Laser desorption/in situ chemical ionization aerosol mass spectrometry for monitoring tributyl phosphate on the surface of environmental particles

Coupling handheld liquid microjunction-surface sampling probe (hLMJ-SSP) to the miniature mass spectrometer for automated and in-situ surface analysis

In-situ surface analysis has always been a significant but challenging issue in many analytical applications. To enable surface sampling and MS analysis on the field, a handheld liquid microjunction-surface sampling probe (hLMJ-SSP) was coupled to a miniature mass spectrometer in this study. The hLMJ-SSP was connected to the miniature mass spectrometer with a 50 cm long flexible tube and controlled by an integrated microcontroller unit (MCU). By simply pressing a button on the probe, automated surface analysis could be carried out and completed within ∼2 min, in which solvent delivery, sample extraction, extract aspiration, injection and MS analysis were performed in sequence. A limit of detection (LOD) as low as 5 pg was achieved. The capability of in-situ surface analysis was also demonstrated by directly analyzing illicit drug residues on fingers and medicines in biological fluids. With the merits of automated operation, high sensitivity and nondestructive analysis, this LMJ-SSP-mini MS system would be a promising tool for various in-situ analytical applications.

Improving the Performance of the Mini 2000 Mass Spectrometer with a Triboelectric Nanogenerator Electrospray Ionization Source

Balancing the contradiction between portability and analytical performances of a miniaturized mass spectrometer is vital to extend its on-site applications. In this study, triboelectric nanogenerator (TENG)-driven ion sources were coupled with our home-built Mini 2000 system and applied to the analyses of different samples. Compared with the conventional direct current (DC) nanoelectrospray ionization (nanoESI) source, the ion intensity of the TENG-nanoESI miniature mass spectrometer was improved by ∼3 times. Moreover, maybe due to the different pathways of ion formation in comparison with DC electrospray, TENG electrospray is shown to reduce the salt suppression effect during ionization. With these figures of merit, the direct detection of reserpine in saliva was demonstrated using the TENG-Mini 2000 system.

A Chemical Ionization Mass Spectrometry Method for the Online Analysis of Organic Aerosols

A new technique employing chemical ionization mass spectrometry (CIMS) is described that allows the composition of organic particles to be determined on the time scale of seconds. With this Aerosol CIMS technique, particles are vaporized thermally at temperatures up to 480 degrees C, and the resulting vapor is chemically ionized and detected with a quadrupole mass spectrometer. The separation of the vaporization and ionization steps allows greater control and more flexibility for the detection of condensed phases than with other chemical ionization methods. Consequently, composition can be correlated to volatility, providing an additional dimension of information. The use of a variety of positive and negative reagent ions, such as H(+)(H(2)O)(2), H(+)(CH(3)OH)(2), NO(+), O(2)(+), O(2)(-), F(-), and SF(6)(-), offers flexibility in the detection sensitivity and specificity. Furthermore, the degree of fragmentation of the resulting ion can be controlled, providing more straightforward identification and quantification than with other commonly used methods, such as electron impact ionization. Examples are given of the detection of aerosols consisting of organics with various functionalities, including alkanes, alkenes, alcohols, aldehydes, ketones, and carboxylic acids. Applications of this technique to laboratory studies of atmospherically relevant aerosol reactions are discussed.

Detection of pesticide residues on individual particles

An aerosol time-of-flight mass spectrometer (ATOFMS) is used to analyze the size and composition of individual particles containing pesticides. Pesticide residues are found in the atmosphere as a result of spray drift, volatilization, and suspension of coated soils. The ability of the ATOFMS to identify the presence of these contaminants on individual particles is assessed for particles created from pure solutions of several commonly used pesticides, as well as pesticides mixed with an organic matrix, and coated on soils. The common names of the pesticides studied are 2,4-D, atrazine, chlorpyrifos, malathion, permethrin, and propoxur. Analysis of the mass spectra produced by single- and two-step laser desorption/ionization of pesticide-containing particles allows for identification of peaks that can be used for detection of pesticide residues in the ambient aerosol. The identified marker peaks are used to approximate detection limits for the pesticides applied to soils, which are on the order of a fraction of a monolayer for individual particles. Results suggest that this technique may be useful for studying the real-time partitioning and distribution of pesticides in the atmosphere immediately following application in agricultural regions.

Current literature in mass spectrometry

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (3 Weeks journals - Search completed at 28th. June 2000)

Laser desorption/ionization coupled to tandem mass spectrometry for real-time monitoring of paraquat on the surface of environmental particles

Aerosol mass spectrometry with laser desorption/ionization was investigated as a possible tool for real-time monitoring of the presence of the pesticide paraquat on the surface of airborne soil particles. Laser desorption/ionization of paraquat dication produced only singly charged ions. The most abundant species were [M](+.), [M - H](+), and [M - CH3](+). Operation of the ion trap mass spectrometer in the MS(3) mode allowed the reduction of the signal dependence on laser fluence fluctuations and permitted the detection of the analyte with good sensitivity and high selectivity. The estimated limit of detection in terms of surface coverage was 0.016 monolayers, approximately 1 attomole of paraquat on the surface of a single micron-sized soil particle.