Performance of a biotrickling filter in the removal of waste gases containing low concentrations of mixed VOCs from a paint and coating plant

The performance of a field-scale biotrickling filter (BTF) in the removal of waste gases containing low concentrations of mixed volatile organic compounds was evaluated. Results showed that acetone and methyl ethyl ketone (MEK) were more easily removed than toluene and styrene. The removal efficiency for acetone and MEK reached over 99% on days 28 and 25 of the operation, whereas those for toluene and styrene were 80 and 63% on day 38. The maximum individual elimination capacities for styrene, toluene, acetone, and MEK were 10.2, 2.7, 4.7, and 8.4 g/m³ h, respectively. These values were achieved at inlet loading rates of 13.9, 3.3, 4.8, and 8.5 g/m³ h, respectively, at an empty bed retention time of 14 s. the removal efficiency for styrene and toluene rapidly increased from 67% and 83% to 86% and over 99%, respectively, when the concentration of ammonia nitrogen (N–NH₄ ⁺) and phosphates (P) in the nutrients increased from 350 to 840 mg/l and 76 to 186 mg/l. When the BTF was restarted after a four-day shutdown, the removal efficiency for toluene was restored to over 99% within a week. However, that for styrene was not restored to its previous level before the shutdown. No noticeable adverse effect on acetone and MEK removal was observed. Denaturing gradient gel electrophoresis results for the bacterial community in the BTF during VOC removal showed that proteobacterial phylum was dominant, and the changes of nutrient concentration and shutdown periods may have played a role in the community structure differences.     

Biofiltration of ketone compounds by a composite bead biofilter

In this study, the biochemical kinetic behaviors of ketone compounds in a composite bead biofilter were investigated. Both microbial growth rate kg and biochemical reaction rate kd would be inhibited at higher average inlet concentration. For the microbial growth process, the inhibitive effect was the least pronounced for acetone and the order of kg value was MEK>MIPK>acetone in the average inlet concentration range of 100-150 ppm. The degree of inhibitive effect was almost the same for three ketone compounds and the order of kg value was acetone>MEK>MIPK in the average inlet concentration range of 200-300 ppm. The values of half-saturation constant Ks for acetone, MEK and MIPK were 26.80, 21.56 and 22.96 ppm, respectively. The values of maximum reaction rate Vm for acetone, MEK and MIPK were 8.55, 9.06 and 7.55 g-C/h-kg packed material, respectively. The zero-order kinetic with the diffusion rate limitation could be regarded as the most adequate biochemical reaction model. For the biochemical reaction process, the inhibitive effect was the most pronounced for MEK and the order of kd value was MEK>acetone>MIPK in the average inlet concentration range of 100-150 ppm. The degree of inhibitive effect was MIPK>MEK>acetone and the order of kd value was acetone>MEK>MIPK in the average inlet concentration range of 200-300 ppm. The maximum elimination capacity of acetone, MEK and MIPK were 0.157, 0.127 and 0.101 g-C/h-kg packed material.     

Performance and Microbial Diversity of a Trickle‐Bed Air Biofilter under Interchanging Contaminants

A trickle‐bed air biofilter (TBAB) was evaluated under conditions of interchanging the feed volatile organic compounds (VOCs) in the sequence methyl ethyl ketone (MEK), toluene, methyl isobutyl ketone (MIBK), styrene, and then back to MEK. The obtained performance results revealed that the biofilter provided high removal efficiency within the critical loading of each VOC, which was previously defined in the non‐interchanging VOC fed biofilter. The biofilter easily acclimated to the oxygenated compounds (MEK and MIBK), but re‐acclimation was delayed for the aromatic compounds (toluene and styrene). Ratios of the molar mass of CO₂ produced per molar mass of VOC removed were investigated. It has been found that the ratios for the aromatic compounds closely resembled the theoretical complete chemical oxidation based ratios while larger differences were encountered with the oxygenated compounds. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes was used to assess the impact of interchanging VOCs on the bacterial community structure in the biofilter. The results from denaturing gradient gel electrophoresis (DGGE) showed that the structure of the microbial community in the biofilter was different after each interchange of VOCs.     

