Concentrations Of Sulfur Compounds Research Articles

Tartaric acid extraction of organotin compounds from sediment samples

A new extraction method for the determination of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) in sediments based on extraction with tartaric acid and methanol has been developed. Tin species were extracted from sediment samples using focused microwave technology, then ethylated with sodium tetraethylborate (NaBEt4) and analyzed by isotope dilution (ID) gas chromatography–mass spectrometry (GC-MS). The advantages of such methodology in comparison with other established extraction methods for the routine speciation analysis of organotin compounds are discussed with respect to sulfur interferences co-extracted from complex matrices.Interferences from elemental sulfur are normally found with acetic acid extraction, but with tartaric acid extraction these interferences were eliminated, demonstrating selective extraction.The accuracy of the analytical procedure was established by analyzing a certified reference material (CRM) (PACS-2, marine sediment) and comparing the results to the certified values. Good agreement between determined and certified values for butyltin compounds was obtained. Finally, some complex sediment samples collected from San Vicente's Bay, Chile, were analyzed with the proposed methodology, demonstrating its potential value for monitoring butyltins in environmental samples with high concentrations of sulfur compounds.

Relationship between nitrogen content in grapes and volatiles, namely heavy sulphur compounds, in wines

Ammonium salts were added to white grape musts, before alcoholic fermentation, in order to evaluate their influence on the heavy sulphur compound and aliphatic higher alcohol composition of resulting wines. Six grape musts were used (Trajadura, Pedernã, Loureiro, Azal Branco, Avesso and Alvarinho). Ammonium supplementation of Trajadura and Pedernã grape musts, with the highest nitrogen level, did not influence the content of heavy sulphur compounds and aliphatic higher alcohols in wines; however, the addition of ammonium salts to grape musts with low initial nitrogen content, such as Loureiro, Azal Branco and Avesso, led to a higher production of 1-propanol and a lower production of isoamyl alcohols and sulphur compounds, e.g. S-methyl thioacetate, 2-mercaptoethanol, acetic acid-3-(methylthio)propyl ester, 3-mercapto-1-propanol, 4-(methylthio)-1-butanol, 3-(ethylthio)-1-propanol, 3-methylthiopropionic acid and N-3-(methylthiopropyl)acetamide. For Alvarinho grape must, a decrease in sulphur compound concentrations in wines was only observed for 3-methylthiopropionic acid, acetic acid-3-(methylthio)propyl ester and 2-mercaptoethanol.

Influence of Microoxygenation on Reductive Sulfur Off-Odors and Color Development in a Cabernet Sauvignon Wine

The effect of microoxygenation on the composition of a red wine was investigated, where oxygen was applied at both low and high rates (5 and 20 mg/L/month) through a diffuser or via permeation through polyethylene tanks. A control with no oxygen was also included. Each treatment was performed in triplicate, using a commercially made Cabernet Sauvignon wine, in nine 300-L stainless-steel and three 300-L polyethylene tanks at 16°C over 16 weeks. Spontaneous malolactic fermentation occurred simultaneously with the microoxygenation treatments. The results indicated that microoxygenation enhanced the wine color development, in which effects on pigments resistant to SO₂ were more marked in the first half of the trial and more obvious influences on color density were seen during the second half of the trial. Microoxygenation, as applied in this study, did not show any effect on the desirable varietal thiol 3-mercaptohexanol, yet led to some decreases in the concentrations of undesirable off-odors, including a lowering in the concentration of methanethiol without an increase in the concentration of dimethyl disulfide. Changes in the concentrations of other reductive sulfur compounds, except the thioesters, were also affected by oxygen and further by the influence of spontaneous malolactic fermentation, indicating the complicated interactions of these compounds in the wine matrix.

