Pathway-specific metabolome analysis with O-labeled via a mass spectrometry-based approach.

Introduction: Oxygen from carbon dioxide, water or molecular oxygen, depending on the responsible enzyme, can lead to a large variety of metabolites through chemical modification.

Objectives: Pathway-specific labeling using isotopic molecular oxygen (O) makes it possible to determine the origin of oxygen atoms in metabolites and the presence of biosynthetic enzymes (e.g.

PlantMAT: A Metabolomics Tool for Predicting the Specialized Metabolic Potential of a System and for Large-Scale Metabolite Identifications.

Custom software entitled Plant Metabolite Annotation Toolbox (PlantMAT) has been developed to address the number one grand challenge in metabolomics, which is the large-scale and confident identification of metabolites. PlantMAT uses informed phytochemical knowledge for the prediction of plant natural products such as saponins and glycosylated flavonoids through combinatorial enumeration of aglycone, glycosyl, and acyl subunits. Many of the predicted structures have yet to be characterized and are absent from traditional chemical databases, but have a higher probability of being present in planta.

Bromination of aromatic compounds by residual bromide in sodium chloride matrix modifier salt during heated headspace GC/MS analysis.

Analytical artifacts attributed to the bromination of toluene, xylenes, and trimethylbenzenes were found during the heated headspace gas chromatography/mass spectrometry (GC/MS) analysis of aqueous samples. The aqueous samples were produced from Fenton-like chemical oxidation reactions and contained aromatic compounds, hydrogen peroxide (H2O2), and ferric sulfate. Prior to GC/MS headspace analysis, the samples were acidified (pH<2), and sodium chloride was amended to the headspace vial as a matrix modifier.

Perchlorate behavior in a municipal lake following fireworks displays.

Perchlorate salts of potassium and ammonium are the primary oxidants in pyrotechnic mixtures, yet insufficient information is available regarding the relationship between fireworks displays and the environmental occurrence of perchlorate. Here we document changes in perchlorate concentrations in surface water adjacent to a site of fireworks displays from 2004 to 2006. Preceding fireworks displays, perchlorate concentrations in surface water ranged from 0.

Analysis of lagoon samples from different concentrated animal feeding operations for estrogens and estrogen conjugates.

Although Concentrated Animal Feeding Operations (CAFOs) have been identified as potentially important sources for the release of estrogens into the environment, information is lacking on the concentrations of estrogens in whole lagoon effluents (including suspended solids) which are used for land application. Lagoons associated with swine, poultry, and cattle operations were sampled at three locations each for direct analysis for estrogens by GC/ MS/MS and estrogen conjugates by LC/MS/MS. Estrogen conjugates were also analyzed indirectly by first subjecting the same samples to enzyme hydrolysis.

Avoiding hydrolysis of fuel ether oxygenates during static headspace analysis.

The determination of fuel ether oxygenates in groundwater was found to be problematic when samples are preserved at pH < 2 and then analyzed using heated headspace sampling. Acid catalyzed the hydrolysis of tert-amyl methyl ether, ethyl tert-butyl ether, and methyl tert-butyl ether during headspace sampling when aqueous samples were heated at 80 degrees C, a typical temperature used for heated headspace sampling. Hydrochloric acid at pH 2 did not cause hydrolysis of oxygenate ethers in samples stored for 28 d at 4 degrees C.

Quantitation of estrogens in ground water and swine lagoon samples using solid-phase extraction, pentafluorobenzyl/trimethylsilyl derivatizations and gas chromatography-negative ion chemical ionization tandem mass spectrometry.

A method was developed for the confirmed identification and quantitation of 17beta-estradiol, estrone, 17alpha-ethynylestradiol and 16alpha-hydroxy-17beta-estradiol (estriol) in ground water and swine lagoon samples. Centrifuged and filtered samples were extracted using solid-phase extraction (SPE), and extracts were derivatized using pentafluorobenzy] bromide (PFBBR) and N-trimethylsilylimidazole (TMSI). Analysis was done using negative ion chemical ionization (NICI) gas chromatography-mass spectrometry-mass spectrometry (GC-MS-MS).