The occupational meaning of smell

The sense of smell has its meaning for a successful performance of certain occupations. It has further a protective meaning. The acuity of smell often changes for different reasons. The prolonged or repeated smelling is combined with the process of smell adaptation, fatigue and habituation. They diminish the flavour sensations and increase the risk of work accidents. Some chemical compounds are characterized by a quick and high adaptation. The occupational changes of smell can be peripheral or central. The qualitative changes of the smell perception are numerous, but they have little sense in industrial hygiene. The hypersensibilisation can be temporal or lasting, where a change of profession is sometimes inevitable. The values of smell thresholds (detection, recognition, distinction) of 25 substances are given. The sensitivity of smell is greater at the smell threshold concentrations. The smell thresholds are put among the main basic properties of chemical compounds which decide about the values of MAC and about the possibilities of their passing over. 68 substances ranged according to their basic characteristics in three groups were studied. There was statistical dependence between the molecular weight, the boiling point, smell thresholds of detection and recognition. In two groups of matters there was a dependence between the threshold of irritation and the smell threshold of recognition and distinction. The regression was linear with the majority of dependencies.     

Approach to the analysis of diuretics and masking agents by high-performance liquid chromatography—mass spectrometry in doping control

The application of thermospray and plasmaspray high-performance liquid chromatography—mass spectrometry to the analysis of diuretics and probenecid has been investigated. The latter method gave better ionization efficiency than the former, and its response was optimized by altering the solvent composition: best results were obtained with water—methanol—acetonitrile—trifluoroacetic acid. Using different proportions of these solvents, three isocratic systems were developed to separate the compounds under study. The principal characteristic of plasmaspray positive-ion mass spectra was a protonated molecular ion and very little fragmentation was evident. In the negative ionization mode, the plasmaspray method gave mass spectra showing more fragmentation, which resulted in additional structural information. The ability of trifluoroacetic acid to form negative cluster ions precluded its use as a mobile phase component. The minimum detectable amounts determined by the analysis in the positive-ion mode was compound-dependent, but generally ca. 10–150 ng. In many cases the compounds could be detected in urine extracts.     

The influence of molecular structure on odor qualities and odor detection thresholds of volatile alkylated phenols

The relationship between chemical structure and odor characteristics of aroma compounds is interesting in terms of establishing a fundamental understanding and, in the long term, a perspective for the prediction of odor qualities and intensities of unknown compounds; on the other hand, such studies provide a useful tool to analytically elucidate compounds that are exceptionally potent odor contributors to a specific smell. In this respect, a broad knowledge of compounds with regard to their odor threshold and smell specificities compiled in a comprehensive odor library would drastically simplify the chemoanalytical process in identifying aromas and smells. Whereas numerous odor-active substance classes have been investigated intensively, such relationships and fundamental data have hitherto not been established for volatile phenols. In this study, a homologous series and isomers of 30 volatile phenols, including monoalkylated phenols and di- and trimethylphenols, were evaluated by determining their aroma attributes and their odor detection thresholds in air. The investigation demonstrates that the odor qualities, among them leather-like, horse stable-like, and medicinal, as well as the respective threshold values clearly depend on the arrangement of the alkyl substituents at the phenol ring. In particular, phenols with monoalkyl groups in the meta-position were found with very low odor detection thresholds of <1 ng/L air. A comparison of some selected phenols and their corresponding toluenes, which were found to be almost odorless, showed in addition that the phenolic hydroxyl group is obviously an important factor for the odor characteristic of this substance class.     

Biodegradation of Methyl Ethyl Ketone and Methyl Isopropyl Ketone in a Composite Bead Biofilter