Process Control and Investigation of Oxidation Kinetics of Postoxidative Effluents Using Gas Chromatography with Pulsed Flame Photometric Detection (GC-PFPD)

This article presents the results of investigations on the use of headspace analysis and gas chromatography with pulsed flame photometric detection (HSA-GC-PFPD) to evaluate the effectiveness of oxidation of postoxidative effluents from the production of bitumens. Samples of effluents from the bitumen oxidation unit were used in the experiments. In addition, the kinetics of effluent oxidation was also investigated. The content of volatile sulfur compounds (VSCs) was determined using HSA-GC-PFPD. The results were correlated with chemical oxygen demand (COD). The changes in concentration of individual volatile sulfur compounds in the course of effluent oxidation were measured, which enabled the determination of the order of the oxidation reactions. The usefulness of the determination of VSCs in the headspace as a reliable technique for evaluating the reduction in emissions of volatile malodorous compounds was demonstrated. The developed method is also useful for process control of the oxidation of postoxidative effluents. The procedure ensures an objective evaluation of the effectiveness of the removal of volatile sulfur compounds from postoxidative effluents. The experimental results revealed that the effectiveness of the oxidation of organosulfur compounds was much higher than that of other classes of organic compounds. Furthermore, the order of oxidation reactions along with the rate constants of thiophenol, p-thiocresol, and hydrogen sulfide were determined. An advantage of the developed procedure is that it can be automated.

ChemInform Abstract: Deep Desulfurization of Diesel Fuel Using Ionic Liquids: Current Status and Future Challenges

AbstractReview: 86 refs.

Optimization of ultrasound assisted-emulsification-dispersive liquid–liquid microextraction by experimental design methodologies for the determination of sulfur compounds in wines by gas chromatography–mass spectrometry

A new method was developed for analyzing sulfur compounds in the aroma of white wines using ultrasound assisted-emulsification-dispersive liquid–liquid microextraction coupled with gas chromatography–mass spectrometry detection. In the present work, the analytical method for simultaneous determination of seven sulfur compounds (methylmercaptoacetate, methyl(methylthio)acetate, 2-methylthioethanol, 3-methylthiopropanol, 3-methylthiohexanol, 4-methylthio-4-methyl-2-pentanone and hexanethiol) is reported. Parameters that affect the efficiency of the methodology such as extracting and dispersing solvents, sample volume, ion strength, cavitation time and centrifugation time were investigated using a fractionated factorial 2 6–1 (R = V) screening design. Then, the factors presenting significant positive effects on the analytical response (extracting volume, ion strength, cavitation time and centrifugation time) were considered in a further central composite design to optimize the operational conditions for the ultrasound assisted-emulsification-dispersive liquid–liquid microextraction procedure. Additionally, multiple response simultaneous optimization by using the desirability function was used to find the optimum experimental conditions. The best results were obtained using pH sample 4.25, extractant volume 150 μL, ionic strength 8.75% NaCl, cavitation time 20 s and centrifugation time 50 s. The use of the optimized ultrasound assisted-emulsification-dispersive liquid–liquid microextraction technique allowed to obtain the best extraction results with the minimum interference from other substances from the matrix, and it allowed to quantify the analytes in white wine samples by calibration graphs. Recoveries ranging from 91.99% to 125.87% for all sulfur compounds proved the accuracy of the proposed method in white wine samples. Method detection limits were in the range of 0.36–1.67 ng mL −1 and limits of quantitation were between 0.63 and 3.02 ng mL −1 for sulfur compounds in white wine samples. The proposed methodology was successfully applied for the determination concentrations of sulfur compounds in different commercial Chardonnay wine samples from Mendoza, Argentine.

