Absorption Of Organic Solvents Research Articles

Exciton Chirality. (A) Origins of and (B) Applications from Strongly Fluorescent Dipyrrinone Chromophores

(A) The origin of exciton interaction and examples of its application to organic stereochemistry are presented. (B) N,N′-Carbonyl-bridged dipyrrinones constitute a new class of highly fluorescent chromophores suitable for investigations of stereochemistry and absolute configuration. N,N′-Carbonylxanthobilirubic acid esters are strongly fluorescent, with a fluorescence quantum yield (φF) ∼0.8, but produce only weak exciton CD from the trans-1,2-cyclohexanediol template. The ester of an analog with benzoic acid replacing propionic, N,N′-carbonyl-8-(4-carboxyphenyl)-3-ethyl-2,7,9-trimethyl-(10H)-dipyrrin-1-one, exhibits strong fluorescence (φF=0.68, λem=493 nm, λex=422 nm in CHCl3) and UV-Vis absorption (ɛ∼21000 at 424 nm) in organic solvents. Its diester with (1S,2S)-cyclohexanediol is fluorescent and exhibits exciton circular dichroism (Δɛ=+15 dm3·mol−1·cm−1, λ=432 nm; Δɛ=−4 dm3·mol−1 cm−1, λ=380 nm) that correlates with the Exciton Chirality Rule.

Organic solvent absorption characteristics of split-type microfiber fabrics

Split-type nylon/polyester microfiber and polyester microfiber fabrics possess drapeability, softness, bulkiness, and smoothness, so that they can be applied in various industrial fields. In particular, these fabrics are able to absorb various organic solvents, and can be used as clean room materials. To investigate the chemical affinity between solvents and the compositional materials of these fabrics, the contact angle of thermally pressed film fabrics was measured with different solvents. The thermally pressed nylon/polyester fabric films showed a chemical attraction to formamide. The sorption properties of the microfiber fabrics were investigated using a real time testing device, and these tests showed that the sorption behavior was more influenced by the structure of the fibrous assembly than by any chemical attraction. The effect of the fabric density, specific weight, and sample structure on the sorption capacity and rate was examined for various organic solvents. The sorption capacity was influenced by the density and the specific weight of the fibrous assembly, and knitted fabric showed a higher sorption capacity than woven fabric. However, the sorption rate was less affected in lower viscosity solvents. On applying Poiseuille’s Law, the lower viscosity solvents showed higher initial sorption rates, and more easily penetrated into the fibrous assembly.

Numerical method to evaluate the influence of organic solvent absorption on the conductivity of polymeric composites

A theoretical analysis that describes the change in electric properties of polymeric composites, filled with conductive aggregates, during organic solvent absorption processes is presented in this work. This methodology takes into account the moving boundaries typical of this phenomena; requiring simple numerical procedures to be solved. The results show no numerical instabilities during the calculation process. The obtained results correlate very close to the available experimental data; therefore could be very useful for chemical sensor design.

Dermal exposure to m-xylene leads to increasing oxidative species and low molecular weight DNA levels in rat skin.

Dermal absorption of organic solvents, such as m-xylene, can lead to skin inflammation and pathological changes within hours after exposure. This study detected oxidative species formation and low molecular weight (LMW) DNA in rat skin as potential indicators of m-xylene-induced skin injury. At 0, 1, 2, 4, and 6 h after the beginning of a 1-h exposure, skin samples were removed and analyzed for oxidative species formation and LMW DNA analysis. At 2 h, mean oxidative species levels increased significantly (P < 0.05) above unexposed samples. Significantly higher (P < 0.05) LMW DNA values were observed at 2, 4, and 6 h compared to unexposed controls. These results show that oxidative species formation and LMW DNA levels in the skin may serve as indicators for predicting safe exposure levels to m-xylene and other volatile organic solvents.

Percutaneous absorption of organic solvents.

Organic solvents pass the cutaneous barriers and may quickly be absorbed in substantial amounts, such that several solvents have "skin" denotations in lists of occupational exposure limit values. Solvents may be absorbed from liquids, upon direct skin contact, and in some cases also from contact with vapors. Environmental factors such as temperature, humidity, vehicle, and ventilation influence absorption. Absorption rates vary considerably; several amphiphilic solvents are absorbed at high rates. Since solvents are volatile, unoccluded repeated exposures result in less absorption than does continuous contact, and adequate ventilation may reduce absorption considerably. Risk assessments of skin absorption of organic solvents have benefited from calculation of quantitative structure-activity relationships based on log P(o/w), which enables skin absorption to be calculated with reasonable accuracy.