Biodegradation of methyl ethyl ketone (MEK) and methyl isopropyl ketone (MIPK) in a composite bead biofilter was investigated. The composite bead represents a spherical PVA/peat/KNO₃/GAC one. Both the microbial growth rate μ and the biochemical reaction rate coefficient k_d could be affected with increasing inlet concentration. For the microbial growth process, an inhibitory effect of almost the same sensitivity for the two ketone compounds and the μ value of MEK was more pronounced than that of MIPK in the inlet concentration range of 100 to 300 ppm. The half‐saturation constant K_s values of MEK and MIPK were 21.56 and 22.96 ppm, respectively. The maximum reaction rate V_m values of MEK and MIPK were 9.06 and 7.55 g C/h kg of packed material, respectively. Zero‐order kinetics with diffusion limitation could be regarded as the most adequate biochemical reaction model. For the biochemical process, the inhibitory effect for MEK was more notable than that for MIPK in the inlet concentration range of 100 to 150 ppm whereas it was the reverse in the inlet concentration range of 150 to 300 ppm. The k_d value of MEK was greater than that of MIPK in the inlet concentration range of 100 to 300 ppm. The maximum elimination capacities of MEK and MIPK were found to be 44.2 and 35.2 g C/h m³ of bed volume. MEK, in particular the compound with a lower number of carbons or no side groups in the main chain, was easier biodegraded by the microorganisms than MIPK.     

Application of solid-phase microextraction and gas chromatography–mass spectrometry for measuring chemicals in saliva of synthetic leather workers

Saliva is of interest as a diagnostic aid for oral and systemic diseases, to monitor therapeutic drugs, and detect illicit drug abuse. It is also attractive for biological monitoring of exposure to hazardous solvents. The major advantage of this indicator over other biological monitoring targets is that the saliva is noninvasive and less confidential in comparison with blood and urine. Salivary analysis is generally acceptable by study subjects and can be applied to investigation of a wide variety of compounds. However, very few studies have been conducted on the saliva matrix to monitor exposure to hazardous solvents. The aim of this study is to establish an analytical method, headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC–MS), by which the saliva matrix can be monitored for multiple compounds with various polarities, such as methyl ethyl ketone (MEK), isopropyl alcohol (IPA), and N,N-dimethyl formamide (DMF) (common solvents used in synthetic leather manufacture), as well as acetone (ACE) and N-methyl formamide (NMF) (metabolites of IPA and DMF, respectively). We studied this technique as an alternative biological monitoring method for investigating exposure to hazardous solvents. A Carboxen/Polydimethylsiloxane (CAR/PDMS 75 μm) fiber coating was employed for this study, and various extraction and desorption parameters were evaluated. The extraction efficiency and reproducibility of analyses was improved by pre-incubation. The limits of detection were 0.004, 0.003, 0.006, 0.05, and 0.10 μg/mL for ACE, MEK, IPA, DMF, and NMF, respectively. Method validation was performed on standards spiked in blank saliva, and a correlation was made between HS-SPME and traditional solvent pretreatment methods. It was found that correlation coefficients (r) were greater than 0.996 for each analyte, with no significant differences (p > 0.05) between two methods. However, the SPME method achieved lower limits of detection, with good accuracy (recovery 95.3–109.2%) and precision (1.17–8.22% CV) for both intra- and inter-assay, when quality control samples were analyzed for all five compounds. The partition coefficient for each compound between the headspace of the saliva sample and the CAR/PDMS fiber coating was 90.9, 170.1, 36.4, 3.70 and 0.92 for ACE, MEK, IPA, DMF and NMF, respectively. Real sample analyses were performed on workers in a synthetic leather factory. In summary, the SPME method is a highly versatile and flexible technique for chemical measurement, and we demonstrate its application for monitoring biological exposure to hazardous solvents. Saliva monitoring using sensitive SPME approaches for determining workplace exposure should prove useful as an alternative exposure monitoring method.     

Olfaction and Environment: Tsimane’ of Bolivian Rainforest Have Lower Threshold of Odor Detection Than Industrialized German People

Olfactory sensitivity varies between individuals. However, data regarding cross-cultural and inter-group differences are scarce. We compared the thresholds of odor detection of the traditional society of Tsimane’ (native Amazonians of the Bolivian rainforest; n = 151) and people living in Dresden (Germany; n = 286) using “Sniffin’ Sticks” threshold subtest. Tsimane’ detected n-butanol at significantly lower concentrations than the German subjects. The distribution of thresholds of the Tsimane’ was very specific, with 25% of Tsimane’ obtaining better results in the olfactory test than any member of the German group. These data suggest that differences in olfactory sensitivity seem to be especially salient between industrialized and non-industrialized populations inhabiting different environmental conditions. We hypothesize that the possible sources of such differences are: (i) the impact of pollution which impairs the olfactory abilities of people from industrialized countries; (ii) better training of olfaction because of the higher importance of smell in traditional populations; (iii) environmental pressures shaping olfactory abilities in these populations.     

