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Octanol
Selected AbstractsChromatographic partitioning of cesium by a macroporous silica-calix[4]arene-crown supramolecular recognition compositeAICHE JOURNAL, Issue 10 2010Anyun Zhang Abstract A macroporous silica-based 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) supramolecular recognition polymeric composite, (Calix[4]+Oct)/SiO2 -P, was synthesized. It was performed by impregnating and immobilizing Calix[4]arene-R14 and n -octanol into the pores of the macroporous SiO2 -P particles support. n -Octanol was used to modify Calix[4]arene-R14 through hydrogen bonding. The effect of eight typical fission products contained in highly active liquid waste (HLW) on the adsorption of Cs(I), one of the heat generators, was investigated at 298 K by examining the effect of contact time and the HNO3 concentration in a range of 0.3,7.0 M. (Calix[4]+Oct)/SiO2 -P showed excellent adsorption ability and high selectivity for Cs(I) at 4.0 M HNO3 over the tested elements. The partitioning of Cs(I) from a simulated HLW was operated by (Calix[4]+Oct)/SiO2 -P packed column. Cs(I) was able to be effectively eluted by water and separated from the tested metals. It is demonstrated that (Calix[4]+Oct)/SiO2 -P is promising to apply in chromatographic separation of Cs(I) from HLW. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Ion-pair mediated transport of angiotensin, neurotensin, and their metabolites in liquid phase microextraction under acidic conditionsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2005J. Léon E. Reubsaet Abstract This paper discusses the behaviour of angiotensin 1 and neurotensin together with their metabolites in a three-phase liquid phase microextraction under acidic conditions. Variations in donor phase, organic phase, and acceptor phase are studied with extraction recovery as response variable. It is proved that for all peptides the transport across the organic phase is mediated by heptane-1-sulphonic acid. n -Octanol gave overall best results as organic phase. A donor phase volume of 1.0 mL was chosen as a compromise between optimal recovery and robustness of the LPME device. The optimal pH of the donor phase (using acceptor phase of pH 2) was found to be different for the peptides, which opens opportunities for selective sample preparation. Decreasing the acceptor phase pH to 1.0 resulted in increased extraction recoveries. On using 1.0 mL of donor phase containing 50 mM heptane-1-sulphonic acid pH 3, n -octanol as organic phase immobilized in the pores of the fibre, and 20 ,L of acceptor phase containing 0.1 mol/L HCl, extraction recoveries up to 82% (enrichment factor = 41) were achieved. To our knowledge this is the first report on liquid phase microextraction of angiotensins and neurotensins. [source] ARE GAP JUNCTIONS TRULY INVOLVED IN INHIBITORY NEUROMUSCULAR INTERACTION IN MOUSE PROXIMAL COLON?CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2006Andrei Sibaev SUMMARY 1Gap junctions exist between circular muscle cells of the colon and between interstitial cells of Cajal (ICC) in the myenteric plexus of the gastrointestinal tract. They also probably couple intramuscular ICC with smooth muscle cells. Recent functional evidence for this was found in dye-coupling and myoelectrical experiments. 2In the present study, we tested the hypothesis of gap junctions putatively being involved in neuromuscular interaction in mouse colon by using different classes of gap junction blockers. 3Electrical field stimulation of the myenteric plexus elicited tetrodotoxin-sensitive and hexamethonium-independent fast and slow inhibitory junction potentials (fIJP and sIJP, respectively) in circular smooth muscle cells, as evaluated by intracellular recording techniques in impaled smooth muscle cells. Heptanol produced a time-dependent hyperpolarization of the membrane potential (MP) and abolished fIJP and sIJP. Octanol had no effect on the MP and abolished fIJP and sIJP. Carbenoxolone produced a time-dependent depolarization of the MP without any effect on fIJP or sIJP. The connexin 43 mimetic gap junction blocker GAP-27 had no effect on MP, fIJP or sIJP. 4Based on the presently available gap junction blockers we found no evidence that gap junctions are involved in neuromuscular transmission in mouse colon, as suggested by morphological studies. [source] Direct chiral analysis of primary amine drugs in human urine by single drop microextraction in-line coupled to CEELECTROPHORESIS, Issue 16 2009Kihwan Choi Abstract Three-phase single drop microextraction (SDME) was in-line coupled to chiral CE of weakly basic amine compounds including amphetamine. SDME was used for the matrix isolation and sample preconcentration in order to directly analyze urine samples with the minimal pretreatment of adding NaOH. A small drop of an acidic aqueous acceptor phase covered with a thin layer of octanol was formed at the tip of a capillary by simple manipulation of the liquid handling functions of a commercial CE instrument. While the saline matrix of the urine sample was blocked by the octanol layer, the basic analytes in a basic aqueous donor phase were concentrated into the acidic acceptor drop through the octanol layer by the driving force of the pH difference between the two aqueous phases. The enantiomers of the enriched amines were resolved by using (+)-(18-crown-6)-tetracarboxylic acid as a chiral selector for the subsequent CE separation. From 10,min SDME with the agitation of the donor phase by a small stirrer retrofit to the CE instrument, enrichment factors were about a 1000-fold, yielding the LOD of 0.5,ng/mL for amphetamine. This low LOD value as well as the convenience of in-line coupled SDME make the proposed scheme well suited for the demanding chiral analysis of amphetamine-type stimulants. [source] Combined use of supported liquid membrane and solid-phase extraction to enhance selectivity and sensitivity in capillary electrophoresis for the determination of ochratoxin A in wineELECTROPHORESIS, Issue 7 2008Sara