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PubMed2002

Comparison of volatile sulfur compound concentrations measured with a sulfide detector vs. gas chromatography.

The accuracy of the Halimeter, an inexpensive, simple instrument that measures total breath volatile sulfur compounds (VSCs), has not been adequately tested. We compared Halimeter measurements with those obtained with a specific and sensitive gas chromatographic (GC) technique. The Halimeter gave different, biexponential responses to a constant concentration of different VSCs: The relative response rate and sensitivity were hydrogen sulfide > methyl mercaptan > dimethylsulfide. The transient peak VSC concentration of oral samples was reached long before the sulfide detector fully responded. The GC measurement of initial total VSCs in breath samples was 2.7+/-0.48 times greater than the peak concentration of the Halimeter. However, the plateau phase measurement of the Halimeter was 25% greater than that of GC. While GC and Halimeter measurements positively correlated, appreciable differences were observed. In studies where relatively precise VSC measurements are required, GC is the preferable technique.

Chromatography, Gas↗
PubMed1994

The South Karelia Air Pollution Study: the effects of malodorous sulfur compounds from pulp mills on respiratory and other symptoms in children.

We assessed the role of long-term exposure to ambient air malodorous sulfur compounds released from pulp mills as a determinant of eye and respiratory symptoms and headache in children. Adverse health effects of environmental exposure to these compounds in children have not been reported previously. The parents of 134 children living in a severely polluted (n = 42), moderately polluted (n = 62) and rural nonpolluted (n = 30) community responded to a cross-sectional questionnaire. The response rate was 83%. The adjusted odds ratios (OR) for symptoms experienced during the previous 4 weeks and 12 months in the severely versus nonpolluted community were estimated in logistic regression analysis controlling for age and gender. The risk of nasal symptoms (4 weeks OR 1.40, 95% CI 0.59-3.31; 12 months OR 2.47, 95% CI 0.93-6.53), cough (4 weeks OR 1.83, 95% CI 0.75-4.45; 12 months OR 2.28, 95% CI 0.95-5.47), eye symptoms (12 months OR 1.15, 95% CI 0.43-3.05), and headache (12 months OR 1.77, 95% CI 0.69-4.54) was considerably increased in the severely polluted community, although not quite reaching statistical significance. The results suggest that exposure to malodorous sulfur compounds may affect the health of children.

Adolescent↗
PubMed2005

Discriminative detection of volatile sulfur compound mixtures with a plasma-polymerized film-based sensor array installed in a humidity-control system.

We demonstrated the discrimination of volatile sulfur compound mixtures with different mixing ratios by using an array of the plasma-polymerized film (PPF)-coated quartz crystal resonators. The PPF sensor array, which contains PPFs prepared from amino acids and synthetic polymers, exhibited different response patterns to mono or mixed volatile sulfur compounds (VSCs) (hydrogen sulfide and methanethiol) under a dry environment. The sensor array was installed in a desktop-size relative humidity controller. The relative humidity and temperature conditions of the sample flow to the sensor cell were equalized to those of the inner atmosphere of the sensor cell based on the concept of the two-separate-temperatures method. In this way, the baseline drift of PPF sensor response caused by the introduction of a highly humid sample was successfully suppressed. We compared the sensor array responses under the controlled humidity conditions. Presorption of water molecules by PPFs caused a decrease of sensor sensitivity, but the films still had the ability to discriminate sub-ppmv VSC mixtures having 6:1, 1:1, and 1:6 mixture ratios of hydrogen sulfide and methanethiol.

Journal Article↗
PubMed2005

Effect of a triclosan/PVM/MA copolymer/fluoride dentifrice on volatile sulfur compounds in vitro.

