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.     

紫外光分解硫化氢制氢的研究

以10W低压汞灯(特征谱线波长,λ=253.7nm,简称UVC)作为光源,硫化钠的水溶液作为反应介质,进行了UVC直接分解硫化氢制氢反应(简称UVC-H₂S-H₂)的研究.考察了反应介质中硫的存在形式、硫化钠的浓度、反应介质pH值以及连续通入硫化氢的流量等反应条件对UVC-H₂S-H₂的影响.实验结果表明,UVC可以在无催化剂条件下直接分解硫化氢制氢.当以0.6mol/L硫化钠水溶液为反应介质,以25mL/h流量连续向反应介质中通入硫化氢时,UVC-H₂S-H₂产氢速率可达3.0mL/W·h.     

A field electrode method for the determination of sulfide

This paper reports the development of a field electrode method for the determination of total sulfide in water. The method involves the use of preweighed sodium sulfide crystals in the standardization process. Sodium sulfide crystals were weighed and sealed in air-tight plastic volumetric flasks. Standards were prepared in the field by adding a sulfide antioxidant buffer to the flasks containing the sulfide crystals and diluting it to mark with deionized deaerated water. Standards of lower concentration were prepared by serial dilutions of first standards.The results of the reproducibility determination revealed that sulfide concentrations as low as 6 ppb could be measured with a reproducibility of better than ±10%.Water samples were collected from a series of lakes in Fort Bend County, Texas (near Houston) and analyzed for sulfide content. The sulfide ion concentrations of these samples were determined directly in the field by use of an Orion Model 407A/F specific meter equipped with a silver/sulfide ion selective electrode in conjunction with a double junction reference electrode.     

Graphene quantum dots combined with copper(II) ions as a fluorescent probe for turn-on detection of sulfide ions

A fluorescent probe for the sensitive and selective determination of sulfide ions is presented. It is based on the use of graphene quantum dots (GQDs) which emit strong and stable blue fluorescence even at high ionic strength. Copper(II) ions cause aggregation of the GQDs and thereby quench fluorescence. The GQDs-Cu(II) aggregates can be dissociated by adding sulfide ions, and this results in fluorescence turn on. The change of fluorescence intensity is proportional to the concentration of sulfide ions. Under optimal conditions, the increase in fluorescence intensity on addition of sulfide ions is linearly related (r ² = 0.9943) to the concentration of sulfide ions in the range from 0.20 to 20 μM, and the limit of detection is 0.10 μM (at 3 σ/s). The fluorescent probe is highly selective for sulfide ions over some potentially interfering ions. The method was successfully applied to the determination of sulfide ions in real water samples and gave recoveries between 103.0 and 113.0 %.

Graphene quantum dots (GQDs) emit strong blue fluorescence which, however, is quenched by copper(II) ions due to the formation of GQDs-Cu(II) aggregates. Fluorescence is recovered by sulfide ions due to the dissociation of GQDs-Cu(II) aggregates.

     

Preparation of Indium Tin Oxide Nanoparticle‐modified 3‐Aminopropyltrimethoxysilane‐functionalized Indium Tin Oxide Electrode for Electrochemical Sulfide Detection

A sulfide sensor based on an indium tin oxide nanoparticle (ITONP)‐modified ITO electrode was developed. To prepare ITONP‐modified ITO, various methods were tested. Drop‐drying of ITONPs (aq.) on aminopropyltrimethoxysilane‐functionalized ITO (APTMS/ITO) was found to be the best method on the basis of voltammetric analysis of the sulfide ion. ITONP‐modified APTMS/ITO (ITONP/APTMS/ITO) yielded much better electrocatalytic properties toward sulfide electro‐οxidation than did bare or APTMS/ITO electrodes. The ITONPs and ITONP‐modified ITO were also characterized using transmission electron microscopy and field emission scanning electron microscopy, respectively. Optimization of the type of inert electrolyte and pH yielded an ITONP/APTMS/ITO detector whose amperometrically and chronocoulοmetrically determined limits of detection for sulfide were 3.0 μM and 0.90 μM, respectively. ITONP/APTMS/ITO electrodes displayed reproducible performance, were highly stable, and were not susceptible to interference by common contaminants. Thus, the developed electrode can be considered as a promising tool for sensing sulfide.     