Almeda Abstract This paper proposes a novel strategy to enhance selectivity and sensitivity in CE, using supported liquid membrane (SLM) and off-line SPE simultaneously. The determination of ochratoxin A (OA) in wine has been used to demonstrate the potential of this methodology. In the SLM step, the donor phase (either a 20,mL volume of a standard solution at pH,1 or a wine sample at pH,8) was placed in a vial, where a micromembrane extraction unit accommodating the acceptor phase (1,mL water, pH,11) in its lumen was immersed. The SLM was constructed by impregnating a porous Fluoropore Teflon (PTFE) membrane with a water-immiscible organic solvent (octanol). In the off-line SPE step, the nonpolar sorbent (C-18, 4,mg) selectively retained the target ochratoxin, enabling small volumes of acceptor phase (1,mL) to be introduced. The captured analytes were eluted in a small volume of methanol (0.1,mL). This procedure resulted in sample cleanup and concentration enhancement. The method was evaluated for accuracy and precision, and its RSD found to be 5%. The LODs for OA in the standard solutions and wine samples were 0.5 and 30,,g/L, respectively. The results obtained demonstrate that SLM combined with off-line is a good alternative to the use of immunoaffinity columns prior to CE analysis. [source] QSARs for aromatic hydrocarbons at several trophic levelsENVIRONMENTAL TOXICOLOGY, Issue 2 2006Walter Di Marzio Abstract Quantitative structure,activity relationships (QSARs) with aromatic hydrocarbons were obtained. Biological response was measured by acute toxicity of several aquatic trophic levels. The chemicals assayed were benzene, toluene, ethylbenzene, o -xylene, m -xylene, p -xylene, isopropylbenzene, n -propylbenzene, and butylbenzene. Acute toxicity tests were carried out with Scenedesmus quadricauda, as representative of primary producers; Daphnia spinulata, a zooplanctonic cladoceran; Hyalella curvispina, a benthic macroinvertebrate; and Bryconamericus iheringii, an omnivorous native fish. The EC50 or LC50 was calculated from analytical determinations of aromatic hydrocarbons. Nonlinear regression analysis between the logarithm of the octanol,water partition coefficient (log Kow) of each compounds and the toxicity end points was performed. QSARs were positively related to increases in log Kow at all trophic levels. Intertaxonomic differences were found in comparisons of algae with animals and of invertebrates with vertebrates. We observed that these differences were not significant with a log Kow higher than 3 for all organisms. Aromatic hydrocarbons with log Kow values of less than 3 showed different toxicity responses, with algae more resistant than fish and invertebrates. We concluded that this was a result of the narcotic mode of action related to liposolubility and the ability of the compound to reach its target site in the cell. The bioconcentration factor (BCF) achieved to start nonpolar narcosis fell almost 1 order of magnitude below the BCF expected from the log Kow. Predicted critical body residues for nonpolar narcosis ranged between 2 and 1 mM. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 118,124, 2006. [source] Sampling in the Great Lakes for pharmaceuticals, personal care products, and endocrine-disrupting substances using the passive polar organic chemical integrative samplerENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2010Hongxia Li Abstract The passive polar organic chemical integrative sampler in the pharmaceutical configuration (i.e., pharmaceutical-POCIS) was calibrated for sampling at water temperatures of 5, 15 and 25°C to determine the influence of temperature on chemical-specific sampling rates (RS), thus providing more robust estimates of the time-weighted average concentrations of pharmaceuticals and personal care products (PPCPs) and endocrine-disrupting substances (EDS) in surface water. The effect of water temperature and flow on the RS of these analytes was evaluated in the laboratory with a static system. The loss of the test compounds from water by uptake into POCIS was linear over an 8-d period, and these experimental data yielded RS values in the range of 0.07 to 2.46 L/d across the temperature range for the 30 compounds tested. Water temperature and flow influenced POCIS uptake rates, but these effects were relatively small, which is consistent with the theory for uptake into POCIS samplers. Therefore, under a narrow range of water temperatures and flows, it may not be necessary to adjust the RS for POCIS. Except for acidic drugs and sulfonamide antibiotics, RS values were positively correlated with octanol,water partition coefficients (log KOW) of the test compounds. A linear relationship was also observed between RS and chromatographic retention times on a C18 reversed-phase column. These observations may provide a rapid method for estimating the RS of additional chemicals in the POCIS. The application of the RS to POCIS deployed for one month in Lake Ontario, Canada, during the summers of 2006 and 2008 yielded estimates of PPCP and EDS concentrations that are consistent with conventional concentration measurements of these compounds in Lake Ontario surface water. Environ. Toxicol. Chem. 2010;29:751,762. © 2009 SETAC [source] Persistent or not persistent?ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2009Polychlorinated biphenyls are readily depurated by grizzly bears (Ursus arctos horribilis) Abstract Major pharmacokinetic processes influencing polychlorinated biphenyl (PCB) accumulation in mammals include uptake, biotransformation, respiration, and excretion. We characterized some of the factors underlying PCB accumulation/loss by evaluating PCB concentrations and patterns in pre- and posthibernation grizzly bears (Ursus arctos horribilis) and their prey. The PCB congeners with vicinal meta - and para -chlorine unsubstituted hydrogen positions consistently showed loss both before and during hibernation, supporting the idea of a dominant role for biotransformation. Retention of all other studied congeners relative to that of PCB 194 varied widely (from <1 to 100%) and was highly correlated with log octanol--water partition coefficient (p < 0.0001). A lack of loss for most of these other congeners during hibernation supports the notion that excretion (e.g., fecal or urinary) or lack of uptake during the feeding season underlies their lack of accumulation, because hibernating bears do not eat or excrete. We estimate that grizzly bears retain less than 10% of total PCBs taken up from their diet. Our results suggest that for grizzly bears, depuration of PCBs via biotransformation is important (explaining ,40% of loss), but that nonbiotransformation processes, such as excretion, may be more important (explaining ,60% of loss). These findings, together with the approximately 91% loss of the persistent PCB 153 congener relative to PCB 194 in grizzly bears, raise important questions about how one defines persistence of PCBs in wildlife and may have bearing on the interpretation of food-web biomagnification studies. [source] Influence of soil pH on the sorption of ionizable chemicals: Modeling advancesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2009Antonio Franco Abstract The soil,water distribution coefficient of ionizable chemicals (Kd) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific Kd values normalized to organic carbon (KOC) from the literature, a method was developed to estimate the KOC of monovalent organic acids and bases. The regression considers pH-dependent speciation and species-specific partition coefficients, calculated from the dissociation constant (pKa) and the octanol,water partition coefficient of the neutral molecule (log Pn). Probably because of the lower pH near the organic colloid,water interface, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of pH on the total sorption is contrasting. In fact, the shortcomings of the model assumptions affect the predictive power for acids and for bases differently. We evaluated accuracy and limitations of the regressions for their use in the environmental fate assessment of ionizable chemicals. [source] Assessing exposure of sediment biota to organic contaminants by thin-film solid phase extractionENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2009Lizanne M. Meloche Abstract Differences in bioavailability among sediments are a source of variability and uncertainty in sediment quality assessment. We present three sets of studies designed to test a thin-film solid phase extraction technique for characterizing the bioavailability of organic chemicals in sediments. Laboratory studies with spiked natural sediments reveal highly reproducible thin-film extractions for chemicals with octanol,water partition coefficients between 104.5 and 108.5, with 95% equilibration times between 1 and 600 h. Studies with field-collected sediments illustrate that method detection limits are sufficiently low for field application at contaminated sites. Bioaccumulation studies with clams (Macoma balthica) show excellent correlations between thin-film and animal tissue concentrations. We conclude that thin-film extraction provides an ecologically relevant, fugacity-based measure of chemical exposure that can be expected to improve sediment quality assessments. [source] Estimating metabolic biotransformation rates in fish from laboratory dataENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2008Jon A. Arnot Abstract A method is proposed for estimating metabolic biotransformation rate constants for nonionic organic chemicals from measured laboratory bioconcentration and dietary bioaccumulation data in fish. Data have been selected based on a quality review to reduce uncertainty in the measured values. A kinetic mass balance model is used to estimate rates of chemical uptake and elimination. Biotransformation rate constants are essentially calculated as the difference between two quantities, a measured bio-concentration factor or elimination rate constant, and a model-derived bioconcentration factor or elimination rate constant estimated assuming no biotransformation. Model parameterization exploits key empirical data when they are available and assumes default values when study specific data are unavailable. Uncertainty analyses provide screening level assessments for confidence in the biotransformation rate constant estimates. The uncertainty analyses include the range for 95% of the predicted values and 95% confidence intervals for the calculated biotransformation values. Case studies are provided to illustrate the calculation and uncertainty methods. Biotransformation rate constants calculated by the proposed method are compared with other published estimates for 31 chemicals that range in octanol,water partition coefficients from approximately 101 to 108 and represent over four orders of magnitude in biotransformation potential. The comparison of previously published values with those calculated by the proposed method shows general agreement with 82% of the estimated values falling within a factor of three. [source] Measured partitioning coefficients for parent and alkyl polycyclic aromatic hydrocarbons in 114 historically contaminated sediments: Part 1.