A Gas Chromatography-Mass Spectrometry Method for the Detection and Quantitation of Monofluoroacetate in Plants Toxic to Livestock.

Monofluoroacetate (MFA) is a potent toxin that occurs in over 50 plant species in Africa, Australia, and South America and is responsible for significant livestock deaths in these regions. A gas chromatography-mass spectrometry (GC-MS) method for the analysis of MFA in plants based on the derivatization of MFA with n-propanol in the presence of sulfuric acid to form propyl fluoroacetate was developed. This method compared favorably to a currently employed high-performance liquid chromatography-mass spectrometry (HPLC-MS) method for the analysis of MFA in plants. The GC-MS method was applied to the analysis of MFA in herbarium specimens of Fridericia elegans, Niedenzuella stannea, N. multiglandulosa, N. acutifolia, and Aenigmatanthera lasiandra. This is the first report of MFA being detected in F. elegans, N. multiglandulosa, N. acutifolia, and A. lasiandra, some of which have been reported to cause sudden death or that are toxic to livestock.

Polycyclic aromatic hydrocarbon concentrations in gas and particle phases and source determination in atmospheric samples from a semiurban area of Dourados, Brazil.

A headspace solid-phase microextraction (HS-SPME) procedure that employs a PDMS/DVB fiber was developed for the analysis of gas-phase polycyclic aromatic hydrocarbons (PAHs) collected in polyurethane foam (PUF) by gas chromatography (GC) mass spectrometry. The method exhibited good linearity (R (2) > 0.99) and repeatability (4.9-25 %) as well as an impressive detection limit that ranged from 1.1 to 3.3 ng. Twenty-two air samples were collected by high-volume samplers from January to November 2007 in a semiurban area of Dourados (Brazil) and were analyzed for their content of total suspended particulates and PAHs. The PAHs were extracted from the PUF samples using the developed procedure (HS-SPME), and PAHs adsorbed on particulate matter were extracted with dichloromethane/methanol (4:1 [v/v]) in an ultrasonic bath. The values of the total daily concentrations of 16 PAHs determined in the samples ranged from 0.375 to 8.407 ng m(-3). In addition, diagnostic ratios were calculated, showing that the PAHs in the atmosphere at the sampling site originated predominantly from vehicle emissions and the combustion of grass and wood. Hierarchical cluster analysis and principal component analysis were performed as well, the results of which indicated (1) the same sources of PAH identified by the diagnostic ratios and (2) that the sampling days could be categorized into three groups depending on the atmospheric conditions. GC retention indices were also used to identify PAHs, biphenyl (phenylbenzene), and heterocyclic organic compounds (benzofurans) in some of the samples.