Ultra-sensitive analysis of exhaled biomarkers in ozone-exposed mice via PAI-TOFMS assisted with machine learning algorithms.

Ground-level ozone ranks sixth among common air pollutants. It worsens lung diseases like asthma, emphysema, and chronic bronchitis. Despite recent attention from researchers, the link between exhaled breath and ozone-induced injury remains poorly understood.

Novel MCP-Windowed EUV Light Source and Its Mass Spectrometric Application for Detecting Chlorinated Methanes.

Various vacuum ultraviolet (VUV) lamps are simple and convenient VUV light sources for mass spectrometry and other research fields. However, the strong absorption of high-energy photons by window materials limits the application of an extreme ultraviolet (EUV) light. In this study, a novel high-flux EUV light source is developed using a microchannel plate (MCP) window to transmit 73.

Insight into the crucial reason causing the difference in secondary organic aerosol yields of monocyclic aromatic hydrocarbons with different methyl substituent numbers.

The secondary organic aerosol (SOA) yield of toluene photooxidation was reported to substantially higher than that of trimethylbenzene due to the effect of the number of methyl substituents. However, the intrinsic mechanism for this disparity is not clear enough. In this study, a highly-sensitive thermal-desorption photoinduced associative ionization mass spectrometer (TD-PAI-MS) was used to real-time characterize the molecular composition and its evolution of the SOA generated from the photooxidation of toluene and 1,2,3-trimethylbenzene (1,2,3-TMB) in a smog chamber.

Real-time emission characteristics, health risks, and olfactory effects of VOCs released from soil disturbance during the remediation of an abandoned chemical pesticide industrial site.

Volatile organic compounds (VOCs) released along with soil disturbance during the remediation of abandoned industrial sites have attracted great attention due to their possible toxicity and odour. However, the real-time emission characteristics of these VOCs and their subsequent effects on health and olfaction are less understood. In this study, the gaseous VOCs released from soil disturbance by excavators and drilling rigs at an abandoned chemical pesticide plant were monitored online with a laboratory-built single photoionization time-of-flight mass spectrometer (SPI-TOFMS).

A Simple High-Flux Switchable VUV Lamp Based on an Electrodeless Fluorescent Lamp for SPI/PAI Mass Spectrometry.

Single-photon ionization (SPI) is a unique soft ionization technique for organic analysis. A convenient high-flux vacuum ultraviolet (VUV) light source is a key precondition for wide application of SPI techniques. In this study, we present a novel VUV lamp by simply modifying an ordinary electrodeless fluorescent lamp.

Rapid Detection of Potential Natural Food Preservatives and Identification of Species via High-Sensitivity Photoionization Mass Spectrometry.

Natural food preservatives are being sought extensively as a safe alternative to chemical food preservatives. This study aimed to identify potential natural preservatives from herbs using single-photon ionization time-of-flight mass spectrometry (SPI-TOF-MS). Five species and four other herbs were analyzed, and the random forest (RF) algorithm was used to simulate olfaction and distinguish the species by identifying the characteristic peaks of volatile terpenoids (VTPs).

Direct detection of acetonitrile at the pptv level with photoinduced associative ionization time-of-flight mass spectrometry.

Photoionization mass spectrometry (PI-MS) has become a versatile tool in the real-time analysis of volatile organic compounds (VOCs) from the atmosphere or exhaled breath. However, some key species, , acetonitrile, are hard to measure due to their higher ionization energies than photon energy. In this study, the direct and sensitive detection of gaseous acetonitrile based on a photoinduced associative ionization (PAI) reaction was investigated with a laboratory-built PAI time-of-flight mass spectrometer (PAI-TOFMS).

Aerosol mass spectrometry of neutral species based on a tunable vacuum ultraviolet free electron laser.

A vacuum ultraviolet free electron laser (VUV-FEL) photoionization aerosol mass spectrometer (AMS) has been developed for online measurement of neutral compounds in laboratory environments. The aerosol apparatus is mainly composed of a smog chamber and a reflectron time-of-flight mass spectrometer (TOF-MS). The indoor smog chamber had a 2 m fluorinated ethylene propylene film reactor placed in a temperature- and humidity-controlled room, which was used to generate the aerosols.

An ultrasensitive SPI/PAI ion source based on a high-flux VUV lamp and its applications for the online mass spectrometric detection of sub-pptv sulfur ethers.