流动注射化学发光法测定痕量硫

基于硫离子对鲁米诺－过氧化氢化学发光反应的增敏作用,建立了测定痕量硫的流动注射化学发光反应的增敏作用,建立了测定痕量硫的流动注射化学发光的新方法。该方法的线性范围为２．０×１０－９～８．０×１０－７ｇ／ｍＬ,检出限为５．６×１０－１０ｇ／ｍＬ,相对标准偏差小于５％（１．０×１０－７ｇ／ｍＬＳ２－,ｎ＝１１）。方法简单,快速,灵敏,已用于环境水样中痕量硫的测定。     

纳米MgO催化发光检测硫化氢

研究了硫化氢在纳米Mg O表面的催化发光现象,发现纳米Mg O对硫化氢具有较好的特异性,据此设计了硫化氢催化发光传感器。通过优化设计建立了一种快速检测硫化氢的新方法,线性范围为2.00~200ppm(r=0.999 3),检出限为0.8 ppm(信噪比S/N=3)。采用此传感器进行人工合成样品中硫化氢的加标回收分析,回收率为88.4%~97.2%。此传感器具有灵敏、快速、操作简便等优点,在硫化氢快速检测领域具有潜在应用前景。该文还探讨了硫化氢的催化发光反应机理。     

Influence of Gas Components on the Formation of Carbonyl Sulfide over Water-Gas Shift Catalyst B303Q

Water-gas shift reaction catalyst at lower temperature (200—400℃) may improve the conversion of carbon monoxide. But carbonyl sulfide was found to be present over the sulfided cobalt-molybdenum/alumina catalyst for water-gas shift reaction. The influences of temperature, space velocity, and gas components on the formation of carbonyl sulfide over sulfided cobalt-molybdenum/alumina catalyst B303Q at 200—400℃were studied in a tubular fixed-bed quartz-glass reactor under simulated water-gas shift conditions. The experimental results showed that the yield of carbonyl sulfide over B303Q catalyst reached a maximum at 220℃with the increase in temperature, sharply decreased with the increase in space velocity and the content of water vapor, increased with the increase in the content of carbon monoxide and carbon dioxide, and its yield increased and then reached a stable value with the increase in the content of hydrogen and hydrogen sulfide. The formation mechanism of carbonyl sulfide over B303Q catalyst at 200—400℃was discussed on the basis of how these factors influence the formation of COS. The yield of carbonyl sulfide over B303Q catalyst at 200-400℃was the combined result of two reactions, that is, COS was first produced by the reaction of carbon monoxide with hydrogen sulfide, and then the as-produced COS was converted to hydrogen sulfide and carbon dioxide by hydrolysis. The mechanism of COS formation is assumed as follows: sulfur atoms in the Co9S8-MOS2/Al2O3 crystal lattice were easily removed and formed carbonyl sulfide with CO, and then hydrogen sulfide in the water-gas shift gas reacted with the crystal lattice oxygen atoms in CoO-MoO3/Al2O3 to form Co9S8-MoS2/Al2O3. This mechanism for the formation of COS over water-gas shift catalyst B303Q is in accordance with the Mars-Van Krevelen's redox mechanism over metal sulfide.     

亚砜还原法合成聚苯醚硫醚的结构与性能研究

以氟苯和氯化亚砜反应合成了4,4’-二氟二苯亚砜,并将其与4,4’二羟基二苯硫醚在N-甲基吡咯烷酮溶剂中进行亲核取代反应合成了聚苯醚硫醚醚亚砜,用乙二酰氯/四丁基碘化铵还原该亚砜聚合物制备了聚苯醚硫醚。用红外光谱和核磁共振谱对合成单体的结构进行了确认,同时对聚合物进行了红外光谱、核磁共振、元素分析、X射线光电子能谱、X射线衍射、DSC分析、TG/DTG以及溶解性测试。结果表明聚苯醚硫醚样品具有氧醚和硫醚交替的线性结构,特性粘度为0.55 dL/g的PPSE熔点达236℃,在氮气条件下,样品起始分解温度和最大分解速率处温度分别为359℃和514℃,在700℃时的重量保留率为43.3%,且在加热条件下能溶解于N-甲基吡咯烷酮(NMP)、二甲基乙酰胺(DMAc)、二甲基甲酰胺(DMF)等极性有机溶剂中。     

Flow Injection Analysis of Sulfide Using a Cinder/Tetracyano Nikelate Modified Screen‐Printed Electrode

Flow injection analysis (FIA) of sulfide is presented using a screen‐printed carbon electrode modified with a cinder/tetracyano nickelate hybrid (designated as cinder/NiTcSPE). Hybridization of NiTc was achieved in iron‐enriched industrial waste cinder material through the bimetallic formation of Fe^III[Ni^II(CN)₄]. The electrocatalytic oxidation of sulfide is mediated by the higher oxidation state of Ni in this hybrid‐bimetallic complex. The system shows a detection limit (S/N=3) of 0.06 μM and a linear working range up to 1 mM in pH 10, 0.1 M KCl solution. Taking into account the relatively low volatility of the analyte in alkaline conditions, the system is ideally suited for the accurate detection of sulfide. The response of the electrode to sulfide is highly reproducible, thereby offering the potential development of a disposable amperometric sensor for sulfide. Selective detection of sulfide in cigarette smoke is presented in this study as an example of a real sample application.     

