Low Molecular Organic Compounds Research Articles

Detection of Cyclic Volatile Organic Compounds Using Single-Step Anodized Nanoporous Alumina Sensors

Conventional methods of fabricating anodic aluminum oxide (AAO) materials have utilized a multistep anodization process to manufacture sensor substrates and templates for nanostructured materials. The multistep anodization produces structured, highly ordered hexagonal nanopores. In this paper, it is demonstrated that a single-step anodization process employed in the manufacturing of moisture sensors produces a nanoporous AAO material suitable for the detection and discrimination of low molecular weight volatile organic compounds. Electrical impedance methods have been employed to analyze the electrical response of the single-step anodized AAO materials in the presence of cyclic organic vapors. The sensor exhibits an impedance response that discriminates cyclohexane, cyclohexene, benzene, toluene, and the three isomers of xylene. The impedance measurements have a direct correlation with the relative permittivity, polarizability, and dipole moments of the organic analytes.

Fungal treatment of hemp-based pulp and paper mill wastes

This paper examined the ability of Penicillium camemberti to degrade hemp-based pulp and paper plant bleachery effluents in batch and up-flow column reactor studies. In batch tests, the highest removals for acid-line effluents (67% AOX (adsorbable organic halogens), 44% TOC 8 total organic carbon), 97% color) were obtained with 2 g/l acetate concentration in 10 days. Acid-line and alkali-line composite effluent was also fed to a column reactor with of 17 mg/l. AOX concentration. In column studies, the highest removals (57% AOX, 67% TOC, and 74% color) and (57% AOX, 48% TOC and 73% color) were obtained with 0.5 and 0.2 g/l feed acetate concentration in 20 days, respectively. Gas chromatography analysis indicated drastic reductions at low molecular weight adsorbable organic halogen compounds. Key words: Hemp, bleaching, adsorbable organic halogens, pulping, Penicillium camemberti, molecular weight, up-flow reactor.

Degradation of Low Molecular Weight Volatile Organic Compounds by Plants Genetically Modified with Mammalian Cytochrome P450 2E1

Cytochrome P450 2E1 (CYP2E1) is a key enzyme in the mammalian metabolism of several low molecular weight volatile organic compounds (VOCs), such as trichloroethylene (TCE), vinyl chloride (VC), carbon tetrachloride (CT), benzene, chloroform, and bromodichloromethane (BDCM), which are all common environmental pollutants that pose risks to human health. We have developed a transgenic tobacco (Nicotiana tabacum cv. Xanthii) that expresses CYP2E1 with increased activity toward TCE and ethylene dibromide. In experiments with tobacco plant cuttings exposed to VOCs in small hydroponic vessels, the transgenic tobacco had greatly increased rates of removal of TCE, VC, CT, benzene, toluene, chloroform, and BDCM, compared to wild-type or vector control tobacco, but not of perchloroethylene or 1,1,1-trichloroethane.

α‐d‐Mannopyranosyl‐(1→2)‐α‐d‐glucopyranosyl‐(1→2)‐glycerate in the thermophilic bacterium Petrotoga miotherma − structure, cellular content and function

The intracellular accumulation of low molecular mass organic compounds in response to stressful conditions was investigated in the thermophilic bacterium Petrotoga miotherma, a member of the order Thermotogales. This led to the discovery of a new solute, whose structure was established as alpha-D-mannopyranosyl-(1-->2)-alpha-D-glucopyranosyl-(1-->2)-glycerate (MGG) by MMR spectroscopy and MS. Under optimum growth conditions (3% NaCl; 55 degrees C), MGG was the major solute [up to 0.6 micromol.(mg protein)(-1)]; alpha-glutamate and proline were also present but in minor amounts [below 0.08 micromol.(mg protein)(-1)]. The level of MGG increased notably with the salinity of the growth medium up to the optimum NaCl concentration. At higher NaCl concentrations, however, the level of MGG decreased, whereas the levels of proline and alpha-glutamate increased about five-fold and 10-fold, respectively. MGG plays a role during low-level osmotic adaptation of Petrotoga miotherma, whereas alpha-glutamate and, to a lesser extent, proline are used for osmoprotection under salt stress. MGG is not part of the cell strategy for coping with heat or oxidative stress. Nevertheless, MGG was an efficient protector of pig heart malate dehydrogenase against heat inactivation and freeze-drying, although mannosylglycerate was better. This is the first report on the occurrence of MGG in living systems.