Influence of evaporation and solvent mixtures on the absorption of toluene and &lt;italic&gt;n&lt;/italic&gt;-butanol in human skin in vitro

The influence of forced ventilation on the percutaneous absorption of butanol and toluene was studied in vitro. Human skin was exposed to the neat solvents and the solvents in binary mixtures with each other and in ternary mixtures with chloroform:methanol. The exposure was either unventilated or ventilated with various flow rates. At the ventilated exposure the skin absorption of all solvents and solvent mixtures was markedly reduced compared to unventilated exposure. Exposure with solvent mixtures increased the amounts of solvent absorbed as well as absorption rates. The absorption of the butanol component was most influenced. Increase in absorption was 11 to 9 times depending on whether toluene or chloroform/methanol was cosolvent. There was also an interindividual variation of absorption rate, varying with a factor of 3.5 for toluene and 4.3 for n-butanol within the 3 skin donors used. Skin absorption of volatile organic solvents at continuous ventilated conditions is related to their volatility and to the ventilation rate.A sufficient workplace ventilation is an important occupational hygienic measure not only to reduce exposure via respiration but to reduce absorption via the skin of volatile compounds as well.

Influence of evaporation and solvent mixtures on the absorption of toluene and n-butanol in human skin in vitro

The influence of forced ventilation on the percutaneous absorption of butanol and toluene was studied in vitro. Human skin was exposed to the neat solvents and the solvents in binary mixtures with each other and in ternary mixtures with chloroform:methanol. The exposure was either unventilated or ventilated with various flow rates. At the ventilated exposure the skin absorption of all solvents and solvent mixtures was markedly reduced compared to unventilated exposure. Exposure with solvent mixtures increased the amounts of solvent absorbed as well as absorption rates. The absorption of the butanol component was most influenced. Increase in absorption was 11 to 9 times depending on whether toluene or chloroform/methanol was cosolvent. There was also an interindividual variation of absorption rate, varying with a factor of 3.5 for toluene and 4.3 for n-butanol within the 3 skin donors used.Skin absorption of volatile organic solvents at continuous ventilated conditions is related to their volatility and to the ventilation rate.A sufficient workplace ventilation is an important occupational hygienic measure not only to reduce exposure via respiration but to reduce absorption via the skin of volatile compounds as well.

Effect of the third acrylated vinyl comonomer on absorption and desorption properties of styrene-divinylbenzene-alkyl acrylate terpolymers, imbibing solvent on a water surface

A series of imbiber terpolymer beads was prepared by radical suspension copolymerization of styrene–divinylbenzene with varied contents of acrylated vinyl monomers, n-butyl acrylate and 2-ethyl hexyl acrylate, as the third comonomer. A DVB content of 6 wt % and a mixture of 60/40 wt % toluene/n-heptane as the diluent were used throughout this study. The influence of acrylated vinyl comonomers on bead properties and swelling properties was investigated. The imbiber beads are capable of absorption and desorption of organic solvents having solubility parameters in the range of 14.9–20.9 (MPa)1/2. Styrenic imbiber beads were swelled in a toluene/n-heptane mixture of 50% by volume and the kinetics of absorption was studied. The imbiber beads could absorb the toluene/n-heptane mixture completely within 20 min and yielded a maximum swelling ratio of 6.8. The diffusion coefficient values of these beads were in the range of 6.40 × 10−6 to 1.52 × 10−5 cm2 s−1. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 504–516, 2001

Orientation and immersion depth of a helical lipopeptaibol in membranes using TOAC as an ESR probe.

Trichogin GA IV is a lipopeptaibol antibiotic characterized by the sequence nOct-Aib1-Gly-Leu-Aib4-Gly-Gly-Leu-Aib8-Gly-Ile- Lol (nOct: n-octanoyl; Aib: alpha-aminoisobutyric acid; Lol, leucinol), which exhibits membrane-modifying properties. We synthesized step-by-step by solution methods three trichogin analogues, each with a single Aib --> 2,2,6,6-tetramethylpiperidin-1-oxyl-4-amino-4-carboxylic acid (TOAC) substitution. The similarity in the conformational propensities of the Calpha-tetrasubstituted alpha-amino acids Aib and TOAC allowed us to exploit these analogues to investigate the orientation and therefore the mechanism of action of trichogin in the membranes by the electron spin resonance (ESR) technique. A conformational analysis by Fourier transform ir absorption and CD in different organic solvents and in a membrane-mimetic environment indicated that the conformation of the natural lipopeptaibol remains almost unchanged in the three analogues. Moreover, for all of the analogues permeability measurements revealed membrane-modifying properties comparable to those of trichogin. Our ESR investigation demonstrated that, in liposomes based on phosphatidylcholine, trichogin lays parallel to the membrane surface with its hydrophobic face oriented toward the membrane interior. These results suggest that trichogin might modify membrane permeability via a carpet-like mechanism, at least in liposomes and in the absence of a transmembrane potential.