OBJECTIVE: The objective of the investigation was to document the in vitro efficacy of a triclosan/PVM/MA copolymer/fluoride (TCF) dentifrice against the formation of volatile sulfur compounds (VSC) as well as the growth of H2S-producing bacteria. Clinical studies using organoleptic judges, gas chromatography, or a portable sulfide monitor have generally been employed in the assessment of treatments for the control of oral malodor. However, these studies are not appropriate for screening purposes because of the expense and time required. METHODS: An in vitro method was developed for the purpose of screening new compounds, agents or formulations for their ability to control VSC formation and for determining bio-equivalence of efficacy when implementing changes in existing formulations. The method combines basic microbiological methods, dynamic flow cell techniques and head space analysis. The in vitro VSC method was validated by comparing the efficacy of two dentifrices containing TCF with a control fluoride dentifrice as the TCF products have been clinically proven to control oral malodor. RESULTS: In the validation studies, the TCF-containing dentifrices were significantly better (P < 0.05) than the control dentifrice in inhibiting VSC formation and reducing H(2)S-producing bacteria. For example, when compared with baseline, the TCF dentifrices reduced VSC formation between 42 and 49% compared with the control dentifrice which reduced VSC formation 3%. There was no significant difference (P > 0.05) between the two TCF dentifrice formulations. CONCLUSION: Using an in vitro breath VSC model, it has been demonstrated that two variants of a dentifrice containing triclosan, PVM/MA copolymer and fluoride have efficacy that is significantly better than a control fluoridated dentifrice and that there is no significant difference between the triclosan/PVM/MA copolymer/fluoride dentifrice variants.

Actinomyces↗
PubMed2006

Cycling of volatile organic sulfur compounds in anaerobically digested biosolids and its implications for odors.

The objectives of this research were to elucidate the mechanisms for production and degradation of volatile organic sulfur compounds (VOSCs), key odor causing compounds produced by biosolids. These compounds included methanethiol (MT), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS). A series of experiments were used to probe various pathways hypothesized to produce and degrade these VOSCs. The production of MT was found to mainly occur from degradation of methionine and the methylation of hydrogen sulfide. DMS was formed through the methylation of MT. DMDS was formed by MT oxidation. All three of the VOSCs were readily degraded by methanogens and a cyclic pathway was proposed to describe the production and degradation of VOSCs. The research demonstrated that the main source of VOSCs was the biodegradation of protein within the biosolids and the results provided a framework for understanding the production of odor from anaerobically digested sludges before and after dewatering.

Anaerobiosis↗
PubMed2002

Analysis of aromatic sulfur compounds in gas oils using GC with sulfur chemiluminescence detection and high-resolution MS.

The analysis of alkylbenzothiophenes (alkyl-BT) and alkyl-dibenzothiophenes (alkyl-DBT) in light cycle oil (LCO) and straight run (SR) gas oils is described. A detailed identification and quantitative analysis of alkyl-BT and alkyl-DBT present in LCO gas oils was carried out using GC-SCD. For the SR gas oils, the simultaneous presence of thiophenic and nonthiophenic compounds does not allow for a selective analysis of thiophenic compounds by GC-SCD. A new method using gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) is proposed to selectively detect and quantify the alkyl-BT and alkyl-DBT in SR gas oils. The development of the method and comparison of results between GC-SCD and GC-HRMS are presented.

Gas Chromatography-Mass Spectrometry↗
PubMed2003

Isothermal Kováts retention indices of sulfur compounds on a poly(5% diphenyl-95% dimethylsiloxane) stationary phase.

Isothermal Kováts retention indices of 21 sulfur compounds relevant to the fuel gas and food industries are reported on a poly(5% diphenyl-95% dimethylsiloxane) capillary column stationary phase. Measurements were performed at four temperatures and the temperature dependence of the values modeled with Antoine-type equations. Indices were calculated using a non-linear technique, and the predicted values were found to agree with values obtained using traditional logarithmic predictions. We demonstrate that there is sufficient separation between retention indices to predict the identity of a compound by its retention index.

Chromatography↗
PubMedDate not supplied

NH2-SEP-PAK cartridges for enrichment of Aromatic Sulfur Compounds from sea water: determination by GC-FID and GC-MS.