Short-term effect of a new mouthrinse formulation on oral malodour after single use in vivo: a comparative, randomized, single-blind, parallel-group clinical study

This study aimed to compare a new chlorhexidine (CHX)-free mouthrinse containing amine fluoride/stannous fluoride (ASF) against a benchmark containing CHX with respect to their effect on oral malodour after single use. A total of 42 male and female subjects with an intraoral cause of bad breath, each with an organoleptic rating (OR) of at least 2 and a total volatile sulfur compound (VSC) concentration higher than 130 ppb, participated in the study. Subjects were allocated to one of three treatment groups (i.e. CHX-free ASF mouthrinse, CHX benchmark mouthrinse or water) according to a randomization list. Participants received written instructions on precautions to be taken for optimal breath analysis. Eight trained and qualified odour judges assessed the subjects' malodour by OR at baseline and 30 min and 4 h after single use of the mouthrinses. Additionally, VSC levels were measured at baseline and 4 h after using the mouthrinse. Treatment with water alone led already to some reduction in OR with mean differences to baseline of −1.13 at 30 min and −0.64, 4 h after treatment. Both CHX-free ASF product (−1.51) and CHX (−1.48) provided a significantly stronger OR reduction than water at 30 min (p < 0.05). Only CHX-free ASF treatment showed a sustained benefit in terms of significantly better OR reduction after 4 h (−1.17, p < 0.05), whereas CHX (−0.81) was not significantly different from water (−0.64, p = 0.517). Both ASF (−90.9%) and CHX (−81.6%) reduced VSC levels significantly stronger than water (−53.5%; p < 0.001). OR and VSC readings in the group using the CHX mouthrinse did not differ significantly from those in the group using the CHX-free ASF formulation. The newly developed CHX-free ASF mouthrinse significantly reduced oral malodour after single use, both in terms of OR and VSC levels. Efficacy was comparable to that of the CHX benchmark product.

Characterization by Volatile Compounds of Microbial Deep Spoilage in Iberian Dry‐Cured Ham

In the present study, volatile compounds of spoiled dry-cured Iberian ham with deep spoilage or "bone taint" were analyzed and correlated with level of spoilage and the microorganisms detected. Volatile compounds extracted by a solid phase micro-extraction technique were assayed by gas chromatography/mass spectrometry. The spoiled hams were evaluated sensorially, and the correlations among volatile compounds, spoilage level, and microbial counts were studied. The spoiled hams had higher concentrations of hydrocarbons, alcohols, acids, esters, pyrazines, sulfur compounds, and other minor volatile compounds than unspoiled hams. The sensorial analysis showed that the spoilage level of hams correlated with several volatile compounds, most of them associated with Gram-positive catalase positive cocci and Enterobacteriaceae counts. Cyclic compounds such as cyclohexanone, some ethers, and pyrazines should be considered as indicators to monitor incipient microbial deep spoilage in the elaboration of this meat product.

Evaluation of an 18-year CMAQ simulation: Seasonal variations and long-term temporal changes in sulfate and nitrate

This paper compares spatial and seasonal variations and temporal trends in modeled and measured concentrations of sulfur and nitrogen compounds in wet and dry deposition over an 18-year period (1988–2005) over a portion of the northeastern United States. Substantial emissions reduction programs occurred over this time period, including Title IV of the Clean Air Act Amendments of 1990 which primarily resulted in large decreases in sulfur dioxide (SO 2) emissions by 1995, and nitrogen oxide (NO x) trading programs which resulted in large decreases in warm season NO x emissions by 2004. Additionally, NO x emissions from mobile sources declined more gradually over this period. The results presented here illustrate the use of both operational and dynamic model evaluation and suggest that the modeling system largely captures the seasonal and long-term changes in sulfur compounds. The modeling system generally captures the long-term trends in nitrogen compounds, but does not reproduce the average seasonal variation or spatial patterns in nitrate.

A comparative study of recycled aggregates from concrete and mixed debris as material for unbound road sub-base

Seven different types of recycled aggregates from construction and demolition waste (CDW) have been evaluated as granular materials for unbound road sub-bases construction. The results showed that recycled concrete aggregates complied with all specifications for using in the construction of unbound structural layers (sub-base) for T3 and T4 traffic categories according to the Spanish General Technical Specification for Road Construction (PG-3). Some mixed recycled aggregates fell short of some specifications due to a high content of sulphur compounds and poor fragmentation resistance. Sieving off the fine fraction prior to crushing the mixed CDW reduce the total sulphur content and improve the quality of the mixed recycled aggregates, by contrast, pre-sieving concrete CDW had no effect on the quality of the resulting aggregates. The results were compared with a crushed limestone as natural aggregate.

