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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). Twelve main VOCs with total mean concentrations ranging from 2350 to 3410 µg m-3 were observed, with dichloromethane (DCM) having a significant contribution. The total concentrations of the remaining 11 VOCs increased substantially during soil disturbance, with the total mean concentrations increasing from 18.65-39.05 to 37.95-297.94 µg m-3 and those of peak concentrations increasing from 28.46-58.97 to 88.38-839.13 µg m-3. This increase in VOC concentrations during soil disturbance leads to an enhanced heath risk for on-site workers. The distinctive difference between the mean and peak concentrations of VOCs indicates the importance of using mean and peak concentrations, respectively, for risk and olfactory evaluation due to the rapid response of the human nose to odours. As a result, the cumulative noncarcinogenic risk at the relatively high pollutant plot was higher than the occupational safety limit, while the total carcinogenic risks at all monitored scenarios exceeded the acceptable limit. Among the VOCs investigated, DCM and trichloroethylene (TCE) were determined to be crucial pollutants for both noncarcinogenic and carcinogenic risks of VOCs. With regard to olfactory effects, organic sulphides, including dimethyl disulphide (DMDS), dimethyl sulphide (DMS), and dimethyl trisulphide (DMTS) were identified as dominant odour contributors (78.28-92.11%) during soil disturbance.

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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. The VUV lamp output was 2.8 × 1015 photons s-1, which was focused into the small ionization zone, and the ion intensity of gaseous benzene under SPI achieved 1.7 × 104 counts per second per pptv (cps pptv-1). This ion source can also function in photoinduced associative ionization (PAI) mode by introducing gaseous CH2Cl2 to initiate an associative ionization reaction. Because of the high efficiency of the ion source, the amount of doped CH2Cl2 needed for PAI was greatly reduced (∼2.5% of that used in previous experiments). PAI exhibited an outstanding protonation effect on monosulfur ethers (CnH2n+1S). The signal intensities of the protonated molecular ions (MH+) were 46-128 times higher than those of the molecular ions (M+) produced by SPI. Since monosulfur ethers generally have lower SPI cross-sections than polysulfur ethers (CnH2n+1S2 or CnH2n+1S3), the PAI and SPI modes were selected for the online measurement of a series of mono- and polysulfur ethers, respectively. The obtained detection sensitivity of the mono- and polysulfur ethers reached 476.5 ± 1.72-2835.1 ± 99.5 and 47.9 ± 0.4-105.1 ± 2.3 counts pptv-1, respectively, in 10 s of sampling time. The corresponding 3σ limits of detection (LODs) were 0.12-0.71 and 0.06-0.14 pptv, respectively. This study provides advances in the development of a high-flux VUV lamp and a highly efficient SPI/PAI ion source, as well as an ultrasensitive analytical method for detecting sulfur ethers.

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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 CH2Cl2-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 2.56 × 105-5.01 × 106 counts ng-1 in a detection cycle (30 s or 100 s). The corresponding 3σ limits of detection (LODs) were 0.08-3.90 pg. Compared with the best-documented LODs via the dielectric barrier discharge ionization (DBDI) and secondary electrospray ionization (SESI), the obtained LODs of the investigated compounds were improved by 2-76 times. Additionally, the measured sensitivity of 2-Chloroethyl ethyl, a proxy for mustard gas, is 550 counts pptv-1, which exceeds the DBDI and SESI's corresponding values (4.4 counts pptv-1 and 6.5 counts pptv-1) nearly by two orders of magnitude. A field application simulation was conducted by putting a strip of PTFE film contaminated with the CWA-related agent into the thermal desorption unit. The simulation showed that the sensitivities of the instrument via swipe surveying could achieve 2.19 × 105 to 5.23 × 106 counts ng-1. The experimental results demonstrate that the excited-state CH2Cl2-induced associative ionization is an ultrasensitive ionization method for CWAs and reveal a prospect for improving the detection of CWA species future.

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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 BRAF 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. The development of faster and more effective techniques is essential for the identification of different biomarkers. The present review summarizes some of the latest methods used for detecting molecular, cellular and volatile biomarkers in LC and their potential use in clinical diagnosis and targeted therapy.

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Excited-state CH2Cl2-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. The ionization efficiencies of o-nitrotoluene (o-NT), m-nitrotoluene (m-NT), and nitrobenzene (NB) were as high as (28 ± 3)%, (27 ± 2)%, and (13 ± 1)%, respectively (∼1-3 ions for every 10 molecules). The measured reaction rate coefficients of these nitroaromatics were (0.5-1.3) × 10-7 molecule-1 cm3 s-1 (∼300 K). These unusual rate coefficients indicated strong long-range interactions between the two neutral reactants, which was regarded as a key factor leading to the ultrahigh ionization efficiency. The detection sensitivities of the nitroaromatics, (1.01-2.16) × 104 counts pptv-1 in 10 s acquisition time, were obtained by an AI time-of-flight mass spectrometer (AI-TOFMS). These experimental results not only provide new insight into the AI reaction but also reveal an excellent ionization method that can improve the detection sensitivity of nitroaromatics to an unprecedented degree.