Presence Of 1-propanol Research Articles

Fingerprinting pattern of orange essential oils in surfactant-free microemulsion by 3D fluorescence spectroscopy

The effect caused by surfactant-free microemulsion (SFME) systems in orange essential oil analysis was evaluated by 3D fluorescence spectroscopy. The SFME formation region was studied at different water:EO proportions (1:4, 1:2, 1:1, 2:1, 4:1 w/w) in the presence of propanol and octanol (10:3 w/w). Conductometric titrations indicated micellar aggregates containing EO (oil-in-water microemulsion) for the 4:1 proportion (droplets of hydrodynamic radius of 95.7 ± 5.3 nm). In such conditions, fluorescence increased allowing the use of 3D fluorescence spectroscopy to obtain spectroscopic fingerprint pattern that was used aiming discriminant analysis, considering nine EO Brazilian brands, along with unfold principal component analysis (UPCA). Cumulative variance of 96.7 % was obtained for the first three principal components and score plots showed distinct location for each group. Preliminary study showed the capability of these systems in evaluating storage conditions, and adulteration. The impact of storage conditions was made over 21 days exposed to light with results showing large spectral differences compared to a sample stored in amber flask at 22 °C. Adulteration of EOs by canola and mineral oil fortification was detected at different levels (1, 5, 10 and 20 %, in mass proportion) and, in addition to the spectral differences, a change in microemulsion stability was observed.

The frequency of ethanol, higher alcohols and other low molecular weight volatiles in postmortem blood samples from unnatural deaths

The determination of various volatiles in postmortem blood samples has been reported in many previous studies. The presence of some of them in postmortem specimens reflects microbial activity in the sample while others are detected mainly after consumption of alcoholic beverages or due to antemortem metabolic processes. This contribution aims to determine in 1954 postmortem blood samples, from respective number of unnatural deaths autopsy cases, the frequency of detection of some common volatile compounds, including acetaldehyde, acetone, 2-propanol, ethyl acetate, methanol, as well as, the higher alcohols 1-propanol, 1-butanol, isobutanol and 2-methyl-1-butanol and 3-methyl-1-butanol; moreover, their patterns in respect to the ethanol and 1-propanol concentrations and the putrefaction state of the corpse at autopsy. Acetone was the most frequently detected volatile (82 %), followed by acetaldehyde (44 %) and 2-propanol (34 %). Methanol was detected in 12 % of the samples and only in the presence of ethanol. The most frequently detected higher alcohol was 1-propanol (51 %), followed by isobutanol (8.5 %), 1-butanol (3.6 %) and methyl-butanols (2.0%); the latter three higher alcohols were detected in the presence of 1-propanol indicating possibly a common origin. Samples from cases with putrefaction had higher 1-propanol concentrations, than those without putrefaction, and, moreover, they were significantly correlated with 1-butanol concentrations.

A new hyper-thermostable carboxylesterase from Anoxybacillus geothermalis D9

Carboxylesterases are attractive biocatalysts for various industrial applications, especially hyperthermophilic carboxylesterases, due to their high tolerance toward extreme environments. Such ability confers many advantages, including cost-effectiveness and an increased manufacturing rate. In the current work, we first described the characterization of EstD9, a new carboxylesterase from thermophilic Anoxybacillus geothermalis D9. Sequence analysis of EstD9 revealed a significant identity (80 %) with thermophilic Est30 and a catalytic triad, composed of Ser93-His22-Asp193. As the protein sequence contained a conserved pentapeptide (GLSLG), EstD9 could be proposed as a new member of family XIII. The putative carboxylesterase was recombinantly expressed in E. coli BL21 (DE3) with a molecular mass of 28 kDa and successfully purified via affinity chromatography with recovery of 88.36 %. Using p-nitrophenyl butyrate, EstD9 presented excellent stability at high temperature range (70 °C–100 °C) and a broad pH tolerance (pH 6–9), with optimal activity at 80 °C and pH 7. Notably, EstD9 activity was stimulated in the presence of 1-propanol and DMSO with 107.8 % and 108.9 % relative activities, respectively. The purified EstD9 maintained 60 % residual activity after 30 min exposure to various surfactants and metal ions. Additionally, the inhibition studies demonstrated strong deactivation by phenylmethylsulfonyl fluoride, dithiothreitol, and β-mercaptoethanol. The estimated Tm value was 72.12 °C. Unlike typical carboxylesterases, in silico 3D model of EstD9 disclosed a topological α/β hydrolase fold with a small α-helix cap. The enzymatic properties of EstD9 suggest this enzyme to be a highly suitable catalyst for industrial bioprocesses under harsh conditions.