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006KOC values Abstract Polycyclic aromatic hydrocarbon (PAH) partitioning coefficients between sediment organic carbon and water (KOC) values were determined using 114 historically contaminated and background sediments collected from eight different rural and urban waterways in the northeastern United States. More than 2,100 individual KC values were measured in quadruplicate for PAHs ranging from two to six rings, along with the first reported KOC values for alkyl PAHs included in the U.S. Environmental Protection Agency's (U.S. EPA) sediment narcosis model for the prediction of PAH toxicity to benthic organisms. Sediment PAH concentrations ranged from 0.2 to 8,600 ,g/g (U.S. EPA 16 parent PAHs), but no observable trends in KOC values with concentration were observed for any of the individual PAHs. Literature KOC values that are commonly used for environmental modeling are similar to the lowest measured values for a particular PAH, with actual measured values typically ranging up to two orders of magnitude higher for both background and contaminated sediments. For example, the median log KOC values we determined for naphthalene, pyrene, and benzo[a]pyrene were 4.3, 5.8, and 6.7, respectively, compared to typical literature KOC values for the same PAHs of 2.9, 4.8, and 5.8, respectively. Our results clearly demonstrate that the common practice of using PAH KOC values derived from spiked sediments and modeled values based on n -octanol,water coefficients can greatly overestimate the actual partitioning of PAHs into water from field sediments. [source] Predicting single and mixture toxicity of petrogenic polycyclic aromatic hydrocarbons to the copepod Oithona davisaeENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2005Carlos Barata Abstract In the present study, the acute toxicity of 10 polycyclic aromatic hydrocarbons (PAH) associated with the Prestige fuel oil spill (Spain, 2002) were evaluated, either as single substances or in mixtures, in adults of the copepod Oithona davisae. All but dimethylphenanthrene had negative effects on O. davisae survival at concentrations below their water solubility, with 48-h median lethal concentrations for naphthalene and pyrene of 56.1 and 0.8 ,mol/L, respectively, making these the least and most toxic compounds. Polycyclic aromatic hydrocarbons had narcotic effects on copepods, as evidenced by the lack of motility at lower concentrations than those causing death. Naphthalene showed the greatest narcotic effects, and phenanthrene showed minor effects. Acute toxicity of the tested PAHs was inversely related (r2 = 0.9) with their octanol,water partition coefficient, thereby confirming the validity of the baseline quantitative structure,activity regression models for predicting the toxicity of PAH compounds in copepod species. When supplied in mixtures, the toxic effect of PAHs was additive. These results indicate that the many PAHs in an oil spill can be considered unambiguous baseline toxicants (class 1) acting additively as nonpolar narcotics in copepods; hence, their individual and combined toxicity can be predicted using their octanol,water partition coefficient. [source] Evaluation of the role of black carbon in attenuating bioaccumulation of polycyclic aromatic hydrocarbons from field-contaminated sediments,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2004Brita Sundelin Abstract The significance of black carbon (BC) for the bioavailability of polycyclic aromatic hydrocarbons (PAHs) was examined by using historically contaminated intact sediment cores in laboratory exposure experiments with the deposit-feeding amphipod Monoporeia affinis. Log values of amphipod biota,sediment accumulation factors (BSAFs) were significantly related to log BC, whereas log BSAFs were related to log octanol,water partition coefficients only in background sediments containing less BC. In the background sediments, the BSAF for polycyclic aromatic hydrocarbons (PAHs) was 1 to 2 for phenanthrene, with lower values for more hydrophobic PAHs, indicating an increase in nonequilibrium conditions with increasing PAH molecular size. For the near-equilibrated phenanthrene and fluoranthene, higher BSAFs were measured during exposure to background sediments, with BSAF decreasing to <0.1 in contaminated sediments in the Stockholm waterways. In situ caged mussels (Dreissena polymorpha) exhibited field BSAF values (relative to sediment-trap,collected suspended matter) for polychlorinated biphenyls (PCBs) of 0.1 to 0.4, but for PAHs of similar hydrophobicity and molecular size, the field BSAFs were much lower and in the range 0.002 to 0.05. This PAH,PCB dichotomy is consistent with recently reported much stronger binding to diesel soot (a form of BC) for PAHs than for PCBs of equal hydrophobicities. Lower BSAFs for the near-equilibrated PAHs (phenanthrene and fluoranthene) in the urban sediments relative to the background sediments were consistent with the larger presence of BC in the urban sediments. This study provides the first linked BSAF,BC field data that supports a causal relationship between strong soot sorption and reduced bioavailability for PAHs. [source] A thermodynamics-based estimation model for adsorption of organic compounds by carbonaceous materials in environmental sorbentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2003Paul C. M. van Noort Abstract A model was developed to estimate Langmuir affinities for adsorption of low-polarity organic compounds from either water or air by carbonaceous sorbents. Sorption enthalpies and entropies provided the basic information for the description of sorption affinities in terms of the entropy of melting and either solubility in water or vapor pressure. For m -xylene, polycyclic aromatic hydrocarbons (PAHs) and chlorobenzenes on 10 different sorbents, 80% of the measured sorption affinities fall within a factor of four of the model estimates. Equations for the limiting distribution coefficients in terms of either octanol,air (KOA) or octanol,water partition (Kow) coefficients were derived from regressions of calculated affinities combined with an estimated relation between experimental Langmuir sorption capacities and Kow. Estimated soot,water distribution coefficients were within a factor of three of measured data for polychlorobiphenyls (PCBs) and lower molecular weight PAHs on automotive soot samples and captured the dependence of PCB distribution coefficients on the extent of ortho substitution. For higher molecular weight PAHs, sorption was underestimated. For soot in sediment,water distribution coefficients of PAHs and PCBs, estimated values captured both the trend of measured data with Kow and the dependence on sorbate planarity. Tentative application to aerosol,air distribution explained the observed independence of distribution coefficient,KOA relations for PCBs on the extent of ortho substitution and