The Aromatic Sulfur Compounds (ASCs) are considered as "markers" of the crude oil age. In this frame, we have considered ASCs as "markers" of remote crude oil sea water pollution for their chemical characteristics, good solubility in water and resistance to the biodegradation. Gas chromatography of ASCs in distilled water and sea water samples has been performed after adsorption from a 80 mL water sample on to a cartridge containing 100 mg NH2-bonded porous silica. The ASCs are desorbed with 2 mL acetone-trichloromethane (1:1), which is concentrated and analysed by GC-FID or GC-MS in SIM mode. The average recovery of 0.1 microg mL(-1) of each ASC from distilled water and 0.04-0.2 microg mL(-1) from sea water samples is > or = 96.3% with a standard deviation < or = 2.2. The limits of detection are 0.06-0.05 ng mL(-1) for thiophen-2-carboxaldehyde and benzothiophene, and 0.006-0.004 ng mL(-1) for dibenzothiophene and thiantrene in GC-FID whereas they are 0.02 ng mL(-1) for thiophen-2-carboxaldehyde and benzothiophene, and 0.003 ng mL(-1) for dibenzothiophene and thiantrene in GC-MS (SIM) with a relative standard deviation < or =7.

Adsorption↗
PubMed2002

Quantification of volatile sulfur compounds in complex gaseous matrices by solid-phase microextraction.

Procedures were assessed for quantifying nine volatile sulfur compounds found in complex gaseous samples collected at a biogas-production plant and a sewage treatment plant. The target compounds were extracted by solid-phase microextraction (using the 75-microm Carboxen-polydimethylsiloxane fiber coating) at 22 degrees C for 20 min, and analyzed by GC-MS. Detection limits ranged between 1 pptv (v/v) for carbon disulfide and 470 pptv (v/v) for hydrogen sulfide. High amounts of organic compounds were found during full-scan analysis of the samples and standard additions to individual sub-samples revealed that the analysis was subject to matrix effects. However, the functions obtained by standard additions were still linear and quantification was possible for all the compounds tested except hydrogen sulfide. No detectable losses were observed during storage in the sampling containers, made of Tedlar film, over a storage period of 20 h. However, water permeated through the walls and the relative humidity in the bag increased during storage until it reached the ambient level. Finally, it was shown that the drying agent, CaCl2, caused no detectable losses of any of the compounds.

Gas Chromatography-Mass Spectrometry↗
PubMed1996

Organic sulfur compounds resulting from the interaction of iron sulfide, hydrogen sulfide and carbon dioxide in an anaerobic aqueous environment.

The reaction of iron sulfide (FeS) with H2S in water, in presence of CO2 under anaerobic conditions was found to yield H2 and a variety of organic sulfur compounds, mainly thiols and small amounts of CS2 and dimethyldisulfide. The same compounds were produced when H2S was replaced by HCl, in the H2S-generating system FeS/HCl/CO2. The identification of the products was confirmed by GC-MS analyses and the incorporation of H2 in the organic sulfur compounds was demonstrated by experiments in which all hydrogen compounds were replaced by deuterium compounds. Generation of H2 and the synthesis of thiols were both dependent upon the relative abundance of FeS and HCl or H2S, i.e. the FeS/HCl- or FeS/H2S-proportions. Whether thiols or CS2 were formed as the main products depended also on the FeS/HCl-ratio: All conditions which create a H2 deficiency were found to initiate a proportional increase in the amount of CS2. The quantities of H2 and thiols generated depended on temperature: the production of H2 was significantly accelerated from 50 degrees C onward and thiol synthesis above 75 degrees C. The yield of thiols increased with the amount of FeS and HCl (H2S), given a certain FeS/HCl-ratio and a surplus of CO2. A deficiency of CO2 results in lower thiol synthesis. The end product, pyrite (FeS2), was found to appear as a silvery granular layer floating on the aqueous surface. The identity of the thiols was confirmed by mass spectrometry, and the reduction of CO2 demonstrated by the determination of deuterium incorporation with DCl and D2O. The described reactions can principally proceed under the conditions comparable to those obtaining around submarine hydrothermal vents, or the global situation about 4 billion years ago, before the dawn of life, and could replace the need for a reducing atmosphere on the primitive earth.

Anaerobiosis↗
PubMed1993

Inhibition of Ammonia Oxidation in Nitrosomonas europaea by Sulfur Compounds: Thioethers Are Oxidized to Sulfoxides by Ammonia Monooxygenase.