Facile synthesis of ZnS/MnS nanocomposites for supercapacitor applications

Journal of Solid State Electrochemistry - In this study, we have reported a facile fabrication of pristine zinc sulfide (ZnS), manganese sulfide (MnS), and ZnS/MnS nanocomposites (NCs) via...     

土壤中硫化物的分析方法研究

硫化物作为土壤中常见的污染物在酸性环境中会生成H_2S,造成环境污染,研究中根据环境质量要求分别针对土壤中易解析的硫化物、酸可溶解性硫化物、酸难溶性硫化物建立了相应的分析测定方法。硫化物分别在磷酸(1+1)、浓硫酸、盐酸(9.8mol/L)作用下形成硫化氢,硫化氢随氮气进入装有乙酸锌吸收液的吸收瓶中,生成硫化锌沉淀,以碘量法定量。结果表明:酸难溶性硫化物的实际样品加标回收率为86%~98%;酸溶性硫化物的实际样品加标回收率为83%~91%,空白加标回收率为92%~97%。精密度实验中,酸溶性硫化物相对标准偏差为6.4%~8.3%。沙土、花园土、黄土、稻田土中酸难溶性硫化物的相对标准偏差分别为2.6%、4.0%、5.5%、5.8%。方法精密度和准确度满足分析要求,可以用来评估土壤中的硫化物污染问题,也可以了解不同类型硫化物的污染情况。     

超声法制备硫化铅/二氧化硅核壳结构亚微米粒子

0 引言 纳米微粒具有的小尺寸效应,表面效应、量子尺寸效应及宏观量子隧道效应等导致纳米粒子的热、磁、光、敏感特性和表面稳定性等不同于常规粒子,这就使得它具有广阔的应用前景.     

Preparation of polymer nanocomposites with “ultrahigh” refractive index

Nanocomposites of lead sulfide and several polymers, especially poly(ethyleneoxide), were prepared by coprecipitation of lead sulfide and polymer, followed by a drying and pressing procedure. Such nanocomposites consist of ca. 90% w/w (or ca. 50% v/v) lead sulfide, of particle dimensions of 2–40 nm. The refractive index of these materials is on the order of 3 and therefore, to the authors' best knowledge, is the highest reported for any polymer composite.     

Kinetic spectrophotometric determination of sulfide, using in-cuvette mixing and titration techniques with computerized data acquisition

In-cuvette mixing and titration techniques have been used for the kinetic determination of sulfide based on its inhibition effect on the oxidation of indigo carmine with hexacyanoferrate(III) in the presence of silver. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of indigo carmine at 612 nm. Both initial rate and fixed-time methods were applied to the in-cuvette technique. Using in-cuvette mixing, sulfide up to 1800 ng was determined and detection limit and relative standard deviation for the determination of 120 ng of sulfide were calculated as 23.0 ng and 1.59%, respectively. On the basis of the titration technique, the upper limit of determination was 25 μg of sulfide and detection limit and average relative standard deviation for the determination of 1 μg of sulfide were 0.025 μg and 4.95%, respectively. The effect of foreign ions on the sulfide determination was studied. The proposed methods were applied to the determination of sulfide in water. Received: 10 March 1999 / Revised: 9 June 1999 / Accepted: 12 June 1999     

Direct electrical measurement of the conversion of metal acetates to metal sulfides by hydrogen sulfide

Copper acetate and related metal salt films react directly with hydrogen sulfide at room temperature to form metal sulfides, resulting in conductivity changes as large as 108. The observed changes in conductivity are related to the solubility product constant (Ksp) and the difference in conductivity between the metal salt and the resulting metal sulfide. A smaller Ksp indicates a more stable metal sulfide and, therefore, greater metal salt reactivity. Polyaniline nanofiber/metal salt composites were also examined and show metal sulfide conversion with changes in resistance up to 106. The direct electrical measurement of the conversion of metal salt to metal sulfide has the potential to be the basis of a new type of sensitive, thin-film chemical sensor.     