Dehalogenation and decolorization of wheat straw-based bleachery effluents by Penicillium camemberti

This paper examined the capability of Penicillium camemberti to dechlorinate and decolorize wheat straw-based pulping and bleaching effluents. In batch tests, the highest removals for CEH (Chlorination-Extraction-Hypochlorite) bleaching sequence [65% organic halides (AOX) 84% color] were obtained with 2 g/l acetate concentration in 10 days under non-shaking conditions. Experiments in shaking flasks containing Tween 80 produced 60% AOX, 79% color removals in 10 days. This removal efficiency was also in accord with gas chromatography analysis indicating drastic reductions at low molecular weight adsorbable organic halogen compounds.

Removal of antibiotics from a model wastewater by RO/NF membranes

Removal of antibiotics by reverse osmosis/nanofiltration (RO/NF) from a model wastewater of a manufacturing plant producing pharmaceuticals for veterinary use was investigated. The rejection of the examined antibiotics by the selected RO and the tight NF membranes is acceptably high, exceeding in most cases 98.5%. The loose NF membrane retains the smaller antibiotics molecules less effective. Relating the solute rejections to the membranes’ porosity has shown that the prevailing rejection mechanism of the examined antibiotics by all the membranes was the size exclusion effect. The rejection of the low molecular organic compounds by all the examined membranes is lower, ranging from 0.517 to 0.976 for the RO and tight NF membranes, and from 0.247 to 0.506 for the loose NF membrane. The rejections also follow the order of the solutes’ molecular size. However, the specific physicochemical effects can influence the rejection of some low molecular organics by the examined membranes.

Studies on the effect of humic acids and phenol on adsorption–ultrafiltration process performance

Application of pressure-driven membrane processes, such as ultrafiltration (UF) and microfiltration (MF) for surface water treatment have become very popular during last decades. Membrane fouling by humic substances (HS) is one of the major limiting factors in these processes. In order to alleviate the unfavorable effects of the presence of HS in the feed on the process performance UF and MF are often combined with adsorption on powdered activated carbon (PAC). The main goal of the present study was to evaluate the effect of humic acid (HA) on membrane fouling during UF. Moreover, the effect of PAC addition to the feed on UF process, especially on flux decline was determined. The applicability of the adsorption-ultrafiltration (PAC/UF) system to purification of water containing low (phenol) and high molecular (HA) was also investigated. Three different polymer UF membranes, prepared from polysulfone (PSF), cellulose acetate (CA) or polyacrylonitrile (PAN) were applied. It was found that the membranes prepared from PSF and CA are very susceptible to fouling caused by HA. The permeate flux decreased for ca. 50% during UF of HA solution through the PSF membrane and for ca. 45%-through the CA membrane. In the case of the PAN membrane, a negligible effect of HA on the flux was observed. On the basis of the FTIR spectra it was found that the drop in the permeate flux through these membranes may result from interactions between the negatively charged functional groups present on the membrane surface, such as carboxyl groups (CA) and sulfone groups (PSF) with HA, which results in coating of the membrane surface with HA. When PAC was added to the feed containing HA, the permeate flux through the CA and PAN membranes was maintained on a practically unchanged level. However, in case of the PSF membrane, a 50% drop in the permeate flux in comparison with the flux value, when process was conducted without PAC addition was observed. That was supposed to be due to attractive forces among hydrophobic PAC particles, HA molecules and PSF membrane surface. The performed studies showed that the application of PAC/UF system was very effective in the removal of organic substances having both, low and high molecular weights. The role of PAC suspended in a feed in the PAC/UF system is the adsorption of low molecular organic compounds, which cannot be removed by UF alone.

Influence of hydrocarbons on element detection in ion images by SIMS microscopy

Ion microscopy on fresh frozen cryostat sections, 5–10 μm thick, is useful to determine the distribution of elements and low molecular organic compounds in the larger areas of the tissues. Fresh frozen cryostat sections of tree frog eyeball were examined. Secondary ion images of Na, Mg, Al, C 2H 3, K, Ca and C 3H 5 were observed by ion microscopy (IMS-6f) using O 2 + as the primary beam source at an energy of 15 keV. The primary beam current was 10 −10 A, the ion image magnification was varied from 300 to 1500 and the mass resolution was set between 300 and 3000. The areas of high intensity ion counts of the organic compounds generally showed low ion counts of elements. After long exposure to the primary ion beam, the intensity of the organic compound ions decreased, whereas the intensity of atomic ions of elements increased.