Styrene-Divinylbenzene Copolymers: Influence of the Diluents on Absorption and Desorption Properties

Styrene-divinylbenzene copolymers with porous structures were prepared by seeded suspension polymerization using toluene and heptane as diluents. The influence of each diluent on the formation of porous structure and the swelling ratio was investigated. The styrene-DVB beads are capable of absorption and desorption of organic solvents having solubility parameters in the range of 17.6–19.6 (MPa)1/2. Styrenic imbiber beads were swelled in toluene and the kinetics of absorption was studied. The imbiber bead could absorb toluene completely within 90 min and yielded a maximum swelling ratio of 12.7. The diffusion coefficient values of these beads were in the range of 1.55 × 10−5 to 3.68 × 10−5 cm2 · s−1.

Schlieren visualization of natural convection in binary gas–liquid systems

Natural convection in 23 gas–liquid systems in a quiescent cell is visualized by Schlieren techniques. CO 2 absorption and desorption in 16 organic solvents and MEA aqueous solutions, and evaporation and condensation in six binary liquid mixtures are studied. Experimental data on densities and surface tensions of mixtures under investigation is presented. An empirical linear relationship between the density effect of CO 2 saturation and solvent density is obtained. Visual evidence is discussed in terms of coupled Rayleigh and Marangoni convection. Observed convection patterns are compared and grouped into four classes according to the signs of Ma and Ra numbers. In Rayleigh-unstable systems, density-driven plume convection dominates and interfacial turbulence is absent or weak. In Rayleigh-stable systems, cellular convection, accompanied sometimes by horizontal stratification and/or interfacial turbulence, is observed. Six distinct types of interfacial turbulence are found and explained by a combination of Marangoni instability and thermal effects. A special type of small-scale interfacial turbulence that occurs during Marangoni-stable CO 2 absorption in organic solvents is attributed to the coupling of thermal effects of gaseous absorption and solvent evaporation. Surface temperature histories are studied for CO 2 absorption into four solvents; thermal effects of absorption are responsible for the diverging flow that accompanies absorption. Intensive density-driven convection that takes place during chemical absorption of CO 2 into MEA aqueous solutions is photographed.

ヘアレスラットにおける有機溶剤の経皮吸収と病理学的変化

ヘアレスラットにおける有機溶剤の経皮吸収と病理学的変化

Is there tissue penetration after application of topical salicylate formulations?

Many of the topical non-steroidal products used for treatment of local pain or inflammation contain either a salicylate ester (methyl, glycol) or salicylate salt (triethanolamine, diethylamine). There is controversy as to whether the active ingredient in these formulations penetrates into deeper tissues after application or is removed by the dermal blood supply to the skin. 1 Roberts MS Favretto WA Meyer A et al. Topical bioavailability of methylsalicylate. Aust N Z J Med. 1982; 12: 305-306 Crossref PubMed Scopus (37) Google Scholar . We measured dermal and subcutaneous concentrations of salicylates after topical application and compared salicylate concentrations in microdialysate 2 Anderson C Anderson T Boman A et al. Cutaneous microdialysis for the measurement in-vivo of the percutaneous absorption of organic solvents. Curr Prob Dermatol. 1996; 25: 37-46 PubMed Google Scholar from dermal and subcutaneous probes with plasma concentrations.

Separation of alkylbenzyl quaternary ammonium compounds by capillary zone electrophoresis Effect of organic solvent in sample solution

The important role played by the organic solvent in the sample solution in the capillary electrophoretic separation of alkylbenzyldimethyl ammonium compounds (ABDACs) is demonstrated. An organic solvent must be added to disrupt the micelles in the sample solution for effective separation of ABDACs. An organic solvent must also be added to the background electrolyte to disrupt micelles. Typically, methanol at a minimal content of 60% (v/v) or acetonitrile at 30% (v/v) is necessary for complete micelle disruption of a sample at a concentration 0.01 m M when using a phosphate buffer (20 m M) containing 30–40% (v/v) acetonitrile at pH 5.0. The effect of organic solvent in the sample solution is interpreted in terms of the absorption of organic solvents by micelles and the disruption of micelles into individual surfactant ions. The extent of disruption of micelles depends on the concentration of the sample. For complete disruption of micelles of ABDACs in a polar non-aqueous solvent, acetonitrile (40%, v/v) must be added to the phosphate buffer.

Cutaneous microdialysis for the measurement in vivo of the percutaneous absorption of organic solvents.

