Harvest Initiated Volatile Organic Compound Emissions from In-Field Tall Wheatgrass.

While crop and grassland usage continues to increase, the full diversity of plant-specific volatile organic compounds (VOCs) emitted from these ecosystems, including their implications for atmospheric chemistry and carbon cycling, remains poorly understood. It is particularly important to investigate VOCs in the context of potential biofuels: aside from the implications of large-scale land use, harvest may shift both the flux and speciation of emitted VOCs. To this point, we evaluate the diversity of VOCs emitted both pre and postharvest from "Alkar" tall wheatgrass (), a candidate biofuel that exhibits greater tolerance to frost and saline land compared to other grass varieties.

Integration of stable isotope and trace contaminant concentration for enhanced forensic acetone discrimination.

We analyzed 21 neat acetone samples from 15 different suppliers to demonstrate the utility of a coupled stable isotope and trace contaminant strategy for distinguishing forensically-relevant samples. By combining these two pieces of orthogonal data we could discriminate all of the acetones that were produced by the 15 different suppliers. Using stable isotope ratios alone, we were able to distinguish 8 acetone samples, while the remaining 13 fell into four clusters with highly similar signatures.

Preliminary effects of real-world factors on the recovery and exploitation of forensic impurity profiles of a nerve-agent simulant from office media.

Dimethyl methylphosphonate (DMMP) was used as a chemical threat agent (CTA) simulant for a first look at the effects of real-world factors on the recovery and exploitation of a CTA's impurity profile for source matching. Four stocks of DMMP having different impurity profiles were disseminated as aerosols onto cotton, painted wall board, and nylon coupons according to a thorough experimental design. The DMMP-exposed coupons were then solvent extracted and analyzed for DMMP impurities by comprehensive 2D gas chromatography/mass spectrometry (GC×GC/MS).

On-matrix derivatization for dynamic headspace sampling of nonvolatile surface residues.

The goal of this study is to extend sampling by the field and laboratory emission cell (FLEC) dynamic headspace technique to applications that target nonvolatile residues. On-matrix derivatization of residues to render analytes stable and more volatile is explored to achieve this goal. Results show that on-matrix derivatizations of nerve agent hydrolysis products (monoalkyl methylphosphonic acids and methylphosphonic acid [MPA]) with diazomethane were successful on glass and painted wallboard (at the 10-μg level).

Integration of gas chromatography mass spectrometry methods for differentiating ricin preparation methods.

The investigation of crimes involving chemical or biological agents is infrequent, but presents unique analytical challenges. The protein toxin ricin is encountered more frequently than other agents and is found in the seeds of Ricinus communis, commonly known as the castor plant. Typically, the toxin is extracted from castor seeds utilizing a variety of different recipes that result in varying purity of the toxin.

Multiple stable isotope characterization as a forensic tool to distinguish acid scavenger samples.

Acid scavengers are frequently used as stabilizer compounds in a variety of applications. When used to stabilize volatile compounds such as nerve agents, the lower volatility and higher stability of acid scavengers make them more persistent in a post-event forensic setting. Compound-specific isotope analysis of carbon, nitrogen, and hydrogen in three acid-scavenging compounds (N,N-diethylaniline, tributylamine, and triethylamine) were used as a tool for distinguishing between different samples.

Profiling of volatile impurities in tetramethylenedisulfotetramine (TETS) for synthetic-route determination.

This study investigated the feasibility of using volatile impurities from the rodenticide tetramethylenedisulfotetramine (TETS) for the discrimination of TETS produced by three synthetic routes. Each route was used to make one batch of TETS by reacting sulfamide with one of three formaldehyde analogs in the presence of either trifluroacetic acid (TFA) or hydrochloric acid. Ten impurities useful for differentiating the three TETS batches were discovered and tentatively identified by headspace solid-phase microextraction comprehensive two-dimensional gas chromatography-mass spectrometry (HS-SPME/GC×CG-MS).

Detection of acetone processing of castor bean mash for forensic investigation of ricin preparation methods.

Samples containing the toxic castor bean protein ricin have been recently seized in connection with biocriminal activity. Analytical methods that enable investigators to determine how the samples were prepared and to match seized samples to potential source materials are needed. One commonly described crude ricin preparation method is acetone extraction of crushed castor beans.

Impurity profiling of a chemical weapon precursor for possible forensic signatures by comprehensive two-dimensional gas chromatography/mass spectrometry and chemometrics.

In this report we present the feasibility of using analytical and chemometric methodologies to reveal and exploit the chemical impurity profiles from commercial dimethyl methylphosphonate (DMMP) samples to illustrate the type of forensic information that may be obtained from chemical-attack evidence. Using DMMP as a model compound of a toxicant that may be used in a chemical attack, we used comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOF-MS) to detect and identify trace organic impurities in six samples of commercially acquired DMMP. The GC x GC/TOF-MS data was analyzed to produce impurity profiles for all six DMMP samples using 29 analyte impurities.

Detection of agar, by analysis of sugar markers, associated with Bacillus anthracis spores, after culture.

Detection of small quantities of agar associated with spores of Bacillus anthracis could provide key information regarding its source or growth characteristics. Agar, widely used in growth of bacteria on solid surfaces, consists primarily of repeating polysaccharide units of 3,6-anhydro-l-galactose (AGal) and galactose (Gal) with sulfated and O-methylated galactoses present as minor constituents. Two variants of the alditol acetate procedure were evaluated for detection of potential agar markers associated with spores.

Individual odortypes: interaction of MHC and background genes.

Genes of the major histocompatibility complex (MHC) influence the urinary odors of mice. Behavioral studies have shown (1) that mice differing only at MHC have distinct urinary odors, suggesting an MHC odor phenotype or odortype; (2) that the MHC odortype can be recognized across different background strains; and (3) that the MHC odortype is not an additive trait. Very little is known about the odorants underlying this behavioral phenotype.

Identification of major histocompatibility complex-regulated body odorants by statistical analysis of a comparative gas chromatography/mass spectrometry experiment.

This paper examines the application of gas chromatography/mass spectrometry (GC/MS) in a comparative experiment to identify volatile compounds from urine that differ in concentration between two groups of inbred mice. A complex mixture might comprise several hundred or even thousands of volatile compounds. Because their number and location in a chromatogram are generally unknown, and because components overlap in populous chromatograms, the statistical problems offer significant challenges beyond traditional two-group screening procedures.

Characterization of plasma membrane proteins from ovarian cancer cells using mass spectrometry.

To determine how the repertoire of plasma membrane proteins change with disease state, specifically related to cancer, several methods for preparation of plasma membrane proteins were evaluated. Cultured cells derived from stage IV ovarian tumors were grown to 90% confluence and harvested in buffer containing CHAPS detergent. This preparation was centrifuged at low speed to remove insoluble cellular debris resulting in a crude homogenate.

Direct surface analysis of fungal species by matrix-assisted laser desorption/ionization mass spectrometry.

In this study various methods of sample preparation and matrices were investigated to determine optimum collection and analysis criteria for fungal analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Intact spores and/or hyphae of Aspergillus niger, Rhizopus oryzae, Trichoderma reesei and Phanerochaete chrysosporium were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The fungal samples were applied to the MALDI sample target as untreated, sonicated, or acid/heat treated samples, or blotted directly from the fungal culture with double-stick tape.