension of feeding. Degradation of FB was followed for a period of 8 months under a continuous flow regime. During the operation of the UFBR, FB was never detected in the reactor effluent, being biodegraded by the microbial biofilm or adsorbed to the granular activated carbon (GAC). Biodegradation of FB was observed from the beginning of the reactor operation, and overall, it accounted for 50% of the total amount fed to the bioreactor. High organic loads of FB (210-260 mg d(-1) dm(-3)) were found to affect the biological removal efficiency, possibly due to an inhibitory effect caused by the higher FB concentrations fed to the bioreactor (149-179 mg l(-1)). When FB feeding was suspended for 1 month, biodegradation continued, indicating that the adsorbed FB became bioavailable. Biofilm bacterial dynamics were followed throughout the UFBR operation by denaturing gradient gel electrophoresis and plate-counting techniques, showing that a quite stable community was found in the bioreactor, and this was mainly attributed to the high selective pressure exerted by the presence of FB.

Biofilms↗
PubMed2006

Adsorption of fluorobenzene onto granular activated carbon: isotherm and bioavailability studies.

The adsorption of a recalcitrant fluoroaromatic compound, fluorobenzene (FB), onto granular activated carbon (GAC) was evaluated. The respective isotherm was obtained and the Langmuir, Freundlich and Redlich-Peterson models were fitted to the experimental data, with the Redlich-Peterson model giving the best fitting. Freundlich model also provided a good fit but the Langmuir model could not adequately fit the experimental data, especially at high FB concentrations. Maximal adsorption capacity of FB onto GAC was found to be 388mg of FB per gram of GAC. The reversibility of the adsorption of FB onto GAC was investigated, both in the absence and presence of microorganisms. Abiotic desorption of FB occurred to a small extent (between 3% and 22%, for amounts of FB initially adsorbed to the GAC between 37 and 388mgg(-1)), and bioregeneration of GAC was shown to occur when the matrix was exposed to a FB degrading culture, with 58-80% of the adsorbed FB being biodegraded. A residual amount of FB showed not to be bioavailable, suggesting that part of the adsorbed FB may be irreversibly bound. The fraction of the non-bioavailable FB increased at higher amounts of adsorbed FB, from 19% to 33%. The results indicate that the GAC employed in this study has a good capacity to adsorb FB and that bioregeneration of this matrix is a feasible process.

Adsorption↗