Is There Any Effect on Smell and Taste Functions with Levothyroxine Treatment in Subclinical Hypothyroidism?

Subclinical hypothyroidism has been accused for coronary heart disease, lipid metabolism disorders, neuropsychiatric disorders, infertility or pregnancy related problems with various strength of evidence. Currently there is insufficient knowledge about olfaction and taste functions in subclinical hypothyroidism. Aim of the present study is to investigate the degree of smell and taste dysfunction in patients with subclinical hypothyroidism. 28 subclinical hypothyroid patients, and 31 controls enrolled in the prospective study in Istanbul, Turkey. Subclinical hypothyroid patients were treated with L-thyroxine for 3 months. Psychophysiological olfactory testing was performed using odor dispensers similar to felt-tip pens (“Sniffin’ Sticks”, Burghart, Wedel, Germany). Taste function tests were made using "Taste Strips" (Burghart, Wedel, Germany) which are basically tastant adsorbed filter paper strip. Patients scored lower on psychophysical olfactory tests than controls (odor thresholds:8.1±1.0 vs 8.9±1.1, p = 0.007; odor discrimination:12.4±1.3 vs 13.1±0.9, p = 0.016; odor identification:13.1±0.9 vs 14.0±1.1, p = 0.001; TDI score: 33.8±2.4 vs 36.9±2.1, p = 0.001). In contrast, results from psychophysical gustatory tests showed only a decreased score for “bitter” in patients, but not for other tastes (5.9±1.8 vs 6.6±1.0, p = 0.045). Three month after onset of treatment olfactory test scores already indicated improvement (odor thresholds:8.1±1.0 vs 8.6±0.6, p<0.001; odor discrimination:12.4±1.31 vs 12.9±0.8, p = 0.011; odor identification:13.1±0.9 vs 13.9±0.8, p<0.001; TDI scores:33.8±2.4 vs 35.5±1.7, p<0.001) respectively. Taste functions did not differ between groups for sweet, salty and, sour tastes but bitter taste was improved after 3 months of thyroxin substitution (patients:5.9±1.8 vs 6.6±1.2, p = 0.045). Correlation of changes in smell and taste, with thyroid function test were also evaluated. TSH, fT4 were found have no correlation with smell and taste changes with treatment. However bitter taste found positively correlated with T3 with treatment(r: 0.445, p: 0.018). Subclinical hypothyroid patients exhibited a significantly decreased olfactory sensitivity; in addition, bitter taste was significantly affected. Most importantly, these deficits can be remedied on average within 3 months with adequate treatment.     

Interaction of benzo [A] pyrene and a hyperplastic agent in epidermal nuclear enlargement in the mouse. A dose response study.

Experiments were conducted on the effects of various dose levels of benzo [a]pyrene (BP) on nuclear size in mouse interfollicular epidermis over a 3-day period. Topical application of BP was made with or without croton oil (CO) (0.1 or 0.5%) in the vehicles acetone, toluene and methyl ethyl ketone (MEK). Nuclear size was measured on histological sections either manually or by Quantimet Image Analyser. Vehicle controls treated with 0.1 or 0.5% CO in acetone or MEK gave rise to epidermal hyperplasia with some nuclear enlargement and toluene without CO produced a similar response. It was found that when BP was applied in a vehicle capable of inducing hyperplasia, the nuclear enlargement produced was greater than that produced by either the vehicle control or BP in a non-irritant vehicle. The enhancement of response to BP when tested in the presence of a hyperplastic agent resulted in lower concentrations of BP being detectable. As the levels of BP detectable by nuclear enlargement under these conditions compared reasonably well with those detectable in long-term tests, this system might be usable as a basis for a short-term test for carcinogens.     