Organic sulfur compounds are well-known nitrification inhibitors. The inhibitory effects of dimethylsulfide, dimethyldisulfide, and ethanethiol on ammonia oxidation by Nitrosomonas europaea were examined. Both dimethylsulfide and dimethyldisulfide were weak inhibitors of ammonia oxidation and exhibited inhibitory characteristics typical of substrates for ammonia monooxygenase (AMO). Depletion of dimethylsulfide required O(2) and was prevented with either acetylene or allylthiourea, two inhibitors of AMO. The inhibition of ammonia oxidation by dimethylsulfide was examined in detail. Cell suspensions incubated in the presence of ammonia oxidized dimethylsulfide to dimethyl sulfoxide. Depletion of six other thioethers was also prevented by treating cell suspensions with either allylthiourea or acetylene. The oxidative products of three thioethers were identified as the corresponding sulfoxides. The amount of sulfoxide formed accounted for a majority of the amount of sulfide depleted. By using gas chromatography coupled with mass spectrometry, allylmethylsulfide was shown to be oxidized to allylmethylsulfoxide by N. europaea with the incorporation of a single atom of O derived from O(2) into the sulfide. This result supported our conclusion that a monooxygenase was involved in the oxidation of allylmethylsulfide. The thioethers are concluded to be a new class of substrates for AMO. This is the first report of the oxidation of the sulfur atom by AMO in whole cells of N. europaea. The ability of N. europaea to oxidize dimethylsulfide is not unique among the ammonia-oxidizing bacteria. Nitrosococcus oceanus, a marine nitrifier, was also demonstrated to oxidize dimethylsulfide to dimethyl sulfoxide.

Journal Article↗
PubMed2002

Observation of sorptive losses of volatile sulfur compounds during natural gas sampling.

The reason for the compound-dependent over-estimation of the recoveries of several volatile organic sulfur compounds when using a Silcosteel cylinder for sample storage as reported earlier was examined. From the different possible sources of errors that were taken into consideration, the silicone tubing, which was used to fill a standard Tedlar sample bag for calibration, was identified as the cause of the artefact. The comparison of different tubing materials showed that PTFE is the best choice since it causes only minor losses (<10%) of propyl- and butylmercaptans.

Fossil Fuels↗
PubMed1981

Reduction of sulfur compounds in the sediments of a eutrophic lake basin.

Concentrations of various sulfur compounds (SO(4), H(2)S, S, acid-volatile sulfide, and total sulfur) were determined in the profundal sediments and overlying water column of a shallow eutrophic lake. Low concentrations of sulfate relative to those of acid-volatile sulfide and total sulfur and a decrease in total sulfur with sediment depth implied that the contribution of dissimilatory sulfur reduction to H(2)S production was relatively minor. Addition of 1.0 mM Na(2)SO(4) to upper sediments in laboratory experiments resulted in the production of H(2)S with no apparent lag. Kinetic experiments with S demonstrated an apparent K(m) of 0.068 mmol of SO(4) reduced per liter of sediment per day, whereas tracer experiments with S indicated an average turnover time of the sediment sulfate pool of 1.5 h. Total sulfate reduction in a sediment depth profile to 15 cm was 15.3 mmol of sulfate reduced per m per day, which corresponds to a mineralization of 30% of the particulate organic matter entering the sediment. Reduction of S occurred at a slower rate. These results demonstrated that high rates of sulfate reduction occur in these sediments despite low concentrations of oxidized inorganic compounds and that this reduction can be important in the anaerobic mineralization of organic carbon.

Journal Article↗
PubMed2004

[The problem and improvement of colorimetric method for determination of sulfite in foods containing sulfur compounds].

The modified Rankine colorimetric method for measuring sulfite added to food as a food additive has a low determination limit and is little influenced by interfering substances from foods. However, it can give erroneous results for foods containing Liliaceae Allium. So, four different methods, alkaline titration, a colorimetric method, ion chromatography and qualitative analysis with potassium iodate-starch paper, were examined. It was found that the sodium azide used in the colorimetric method forms sulfur dioxide during bubbling and heating. The proposed colorimetric method can be applied to food containing sulfur compounds, if sodium azide is omitted and 1% triethanolamine solution is used as an absorbent instead of 0.1 mol/L sodium hydroxide solution.