阴离子交换色谱-脉冲安培法检测味精中的硫化物

建立了阴离子交换色谱柱分离、脉冲安培检测器测定味精中微量硫化物的方法。味精样品经2 g/L氢氧化钠溶液直接溶解并过滤后直接进样,硫离子与高浓度谷氨酸等阴离子在IonPac AS7阴离子色谱柱(250 mm×4 mm)上可实现较好的分离。以100 mmol/L氢氧化钠-500 mmol/L醋酸钠-0.5%乙二胺为淋洗液等度淋洗,6 min内可完成一次样品测定。脉冲安培检测器检测硫离子的检出限(25 μL进样,信噪比为3)为0.3 μg/L,并具有较宽的线性范围(0.001～1 mg/L),样品加标回收率为94.2%～99.0%。应用该方法检测99%味精、增鲜味精和加盐味精样品中的硫化物,结果表明该方法具有简便快捷、高选择性、高灵敏度等优点。     

TG-MS与Py-GC相结合法研究惰性气氛下含硫模型化合物热解过程中硫的脱除及释放行为研究

采用热重-质谱法(TG-MS)和热解-气相色谱法(Py-MS)相结合的方法对模型化合物(十四硫醇、二丁基硫醚、苯硫醚、二甲基噻吩、苯并噻吩和二苯并噻吩等)在惰性气氛下硫的脱除及释放行为进行研究。惰性气氛下硫的脱除顺序为:十四硫醇>二丁基硫醚>二甲基噻吩>苯并噻吩>苯硫醚>二苯并噻吩,苯硫醚除外,该顺序与含硫官能团的热分解顺序一致。在热解过程中,所有模型化合物在质谱和气相色谱仪上均被检测到SO₂;除苯硫醚和二苯并噻吩外,其他模型化合物中均检测到了COS;而只在十四硫醇、二丁基硫醚和二甲基噻吩中检测到了H₂S。且热解气中SO₂含量要显著高于H₂S和COS。这是由于活性炭作载体时,惰性气氛下内部氢的含量显著小于内部氧的含量,所以大多数的含硫自由基易与内部氧结合以SO₂的形式逸出。对于苯硫醚、苯并噻吩和二苯并噻吩中没有检测到H₂S,是由于内部氢的不足,使得含硫自由基不能与内部氢结合,所以没有检测到H₂S逸出。     

Determination of Sulfide by Hematoxylin Multiwalled Carbon Nanotubes Modified Carbon Paste Electrode

This study investigates a new approach for the amperometric determination of sulfide using a hematoxylin multiwalled carbon nanotubes modified carbon paste electrode (HM‐MWCNTs/CPE). The experimental results show that HM‐MWCNTs/CPE significantly enhances the electrocatalytic activity towards sulfide oxidation. Cyclic voltammetric studies show that the peak potential of sulfide shifted from +400 mV at unmodified CPE to +175 mV at HM‐MWCNTs/CPE. The currents obtained from amperometric measurements at optimum conditions were linearly correlated with the concentration of sulfide. The calibration curve was obtained for sulfide concentrations in the range of 0.5–150×10^?6 mol L^?1. The detection limit was found to be 0.2×10^?6 mol L^?1 for the amperometric method. The proposed method was successfully applied to a river water sample in Pardubice, Czech Republic.     

Organic semiconductor polymer nanodots as a new kind of off-on fluorescent probe for sulfide

The authors describe a fluorescent probe for sulfide that is based on carboxy-functionalized semiconducting polymer dots (P-dots). The dots were prepared from carboxy-functionalized poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-2,1′-3-thiadiazole)] (referred to as COOH-PFBT) via co-precipitation. The P-dots aggregate on addition of Cu(II) ions and their green fluorescence (with excitation/emission peaks at 455/540 nm) is then quenched. Fluorescence is restored on addition of sulfide to the aggregates due to the formation of CuS. This quenching-recovery (“off-on”) mechanism forms the basis for a new sulfide detection scheme. Fluorescence increases linearly in the 1.25 to 75.0 μM sulfide concentration range, with a 0.45 μM detection limit. Good selectivity over other anions is demonstrated. The method shows recoveries ranging between 98.6% and 105.7% when applied to the determination of sulfide in spiked real water samples.

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Graphical abstract Schematic of a fluorescent off-on sensor for (hydrogen) sulfide based on the use of semiconducting polymer dots (PFBT-COOH) whose fluorescene is quenched by Cu(II) ion but restored on addition of (hydrogen) sulfide.