Formation and characterization of microemulsion with novel anionic sodium N-lauroylsarcosinate for personal care

Microemulsions are unique clear systems comprising of oil, water, surfactant and cosurfactants that offered stimulating perspectives in various applications. The purpose of these study was to create a microemulsion using novel amino acid based anionic sodium N-lauroylsarcosinate (SNLS) surfactant for application in personal care formulations. Triglyceride oils such as caprylic acid, oleic acid and carboxylic acid ester isoamyl acetate were used as oil phase, while short chain alcohols like propanol and butanol were used as cosurfactants. The gradual variations happening in the microstructure of the microemulsions were explored via several complementary characterization techniques. Phase diagrams constructed with or without cosurfactants and using different ratio of surfactant/ cosurfactant (Smix) showed that largest microemulsion region was observed only in the presence of cosurfactant and from Smix of 1:1. Solubility of SNLS in pure water is around 30 wt%, which upsurges in presence of propanol or butanol up to around 85 wt%. This leads to increase in microemulsion region in phase diagram with increasing solubility of oils in the SNLS solution. Microemulsions were relatively stable at an ambient temperature of 27 °C. The optical microscopy, electrical conductivity and viscosity measurement were performed to examine the microstructural changes within the microemulsion region. Three different phases such as water in oil (w/o), bicontinuous, and oil in water (o/w) microemulsion were observed. Foaming behavior specifies increased foam stability of SNLS in the presence of certain amount of oils. Dynamic light scattering study supports the well-defined microemulsion stability even after the manifold dilution. The results obtained from this study may have implications for the developments of an appropriate tactic to prepare stable microemulsion from SNLS which could be exceedingly favorable for personal care formulations.

Highly active organosulfonic aryl-silica nanoparticles as efficient catalysts for biomass derived biodiesel and fuel additives

Post-grafting methodologies were used to prepare aryl-organosulfonic acid functionalized silica nanoparticles (SO3H-aryl-SiO2NPs) as highly active heterogeneous acid catalysts for catalytic esterification of free fatty acids (FFA) and levulinic acid (LA), and aldol condensation of furfural with 3-methylfuran, well known renewable feedstocks for biodiesel and fuel additives production. The chemical and structural characterization of the SO3H-aryl-SiO2NPs confirmed the success of the functionalization. Complete conversion for all FFA was observed using SO3H-aryl-SiO2NPs after 2 h of reaction. SiO2NPs_CSPTMS showed to be the most active and stable catalyst with no significant loss of activity in the first 5 cycles. In the LA esterification in the presence of an alcohol, complete conversion and selectivity and high reusability were observed (e.g., 83.2% yield after 10 cycles in the presence of 1-propanol, SiO2NPs10_CSPTMS, at 120 °C and 2h reaction). Finally, aldol condensation of furfural and 3-methylfuran had been performed using SiO2NPs_CSPTMS catalysts with almost 100% yield after 10 min at 65 °C, high stability and reusability for 7 catalytic cycles.In general, the prepared SO3H-aryl-SiO2NPs have demonstrated promising catalytic performance for transformation of biomass-derived feedstocks into biodiesel and fuel additives.

Investigating the interaction of porcine pancreatic elastase and propanol: A spectroscopy and molecular simulation study

The response of porcine pancreatic elastase (PPE) to propanol was examined by various techniques including UV–vis spectrophotometry, spectrofluorometry and circular dichroism, as well as molecular docking and molecular simulation. These techniques were used to investigate the structural changes and elastase activity in the presence of propanol. This work was performed at three temperatures of 303, 313 and 323 K, with the pH value of 8.5 (Tris buffer). The results of the UV–vis spectrophotometry indicated the transfer of tryptophan to an environment with low hydrophobicity. Fluorescence measurements also revealed the quenching of fluorescence intensity was induced by propanol, and dynamic quenching was the proposed quenching mechanism. Kinetic studies also suggested the inhibitory effect (noncompetitive) of propanol on elastase. Further, Circular Dichroism (CD) spectra showed that propanol caused slight alterations in the secondary structures of PPE (0.3% increase for the α-helix and 0.5% decrease for the β-sheet). Addition of propanol decreased the Tm (Melting Temperature) parameter from 332.8 K to 330.1 K.