Volatile sulphur compounds composition of monovarietal white wines

The sulphur compounds composition of wines produced experimentally from six white cultivars (Alvarinho, Loureiro, Trajadura, Pedernã, Azal Branco and Avesso) was evaluated during two consecutive vintages. Results show that wines could be differentiated according to their sulphur compounds content. In general, Loureiro, Trajadura and Pedernã cultivars led to wines with low concentrations of sulphur compounds; however, Loureiro wines were characterised by significant amounts of dimethyl sulphone, whereas Trajadura wines possessed a high content of 3-(methylthio)propyl acetate and 4-(methylthio)-1-butanol. Alvarinho and Avesso wines showed high levels of S-methyl thioacetate, 3-mercapto-1-propanol, 3-(ethylthio)-1-propanol and 3-methylthiopropionic acid. Significant amounts of 2-methyltetrahydrothiophen-3-one, cis- and trans-2-methyltetrahydrothiophen-3-ol were also found in Avesso wines. Azal Branco wines were low in 3-(methylthio)propyl acetate and 2-(methylthio)ethanol, and high contents in S-methyl thioacetate, 3-mercapto-1-propanol and 2-mercaptoethanol. A linear discriminant analysis of sulphur compounds levels showed a differentiation of wines according to their varietal origin.

Volatiles From Mansoa standleyi (Steyerm.) A. H. Gentry

Essential oils of Mansoa standleyi collected at four municipalities of the State of Pará were obtained by hydro-distillation and analyzed by GC-FID and GC/MS. All samples analyzed showed a high content of sulfur compounds, among them diallyl disulfide (42.2–69.2%) and diallyl trisulfide (20.1–37.0%) were major. Oils from the leaves, stems, roots, tendrils, seeds, fruit pulp and fruit skin were obtained separately: allyl disulfide was major in seed oil (78.1%), and pulp fruit oil (70.2%), followed by the leaf and stem oils (60.2%). The lowest amount of ally disulfide was in the root oil (51.1%). In all samples the amount of diallyl disulfide was counterbalanced by the amount of diallyl trisulfide.

Análise de compostos sulfurados em efluentes gasosos de refinaria de petróleo

This work discusses an analytical procedure for analysis of sulfur compounds in treated petroleum refinery gaseous effluents using a sulfur chemiluminescence detector with dual plasma burner (SCD-DP). Calibration was accomplished by using standards and gaseous streams of known concentration of sulfur compounds. The response factors agree with the calibration table of ASTM standard D 5504 (2008). The detection range for sulfur compounds is in μg m-3. The analytical procedure allowed the construction of a chromatographic chart of sulfur compounds present in several refinery gaseous effluents. SO2 was the most difficult compound to be determined because of its high reactivity.

Deep desulfurization of diesel fuel using ionic liquids: current status and future challenges

Deep desulfurization of diesel fuel has attracted the attention of a growing number of scientists and engineers due to the stringent regulations imposed on the presence of sulfur in fuel (10 ppm). To bring down the concentration of sulfur compounds to less than 10 ppm is very challenging and demands newer technologies. Novel processes are being proposed for this purpose. It is observed that ionic liquids as class of green solvents can play a major role in the deep desulfurization of diesel fuel. For this reason, this review focuses on the current status in application of ionic liquids for achieving ultra-low-sulfur diesel (ULSD). To get a comprehensive perspective about the topic, other techniques of desulfurization are also discussed in brief in the introduction. Here we propose that the appropriate removal method should be selected according to different systems. To achieve deep desulfurization using ionic liquids, a better understanding regarding the regeneration of ionic liquids is vitally important.