Single-photon ionization mass spectrometry (SPI-MS) is an attractive analytical technique for the online detection of volatile organic compounds; however, the low photon flux of the vacuum ultraviolet (VUV) lamp commonly used in the SPI ion source and the corresponding low detection sensitivity remain a constraint to its wide field applications. In this study, a new VUV lamp-based SPI ion source was developed. By increasing the discharging volume and optimizing the configuration of the lens and ionizer, the photon flux of the VUV lamp and the sensitivity of the ion source were significantly improved.

Exploring breath biomarkers in BLM-induced pulmonary fibrosis mice with associative ionization time-of-flight mass spectrometry.

Pulmonary fibrosis (PF) is a common but fatal disease that threatens human health worldwide. Developing effective diagnostic methods is of great importance for the early detection of PF in patients. In this study, bleomycin (BLM) was used in mice to mimic idiopathic pulmonary fibrosis (IPF).

Ultrasensitive detection of trace chemical warfare agent-related compounds by thermal desorption associative ionization time-of-flight mass spectrometry.

A thermal desorption associative ionization time-of-flight mass spectrometer was developed for ultrasensitive detection of semi-volatile chemical warfare agents (CWAs). The excited-state CHCl-induced associative ionization method presented a soft ionization characterization and an excellent sensitivity towards CWAs. The detection sensitivities of the investigated nine CWA-related substances were 2.

Emerging non-invasive detection methodologies for lung cancer.

The potential for non-invasive lung cancer (LC) diagnosis based on molecular, cellular and volatile biomarkers has been attracting increasing attention, with the development of advanced techniques and methodologies. It is standard practice to tailor the treatments of LC for certain specific genetic alterations, including the epidermal growth factor receptor, anaplastic lymphoma kinase and genes. Despite these advances, little is known about the internal mechanisms of different types of biomarkers and the involvement of their related biochemical pathways during the development of LC.

Kinetic Understanding of the Ultrahigh Ionization Efficiencies (up to 28%) of Excited-State CHCl-Induced Associative Ionization: A Case Study with Nitro Compounds.

Excited-state CHCl-induced associative ionization (AI) is a newly developed ionization method that is very effective for oxygenated organics. However, this method is not widely known. In this study, an unprecedented ionization efficiency and ultrafast reaction rate of AI toward nitro compounds were observed.

Ultrasensitive detection of volatile aldehydes with chemi-ionization-coupled time-of-flight mass spectrometry.

The chemi-ionization reaction is a high-efficiency pathway to produce molecular ions in plasma, however, it has rarely been applied in mass spectrometry to directly produce analyte ions. In this study, a novel chemi-ionization technique for mass spectrometry was applied for the direct and ultrasensitive detection of gaseous aldehydes. The ionization technique was enacted by a recently observed chemi-ionization reaction: the efficient proton transfer from HO to oxygenated compounds was stimulated by vacuum ultraviolet (VUV)-excited CHCl.

Comparison of secondary organic aerosol (SOA) formation during o-, m-, and p-xylene photooxidation.

Despite extensive effort to characterize xylene-isomer-derived secondary organic aerosols (SOAs) over the past decade, differences in SOA composition among xylene isomers, and their relative contributions to SOA formation remain poorly understood. Herein, we reinvestigated the photooxidation of o-, m-, and p-xylene under two limiting NO conditions. Dicarbonyls, TBM (the acronym of C-trione, 2,3-butanedione, and 3-methyl-2-oxiranecarbaldehyde with the same [M+H]m/z value of 87), and highly oxidized species (HOS), based on the m/z 61 fragment, were determined to be the predominant SOA components arising from xylene photooxidation; however, their relative contributions to SOA formation appear to depend on the xylene substitution pattern.

Rapid detection of taste and odor compounds in water using the newly invented chemi-ionization technique coupled with time-of-flight mass spectrometry.

Taste and odor (T&O) compounds are widespread in water environments and have attracted considerable public attention. Nowadays, the standard detections of these chemicals rely mainly on off-line methods such as GC-MS or evaluation by trained analysts' senses. In this study, we report a method for the rapid detection of T&O compounds in water by exploiting a newly invented chemi-ionization source, in combination with headspace vapor measurement at room temperature.

