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Fatty acid (FA) profiling provides phenotypic information and is increasingly used in a broad range of biological and biomedical studies. Quantitation of unsaturated FAs with confident carbon-carbon double bond (C-C) location assignment is both sample and time consuming using traditional gas chromatography mass spectrometry analysis. In this study, we developed a rapid, sensitive, and quantitative method for profiling unsaturated FAs without using chromatographic separations. This method was based on a combination of in-solution photochemical tagging of a C-C in FAs and a subsequent gas-phase detagging via tandem (neutral loss scan) mass spectrometry. It enabled quantitation of unsaturated FAs from various biological samples (blood, plasma, and cell lines). More importantly, quantitative information on FA C-C location isomers, which was traditionally overlooked, could now be obtained and applied to studying FA changes between normal and cancerous human prostate cells. [ABSTRACT FROM AUTHOR]

Surface waters In Europe and North America are slowly recovering from acidification following major reductions in emissions of sulfur dioxide (SO2) since the 1980s. In contrast, regions affected by acid rain have been reported to be growing in China. Here we show that the rapid change in surface water chemistry in the 1990s in large areas in Southwestern China, specifically the tributary rivers of the Upper Yangtze River, caused by increasing SO2 emissions, has leveled off. During the 1990s the sulfate (SO42-) concentrations in river water increased rapidly and, on average, doubled in only eight years. Simultaneously, calcium (Ca2+) concentrations increased, while pH values decreased. In the following decade (2000s), SO2 emissions stabilized, causing a subsequent stop to the increasing SO42- concentrations and pH decline in river water. Although a rapid response to future reduction in SO2 emissions can be expected, a rapid increase of nitrogen (N) emissions could lead to increases in N leaching and delay recovery. [ABSTRACT FROM AUTHOR]

A simple and easy-to-build high-throughput analysis system was constructed. The system consisted of three major components: (1) a multichannel device with 16 parallel capillaries, (2) a desorption electrospray ionization (DESI) source, and (3) a linear ion trap mass spectrometer. When analyses were performed, the multichannel device was moved horizontally on a translation stage controlled by a step motor. Our design expands the functions of DESI, in which the liquid sample in capillary was driven out by the nebulizing gas, ionized, and then transferred to a mass spectrometer. To assess the high-throughput performance of the system, 5 mg/L 1,3-diethyl-1,3-diphenylurea (DDU) solution and 10 mg/L angiotensin 1 solution were alternatively loaded into the reservoirs and capillaries in the multichannel device. Results indicated that analyses of the all the samples in 16 capillaries were completed within 1.6 mm, which means a throughput of 600 samples/h. Reactive DESI experiment was also successfully performed with this system to show the feasibility of online derivatization. The relative standard deviations for a single capillary and five identical capillaries were 7.6 (n = 16) and 12.3%, respectively. Linear relative abundance response was achieved for DDU (r=0.9971). [ABSTRACT FROM AUTHOR]