The effect of organic acids and alcohols on precipitation of phosphate using calcined seashell powder

This study elaborates on the use of calcined seashell powder (SP) for the precipitation of phosphate from solutions containing high concentrations of organic compounds. Precipitation of phosphate was carried out in pure phosphate solution containing 0.1, 0.5 or 1 g L−1 phosphate or pure phosphate solutions containing ethanol, propanol, propionic acid or lactic acid. The concentration of each organic compound was 1 M and the amount of calcined SP added to each batch was 2 g L−1. This amount of SP was sufficient to remove 0.5 g L−1 phosphate. Interestingly, at 1 g L−1 phosphate and in presence of propanol, propionic acid or lactic acid the precipitation was finished within 10 min. Contrarily, 120 min was needed in water or ethanol. In 1 M lactic acid and 0.1 or 0.5 g L−1 phosphate no or inhibited phosphate removal, respectively, was observed. The outcomes of this study revealed that organic acids and alcohols can have a positive or negative effect on the precipitation of phosphate. The effect is not only dependent on the organic compound, but also on the concentration of phosphate.

Propanol-Triggered Luminescence for Rapid Screening of Crystal Facets in Noble Metal.

The rapid and effective recognition techniques for crystal facets in noble metal nanocrystals (NCs) are highly desirable in evaluation of their catalytic performances. Herein, it was found that the variation trend of cataluminescence (CTL) intensity in the presence of propanol was proportional to the crystal facets index change of LDH-supported Pd@Au NCs. The mechanism investigation for the propanol-triggered CTL on the surface of layered double hydroxide (LDH)-supported Pd@Au NCs revealed that the abundant negative charge in the high-index facets of LDH-supported Pd@Au NCs facilitated electron transfer between NCs and volatile propanol, resulting in acceleration of the CTL reactions. Accordingly, the propanol-triggered CTL can be as an indicator for rapid screening of crystal facets in NCs. Its universality had further been verified by screening crystal facets in LDH-supported Pd NCs. The crystal facets detected by propanol CTL probe were well-matched with those obtained by conventional high-resolution transmission electron microscope. The proposed CTL strategy exhibits some advantages, such as convenient operation, rapid response, long-term stability, and low cost. And it is expected crystal facets of other kinds of NCs could be screened by replaceable CTL probe.

In-situ functionalized monolithic polysiloxane-polymethacrylate composite materials from polythiol-ene double click reaction in capillary column format for enantioselective nano-high-performance liquid chromatography

This work reports on the proof-of-principle of preparation of novel one step in-situ functionalized monolithic polysiloxane-polymethacrylate composite materials in capillary columns for enantioselective nano-HPLC using a thiol-ene click reaction. Quinine carbamate as functional monomer and ethylene dimethacrylate as crosslinker were both used as ene components in a thermally initiated double click-type polymerization reaction with poly(3-mercaptopropyl)methylsiloxane as thiol component in presence of 1-propanol as porogenic solvent. Elemental analysis and on-capillary fluorescence measurement proved the successful incorporation of the functional chiral monomer into the polymer. Scanning electron microscopy images revealed a macroporous polymer morphology which is typical for a nucleation and growth mechanism of pore formation. The individual microglobules appear relatively spherical and smooth indicating a non-porous nature. Nano-HPLC experiments of the chiral monolithic capillary column provided successful enantiomer separation of N-3,5-dinitrobenzoylleucine as test compound in polar organic elution mode clearly documenting the successful implementation of the proposed concept towards new functionalized monolithic composite materials.

Photocatalytic degradation of Reactive Black 5 and Malachite Green with ZnO and lanthanum doped nanoparticles

Here we report the preparation of ZnO particles with different concentrations of La3+ doping (0, 0.5 and 1 wt%) via sol-gel method. The nanoparticles are synthesized directly from Zn(CH3COO)2.2H2O in the presence of 1-propanol and triethylamine at 80°C. The conditions are optimized to obtain particles of uniform size, easy to isolate and purify. The nanoparticles are characterized by SEM, XRD and UV-Vis analysis. The photocatalytic properties of pure and La-doped ZnO are studied in the photobleaching of Malachite Green (MG) and Reactive Black 5 (RB5) dyes in aqueous solutions upon UV illumination. It is observed that the rate constant increases with the La loading up to 1 wt%. The doping helps to achieve complete mineralization of MG within a short irradiation time. 1 wt% La-doped ZnO nanoparticles show highest photocatalytic activity. The La3+ doped ZnO particles degrade faster RB5 than MG. The reason is weaker N=N bond in comparison with the C-C bond between the central carbon atom and N,N-dimethylaminobenzyl in MG. The as-prepared ZnO particles can find practical application in photocatalytic purification of textile wastewaters.

