Dimethyl Sulfide In Air Research Articles

Challenges associated with the sampling and analysis of organosulfur compounds in air using real-time PTR-ToF-MS and offline GC-FID

Abstract. Organosulfur compounds (OSCs) are naturally emitted via various processes involving phytoplankton and algae in marine regions, from animal metabolism, and from biomass decomposition inland. These compounds are malodorant and reactive. Their oxidation to methanesulfonic and sulfuric acids leads to the formation and growth of atmospheric particles, which are known to influence clouds and climate, atmospheric chemical processes. In addition, particles in air have been linked to negative impacts on visibility and human health. Accurate measurements of the OSC precursors are thus essential to reduce uncertainties in their sources and contributions to particle formation in air. Two different approaches, proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) and canister sampling coupled to gas chromatography with flame ionization detector (GC-FID), are compared for both laboratory standards (dimethyl sulfide, DMS; dimethyl disulfide, DMDS; dimethyl trisulfide, DMTS; and methanethiol, MTO) and for a complex sample. Results show that both techniques produce accurate quantification of DMS. While PTR-ToF-MS provides real-time measurements of all four OSCs individually, significant fragmentation of DMDS and DMTS occurs, which can complicate their identification in complex mixtures. Canister sampling coupled with GC-FID provides excellent sensitivity for DMS, DMDS, and DMTS. However, MTO was observed to react on metal surfaces to produce DMDS and, in the presence of hydrogen sulfide, even DMTS. Avoiding metal in sampling systems seems to be necessary for measuring all but dimethyl sulfide in air.

The method for on-site determination of trace concentrations of methyl mercaptan and dimethyl sulfide in air using a mobile mass spectrometer with atmospheric pressure chemical ionization, combined with a fast enrichment/separation system.

A method for fast simultaneous on-site determination of methyl mercaptan and dimethyl sulfide in air was developed. The target compounds were actively collected on silica gel, followed by direct flash thermal desorption, fast separation on a short chromatographic column and detection by means of mass spectrometer with atmospheric pressure chemical ionization. During the sampling of ambient air, water vapor was removed with a Nafion selective membrane. A compact mass spectrometer prototype, which was designed earlier at Trofimuk Institute of Petroleum Geology and Geophysics, was used. The minimization of gas load of the atmospheric pressure ion source allowed reducing the power requirements and size of the vacuum system and increasing its ruggedness. The measurement cycle is about 3 min. Detection limits in a 0.6 L sample are 1 ppb for methyl mercaptan and 0.2 ppb for dimethyl sulfide.

A chemical ionization mass spectrometer for continuous underway shipboard analysis of dimethylsulfide in near-surface seawater

Abstract. A compact, low-cost atmospheric pressure, chemical ionization mass spectrometer ("mini-CIMS") has been developed for continuous underway shipboard measurements of dimethylsulfide (DMS) in seawater. The instrument was used to analyze DMS in air equilibrated with flowing seawater across a porous Teflon membrane equilibrator. The equilibrated gas stream was diluted with air containing an isotopically-labeled internal standard. DMS is ionized at atmospheric pressure via proton transfer from water vapor, then declustered, mass filtered via quadrupole mass spectrometry, and detected with an electron multiplier. The instrument described here is based on a low-cost residual gas analyzer (Stanford Research Systems), which has been modified for use as a chemical ionization mass spectrometer. The mini-CIMS has a gas phase detection limit of 220 ppt DMS for a 1 min averaging time, which is roughly equivalent to a seawater DMS concentration of 0.1 nM DMS at 20°C. The mini-CIMS has the sensitivity, selectivity, and time response required for underway measurements of surface ocean DMS over the full range of oceanographic conditions. The simple, robust design and relatively low cost of the instrument are intended to facilitate use in process studies and surveys, with potential for long-term deployment on research vessels, ships of opportunity, and large buoys.

Oxidation of Dimethyl Sulfide in Air Using Electron-Beam Irradiation, and Enhancement of its Oxidation Via an MnO2 Catalyst

The decomposition of dimethyl sulfide (DMS) at initial concentrations of 4.5–18.0 ppmv in air was studied under electron-beam (EB) irradiation. Doses to decompose 90% of input DMS were 2.5 kGy for 4.5 ppmv, 3.4 kGy for 10.6 ppmv, and 3.9 kGy for 18.0 ppmv. HCOOH, (CH3)2SO, and trace CH3OH and (CH3)2SO2 were produced as irradiation products in addition to CO2 and CO. Application of an O3 decomposition catalyst to an irradiated sample gas led to an enhancement in the oxidation of DMS and its products into CO2 and the decomposition of O3. For 10.6 ppmv DMS/air, the mineralization ratio increased from 41% via only EB irradiation to 100% via the combination treatment at 6.3 kGy. The yield of CO2 to COx increased from 5.3 to 87.6% by combination with catalytic oxidation. This combination treatment enables the irradiation energy used to deodorize gas streams containing DMS to be reduced.