Mode of action of photosynthesis inhibiting 4-hydroxy-benzonitriles containing nitro group

The effects of 3,5-disubstituted 4-hydroxy-benzonitriles — bromoxynil and compounds containing nitro group — on some photosynthetic parameters of spinach and wheat were investigated. There is considerable difference in the effectivity of the compounds even at the level of chloroplasts. On the basis of their effect on the development of CO₂ fixation of greening wheat seedlings bromoxynil and 3,5-dinitro-4-hydroxy-derivative were ineffective, while the asymmetric — 3-nitro-5-halogenic-substituted — compounds showed a strong effectivity. The bromine and iodine containing asymmetric compounds reduced the intensity of the short wavelength fluorescence. All asymmetric compounds shifted the long wavelength fluorescence maximum with 5–8 nm to shorter wavelength. These results refer to inhibition of formation of chlorophyll forms absorbing at longer wavelengths and to the change in the conditions of energy migration. The ultrastructure of the chloroplasts in the treated seedlings became similar to the shade adapted chloroplasts.     

Qualitative and quantitative analysis of some synthetic, chemically acting laxatives in urine by gas chromatography—mass spectrometry

A method for the qualitative and quantitative simultaneous analysis of dioxyanthraquinone, desacetyl-Bisacodyl, phenolphthalein and Oxyphenisatin in human urine using gas chromatography—mass spectrometry (GC—MS) has been developed. The compounds were extracted from urine at pH 7.5 with diethyl ether using Extrelut extraction columns, followed by evaporation and trimethylsilylation.The method used electron beam ionization GC—MS employing a computer-controlled multiple-ion detector (mass fragmentography). The recovery from urine for the various compounds was between 80% and 100%. The detection limit for these compounds was in the range 0.01–0.05 μg/ml of urine.The method proved to be suitable for measuring urine concentrations for at least four days after administration of a single oral low therapeutic dose of the laxatives to sixteen healthy volunteers.     

Comparative studies of products obtained from solvolysis liquefaction of oil palm empty fruit bunch fibres using different solvents

Solvolysis of oil palm empty fruit bunches (EFB) fibres using different solvents (acetone, ethylene glycol (EG), ethanol, water and toluene) were carried out using an autoclave at 275°C for 60 min. The solvent efficiency in term of conversion yield was found to be: EG>water>ethanol>acetone>toluene. The liquid products and residue obtained were analyzed using Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass selectivity. The obtained results showed that the chemical properties of the oil product were significantly affected by the type of solvent used for the solvolysis process. The higher heating value (HHV) of oil products obtained using ethanol is ～29.42 MJ/kg, which is the highest among the oil products produced using different solvents. Water, ethanol and toluene yield major phenolic compounds. While EG favors the formation of alcohol compounds and acetone yields ketone and aldehyde compounds.     

Molecular weight distribution of cellulose in primary cell walls

The distribution pattern of the degree of polymerization (DP) of cellulose present in the cell walls of mesophyll- and suspension-cultured cells of tobacco was compared to that of newly synthesized ¹⁴C-labeled cellulose from regenerating tobacco protoplasts and suspension-cultured cells. The cellulose was nitrated, and, after fractionation according to differences in solubility in acetone/water, the DP pattern of labeled or unlabeled cellulose nitrate was determined by viscosity measurements. A low (DP<500) and high DP-fraction (DP>2500) of cellulose were predominant in the cell walls of protoplasts, suspension — cultured cells, and mesophyll cells. The average DP of the high molecular weight fraction of cellulose in the cell walls of mesophyll was higher (DP4,000) than in protoplasts or suspension — cultured cells (DP 2,500-3,000). In all cell walls tested, minor amounts of cellulose molecules with a broad spectrum of a medium DP were present. Pulse — chase experiments with either protoplasts or suspension —cultured cells showed that a large proportion of the low and medium DP-cellulose are a separate class of structural components of the cellulose network. The results are discussed in relation to the organization of cellulose in the primary cell wall.Abbreviations DP degree of polymerisation - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid     

Determination of conjugated bile acids in human urine by high-performance liquid chromatography with chemiluminescence detection

A qualitative and quantitative analysis of the conjugated 1β- and 6α-hydroxy bile acids, including common bile acids, in human urine using high-performance liquid chromatography with chemiluminescence detection is described. After extraction of urine with C₁₈ silica cartridges, the bile acids were separated into non-conjugated, glycine, taurine and sulphate fractions by ion-exchange chromatography on a lipophilic gel. Solvolysis of the sulphate was carried out by treatment with trifluoroethanol in acetone containing hydrochloric acid, and the liberated amino acid conjugates were fractionated again. The individual bile acids were separated on a reversed-phase C₁₈ column (Bile Pak II), with detection by an immobilized 3α-hydroxysteroid dehydrogenase enzyme reactor and chemiluminescence reaction of the generated NADH using 1-methoxy-5-methylphenazinium methylsulphate—isoluminol—microperoxidase system. The assay method showed the detection limits ranging from 8 to 250 pmol for the bile acids tested. Analysis of urine samples obtained from newborns, non-pregnant women and women in late pregnancy showed a large difference in bile acid composition and conjugation mode, suggesting that bile acid metabolism is different during fetal and neonatal periods.     