suggested nonequilibrium conditions for PAHs in comparison with recent measurements. [source] Using measured octanol-air partition coefficients to explain environmental partitioning of organochlorine pesticidesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2002Mahiba Shoeib Abstract Octanol-air partition coefficients (Koa) were measured directly for 19 organochlorine (OC) pesticides over the temperature range of 5 to 35°C. Values of log Koa at 25°C ranged over three orders of magnitude, from 7.4 for hexachlorobenzene to 10.1 for 1,1-dichloro-2,2-bis (p-chlorophenyl) ethane. Measured values were compared to values calculated as KowRT/H (where R is the ideal gas constant [8.314 J mol,1 K,1], T is absolute temperature, and H is Henry's law constant) were, in general, larger. Discrepancies of up to three orders of magnitude were observed, highlighting the need for direct measurements of Koa. Plots of Koa versus inverse absolute temperature exhibited a log-linear correlation. Enthalpies of phase transition between octanol and air (,Hoa) were determined from the temperature slopes and were in the range of 56 to 105 kJ mol,1 K,1. Activity coefficients in octanol (,o) were determined from Koa and reported supercooled liquid vapor pressures (p), and these were in the range of 0.3 to 12, indicating near-ideal solution behavior. Differences in Koa values for structural isomers of hexachlorocyclohexane were also explored. A Koa -based model was described for predicting the partitioning of OC pesticides to aerosols and used to calculate particulate fractions at 25 and ,10°C. The model also agreed well with experimental results for several OC pesticides that were equilibrated with urban aerosols in the laboratory. A log-log regression of the particle-gas partition coefficient versus Koa had a slope near unity, indicating that octanol is a good surrogate for the aerosol organic matter. [source] Estimations of vapor pressure and activity coefficients in water and octanol for selected aromatic chemicals at 25°CENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Sum Chi Lee Abstract A roupcontribution method is developed to estimate the supercooled liquid vapor pressure and the activity coefficients in water and octanol at 25°C of 98 selected monoaromatic compounds, many of which are or have been produced as chlorinated by-products in the manufacture of pulp and paper. The set includes alkylphenols, chlorinated phenols, anisoles, catechols, cymenes, guaiacols, syringols, and veratroles. The method can be used to estimate vapor pressures, solubilities in water, octanol-water partition coefficients, octanol-air partition coefficients, and Henry's law constants. It can also be used for predicting these partition coefficients as well as solubilities and vapor pressures for these and structurally similar compounds. [source] Technical basis for narcotic chemicals and polycyclic aromatic hydrocarbon criteria.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2000Abstract A method is presented for developing water quality criteria (WQC) for type I narcotic chemicals in general and PAHs in particular. The criteria can be applied to any individual or mixture of narcotic chemicals using only the chemical's octanol-water partition coefficient KOW. It is derived from a database of LC50s comprising 156 chemicals and 33 species, including fish, amphibians, arthropods, mollusks, polychaetes, coelenterates, and protozoans. A target lipid model is proposed that accounts for variations in toxicity due to differing species sensitivities and chemical differences. The model is based on the idea that a target lipid is the site of action in the organism. Further, it is assumed that target lipid has the same lipid-octanol linear free energy relationship for all species. This implies that the slope of the log(LC50),log(KOW) relationship is the same for all species. However, individual species may have varying target lipid body burdens that cause toxicity. The target lipid LC50 body burdens derived from concentration data in the water only are compared to measured total lipid LC50 body burdens for five species. They are essentially equal, indicating that the target lipid concentration is equal to the total extracted lipid concentration. The precise relationship between partitioning in target lipid and octanol is established. The species-specific body burdens are used to determine the WQC final acute value, i.e., the 95-percentile level of protection. An acute-to-chronic ratio is used to compute the body burden corresponding to the WQC final chronic value, which is the procedure used to derive the U.S. Environmental Protection Agency water quality criteria. The criteria are expressed either as dissolved concentrations in the water column or as tissue concentrations. [source] Composition of the essential oil of Centaurea huber-morathii Wagenitz isolated from seeds by microdistillationFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2006K. Hüsnü Can Ba Abstract The volatile constituents of the seeds of Centaurea huber-morathii Wagenitz (Asteraceae), obtained by microdistillation, were analysed by GC and GC,MS. Eighty-five constituents were identified in the oil, with octanol (17.8%), hexadecanoic acid (8.0%), p -cymene (4.9%) and caryophyllene oxide (3.3%) as the major components. Copyright © 2006 John Wiley & Sons, Ltd. [source] Synthesis of morphologically different, metal absorbing aniline-formaldehyde polymers including micron-sized sphere using simple alcohols as morphology modifierJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Rik Rani Koner Abstract Aniline-formaldehyde condensate (AFC) is an amine functional group containing polymer. The sticky resinous nature of the polymer limits its usefulness. Synthesis of AFC in presence of methanol, isopropanol, t -butanol, n -octanol or glycerine formed solid cakes instead of resinous material. The scanning electron microscopic (SEM) picture of the polymer synthesized in presence of t -butanol shows the formation of micron sized spheroids while the presence of methanol, isopropanol, n -octanol and glycerine leads to amorphous polymer. The polymers were characterized with IR, MALDI-TOF mass and Energy Dispersive X-ray (EDAX) analysis. To probe the accessibility of the amine functional groups by external reagents and as an application, metal removal property of the polymers were tested using aqueous Cr(VI) solution. All the polymers remove Cr(VI) efficiently at pH 3 with extent of metal removal depends on their morphology. Polymer synthesized in presence of isopropanol removes , 66% Cr(VI) removal from an initial concentration of 9 mg/L. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Effect of octanol:water partition coefficients of organophosphorus compounds on biodistribution and percutaneous toxicity,,JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 5 2006Steven E. Czerwinski Abstract Knowledge of partition coefficient (log P) data can play a critical role in understanding the pharmacokinetic and pharmacodistributive properties of toxic organophosphorus (OP) compounds. Using a recently published gas chromatographic method, the octanol:water log P values for the compounds tabun (GA), sarin (GB), cyclosarin (GF), and O -ethyl- S -(2-diisopropylaminoethyl) methylphosphonothiolate (VX) were determined to be 0.384 ± 0.033, 0.299 ± 0.016, 1.038 ± 0.055, and 0.675 ± 0.070, respectively. Based on these data, the log P value of the fluorophosphonate fragment, common to GB, soman (GD), and GF, was determined to be ,2.256 ± 0.273. The predictive value for absorption and distribution of the determined log P values was compared to measured values. The time to onset of local fasciculations (47.3, 29.0, 8.8, 8.5, and 6.3 min, respectively) in guinea pigs exposed percutaneously to equilethal doses of GA, VX, GF, GB, or GD was used as an indicator of dermal penetration. There was a good correlation (r = 0.95) between the measured log P value and the rate of onset of local fasciculations. Assuming a direct correspondence, equilibrium tissue:blood log P may be estimated from octanol:water log P. Comparison of the estimated and directly measured tissue:blood log P revealed a correlation of 0.8 for GD in liver, muscle, and adipose tissue. Our results demonstrate the use of log P data to both predict absorption and determine the distribution of OP compounds in tissues. This facilitates further estimates of in vivo OP effects from in vitro experiments. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:241,246, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20140 [source] Solubilization of methanol and ethanol in palm oil stabilized by medium- and long-chain alkanolsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2002K Dzulkefly Abstract Solubilization of methanol and ethanol in crude palm oil, refined, bleached and deodorized palm oil (RBD PO) and RBD palm olein (POL) was studied using medium- and long-chain alkanols (C4,C12). Ternary phase diagrams were constructed to determine the solubilization (isotropic) region. The results showed that methanol and ethanol are solubilized to a greater extent in an unsaturated palm olein than the saturated CPO and RBD PO in the presence of long-chain alkanols. The minima of the solubilization curves for dodecanol, decanol and octanol were 27%, 30% and 33% of alkanol respectively in the methanol system, whereas in the ethanol system, the minima for the same alkanols were found at 22%, 24% and 27%. The longer chain-length alkanol (dodecanol) requires a lesser amount (21% and 32%) to achieve miscibility compared with 53% and 57% for butanol in mixtures containing 70:30 and 50:50 wt ratios respectively. The kinematic viscosity of the isotropic solutions increases with the chain-length and percentage of alkanols. Solubilization using a POL/methanol/butanol system significantly reduced the kinematic viscosity of POL from 72.7,mm2,s,1 to the value allowable for No 2 diesel fuel (1.9,4.1,mm2,s,1) or about a 96% reduction from the initial kinematic viscosity of POL. © 2002 Society of Chemical Industry [source] Prediction of octanol,water partition coefficients of organic compounds by multiple linear regression, partial least squares, and artificial neural networkJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2009Hassan Golmohammadi Abstract A quantitative structure,property relationship (QSPR) study was performed to develop models those relate the structure of 141 organic compounds to their octanol,water partition coefficients (log Po/w). A genetic algorithm was applied as a variable selection tool. Modeling of log Po/w of these compounds as a function of theoretically derived descriptors was established by multiple linear regression (MLR), partial least squares (PLS), and artificial neural network (ANN). The best selected descriptors that appear in the models are: atomic charge weighted partial positively charged surface area (PPSA-3), fractional atomic charge weighted partial positive surface area (FPSA-3), minimum atomic partial charge (Qmin), molecular volume (MV), total dipole moment of molecule (,), maximum antibonding contribution of a molecule orbital in the molecule (MAC), and maximum free valency of a C atom in the molecule (MFV). The result obtained showed the ability of developed artificial neural network to prediction of partition coefficients of organic compounds. Also, the results revealed the superiority of ANN over the MLR and PLS models. