A homemade portable vacuum ultraviolet single photon ionization time-of-flight mass spectrometer (SPI-TOFMS) combined with a membrane inlet (MI) has been developed for the on-line monitoring of volatile organic compounds (VOCs) in environmental air. A description of the principle, configuration and key features of this MI-SPI-TOFMS is presented. A dimethylsiloxane (PDMS) membrane was used to concentrate the VOCs, and the vacuum ultraviolet (VUV) light (10.6 eV) for the ionization was generated by a commercial krypton lamp. A miniature reflectron TOF analyzer was used to make the instrument portable with quite high mass resolution (R = 450 at 106 amu). The limits of detection (LOD) of toluene and xylene can achieve 0.5 ppbv and 0.4 ppbv for 1 s measurement with scan frequency of 10 kHz, respectively. The dimension of the instrument is 30 cm × 20 cm × 20 cm with a total weight 13 kg without battery. The application of on-line monitoring air inside passenger cabin of brand new cars was shown in this paper.Graphical abstractHighlights► A home-made portable membrane inlet single photon ionization time-of-flight mass spectrometer (MI-SPI-TOFMS) was developed. ► The dimension of MI-SPI-TOFMS is 30 cm × 20 cm × 20 cm and total weight is 13 kg without battery. ► The LOD of toluene and xylene can achieve 0.5 ppbv and 0.4 ppbv for 1 s measurement with scan frequency of 10 kHz, respectively. ► It was used for on-line monitoring of the air quality inside of new motorcars for the first time in China.

A time-of-flight mass spectrometer was developed for the detection of ions with wide energies distribution. The instrument associated with an electron impact source. The ions flow was effectively modulated by a lens system and then introduced into the time-of-flight mass analyzer which included a dual field of acceleration region, a reflection region, and a large-size micro channel plate (MCP) detection device. The characteristics of the spectrometer were as follows: half-peak width of single ion signal was about 2 ns, resolution of the instrument was better than 1600 FWHM, mass range of actual samples was 1–127 amu in comparison with the theoretical mass detection limit of higher than 800 amu, and ion energy detection range was better than two orders of magnitude (3–140 eV). If coupled with short-instantaneous pulse discharge ion source, the TOF mass analyzer would be used in the field of rapid detection of high-energy ion beam, such as vacuum cathode discharge preparation of thin films, ion injection material characterization, ion charge state distribution of conductive material and determination of ion diffusion speed.A time-of-flight mass spectrometer was developed for the detection of ions with wide energies distribution. The whole instrument includes vacuum system, electron impact ion source, time-of-flight mass analyzer, data acquisition system and so on. Ions with different energies distribution flied out of angle reflection region, which would hit on different positions of ion detector, and were detected by the dual anode plates finally.

Single particle aerosol mass spectrometer (SPAMS) is an advanced instrument for simultaneous detection of aerodynamic size and chemical composition of individual aerosol particles in real time. In this study, the principle, configuration and features of our newly independent R&D SPAMS were described. Its application on the study of cigarette smoke aerosol analysis was also discussed. Aerodynamic focusing lens and double beam particle sizing system of the SPAMS were used to measure the aerodynamic diameter of particles. The laser ionization system realizes the accurate ionization of particles, and bipolar grid-reflection time-of-flight mass analyzer realizes the simultaneous detection of positive and negative ions. The results indicate that the fresh cigarette smoke particles have a relatively broader size distribution than that of aged smoke, and, in the aged smoke, the fraction of particles containing CN− nitrate, sulfate and ammonium all increased compared with fresh smoke; in contrast, the fraction of containing chloride reduced. The results can be explained by the translation of gas phase to particle phase as well as the heterogeneous reactions between the gas and particles. The reason for the reduction of chloride may be due to the heterogeneous reactions between HNO3 and chloride.

This paper describes a new built single particle laser desorption/ionization time of flight mass spectrometer capable of determining the size and chemical compositions of individual aerosol particles in real-time. The instrument was compactly designed with bipolar grid reflectron mass analyzers for higher mass resolution. It measures 90 cm long × 70 cm wide × 170 cm high, weights ∼170 kg and has a total power consumption of less than 2000 W. Standard polystyrene latex particles (PSL) and metallic solution were used to perform size and mass calibration, respectively, and the effect of inlet pressure of the aerodynamic lens on size calibration was also investigated. The instrument was first used for the ambient aerosol detection in Guangzhou City, China, and the preliminary measurements show its’ ability to characterize the atmospheric aerosol particles containing different chemical compositions with diameters ranging from 250 to 2000 nm and a total hit rate above 30%. The preliminary measurements also show that the aerosol particles in Guangzhou, China can be mainly classified into five types, which are rich K, rich Na, Nark, carbonaceous, and metal containing, and their formations are also generally discussed.Graphical abstractThis paper describes a new built single particle laser desorption/ionization time of flight mass spectrometer capable of determining the size and chemical compositions of individual aerosol particles ranging from 250 nm to 2000 nm in real-time.Research highlights► A new built aerosol mass spectrometer capable of determining the size and chemical compositions of individual particles ranging from 250 nm to 2000 nm in real-time and achieving a total hit rate above 30%. ► The mechanical structure of the instrument is compact and the vacuum system is simplified. ► Bipolar grid reflectron mass analyzers with ion focus technology increase the mass resolution and ion transmission efficiency. ► The preliminary ambient aerosol detection shows that it has great potential applications in environmental aerosol measurements and laboratory aerosol mechanics researches in China.

A home-made vacuum ultraviolet single-photon ionization time-of-flight mass spectrometer (VUV-SPI-TOFMS) including vacuum system, sampling inlet system, vacuum ultraviolet ionization source, reflection time-of-flight mass analyzer and data acquisition system was introduced. Single-photon ionization with vacuum ultraviolet light is a particularly soft ionization technique. Volatile organic compounds (VOCs) with ionization energy less than the photon energy (10.6 eV) can be ionized into molecular ions. It is nearly fragmentation free compared with electron ionization, and very suitable for qualitative analysis. The mass resolution of the instrument is higher than 800 (Full width at half maximum, FWHM) and the mass accuracy is better than 100 ppm. The initial experiments detected more than 60 components in the mainstream smoke from cigarette, and the limits of detection for acetone, cyclohexane, ethyl acetate and toluene were 0.33, 0.27, 0.42 and 0.11 ppm, respectively. This instrument can be used for real-time and online analysis of VOCs in various environmental media (gas, solid, liquid), and if combined with a membrane inlet system, heating device or purge and trap system, a higher sensitivity could be achieved.

A new analyzing system for gas analysis from metallurgical materials was developed by coupling a homemade electron ionization time-of-flight mass spectrometer (EI-TOFMS) with an inert gas fusion unit. A description of principle, configuration along with key features of the system especially the EI-TOFMS was presented. The properties of the EI-TOFMS were checked by the indoor air and standard gas sample, and the initial results for the system measuring of the steel samples show that oxygen, nitrogen, hydrogen and argon could be measured simultaneously and quantitatively at a detection limit of μg/g level.A new analyzing system for gas analysis from metallurgical materials was developed by coupling a homemade EI-TOFMS with an inert gas fusion unit. The system can be used to analyze H, O, N and Ar simultaneously and quantitatively with a detection limit at μg/g level.