Systématique des Saccharomyces: Osidases et besoins vitaminiques

A study of the genus Saccharomyces by new biocharacters demonstrates indirectly the genotype of each species; intracellular osidases (lactose — maltose — cellobiase — melibiase — invertase — trehalase) and vitamine requirements (biotin — folic acid — inositol — niacine — pantothénate —para-aminobenzoïc acid — pyridoxine — thiamine) reveal some phylogenetic links between the species. It appears that Van der Walt's group I is very homogeneous and must be restricted to only 7 species. The Torulospora group seems very similar to the genus Debaryomyces when vitamine needs and osidases are considered; the relations between the 2 groups are discussed. When other biocharacters are studied (nitrite reductase-immunological properties, etc. ...) the value in the GC content (4–5% lower in Debaryomyces) will be established.These results confirm that intracellular osidases and vitamine needs are very valuable tools for systematic criteria.

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Collaboration technique: Mme Billon-Grand.     

Determination of metronidazole, misonidazole and its metabolite in serum and urine on RP-18 high-performance thin-layer chromatographic plates

A method for the determination of radiotherapeutic concentrations of metronidazole, misonidazole and its metabolite is described. The biological fluid (serum or urine) was deproteinized with acetone containing 2-nitroimidazole as internal standard, centrifuged and the supernatant evaporated under vacuum. The residue, dissolved in acetone, was applied to an HPTLC-RP-18 layer and, after development, quantitation was achieved with a scanning densitometer. The response was linear up to 180 μg/ml for all tested compounds and the detection limit was 0.5 μg/ml. Owing to its rapidity and sensitivity the method can be considered to be equivalent to high-performance liquid chromatography.     

Thermospray and particle beam liquid chromatographic—mass spectrometric analysis of coumarin anticoagulants

Positive ion mass spectra were obtained from several coumarin oral anticoagulants (phenprocoumon, warfarin, acenocoumarol and dicoumarol) and derivatives by liquid chromatography—thermospray mass spectrometry (LC—TSP-MS) and liquid chromatography—electron impact mass spectrometry (LC—EI-MS) to assess the use of LC—MS methods for the determination of these compounds in biological materials. LC—TSP mass spectra showed a single [M + 1]⁺ ion with no fragmentation; LC—EI mass spectra showed fragment ions which were similar in mass and relative intensities to those obtained by conventional EI-MS. These data should serve as a basis for the development of LC—MS methods for the qualitative and quantitative analysis of coumarin anticoagulants in biological samples. LC—TSP-MS was applied to the determination of phenprocoumon in a plasma extract from an anticoagulated patient.     

Pre-column derivatization of free bile acids for high-performance liquid chromatographic and gas chromatographic—mass spectrometric analysis

Pentachlorophenyl (PCP) esters of five free bile acids (FBA) were obtained by reacting the FBA and Kovacs' complex (KC) in a 1:8 molar ratio in acetone at 65°C, and were purified by column chromatography on silica gel. The esters were crystallized from benzene—hexane, derivatized as trimethylsilyl ethers for gas chromatography on a DB-1 capillary column and for gas chromatography—mass spectrometry with a DB-5 column, and mass spectrometry (MS) in the electron-impact (EI) positive-ion mode at 70 eV. The reaction is specific for FBA even in the presence of glycine and taurine conjugates of bile acids. The PCP esters were treated with benzylamine in chloroform or methanol to produce N-benzyl derivatives of FBA. The N-benzylamides were separated by high-performance liquid chromatography (HPLC) on a 4-μm Nova-Pak C₁₈ column, studied by thermospray—LC—MS, and in the direct insertion probe—EI positive-ion mode.