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

Portable mass spectrometry system: instrumentation, applications, and path to 'omics analysis

Mass spectrometry (MS) is an information rich analytical technique and plays a key role in various 'omics studies. Standard mass spectrometers are bulky and operate at high vacuum, which hinder their adoption by the broader community and utility in field applications. Developing portable mass spectrometers can significantly expand the application scope and user groups of MS analysis. This review discusses the basics and recent advancements in the development of key components of portable mass spectrometers including ionization source, mass analyzer, detector, and vacuum system. Further, major areas where portable mass spectrometers are applied are also discussed. Finally, a perspective on the further development of portable mass spectrometers including the potential benefits for 'omics analysis is provided.

Odor impact assessment of trace sulfur compounds from working faces of landfills in Beijing, China

Odor pollution from landfills is causing a growing number of public complaints and concerns. Compared with hydrogen sulfide (H₂S) and ammonia (NH₃), odor impacts of trace sulfur compounds (TSCs) are arousing concerns due to their low odor threshold values (OTVs). Working face on landfill sites has been claimed as major source of odor impacts. This study estimated the odor impacts of fugitive TSCs from the working face of a large typical municipal solid waste (MSW) landfill in Beijing, China. A modified wind tunnel system was introduced to estimate emission rates of TSCs, which is a basic requirement for odor impact assessment. The odor activity value (OAV) method was introduced for odor evaluation. Fieldwork in the selected landfill was conducted from 2014 to 2015. Methyl mercaptan (CH₃SH), dimethyl sulfide, dimethyl disulfide (DMDS), and carbon disulfide (CS₂) were the TSCs studied in this work. The spatial concentration distributions of the TSCs were calculated on the basis of the Gaussian dispersion model in a "normal case" scenario and a "worst case" scenario. DMDS showed the highest emission rate (7.18 μg m^-2 s^-1), and CH₃SH was the dominant odorous compound with an average emission rate of 4.58 μg m^-2 s^-1. The dispersion modeling indicated that the odor impact distances of the TSCs in the studied landfill for the normal case and worst case scenarios were 495 ± 96 m and 9230 m at the downwind regions, respectively. Results of this study can benefit the formulation of strategies for odor control and abatement in landfill sites.

Determination of reduced sulfur compounds in air samples for the monitoring of malodor caused by landfills

A reliable method for determining malodorous reduced sulfur compounds (RSC) in atmospheric samples has been developed. The method uses an activated coconut solid-phase sorbent for active sampling, hexane as desorption solvent, and gas chromatography-mass spectrometry (GC-MS) technique for specific and sensitive separation-detection. The compounds analyzed were hydrogen sulfide, ethyl mercaptan, dimethyl sulfide, carbon disulfide, butyl mercaptan and dimethyl disulfide. Recovery efficiency varied between 75% and 97% and no detectable losses were observed during storage at -20°C. Satisfactory analytical parameters were reported, such as good linearity (r(2)>0.98), low detection limits (0.6-59 pg m(-3)), adequate repeatability (9%) and reproducibility (17%), and fast GC-MS analysis (<6.5 min). The accurate determination of RSCs, free of interferences from atmospheric components, such as ozone or water was demonstrated. The method has been applied to analyze the composition of environmental air close to three landfills processing urban and industrial solid wastes. The results indicated that hydrogen sulfide and ethyl mercaptan were the main molecules responsible of malodor phenomenon in the study areas.

Sensing properties of pristine, Al-doped, and defected boron nitride nanosheet toward mercaptans: a first-principles study

We report an Al-doped hexagonal boron nitride nanosheet as a new adsorbent for mercaptans.