Determination of Sulfur Compounds in Water Samples by Ion Chromatography Dynamic Reaction Cell Inductively Coupled Plasma Mass Spectrometry

AbstractAn ion chromatography‐inductively coupled plasma mass spectrometric (IC‐ICP‐MS) method for the speciation of sulfur compounds, namely sulfite [SO32−], sulfate [SO42−] and thiosulfate [S2O32−], was described. Ionic sulfur compounds were well separated in about 3 min by ion chromatography with a Hamilton PRP‐X100 column as the stationary phase and 60 mmol L−1 NH4NO3 and 0.1% v/v formaldehyde (HCHO) solution (pH = 7) as the mobile phase. The analyses were carried out using dynamic reaction cell (DRC) ICP‐MS. The sulfur‐selective chromatogram was determined at m/z 48 as 32S16O+ by using its reaction with O2 in the reaction cell. The method avoided the effect of polyatomic isobaric interferences at m/z 32 caused by 16O16O+ and 14N18O+ on 32S+ by detecting 32S+ as the oxide ion 32S16O+ at m/z 48, which is less interfered. The detection limit of various species studied was in the range of 3.6–4.6 ng S mL−1. The accuracy of the method has been verified by comparing the sum of the concentrations of individual sulfur compounds obtained by the present procedure with the total concentration of sulfur in several natural water samples. The recovery was in the range of 97–102% for various compounds studied.

Chemical Composition and Antimicrobial Activity of Wild Garlic Allium ursinum of Bulgarian Origin

The chemical composition of fresh flowers from Allium ursinum (ramsons, bear's garlic, wild garlic) growing in Bulgaria has been studied. Thymidine (1), adenosine (2), astragalin (kaempferol-3-O-beta-D-glucopyranoside (3), kaempferol-3-O-beta-D-glucopyranosyl-7-O-beta-D-glucopyranoside (4), kaempferol-3-O-beta-D-neohesperoside (5), and kaempferol-3-O-beta-D-neohesperoside-7-O-beta-D-glucopyranoside (6) were isolated from the n-butanol extract and identified by different spectroscopic and spectrometric methods. Thymine (7), uridine (8), uracil (9) and 5-chloro-uridine (10) were detected in the same extract by GC-MS. This is the first report of the occurrence of 1, 2, 4, 7 - 10 in the flowers of A. ursinum. GC-MS of the volatile components of fresh flowers and leaves from the same plant revealed a high content of sulfur compounds, some of which are reported for the first time for A. ursinum. The antimicrobial activities of extracts from fresh flowers and leaves of A. ursinum have been tested; some extracts exhibited moderate antifungal properties.

Chicken manure increased concentration of organic sulfur compounds in field-grown onions

A field study was conducted at Kentucky State University (KSU) Research Farm. The soil in five plots was mixed with sewage sludge, five plots were mixed with yard waste compost, five plots were mixed with laying hen manure each at 15 t acre−1, and five unamended plots that never received soil amendments were used for comparison purposes. Plots were planted with onion, Allium cepa L. var. Super Star-F1. The objectives of this investigation were to: 1) determine the concentrations of two organosulfur compounds (dipropyl disulfide and dipropyl trisulfide) in onion bulbs and 2) investigate the effect of mixing soil with three amendments (sewage sludge, yard waste, and chicken manure) on the concentration of dipropyl disulfide and dipropyl trisulfide in onion bulbs. Gas chromatographic/mass spectrometric (GC/MS) analyses of onion oil in chloroform extracts revealed the presence of two major fragment ions that correspond to dipropyl disulfide and – trisulfide. Concentration of these two organic sulfur compounds was greatest (1.5 and 0.8 mg 100 g−1 fresh weight, respectively) in onion bulbs of plants grown in chicken manure and lowest (0.4 and 0.07 mg 100 g−1 fresh weight, respectively) in onion bulbs of plants grown in yard waste compost treatments. We concluded that chicken manure could be exploited in growing onions with health-promoting properties.

