Compound specific stable isotope analysis of aromatics in diesel fuel to identify potential cocktailing.

Estimates suggest billions of dollars are lost annually in the US due to fuel tax fraud. One method of fuel fraud is called "cocktailing" and involves blending products that are non-taxed, lower value, taxed at a lower rate, or unwanted/less-refined petroleum to diesel fuels. The goal of this study was to investigate compound specific isotope analysis (CSIA) using isotope ratio mass spectrometry (IRMS) for small aromatics contained in diesel fuel to determine whether this approach could be used to identify cocktailing and potentially fingerprint possible sources.

A multistep enrichment process with custom growth medium improves resuscitation of chlorine-stressed coliforms from secondary sewage effluents.

Resuscitation and detection of stressed total coliforms in chlorinated water samples is needed to assess and prevent health effects from adverse exposure. In this study, we report that the addition of a growth enhancer mix consisting of trehalose, sodium pyruvate, magnesium chloride, and 1× trace mineral supplement improved growth of microorganisms from chlorinated secondary effluent in the base medium with Colilert-18. Improving growth of chlorine stressed microorganisms from secondary effluent is crucial to decreased detection time from 18 to 8 h.

Probabilistic Limit of Detection for Ricin Identification Using a Shotgun Proteomics Assay.

Robust and highly specific methods for the detection of the protein toxin ricin are of interest to the law enforcement community. In previous studies, methods based on liquid chromatography-tandem mass spectrometry shotgun proteomics have been proposed. The successful implementation of this approach relies on specific data evaluation criteria addressing (1) the quality of the mass spectrometric data, (2) the confidence of peptide identifications (peptide-spectrum matches), and (3) the number and sequence specificity of peptides detected.

Ricin-like proteins from the castor plant do not influence liquid chromatography-mass spectrometry detection of ricin in forensically relevant samples.

The toxic protein ricin (also known as RCA60), found in the seed of the castor plant (Ricinus communis) is frequently encountered in law enforcement investigations. The ability to detect ricin by analyzing its proteolytic (tryptic) peptides by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is well established. However, ricin is just one member of a family of proteins in R.

Evaluation of Immunoassays and General Biological Indicator Tests for Field Screening of Bacillus anthracis and Ricin.

There is little published data on the performance of biological indicator tests and immunoassays that could be used by first responders to determine if a suspicious powder contains a potential biothreat agent. We evaluated a range of biological indicator tests, including 3 protein tests, 2 ATP tests, 1 DNA test, and 1 FTIR spectroscopy instrument for their ability to screen suspicious powders for Bacillus anthracis (B. anthracis) spores and ricin.

Investigation of Yersinia pestis Laboratory Adaptation through a Combined Genomics and Proteomics Approach.

The bacterial pathogen Yersinia pestis, the cause of plague in humans and animals, normally has a sylvatic lifestyle, cycling between fleas and mammals. In contrast, laboratory-grown Y. pestis experiences a more constant environment and conditions that it would not normally encounter.

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.

Determination of post-culture processing with carbohydrates by MALDI-MS and TMS derivatization GC-MS.

Biological materials generally require stabilization to retain activity or viability in a dry form. A number of industrial products, such as vaccines, probiotics and biopesticides have been produced as dry preparations. The same methods and materials used for stabilizing commercial microbial products may be applicable to preserving biothreat pathogens in a dry form.

The effect of growth medium on B. anthracis Sterne spore carbohydrate content.

The expressed characteristics of biothreat agents may be impacted by variations in the culture environment, including growth medium formulation. The carbohydrate composition of B. anthracis spores has been well studied, particularly for the exosporium, which is the outermost spore structure.

Analysis of carbohydrate and fatty acid marker abundance in ricin toxin preparations for forensic information.

One challenge in the forensic analysis of ricin samples is determining the method and extent of sample preparation. Ricin purification from the source castor seeds is essentially a protein purification through removal of the nonprotein fractions of the seed. Two major, nonprotein constituents in the seed are the castor oil and carbohydrates.

ROC-curve approach for determining the detection limit of a field chemical sensor.

The detection limit of a field chemical sensor under realistic operating conditions is determined by receiver operator characteristic (ROC) curves. The chemical sensor is an ion mobility spectrometry (IMS) device used to detect a chemical marker in diesel fuel. The detection limit is the lowest concentration of the marker in diesel fuel that obtains the desired true-positive probability (TPP) and false-positive probability (FPP).