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 [source] Ab initio computational study of positron emission tomography ligands interacting with lipid molecule for the prediction of nonspecific bindingJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 14 2008Lula Rosso Abstract Nonspecific binding is a poorly understood biological phenomenon of relevance in the study of small molecules interactions in vivo and in drug development. Nonspecific binding is thought to be correlated in part to a molecule's lipophilicity, typically estimated by measuring (or calculating) octanol,water partition coefficient. This is, however, a gross simplification of a complex phenomenon. In this article, we present a computational method whose aim is to help identify positron emission tomography (PET) ligands with low nonspecific binding characteristics by investigating the molecular basis of ligand,membrane interaction. We considered a set consisting of 10 well-studied central nervous system PET radiotracers acting on a variety of molecular targets. Quantum mechanical calculations were used to estimate the strength of the interaction between each drug molecule and one phospholipid molecule commonly present in mammalian membranes. The results indicate a correlation between the computed drug,lipid interaction energy and the in vivo nonspecific distribution volume relative to the free tracer plasma concentration, calculated using standard compartmental modeling for the analysis of PET data. Significantly, the drugs whose interaction with the lipid molecule more favorably possessed, in general, a higher nonspecific binding value, whereas for the drugs taken in consideration in this study, the water-octanol partition coefficient, log P, did not show good predictive power of the nonspecific binding. This study also illustrates how ab initio chemical methods may offer meaningful and unbiased insights for the understanding of the underlying chemical mechanisms in biological systems. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] Dispersion and repulsion contributions to the solvation free energy: Comparison of quantum mechanical and classical approaches in the polarizable continuum modelJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2006Carles Curutchet Abstract We report a systematic comparison of the dispersion and repulsion contributions to the free energy of solvation determined using quantum mechanical self-consistent reaction field (QM-SCRF) and classical methods. In particular, QM-SCRF computations have been performed using the dispersion and repulsion expressions developed in the framework of the integral equation formalism of the polarizable continuum model, whereas classical methods involve both empirical pairwise potential and surface-dependent approaches. Calculations have been performed for a series of aliphatic and aromatic compounds containing prototypical functional groups in four solvents: water, octanol, chloroform, and carbon tetrachloride. The analysis is focused on the dependence of the dispersion and repulsion components on the level of theory used in QM-SCRF computations, the contribution of those terms in different solvents, and the magnitude of the coupling between electrostatic and dispersion,repulsion components. Finally, comparison is made between the dispersion,repulsion contributions obtained from QM-SCRF calculations and the results determined from classical approaches. © 2006 Wiley Periodicals, Inc. J Comput Chem, 2006 [source] Chromatographic partitioning of cesium by a macroporous silica-calix[4]arene-crown supramolecular recognition compositeAICHE JOURNAL, Issue 10 2010Anyun Zhang Abstract A macroporous silica-based 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) supramolecular recognition polymeric composite, (Calix[4]+Oct)/SiO2 -P, was synthesized. It was performed by impregnating and immobilizing Calix[4]arene-R14 and n -octanol into the pores of the macroporous SiO2 -P particles support. n -Octanol was used to modify Calix[4]arene-R14 through hydrogen bonding. The effect of eight typical fission products contained in highly active liquid waste (HLW) on the adsorption of Cs(I), one of the heat generators, was investigated at 298 K by examining the effect of contact time and the HNO3 concentration in a range of 0.3,7.0 M. (Calix[4]+Oct)/SiO2 -P showed excellent adsorption ability and high selectivity for Cs(I) at 4.0 M HNO3 over the tested elements. The partitioning of Cs(I) from a simulated HLW was operated by (Calix[4]+Oct)/SiO2 -P packed column. Cs(I) was able to be effectively eluted by water and separated from the tested metals. It is demonstrated that (Calix[4]+Oct)/SiO2 -P is promising to apply in chromatographic separation of Cs(I) from HLW. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Different mechanisms influencing permeation of PDGF-AA and PDGF-BB across the blood,brain barrierJOURNAL OF NEUROCHEMISTRY, Issue 1 2003Abba J. Kastin Abstract Platelet-derived growth factor (PDGF) exerts neurotrophic and neuromodulatory effects on the CNS. To determine the permeability of the blood,brain barrier (BBB) to PDGF, we examined the blood-to-brain influx of radioactively labeled PDGF isoforms (PDGF-AA and PDGF-BB) by multiple-time regression analysis after intravenous (i.v.) injection and by in-situ perfusion, and also determined the physicochemical characteristics which affect their permeation across the BBB, including lipophilicity (measured by octanol:buffer partition coefficient), hydrogen bonding (measured by differences in octanol : buffer and isooctane : buffer partition coefficients), serum protein binding (measured by capillary electrophoresis), and stability of PDGF in blood 10 min after i.v. injection (measured by HPLC). After i.v. bolus injection, neither 125I-PDGF-AA nor 125I-PDGF-BB crossed the BBB, their influx rates being similar to that of the vascular marker 99mTc-albumin. 