Interannual variability of dimethylsulfide in air and seawater and its atmospheric oxidation by‐products (methanesulfonate and sulfate) at Dumont d'Urville, coastal Antarctica (1999–2003)

A multiple year‐round study of atmospheric dimethyl sulfide (DMS) (from December 1998 to April 2003) as well as sulfur‐derived aerosols (methanesulfonic acid (MSA) and non‐sea‐salt sulfate) (from March 1991 to February 2003) was conducted at Dumont d'Urville, coastal Antarctica. The three sulfur‐derived species exhibit a seasonal cycle characterized by maxima in midsummer (January). Whereas the interannual variability of winter levels remains low, a strong interannual variability is shown in summer, particularly for DMS and MSA, and to a lesser extent for non‐sea‐salt sulfate. Over the 1998–2003 time period, January 2002 stands out with high values for all sulfur species. These interannual variabilities of atmospheric summer levels are examined in the light of seawater chlorophyll a content derived from Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) data (themselves compared to field measurements made south of 60°S), oceanic DMS levels estimated from chlorophyll a SeaWiFS data, and various sea‐ice indices.

Photooxidation of dimethylsulfide in the gas phase: A comparison between TiO2–silica and photosensitizer-silica based materials

The photooxidation of dimethylsulfide (DMS) in the gas phase was studied with two different materials, under identical conditions. The first material (TiO2-QZ) is based on titanium dioxide (TiO2) deposited on quartz bars by the sol–gel method. The second one (DCA-SG) is based on the well known photosensitizer, 9,10-dicyanoanthracene (DCA) encapsulated in a sol–gel silica network. In spite of non-optimized conditions, both materials allow the oxidation of DMS in air under irradiation. However, the oxidation products are strikingly different: dimethyldisulfide is the main product detected in the gas phase with TiO2-QZ due to a too short residence time to achieve complete mineralization. With DCA-SG no gaseous product is detected in the treated gaseous flow for more than 100h, due to the exclusive formation of polar dimethylsulfoxide and dimethylsulfone which are totally adsorbed on the highly polar silica gel. The efficiency of this latter reaction depends on the DMS concentration, gas flow and light intensity, but is not affected by the presence of small amounts of water. Singlet oxygen appears to be formed efficiently under these conditions. The saturation of DCA-SG by the oxidation products was demonstrated by several complementary methods, and some possible solutions to regenerate the material are proposed. The complementarities of both TiO2-QZ and DCA-SG could be used to achieve the oxidation of different classes of pollutants.

Analysis of Sulfuric Acid Aerosols by Laser-Induced Breakdown Spectroscopy and Laser-Induced Photofragmentation

Laser-induced breakdown spectroscopy and laser photofragmentation spectroscopy are investigated as potential approaches to the detection and quantification of the sulfuric acid aerosols resulting from the oxidation of dimethylsulfide in air. The former, direct technique, where aerosols are introduced in the plasma formed by focusing the fundamental frequency of a Nd:YAG laser in air, and atomic sulfur emission is measured in the region 180 nm, gives a limit of detection of 165 ppbv for a 15 min integration time, which is inadequate for our purposes. The second, indirect approach, based on the photofragmentation, with 193 nm photons, of the compound resulting from interaction between sodium chloride and sulfuric acid aerosols, gives a detection limit of 46.5 ppbv in 10 s measuring time. With this method, a complete “titration curve” for sulfuric acid aerosols can be obtained in “quasi” real-time.

Dimethyl sulfide, methane sulfonic acid and physicochemical aerosol properties in Atlantic air from the United Kingdom to Halley Bay

The concentrations of dimethyl sulfide in air were obtained during a cruise between the United Kingdom and the Antarctic in the period October 1992 to January 1993 using a method of sampling and analysis optimized to avoid interferences from oxidants. In equatorial regions (30°N to 30°S) the atmospheric DMS concentration ranged from 3 to 46 ng (S) m−3, with an average of 18 ng (S) m−3. In the polar waters and regions south of the Falkland Islands, concentrations from 3 to 714 ng (S) m−3 were observed, with a mean concentration of 73 ng (S) m−3. The concentrations of a range of DMS oxidation products were also obtained. No clear relationships between reactant and product concentrations were seen. Information on particle number concentration, Fuchs surface area and the thermal volatility characteristics of the ambient aerosol was obtained, but again no clear relationships with sulfur concentrations were observed. Accumulation mode particle concentrations averaged 25 cm−3 in the clean marine and polar air masses south of 58°S while background condensation nuclei (CN) concentrations were of the order of 400–600 cm−3. Simplistic calculations suggest that a particle source strength of about 20–60 particles cm−3 d−1 is required to sustain this background CN concentration. It is not clear whether boundary layer nucleation of new CN or entrainment from the free troposphere provided the source of CN. Periods of elevated CN concentrations (>4000 cm−3) were regularly observed in the boundary layer over the Weddell Sea and were attributed to “bursts” of new particle formation. However, shortly after these nucleation events the CN concentration rapidly decayed to the background level through coagulation losses, suggesting little impact on the background CN or cloud condensation nuclei (CCN) concentration.