Immobilized lipase from Hypocrea pseudokoningii on hydrophobic and ionic supports: Determination of thermal and organic solvent stabilities for applications in the oleochemical industry

Hypocrea pseudokoningii purified lipase was immobilized on hydrophobic supports (phenyl-sepharose, butyl-sepharose, octyl-sepharose, Hexyl Toyopearl, Lewatit, Purolite, Decaoctyl sepabeads) and ionic supports (Duolite, DEAE-agarose, PEI-agarose, MANAE-agarose, and Q-sepharose). The immobilization processes resulted in derivatives with excellent thermal stabilities, increasing the half-life up to 500-fold. The derivatives had excellent stability to organic solvents compared to the crude lipase. In the presence of 50% ethanol, hexyl and Decaoctyl derivatives increased by about 6- and 3.5-fold their stability to organic solvents, respectively. When tested for methanol, phenyl-sepharose derivative also increased their stability to organic solvents in approximately 2-fold. Octyl-sepharose derivative was fully stable for 48h in the presence of propanol, which showed a half-life of about 7.5h. The greater activation of the derivatives occurred using 50% cyclohexane, in which the hexyl derivative obtained an increase in the activity of 9-fold and phenyl and octyl derivatives had their activity increased by 6-fold. The lipase showed activity on different oils. Therefore, the adsorption of lipases in low ionic strength and highly hydrophobic supports is shown to be a simple and rapid tool for the immobilization of H. pseudokoningii lipase. These derivatives strongly increase the chances of this biocatalyst for industrial application.

The influence of SDS micelle on the oxidative transformation of propanol to propionaldehyde by quinquivalent vanadium in aqueous medium at room temperature

The kinetics of propanol oxidation by quinquivalent vanadium in the presence of H2SO4 has been followed by UV-spectrophotometer at 30 °C temperature. It has been found that sodium dodecyl sulfate (SDS) micelles produce a large catalytic effect on this oxidation process. The pseudo-first-order rate constants for the reaction increases with SDS concentrations. The kinetic results have been explained by considering the preferential partitioning of reactants between the micellar and aqueous phase and also local the concentration effect. The oxidized product propionaldehyde is identified by 2,4-DNP test and 1H-NMR spectral measurement. The formation of aggregate in reaction condition was confirmed by measuring the CMC value of SDS in aqueous medium and in the presence of propanol by conductivity measurements. The change in the size of aggregate, from DLS measurement, confirms the localization of reactant species towards the aggregate, which is the consequence of rate enhancement.

Morphology and conductivity tuning of polyaniline using short-chain alcohols by heterophase polymerization

Conducting polyaniline (PANI) nanostructures were obtained by heterophase polymerization of aniline monomer using sodium dodecyl sulfate (SDS) as surfactant in presence of the short-chain alcohols: ethanol, propanol, butanol, pentanol, and hexanol as co-surfactants, and ammonium persulfate (APS) as oxidizing agent. The resulting polymers were analyzed by Field Emission, high resolution scanning electron microscopy (FE-HRSEM), UV/Vis, FTIR, cyclic voltammetry, and X-ray diffraction (XRD). It was observed from FE-HRSEM analysis that fiber-like particles were obtained when polymerizing without alcohol and in presence of ethanol, while very big agglomerates were obtained in presence of propanol and butanol; using pentanol as co-surfactant well-defined and spherical nanoparticles were obtained, the presence of hexanol through polymerization gives both spherical agglomerated and needle-like nanostructures. Final conversions were between 50 and 73 %, in the following order: hexanol = pentanol > butanol > thanol > propanol > without alcohol. Conductivities were in the range of 0.81 to 1.1 S/m with the higher value for that synthesized in presence of pentanol. Difference in conductivity of PANI was ascribed to formation of organic acids as a consequence of reaction between alcohols and APS, thus doping in situ PANI.

Vigabatrin in dried plasma spots: validation of a novel LC-MS/MS method and application to clinical practice.