125I-PDGF-AA degraded significantly faster in blood than 125I-PDGF-BB. PDGF-BB, however, was completely bound to a large protein in serum whereas PDGF-AA showed no binding. Thus, degradation might explain the poor blood-to-brain influx of PDGF-AA, whereas protein binding could explain the poor influx of circulating PDGF-BB. Despite their lack of permeation in the intact mouse, both 125I-PDGF-AA and 125I-PDGF-BB entered the brain by perfusion in blood-free buffer, and the significantly faster rate of 125I-PDGF-AA than 125I-PDGF-BB may be explained by the lower hydrogen bonding potential of 125I-PDGF-AA. Thus, the lack of significant distribution of PDGF from blood to brain is not because of the intrinsic barrier function of the BBB but probably because of degradation and protein binding. Information from these studies could be useful in the design of analogues for delivery of PDGF as a therapeutic agent. [source] Reverse osmosis of nonaqueous solutions through porous silica-zirconia membranesAICHE JOURNAL, Issue 2 2006Toshinori Tsuru Abstract Porous silica-zirconia membranes with pore diameters from 0.8 to 2 nm were prepared by a sol-gel process, and applied to the separation of alcohols (hexanol, octanol, decanol) and alkanes (hexane, decane, tetradecane) in ethanol solutions by reverse osmosis over the temperature range from 25 to 60° C. A silica-zirconia membrane with a pore diameter of 1 nm showed a molecular weight-cut-off (MWCO) of 200 in ethanol solutions. Rejection increased with the applied pressure, for both alcohol and alkane solutes. However, the rejection of alcohols was found to decrease with temperature, while that for alkanes remained nearly constant. The separation characteristics were examined for the following membrane parameters: solvent permeability, Lp, reflection coefficient, ,, and solute permeability, P, based on the Spiegler-Kedem equation. The viscosity of solutions and the diffusivity of alkanes and alcohol solutes in nano-sized pores were found to show a larger temperature dependency than in bulk. The diffusivity of alkane solutes showed the same temperature dependency as the viscosity of ethanol in nano-sized pores, while the diffusivity of alcohol solutes showed a larger temperature dependency than the viscosity of ethanol, probably because of a larger interaction between alcohol solutes and the hydrophilic surface of silica-zirconia membranes. Diffusion experiments were carried out to confirm the temperature dependency of the diffusivities in nano-sized pores. A bilayer model verified that solute permeabilities by reverse osmosis and diffusion experiments were consistent with each other. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] Synthesis, pharmacology, crystal properties, and quantitative solvation studies from a drug transport perspective for three new 1,2,4-thiadiazolesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2010German L. Perlovich Abstract A novel 1,2,4-thiadiazoles were synthesized. Crystal structures of these compounds were solved by X-ray diffraction experiments and comparative analysis of molecular conformational states, packing architecture, and hydrogen bonds networks were carried out. Thermodynamic aspects of sublimation processes of studied compounds were determined using temperature dependencies of vapor pressure. Thermophysical characteristics of the molecular crystals were obtained and compared with the sublimation and structural parameters. Solubility and solvation processes of 1,2,4-thiadiazoles in buffer, n -hexane and n -octanol were studied within the wide range of temperature intervals and thermodynamic functions were calculated. Specific and nonspecific interactions of molecules resolved in crystals and solvents were estimated and compared. Distribution processes of compounds in buffer/n -octanol and buffer/n -hexane systems (describing different types of membranes) were investigated. Analysis of transfer processes of studied molecules from the buffer to n -octanol/n -hexane phases was carried out by the diagram method with evaluation of the enthalpic and entropic terms. This approach allows us to design drug molecules with optimal passive transport properties. Calcium-blocking properties of the substances were evaluated. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3754,3768, 2010 [source] Thermodynamic and structural aspects of sulfonamide crystals and solutionsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2009German L. Perlovich Abstract The crystal structures of three sulfonamides with the general structure 4-NH2 -C6H4 -SO2NH-C6H4/3 -R (R,=,4-Et; 4-OMe; 5-Cl-2-Me) have been determined by X-ray diffraction. On the basis of our previous data and the results obtained a comparative analysis of crystal properties was performed: molecular conformational states, packing architecture, and hydrogen bond networks using graph set notations. The thermodynamic aspects of the sulfonamide sublimation process have been studied by investigating the temperature dependence of vapor pressure using the transpiration method. A regression equation was derived describing the correlation between sublimation entropy terms and crystal density data calculated from X-ray diffraction results. Also correlations between sublimation Gibbs energies and melting points, on the one hand, and between sublimation enthalpies and fusion enthalpies at 298 K, on the other hand, were found. These dependencies give the opportunity to predict sublimation thermodynamic parameters by simple thermo-physical experiments (fusion characteristics). Solubility processes of the compounds in water, n -hexane, and n -octanol (as phases modeling various drug delivery pathways and different types of membranes) were investigated and corresponding thermodynamic functions were calculated as well. Thermodynamic characteristics of sulfonamide solvation were evaluated. For compounds with similar structures processes of transfer from one solvent to another one were studied by a diagram method combined with analysis of enthalpic and entropic terms. Distinguishing between enthalpy and entropy, as is possible through the present approach, leads to the insight that the contribution of these terms is different for different molecules (entropy- or enthalpy-determined). Thus, in contrast to interpretation of only the Gibbs energy of transfer, being extensively used for pharmaceuticals in the form of the partition coefficient (log,P), the analysis of thermodynamic functions of the transfer process provides additional mechanistic information. This may be important for further evaluation of the physiological distribution of drug molecules and may provide a better understanding of biopharmaceutical properties of drugs. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:4738,4755, 2009 [source] | |||||||||||||||||||