Photochemical Properties of Polyethylene Modified by Low-Molecular Organic Compounds

Commercial polyethylene (LDPE) was physically modified by low-molecular organic compounds for acceleration of photodegradation. Two ketones (acetophenone, benzophenone) and two aromatic chloro-derivatives (benzyl chloride and 1-chloromethyl naphthalene) in the same amounts (1%wt) were used for PE modification. The influence of UV irradiation on thin films of doped PE was studied using Fourier transform infrared (FT-IR) and UV-vis spectroscopy. Much higher yields of photoprocesses in polyethylene (PE) containing modifiers were confirmed. Effectiveness of modifier depends on chemical structure and absorption of incident UV-radiation. The possibility of obtaining of degradable packaging films based on modified PE is suggested.

Degradation of 2-Chlorophenol by Fenton and Photo-Fenton Processes—A Comparative Study

The oxidation potentiality of simulated aqueous solution of 2-chlorophenol (2-CP) by Fenton's reagent was assessed for wastewater treatment. Batch experiments were carried out to investigate the effects of pH, hydrogen peroxide (H2O2), and ferrous ion (Fe2+) concentrations. Degradation reaction occurred within a limited pH range of 2.5–4.0. Maximum degradation occurred at a concentration of 22 mM of H2O2 and at 0.45 mM of Fe2+. Influence of temperature on degradation of 2-CP was investigated. Arrhenius plot for the degradation of 2-CP at various temperatures was plotted based on the experimental data. The role of solar light and UV in photo-fenton degradation of 2-CP was investigated and compared with Fenton process. In both Fenton and photo-fenton processes, free chloride ion generated from 2-CP degradation process reached a maximum concentration at a very short interval of time. Maximum DOC removal of 39% was achieved in Fenton's process (i.e.,) only 2/5th of compound was mineralized. The efficiency of mineralization was considerably improved to 95–97% in photo-fenton processes. Low molecular weight aliphatic organic compounds like oxalic acid and acetic acid formed during the reaction were monitored for Fenton's process. The fate of these stable intermediates compounds in photo-fenton processes were also discussed.

Size fractionation of non-volatile dissolved organic compounds and metal species in German white wines by combining on-line tangential-flow multistage ultrafiltration, a home-built carbon analyser, and inductively coupled plasma mass spectrometry.

Organic metal species and their size fractions in three German white wines were characterized by combining multistage ultrafiltration (MST-UF), determination of non-volatile dissolved organic carbon (NV-DOC) by a home-built carbon analyser, and metal quantification by inductively coupled plasma mass spectrometry (ICP-MS). First, NV-DOC and metal species in selected "dry" German white wines were fractionated on-line using MST-UF in the size range of >100 kDa to <1 kDa. For this purpose a 20 mL sample of the wine under study diluted 1:10 with high-purity water was processed through a cascade system of hydrophilized polyethersulfone-based flat membranes of decreasing cut-off (100, 50, 10, 5, and 3 kDa). An aliquot of the fraction <3 kDa was additionally processed through a commercial UF tube (MidGee system, cut-off: 1 kDa) to obtain low-molecular size fractions also. A home-built carbon analyser was applied to determine NV-DOC in the wines and their size fractions. The NV-DOC found in a German reference wine and its size fractions was as follows: total NV-DOC: 8.97 mg mL(-1); F(1) (>100 kDa), 0.15%; F(2) (50-100 kDa), 0.44%; F(3) (10-50 kDa), 0.74%; F(4) (5-10 kDa), 0.76%; F(5) (5-3 kDa), 0.7%; F*(6) (3-1 kDa), 0.9%; F(7) (<1 kDa), 81.6% (related to total NV-DOC). The NV-DOC recovery was 85.2%. Accordingly, most of the NV-DOC in this wine consists of low-molecular mass organic compounds of <1 kDa, presumably carboxylic acids as typical in wine. Parallel metal determinations in these wines and their fractions were performed by ICP-MS. The measurements showed that the major part of the metals investigated, up to 25 elements, were dissolved in the size fraction of <1 kDa except Ba, Sr and Pb which appeared also in other fractions. In addition, conventional UV-VIS spectroscopy was applied to characterise the studied wines and their size fractions. According to this, the UV absorbance between 254 and 280 nm of these white wines shows a parallel trend to their NV-DOC.

Treatment of diseases due to infections and old age using anti-foaming agents

The biochemical changes taking place in the organism in the course of ageing and infectious processes result in substantial catabolic processes during which a variety of gases are created (in addition to carbon dioxide and nitrogen, depending on the conditions, methane, ammonia, hydrogen sulphide, mercaptan, etc. are also created) in addition to peptides and low molecular organic compounds. These gases are dispersed in the extra-cellular space and in the capillary system of blood and lymph in the form of micro-foam. The accompanied disturbance in the ability to flow considerably impairs the immune defence system which is inseparably connected to the transport of catabolic products. Any resulting diseases can be alleviated or even removed by the application of a simple physical–chemical principle. Anti-foaming agents (solutions, all types of dispersions, micro-emulsions) based on polydimethylsiloxane but also based on fatty acid esters (preferably unsaturated fatty acids) are proposed for treatment purposes.