This paper presents a LC-MS/MS method for the determination of antiepileptic drug vigabatrin in dried plasma spots (DPS). Due to its zwitterionic chemical structure, a pre-column derivatization procedure was performed, aiming to yield enhanced ionization efficiency and improved chromatographic behaviour. Propyl chloroformate, in the presence of propanol, was selected as the best derivatization reagent, providing a strong signal along with reasonable run time. A relatively novel sample collection technique, DPS, was utilized, offering easy sample handling and analysis, using a sample in micro amount (∼5μL). Derivatized vigabatrin and its internal standard, 4-aminocyclohexanecarboxylic acid, were extracted by liquid-liquid extraction (LLE) and determined in positive ion mode by applying two SRM transitions per analyte. A Zorbax Eclipse XDB-C8 column (150×4.6mm, 5μm particle size) maintained at 30°C, was utilized with running mobile phase composed of acetonitrile: 0.15% formic acid (85:15, v/v). Flow rate was 550μL/min and total run time 4.5min. The assay exhibited excellent linearity over the concentration range of 0.500-50.0μg/mL, which is suitable for the determination of vigabatrin level after per os administration in children and youths with epilepsy, who were on vigabatrin therapy, with or without co-medication. Specificity, accuracy, precision, recovery, matrix-effect and stability were also estimated and assessed within acceptance criteria.

Synthesis and Characterization of Nickel Oxide Nanoparticles from Ni(salen) as Precursor

Nickel oxide nanoparticles have been synthesized by thermal treatment of N,N′-(bis(salicylidene)-ethylene-1,2-diamine)Nickel(II); [Ni(salen)]; as precursor which has been synthesized via two methods: [Ni(salen)] were obtained by solid state reaction in absence solvent and co-precipitation reaction in presence of propanol as solvent, respectively. Nickel oxide nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy.

Preparation and application of hydrophobic hybrid monolithic columns containing polyhedral oligomeric silsesquioxanes for capillary electrochromatography

Hydrophobic organic-inorganic hybrid monolithic columns were synthesized via thermally initiated free radical polymerization with the confines of 75 μm id capillary using a polyhedral oligomeric silsesquioxane (POSS) reagent containing eight or more methacrylate groups as the crosslinker. Three organic functional monomers, butyl methacrylate (BuMA), lauryl methacrylate (LMA) and methacrylic acid (MAA), were selected and copolymerized with the POSS in the presence of 1-propanol and 1,4-butanediol to prepare the poly(POSS-co-BuMA), poly(POSS-co-LMA), and poly(POSS-co-MAA) monoliths, respectively. The 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) was copolymerized as ionizable monomer into the poly(POSS-co-BuMA) and poly(POSS-co-LMA) for the generation of EOF in capillary electrochromatography (CEC). A hybrid poly(POSS-co-LMA-co-MAA) monolith was also similarly prepared by copolymerizing ternary monomers of POSS, LMA, and MAA, and compared with poly(POSS-co-BuMA), poly(POSS-co-LMA), and poly(POSS-co-MAA) monoliths. The resulting four kinds of POSS-contained hybrid monoliths exhibited good permeability and mechanical stability. Their column efficiencies were evaluated by the separation of alkylbenzene homologues and polar compounds in CEC. The results indicated that the highest efficiencies of 194,100 and 102,100 theoretical plates per meter for thiourea and benzene were obtained on the poly(POSS-co-LMA-co-MAA) monolith. Additionally, the poly(POSS-co-LMA-co-MAA) monolith exhibited better selectivity for separation of polar compounds than those of other hybrid monoliths.

Short monolithic columns for purification and fractionation of peptide samples for matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry analysis in proteomics

This study records a novel application of methacrylate-based monolithic columns for MALDI-TOF/TOF MS analyses in proteomics for pre-concentration and separation of peptides derived from protein digestion. Reversed-phase monolithic capillary columns (30 mm × 0.32 mm i.d.) were created inside the fused silica capillary via thermal-initiated free-radical polymerization of ethylene glycol dimethacrylate and lauryl methacrylate monomers in the presence of 1-propanol and 1,4-butandiol as a porogen system. The elution of peptides was achieved using a linear gradient of acetonitrile from 0 to 60% in water with 0.1% trifluoroacetic acid formed in a microsyringe. Individual fractions of separated peptides were collected on the MALDI target spots covered with alpha-cyano-4-hydroxycinnamic acid used as a matrix and then they were analyzed using MALDI-TOF/TOF mass spectrometry. The developed method was tested with a mixture of tryptic peptides from bovine serum albumin and its applicability was also tested for tryptic in-gel digests from barley grain extracts of water soluble proteins separated using SDS gel electrophoresis. The number of detected peptides was approximately three to four times higher compared to the analysis without previous separation. These results show an improved quality of sample information with the higher amount of identified peptides which increased protein sequence coverage and improved sensitivity of mass spectrometry measurements.