Biogenic sulfur emissions and aerosols over the tropical South Atlantic: 3. Atmospheric dimethylsulfide, aerosols and cloud condensation nuclei

We measured dimethylsulfide in air (DMSa) and the number concentration, size distribution, and chemical composition of atmospheric aerosols, including the concentration of cloud condensation nuclei (CCN), during February‐March 1991 over the tropical South Atlantic along 19°S (F/S Meteor, cruise 15/3). Aerosol number/size distributions were determined with a laser‐optical particle counter, condensation nuclei (CN) concentrations with a TSI 3020, and cloud condensation nuclei (CCN) with a Hudson‐type supersaturation chamber. Aerosol samples were collected on two‐stage stacked filters and analyzed by ion chromatography for soluble ion concentrations. Black carbon in aerosols was measured by visible light absorption and used to identify and eliminate periods with anthropogenic pollution from the data set. Meteorological analysis shows that most of the air masses sampled had spent extended periods over remote marine areas in the tropical and subtropical region. DMSa was closely correlated with the sea‐to‐ air DMS flux calculated from DMS concentrations in seawater and meteorological data. Sea salt made the largest contribution to aerosol mass and volume but provided only a small fraction of the aerosol number concentration. The submicron aerosol had a mean composition close to ammonium bisulfate, with the addition of some methanesulfonate. Aerosol (CN and CCN) number and non‐sea‐salt sulfate concentrations were significantly correlated with DMS concentration and flux. This suggests that DMS oxidation followed by aerosol nucleation and growth in the marine boundary layer is an important, if not dominating, source of CN and possibly CCN. The degree of correlation between DMS and particle concentrations in the marine boundary layer may be strongly influenced by the different time scales of the processes regulating these concentrations. Our results provide strong support for several aspects of the CLAW hypothesis, which proposes the existence of a feedback loop linking DMS emission from marine plankton to sulfate aerosol and global climate.

Biogenic sulfur emissions and aerosols over the tropical South Atlantic: 1. Dimethylsulfide in sea water and in the atmospheric boundary layer

We measured dimethylsulfide (DMS) in air (DMSa) and surface seawater (DMSw) on board the R/V Meteor during February–March 1991 on the tropical South Atlantic. Samples for the determination of DMSa were taken through a fluorinated ethylene/propylene Teflon inlet ≈33 m above sea level, preconcentrated by adsorption onto gold wool in quartz tubes, and analyzed by gas chromotography with flame photometric detection. The DMSa instrument is fully automated, providing improved precision, and processes up to four samples per hour. Over most of the cruise track, which followed the 19°S parallel between Brazil and Africa, DMSw, was significantly correlated to climatologically averaged chlorophyll concentrations obtained from coastal zone color scanner data, suggesting that remote sensing may be useful for estimating seawater DMS levels at least in some ocean regions. The cruise track proceeded from waters of low roductivity (off the coast of Brazil and in the subtropical gyre) to higher productivity (the Benguela Current and the upwelling region off Namibia and Angola); meteorological conditions were steady with consistent easterly winds. DMS values for air and water were low (≈ 50 ppt and 1–2 nmol L−1, respectively) in the areas of low productivity and increased simultaneously (≈ 100–300 ppt and 3–15 nmol L−1) as productivity increased. DMS sea‐to‐air fluxes (average 7.3 μmol m−2 d−1) were calculated based on different parameterizations; for the study region the differences between the results obtained from the different models were minor. DMSa was strongly correlated to its emission flux from the sea surface as estimated from DMSw and meteorological parameters. This suggests that the air/sea transfer parameterizations used are suitable for providing estimates of DMS flux from the oceans.