Formation mechanism of secondary organic aerosol from ozonolysis of gasoline vehicle exhaust.

Gasoline vehicles are a major source of anthropogenic secondary organic aerosols (SOAs). However, current models based on known precursors fail to explain the substantial SOAs from vehicle emissions due to the inadequate understanding of the formation mechanism. To provide more information on this issue, the formation of SOAs from ozonolysis of four light-duty gasoline vehicle exhaust systems was investigated with a vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS).

Vacuum-Ultraviolet-Excited and CHCl/HO-Amplified Ionization-Coupled Mass Spectrometry for Oxygenated Organics Analysis.

The mass spectrometry analysis of oxygenated volatile organic compounds (OVOCs) remains challenging due to their limited ionization efficiencies. In this study, we surprisingly found that, under vacuum-UV (VUV) excitation, a gaseous mixture of CHCl/HO/analyte (OVOCs) in N buffer generated large amounts of HO and protonated analyte even when the photon energy was lower than the ionization energy of the neutral species involved. In contrast to those obtained with VUV photoionization alone, the signal intensities of oxygenated organics can be amplified by more than 3 orders of magnitude.

A rapid detection method for policy-sensitive amines real-time supervision.

Many organic amines that comprise a benzene ring are policy-sensitive because of their toxicity and links to social harm. However, to date, detection of such compounds mainly relies on offline methods. This study proposes an online pptv (parts per trillion by volume) level of detection method for amines, using the recently-built vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) combined with a new doping technique.

Characterization of secondary organic aerosol from photo-oxidation of gasoline exhaust and specific sources of major components.

To further explore the composition and distribution of secondary organic aerosol (SOA) components from the photo-oxidation of light aromatic precursors (toluene, m-xylene, and 1,3,5-trimethylbenzene (1,3,5-TMB)) and idling gasoline exhaust, a vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) was employed. Peaks of the molecular ions of the SOA components with minimum molecular fragmentation were clearly observed from the mass spectra of SOA, through the application of soft ionization methods in VUV-PIMS. The experiments comparing the exhaust-SOA and light aromatic mixture-SOA showed that the observed distributions of almost all the predominant cluster ions in the exhaust-SOA were similar to that of the mixture-SOA.

Detection of sub-pptv benzene, toluene, and ethylbenzene via low-pressure photoionization mass spectrometry.

This paper reports on the advanced development of an ultrasensitive method for the detection of benzene, toluene, and ethylbenzene (or BTE) by low-pressure photoionization mass spectrometry (LPPI-MS). The LPPI source is composed of a laboratory-assembled krypton lamp and a stainless steel cylindrical ionizer. A compact V-shaped mass spectrometer is coupled to the LPPI source with a set of ion immigration optics under dc bias.

Doping-assisted low-pressure photoionization mass spectrometry for the real-time detection of lung cancer-related volatile organic compounds.

Real-time detection of lung cancer-related volatile organic compounds (VOCs) is a promising, non-intrusive technique for lung cancer (LC) prescreening. In this study, a novel method was designed to enhance the detection selectivity and sensitivity of LC-related polar VOCs by dichloromethane (CHCl) doping-assisted low-pressure photoionization mass spectrometry (LPPI-MS). Compared with conventional LPPI-MS, CHCl doping-assisted LPPI-MS boosted the peak intensities of n-propanol, n-pentanal, acetone, and butyl acetate in nitrogen specifically by 53, 18, 16, and 43 times, respectively.

Protonation enhancement by dichloromethane doping in low-pressure photoionization.

Doping has been used to enhance the ionization efficiency of analytes in atmospheric pressure photoionization, which is based on charge exchange. Compounds with excellent ionization efficiencies are usually chosen as dopants. In this paper, we report a new phenomenon observed in low-pressure photoionization: Protonation enhancement by dichloromethane (CHCl) doping.

Evaluating the relationship between cell viability and volatile organic compound production following DMSO treatment of cultured human cells.

Methylsulfinylmethane (dimethyl sulfoxide; DMSO) is widely used in clinical treatment and bioresearch. Moreover, there is bioconversion between methylsulfanylmethane (dimethyl sulfide; DMS), DMSO, and methylsulfonylmethane (DMSO2) in mammalian metabolism. Due to the real-time detection limits for volatile compounds, most research has focused on DMSO2 as a stable byproduct of DMSO.