Identification of Odor‐Active Organic Sulfur Compounds in Gypsum Products

AbstractGypsum is widely used in building products, e. g., as drywall, stucco or constituent in mortar, because it is easy to handle and it is assigned creating a good indoor air quality. Odor analysis of a gypsum product with a sulfurous off‐odor by means of gas chromatography‐olfactometry compared to two unobtrusive commercial gypsum products revealed – apart from typical odor compounds previously found in building products like aldehydes, ketones and acids – various organic sulfur compounds as odorants at very small concentrations (≪1 μg/m3) not allowing structural identification. Gypsum deposits naturally contain impurities and elemental sulfur, which can react in nature due to tectonic pressure and temperature or during production with organic compounds, e. g., from beater additives, to form organic sulfur compounds. Odor analysis of a gypsum raw material and its semi‐processed product from a Chinese deposit with a very intense sulfurous off‐odor revealed high concentrations of organic sulfur compounds, which were identical in analytical, chromatographic and sensory properties to the unidentified sulfur compounds of the commercial products and are therefore suitable for structural identification of those unknowns. In this way, a number of sulfides, disulfides, thiols and aromatic sulfur compounds could be identified as contributing to the odor of gypsum products.

Determination of volatile fractions in raw milk and ripened cheese by means of GC-MS.Results of a survey performed in the marginal area between Italy and Slovenia

abstractThe volatile fractions of milk and their evolution in ripened cheese were studied using purge and trap extraction and gas chromatography-mass spectrometry analysis (GC-MS). Eighteen samples of raw milk and cheese ripened for 70 days were collected in 2 consecutive years from dairy farms located in the border area between Italy and Slovenia. Twenty one volatile compounds not detected in the fresh milk used for cheese manufacturing, belonging mainly to the class of esters and alcohols, were found, while 8 compounds detected in milk were not found in cheese after 70 days of ripening. In cheese the majority of compounds increased significantly, even though the variations differed between the classes of volatile compounds. Concentration of alcohols, in particular ethanol, 1-propanol, 2-propanol, 3-methyl-1-butanol and 2-pentanol, increased considerably, while the content of ketones and terpenes was characterized by a significant, although small, rise that was largely related to a quantitative variation of only few compounds. Also esters, despite the high number of volatile compounds of new formation, showed a lower increase of concentration than that observed for the alcohols. Concentration of aldehydes, hydrocarbons and sulphur compounds remained unchanged, despite relevant variations involving the individual chemical compounds. Significant differences were also observed between the dairy product of the two countries, mainly for the concentration of volatile compounds belonging to the classes of alcohols, ketones and esters.

Autotrophic denitrification and inhibitory effect caused by the injection of spent sulfidic caustic in a modified Ludzack-Ettinger process

As spent sulfidic caustic (SSC) from petroleum plants contains a high concentration of alkalinity and sulfur compounds, SSC can be applied in sewage treatment system as an electron donor for autotrophic denitrification. In our previous study, the reuse of SSC in the biological nitrogen process was successful, and some neutralization may be required for stable treatment performance. In this study, the pH of SSC was neutralized to 12.0 from 13.3, and the modified Ludzack-Ettinger process was conducted for 90 days with the municipal wastewater. Some toxic effects of SSC on microorganisms were tested via a specific oxygen uptake rate (SOUR) assay. According to the SOUR assay, as compared with no SSC injection condition, SOUR was reduced by approximately 5.4% when 4 mL SSC/L was injected and the effective concentration of a toxicant causing 50% inhibition of the microorganism’s activity (EC50) was 22.6 mL/L. During the days of operation, the COD removal and nitrification efficiency were over 53.0 and 98.2%, respectively. The TN removal efficiency was 56.6% and the nitrogen removal rate (NRR) was 0.15 kg/m3·d when the hydraulic retention time (HRT) in the anoxic tank was 3 h. The ratio of nitrifying bacteria was unaffected by the HRT, and Nitrobacter spp. and Nitrospira genus existed at similar ratios. The ratio of T. denitrificans increased after the injection of SSC and was approximately 6.5%.