Reactivity of Contact Allergenic Haptens to Amino Acid Residues in a Model Carrier Peptide, and Characterization of Formed Peptide-Hapten Adducts1

The type of chemical reaction between hapten and carrier protein in the formation of a complete antigen in vivo giving rise to an allergic contact dermatitis (ACD, type IV allergy) is essentially unknown. About 4,000 low-molecular organic compounds are known to have allergenic properties. α,β-Unsaturated carbonyl structures are frequently present among these compounds. Haptens giving rise to antibody formation and type I allergy have been shown to add predominantly to lysine in the carrier protein. In this paper, the reactivity of activated type IV haptens to a model peptide is reported. Essentially all amino acids with nucleophilic properties were present in the model peptide. Investigation of the relative reactivities of the amino acid residues to activated haptens under biomimetic conditions is performed in order to determine the proportions between the adducts of the different amino acid moieties. In all cases, the electrophilic α,β-unsaturated haptens were found to be added to the cysteine residue and no lysine adduct was recorded. Nuclear magnetic resonance (NMR) spectroscopy was used to exclude steric hindrance of any amino acid residue in the addition reaction. The hapten-modified peptides were isolated and characterized by NMR and mass spectrometry.

A Study of Sensitivity of Ceriodaphnia affinis Lilljeborg to Tap Water of the City of Kiev

The reliability of toxicity tests with the use of Ceriodaphnia affinis Lilljeborg as test objects can be significantly reduced or eliminated because of the use of tap water for blanks and dilution, as it is recommended by the relevant Ukrainian regulatory document. In order to get at least a rough idea about the causes of toxicity, tap water was treated physically and chemically to exclude various groups of toxicants. The results show that low-molecular organic compounds rather than inorganic ones cause the difficulties at determination of harmfulness of drinking tap water. Further gas- chromatographic analyses should be carried out to specify those compounds, but it is already obvious that the Ukrainian regulatory document should be changed in this point.

Complexes of bivalent metal cations in electrospray mass spectra of common organic compounds.

In the standard electrospray ionization mass spectra of many common, low molecular mass organic compounds dissolved in methanol, peaks corresponding to ions with formula [3M + Met](2+) (M = organic molecule, Met = bivalent metal cation) are observed, sometimes with significant abundances. The most common are ions containing Mg(2+), Ca(2+) and Fe(2+). Their presence can be easily rationalized on the basis of typical organic reaction work-up procedures. The formation of [3M + Met](2+) ions has been studied using N-FMOC-proline methyl ester as a model organic ligand and Mg(2+), Ca(2+), Sr(2+), Ba(2+), Fe(2+), Ni(2+), Mn(2+), Co(2+) and Zn(2+) chlorides or acetates as the sources of bivalent cation. It was found that all ions studied form [3M + Met](2+) complexes with N-FMOC-proline methyl ester, some of them at very low concentrations. Transition metal cations generally show higher complexation activity in comparison with alkaline earth metal cations. They are also more specific in the formation of [3M + Met](2+) complexes. In the case of alkaline earth metal cations [2M + Met](2+) and [4M + Met](2+) complex ions are also observed. It has been found that [3M + Met](2+) complex ions undergo specific fragmentation at relatively low energy, yielding fluorenylmethyl cation as a major product. [M + Na](+) ions are much more stable and their fragmentation is not as specific.

Organic Matter Utilization and Destruction in Water Bodies at Different Trophic Level

It has been established that phytoplankton actively takes up low-molecular organic compounds, while high-molecular organic matter is utilized mainly by bacterioplankton. It has been found that algae utilize high-molecular compounds only in the presence of bacteria, because the latter take up final products of hydrolysis rather than release lytic enzymes into the environment.

