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Complex biologicalmatrices can be effectively removed in the analyte migration process because of their weak solubility in organic solvents. This technique offers other potential advantages, including high-sensitivity and the capability of performing a direct analysis of the components and their metabolites in small-volume raw samples without any pretreatment. [ABSTRACT FROM AUTHOR]

A simple and fast (<5 s) method for in situarsenic speciation on solid surfaces has been developed based on desorption electrospray ionization-tandem mass spectrometry (DESI-MS). Arsenic-polluted environmental samples such as animal feed and plant tissues could be directly monitored by DESI-MS. Each arsenic species in this study, including monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), arsenocholine (AsC), 4-arsanilic acid (p-ASA), 4-hydroxyphenylarsonic acid (4-OH), Nitarsone, Roxarsone and two inorganic arsenic species, arsenate As(v) and arsenite As(iii), could be detected by their typical m/zand collision induced dissociation (CID) behavior respectively. By the characteristic information, mixtures of different arsenic species could be detected without any sample preparation and separation process. This method could give absolute detection limits of the arsenic species at ng/mm2to pg/mm2level with a best RSD of 5.3% (n= 5). The method could be potentially applied to in situenvironmental monitoring of arsenic pollution, especially that caused by arsenic pesticides, animal feed additives, herbicides and wood treatment. [ABSTRACT FROM AUTHOR]

Real-time and in-situmonitoring of ongoing chemical reactions by mass spectrometry was achieved by simply directing the low-temperature plasma (LTP) to the surface of the reaction system for analyte desorption and ionization without any sample pretreatment. [ABSTRACT FROM AUTHOR]

In this paper, we have constructed a low temperature plasma (LTP) probe using dielectric barrier discharge (DBD) and employed it for the detection of explosives on a variety of substrates under ambient conditions. Upon discharge, a transient, low-temperature non-equilibrium plasma comprising ions, electrons and metastable atoms are generated between the electrodes. Three common explosives, 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-trinitro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN), were directly desorbed and ionized from solid surfaces, followed by subsequent analysis using the mass spectrometer in the negative ion mode. Limits of detection (LODs) were 500 fg for TNT, 1 pg for RDX, and 500 fg for PETN. The reliability of the method was characterized by a successful analysis of a mixture of the three explosives. The ion source also allowed direct detection of trace explosives on both conductive and non-conductive substrates, thus expanding the applicability of low temperature plasma desorption mass spectrometry. [ABSTRACT FROM AUTHOR]