Ocean color and atmospheric dimethyl sulfide: On their mesoscale variability

The mesoscale variability of dimethyl sulfide (DMS) and ocean color is explored to determine the feasibility of a predictive relationship. During NASA's Global Tropospheric Experiment/Chemical Instrumentation Test and Evaluation (GTE/CITE 3), simultaneous shipboard and aircraft studies were carried out in the North Atlantic, followed by aircraft studies in the South Atlantic. Surface concentrations of chlorophyll a were measured with an airborne spectroradiometer, the Ocean Data Acquisition System (ODAS), with simultaneous determinations of tropospheric DMS. Shipboard measurements of DMS in air and water as well as in situ chlorophyll a were taken in the North Atlantic. No relation was observed between shipboard aquatic DMS and chlorophyll a or primary productivity. Higher levels of aqueous DMS were not always reflected by atmospheric DMS, although shipboard and aircraft measurements of atmospheric DMS agreed very well. A significant relationship between atmospheric DMS and ocean color was seen once at low altitudes in both the North and South Atlantic only under clean air conditions. Atmospheric DMS levels during the North Atlantic experiment were probably lowered by the presence of mostly polluted air masses in the study area and were, overall, probably not representative of the in situ sea‐to‐air flux of DMS. Changes in concentration of aircraft‐sensed chlorophyllous pigments were not reflected by atmospheric DMS. If a predictive algorithm is to be found, phytoplankton blooms should probably be the first place to study an ocean color‐DMS relationship.

Grab sampling for the determination of sulfur dioxide and dimethyl sulfide in air by isotope dilution gas chromatography/mass spectrometry

Developments allowing the direct determination of sulfur dioxide and dimethyl sulfide in grab samples by gas chromatography/mass spectrometry with isotopically labeled standards (GC/MS/ILS) are reported. Isotopomers of DMS and SO2 are used as internal standards. Spiked air samples are dried to a dew point of <−60 °C and trapped cryogenically in loops of Teflon tubing. Sealed samples are transported to the laboratory under liquid nitrogen and later subjected to GC/MS analysis. Holding times of up to one month do not result in significant sample loss. For samples collected in a clean marine environment, concentrations of SO2 and DMS greater than 5 and 8 pptv, respectively, are significantly different from blanks at the 95% confidence level. Average measurement precision derived from a propagation of errors are 9% for SO2 and 42% for DMS at concentrations from 5–15 pptv.

Formation of sulfur dioxide and methanesulfonic acid in the photooxidation of dimethyl sulfide in the air

Photooxidation of dimethyl sulfide (DMS) in air in the presence of NO was studied. Sulfur dioxide (SO2) and methanesulfonic acid (CH3SO3H) are major sulfur‐containing products. In the reaction systems of DMS‐NO‐air with low initial NO concentration and DMS‐CH3ONO‐air, in which OH radical‐initiated photooxidation prevails, the yield of SO2 was determined to be 20.7 ± 1.2 %. The yield of methanesulfonic acid is more than 50 % of the consumed DMS. Sulfuric acid was also detected as a minor product with a yield of less than 2 %. The implications of these results on the atmospheric sulfur cycle are discussed.

The photolysis of dimethyl sulfide in air.

The body of information presented in this paper is directed to those individuals interested in chemical methods for control of kraft pulping emissions and also to those interested in the fate of kraft air pollutants in the atmosphere.

Deodorization of Exhaust Gas in Kraft Pulping (Part 2)

Adsorption capacities and absorption capacities for malodorous components were estimated at 20 and 29°C. Adsorption capacity of activated carbon for methyl merccaptan was larger than that for dimethyl sulfide. For the hydrogen sulfide, activated carbon acted not only as a adsorbent but also as a catalyst, and so adsorption capacity of activated carbon for hydrogen sulfide was larger than that for formers. When mixture of dimethyl sulfide and methyl mercaptan was adsorbed on activated carbon, the total adsorption capacity of activated carbon was medium capacity between those for individual components. Because real kraft pulp blow gas is mixture of methyl mercaptan, dimethyl sulfide and others, adsorption of activated carbon for one was the mixture adsorption, and the adsorption capacity was 30 to 40%. Absorption capacity of poly-vinyl chloride for dimethyl sulfide was moderately large, but dimethyl sulfide in air was absorbed partially by poly-vinyl chloride. Absorption reaction of ferric oxide for hydrogen sulfide makes water a reaction product, therefore exact measurement of absorption is difficult. It was found that under pyrolysis gas chromatograph of activated carbon, which adsorbed methyl mercaptan, methyl mercaptan decomposed into hydrogen sulfide at 570 to 790°C.

Studies on the Utilization of Alkali Lignin (Part 4)

Dimethyl sulfide is easily oxidized by ozone at low temperature. In ozone oxidation, residue from ozone is O2 only, and so recovery of reaction products is easy. In this report, we describe the outline of ozone oxidation and then the purity of dimethyl sulfoxide, by gas chromatograph and IR spectrum.Ignition point of dimethyl sulfide in air is 206°C and in oxygen is 204.5°C. The difference between the former and the latter is small.Dimethyl sulfide composes the explosion mixture with O2. In this meaning, we would describe the ozone oxidation condition.