Rapid contamination screening of river sediments by flash pyrolysis-gas chromatography–mass spectrometry (PyGC–MS) and thermodesorption GC–MS (TdGC–MS)

For 20 years, pyrolysis-gas chromatography–mass spectrometry (PyGC–MS) has been currently used in order to improve the knowledge on recent (soils and sediments) and fossil complex organic matter. Actually, PyGC–MS is also proposed as a rapid tool for the investigation of different types of sediment contaminations. Such rapid investigations allowed to increase the number and the frequency of the controls of river sediments, which are generally time and money consuming. However, during flash pyrolysis, the molecules generated derive from both macromolecules breakdown and thermovaporization of free compounds. Then, a methodology allowing the fractionation of these two types of effluents should be developed. Two river sediments showing different contamination degrees have been investigated in order to test the different modes of pyrolysis. The efficiency of thermodesorption-gas chromatography–mass spectrometry (TdGC–MS) at low temperature (300°C) for the study of free molecules (PAH, hydrocarbons, …) is compared with the results derived from traditional analysis (extraction, liquid chromatography and GC–MS). On the other hand, pyrolysis of pre-thermodesorbed sediments is carried out in order to analyze the residual organic matter. However, the use of thermodesorption instead of solvent extraction for free organic matter removal is not always efficient especially for high molecular mass compounds. On the other hand, although heavy molecular mass compounds are frequently underestimated, the use of TdGC–MS remains an efficient tool for the rapid screening for contaminant investigation. Moreover, low molecular mass organic compounds which are generally lost during traditional pre-treatment (extraction followed by reconcentration steps) are detected after thermodesorption of the raw sediment.

Autowave exothermic organic synthesis in the mixes of organic solids

The autowave modes of organic exothermic synthesis in the mixes of organic solids were studied. A traveling wave of exothermic reaction of organic synthesis appeared in the mixes at local thermal ignition. Useful low-molecular organic compounds having, at least, synthetic value were found out with good yields after the reactions. Autowave modes were observed in different classes of organic reactions – red-ox, halogenation, protonation, acylation, imination etc. The possibility to organize the autowave modes is determined by the exothermic nature of the reaction (≥20 kJ/mol), phase condition and thermal stability of the reagents and products. Main peculiarities, kinetics and mechanisms of the reactions in autowave modes were investigated. The basic advantages of autowave exothermic synthesis in organic solids were analyzed.

Photoinitiated degradation of polystyrene in the presence of low-molecular organic compounds

The influence of low-molecular organic compounds such as benzophenone (BPh), anthraquinone (AQ) and benzoyl peroxide (BPo) on the phototransformations of polystyrene has been investigated. The viscometry, gravimetry, infrared and UV–vis spectroscopy has been used in these studies. The results indicate that additives applied accelerate and increase the efficiency of photodegradation, photodestruction and photo-oxidation processes in polystyrene but they hamper the photocrosslinking and formation of the double bonds in this polymer. In all these processes, BPh showed the greater activity as photoinitiator comparing to AQ and BPo.

ADSORPTION OF FLUOMETURON AND NORFLURAZON: EFFECT OF TILLAGE AND DISSOLVED ORGANIC CARBON

Adsorption is an important process that influences the fate and behavior of herbicides in soil. The herbicide adsorption process is influenced by both the dissolved and the solid soil organic carbon (DOC and SOC) content of soil. Both properties are affected by tillage management and biosolid utilization. This study was undertaken to examine the influence of tillage practice and various DOC sources and concentrations on the adsorption and desorption of fluometuron (N, N-dimethyl-N′-[3-(trifluoromethyl)phenyl] urea) and norflurazon (4-chloro-5(methylamino)-2-(3-(trifluoromethyl)phenyl)-3(2H)-pyridazinone) in the Lexington silt loam (fine-silty, mixed, thermic, Typic Paleudalf). Batch adsorption/desorption studies were performed in the presence and absence of DOC extracted from poultry litter, dairy manure, and no-till surface soil. Herbicide adsorption is influenced strongly by soil organic carbon (SOC) content, with all soils having a greater affinity for norflurazon, relative to fluometuron. Average Koc values of 100 and 500 were determined for fluometuron and norflurazon. The influence of DOC on herbicide adsorption was a function of DOC source and concentration. Poultry litter DOC, characterized as having greater hydrophobicity and high-molecular-mass organic compound content, and dairy manure DOC (containing both low- and high-molecular-mass organic compounds) reduced herbicide adsorption. No-till DOC (hydrophilic with low molecular mass organic compounds) did not influence herbicide adsorption. In general, herbicide desorption was completely reversible. However, the equilibration period required to achieve reversibility varied with herbicide type, adsorption condition (DOC vs. no DOC), and DOC source and concentration in the desorption system. The reduction in herbicide adsorption in the presence of DOC could be attributed to the formation of soluble herbicide-DOC complexes. Further, herbicide desorption from mineral surfaces (low SOC soil) was observed to be more kinetically restricted relative to desorption from SOC (high SOC soil).