Sonochemical reduction of permanganate to manganese dioxide: The effects of H 2O 2 formed in the sonolysis of water on the rates of reduction

Chemical effects of ultrasound have been actively researched in the field of the synthesis of various metal nanoparticles and nanostructured materials. It is very important to understand the reduction mechanism of metal ions, because the reduction processes can be often applied to the synthesis of various materials. In this study, the sonochemical reduction of MnO 4 - to MnO 2 in water under Ar atmosphere was investigated to discuss the reduction mechanism. It has been reported that H, OH, H 2 and H 2O 2 are formed from the sonolysis of water. To understand the roles of H 2O 2 on the reduction, the reaction of MnO 4 - with H 2O 2 without ultrasonic irradiation was investigated. The obtained results suggested the progress of the following reaction: 2 MnO 4 - + 3 H 2 O 2 → 2 MnO 2 + 3 O 2 + 2 OH - + 2 H 2 O . In addition, the rates of the sonochemical reduction of MnO 4 - were investigated in the presence of 1-propanol, where 1-propanol acted as an OH radical scavenger so that the amounts of the sonochemically formed H 2O 2 molecules were able to be controlled. The results clearly indicated that the sonochemically formed H 2O 2 molecules as well as H 2 molecules and H atoms play an important role for MnO 4 - reduction. This mechanism was also supported by the analysis of pH changes during ultrasonic irradiation: the pH value increased as the sonochemical reduction of MnO 4 - proceeded.

The adsorption tendency of cetylpyridinium bromide at water–air interface and micelles formation in the presence of propanol

The effect of propanol concentration on the adsorption behaviour at water–air interface and micelle formation of cetylpyridinium bromide (CPBr) was investigated by surface tension measurements of aqueous solutions of CPBr and propanol mixtures. The measured values of surface tension as a function of propanol concentration in the range from 0 to 6.67 M were compared with those calculated from Miller et al. equation. From comparison it results that the mixtures of the CPBr and propanol in the surface monolayer behaved as ideal ones if the monolayer was formed by adsorption of CPBr and propanol from the solution in the concentration range of CPBr corresponding to unsaturated layer of CPBr in the absence of propanol. However, at concentration of CPBr in aqueous solution corresponding to saturated monolayer of CPBr without propanol the deviation from ideal behaviour was observed, and the pressure of the mixed monolayer cannot be predicted by Miller et al. equation derived for the mixtures of the homological series of surfactants or surfactant and alcohols having comparable hydrocarbon chain. On the basis of the obtained experimental and calculated results it was suggested that the aggregation process influences not only CPBr adsorption at solution–air interface but also the micelle formation in the bulk phase. The obtained relationship between CMC and propanol concentration indicates that CMC values considerably increase at the propanol concentration close to that at which probably aggregation of propanol molecules takes place. Above this concentration no formation of CPBr micelles was observed. The measured values of the surface tension were used in Gibbs equation for calculations of surface excess concentration of CPBr and propanol. Next, taking into account the calculated values from this equation and assuming a certain thickness of the interface region, the values of CPBr and propanol concentration in this region were determined. The values for propanol are going through a maximum corresponding to propanol concentration in the bulk phase equal to 1.07 M. On the basis of the values of CPBr and propanol concentration in the surface layer and the bulk phase, the values of the standard free energy of adsorption were calculated. The values of the standard free energy of adsorption obtained in this way were compared with those calculated from the modified Langmuir equation.

Interaction of alcohols with serum LDL: An infrared study

The interaction of low molecular weight alcohols with low density lipoprotein (LDL) has been studied using amide I band-fitting, thermal profiling and two-dimensional infrared correlation spectroscopy (2D-IR). At 0.3 M alcohol, no changes in secondary structure are observed. In the presence of 1 M alcohol, ethanol and propanol decreases protein denaturation temperature and produces changes in the amide I thermal profiles of protein components and in the lipid bands. The 2D-IR synchronous map corresponding to protein or lipid component at 20–37 °C suggests differences in the presence of propanol. The asynchronous map corresponding to the lipid component indicates changes in bandwidth, compatible with a more fluid environment. In the 37–80 °C temperature range the thermal profile is different in the presence of propanol, both for the lipid and protein components. The results presented show that when alcohols affect the protein component, the lipid spectrum also varies pointing to an effect on the lipid-protein interaction.