Cutaneous microdialysis for the measurement in vivo of the percutaneous absorption of organic solvents.

Investigation of the contact charge transfer absorption of organic solvents with oxygen for use in oxygen determination

The contact charge transfer (CCT) absorption spectra of dimethylsulphoxide (DMSO), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), ethanol, methanol, water, benzene (Bz), N, N'-diethylaniline (DEA), N, N'-dimethyl- p-toluidine (DMT) and N, N'-diethyl- p-toluidine with molecular oxygen have been investigated. These solvents form strong ultraviolet/visible CCT absorption spectra with intensities that are related to the partial pressure of the applied oxygen. DMSO, DMF, DMA, Bz, DEA and DMT are shown to form 1:1 molecular contact complexes with molecular oxygen. A simple oxygen sensing system is described using CCT absorption spectroscopy of DMT at a wavelength of 400 nm, with a gas flow rate of 60 cm 3 min −1 through the solvent in a cuvette with a pathlength of 1 cm. Inexpensive plastic fibres are used to relay the light from a xenon lamp source to the cuvette and back to a photo-detector. The response of the sensing system to changes in oxygen concentration is reversible, non-linear and in good agreement with the Beer-Lambert law. The most sensitive response region is from 0 to 20% O 2 with a change in signal level of about 35%. The solvent used shows no deterioration in performance over a long period and can be used to determine gaseous oxygen concentrations from 0 to 100%. It does not respond to carbon dioxide.

Percutaneous absorption of organic solvents during intermittent exposure in guinea pigs.

Skin absorption under intermittent exposure of guinea pigs to n-butanol, toluene, 1,1,1-trichloroethane was studied. Groups of guinea pigs were exposed to test organic solvents for 1 min at 30-min intervals during 4 h, in all 8 exposures. Skin absorption of solvent was assessed by following the concentration of solvent in the blood. This intermittent exposure was compared to continuous exposure over 4 h. Absorption of toluene and 1,1,1-trichloroethane was low, but a considerable amount of butanol was absorbed through the skin on intermittent exposure. A typical serrated absorption profile was seen for butanol that was less pronounced for toluene and 1,1,1-trichloroethane. The absorption of butanol was highest at the end of the exposure period. The differences in absorption profiles may be due to the differences in vapour pressure in the solvents in association with the animal method used. The amount absorbed varied inversely with vapour pressure. Hair stubble may act as a trap for solvents with low vapour pressure. Adequate ventilation reduces unoccluded skin absorption of volatile organic solvents.

Thermal lensing resulting from one- and two-photon absorption studied with a two-color time-resolved Z scan

The dual-beam (pump, probe) time-resolved Z-scan technique is used to study the thermal changes in refractive index that are due to one- and two-photon absorption in organic solvents. The time resolution enabled us to select a pure thermal signal and to measure absolute variations as small as 10−6 that were due to heating. Gaussian approximation was used for the pump and probe beams to fit experimental and calculated model dependencies.

Triazinylaniline derivatives as fluorescence probes. Part 1. Absorption and fluorescence in organic solvents and in aqueous media in relation to twisted intramolecular charge-transfer state formation, hydrogen bonding, and protic equilibria

The UV absorption and fluorescence characteristics of new optical probes based on a 1,3,5-triazinylaniline chromophore and of general structure p-Et2NC6H4C3N3(Cl)NR1R2 are reported. Increase in alkanol solvent polarity strongly quenches the fluorescence by a process attributed to TlCT (twisted intramolecular charge-transfer) state formation with co-operative solvent relaxation (log kNR/s–1 8.5–10.5). In aqueous media no changes in fluorescence band position or intensity are observed in the pH range 3.5 to 11 but below pH 3.5 protonation of the anilino nitrogen (pKaca. 2.4) eliminates both the λ= 360 nm absorption band and the weak λ= 460 nm fluorescence band. Free and hydrogen-bonded species, with respect to the anilino nitrogen centre, are present in aqueous dioxane solutions.The triazinylaniline derivatives are prototypes of promising sensitive probes for organized media and as models of proteins labelled with the triazinylaniline fluorophore.

Percutaneous absorption of 3 organic solvents in the guinea pig

The efficacy of 3 protective glove materials against percutaneous absorption of organic solvents was investigated in the guinea pig. All 3 materials gave a reduction in blood concentration of the solvents, particularly in the early phase of exposure. Of the tested materials, butyl rubber showed the best protective effect, followed by PVC and natural rubber. Gloves of polymeric material can be considered as offering sufficient protection against percutaneous absorption of organic solvents only if their selection is based on results obtained in a controlled and adequately performed test.