Colorimetry↗
PubMed1982

The effects of short-term fasting on the excretion of sulfur compounds in healthy subjects.

The urinary excretion of sulfur-containing compounds was studied before, on the third, and on the seventh day of fasting in 10 healthy subjects. The excretion of total sulfur, inorganic sulfate, ester sulfate, "non-sulfate sulfur", methionine, cystathionine, cysteine, N-acetylcysteine, taurine, thiosulfate and thiocyanate was decreased during fasting, whereas the excretion of mercaptoacetate was unaltered and that of mercaptolactate increased. The excretion of inorganic sulfate, taurine and thiocyanate was also decreased when calculated relative to that of total sulfur, suggesting that these compounds are derived mainly from dietary sulfur amino acids. The output of ester sulfate, methionine, cystathionine, cysteine and thiosulfate was unaltered in relation to that of total sulfur, indicating that these compounds are derived from both dietary and endogenous sulfur amino acids, liberated during protein catabolism. By contrast, the excretion of mercaptolactate and mercaptoacetate was increased relative to that of total sulfur, suggesting that these compounds are derived mainly from endogenous sulfur amino acids formed by the enhanced protein catabolism seen during fasting.

Adult↗
PubMed1986

Metabolism of reduced methylated sulfur compounds in anaerobic sediments and by a pure culture of an estuarine methanogen.

Addition of dimethylsulfide (DMS), dimethyldisulfide (DMDS), or methane thiol (MSH) to a diversity of anoxic aquatic sediments (e.g., fresh water, estuarine, alkaline/hypersaline) stimulated methane production. The yield of methane recovered from DMS was often 52 to 63%, although high concentrations of DMS (as well as MSH and DMDS) inhibited methanogenesis in some types of sediments. Production of methane from these reduced methylated sulfur compounds was blocked by 2-bromoethanesulfonic acid. Sulfate did not influence the metabolism of millimolar levels of DMS, DMDS, or MSH added to sediments. However, when DMS was added at approximately 2-muM levels as [C]DMS, metabolism by sediments resulted in a CH(4)/CO(2) ratio of only 0.06. Addition of molybdate increased the ratio to 1.8, while 2-bromoethanesulfonic acid decreased it to 0, but did not block CO(2) production. These results indicate the methanogens and sulfate reducers compete for DMS when it is present at low concentrations; however, at high concentrations, DMS is a "noncompetitive" substrate for methanogens. Metabolism of DMS by sediments resulted in the appearance of MSH as a transient intermediate. A pure culture of an obligately methylotrophic estuarine methanogen was isolated which was capable of growth on DMS. Metabolism of DMS by the culture also resulted in the transient appearance of MSH, but the organism could grow on neither MSH nor DMDS. The culture metabolized [C]-DMS to yield a CH(4)/CO(2) ratio of approximately 2.8. Reduced methylated sulfur compounds represent a new class of substrates for methanogens and may be potential precursors of methane in a variety of aquatic habitats.

Journal Article↗
PubMed2002

Trace determination of volatile sulfur compounds by solid-phase microextraction and GC-MS.

A method was developed for the simultaneous determination of the following nine volatile sulfur compounds in gas samples: carbon disulfide, carbonyl sulfide, ethyl sulfide, ethyl methyl sulfide, hydrogen sulfide, isopropanethiol, methanethiol, methyl disulfide and methyl sulfide. The target compounds were preconcentrated by solid-phase microextraction (SPME) and determined by gas chromatography combined with mass spectrometry. Experimental design was employed to optimize the extraction time and temperature and concurrent detection of the nine compounds was achieved by using an SPME fiber coated with Carboxen-polydimethylsiloxane (75 microns). Detection limits ranged from 1 ppt (v/v) for carbon disulfide to 350 ppt (v/v) for hydrogen sulfide and calibration functions were linear up to 20 ppb (v/v) for all the compounds investigated.

Gas Chromatography-Mass Spectrometry↗