A Distillation Approach to Phase Equilibrium Measurements of Multicomponent Fluid Mixtures.

By building on the Advanced Distillation Curve (ADC) approach to measuring the volatility of fuels and other fluid mixtures, the ADC with Reflux or ADCR technique was developed to address the difficulty of experimentally determining the vapor-liquid equilibrium of fluids containing many components. For fuels and other multicomponent mixtures, the ADCR collects data about the chemical compositions of both liquid and vapor phases across a range of temperatures, elucidating the two-phase region at constant pressure. Two simple mixtures were used to demonstrate the ADCR method: an -decane/-tetradecane binary and the Huber-Bruno surrogate, a ternary mixture designed to represent the volatility of an aviation turbine kerosene.

Composition Determination of Low-Pressure Gas-Phase Mixtures by H NMR Spectroscopy.

H NMR spectroscopy was used to analyze gas-phase mixtures of methane and propane at pressures near 0.1 MPa. The mixtures were prepared gravimetrically and had low uncertainty in their composition.

Application of the Advanced Distillation Curve Method to the Comparison of Diesel Fuel Oxygenates: 2,5,7,10-Tetraoxaundecane (TOU), 2,4,7,9-Tetraoxadecane (TOD), and Ethanol/Fatty Acid Methyl Ester (FAME) Mixtures.

Although they are amongst the most efficient engine types, compression-ignition engines have difficulties achieving acceptable particulate emission and NO formation. Indeed, catalytic after-treatment of diesel exhaust has become common and current efforts to reformulate diesel fuels have concentrated on the incorporation of oxygenates into the fuel. One of the best ways to characterize changes to a fuel upon the addition of oxygenates is to examine the volatility of the fuel mixture.

Determination of Cannabinoid Vapor Pressures to Aid in Vapor Phase Detection of Intoxication.

The quest for a reliable means to detect cannabis intoxication with a breathalyzer is ongoing. To design such a device, it is important to understand the fundamental thermodynamics of the compounds of interest. The vapor pressures of two important cannabinoids, cannabidiol (CBD) and Δ-tetrahydrocannabinol (Δ-THC), are presented, as well as the predicted normal boiling temperature (NBT) and the predicted critical constants (these predictions are dependent on the vapor pressure data).

Comprehensive Assessment of Composition and Thermochemical Variability by High Resolution GC/QToF-MS and the Advanced Distillation-Curve Method as a Basis of Comparison for Reference Fuel Development.

Commercial and military aviation is faced with challenges that include high fuel costs, undesirable emissions, and supply chain insecurity that result from the reliance on petroleum-based feedstocks. The development of alternative gas turbine fuels from renewable resources will likely be part of addressing these issues. The United States has established a target for one billion gallons of renewable fuels to enter the supply chain by 2018.

Diesel Surrogate Fuels for Engine Testing and Chemical-Kinetic Modeling: Compositions and Properties.

The primary objectives of this work were to formulate, blend, and characterize a set of four ultralow-sulfur diesel surrogate fuels in quantities sufficient to enable their study in single-cylinder-engine and combustion-vessel experiments. The surrogate fuels feature increasing levels of compositional accuracy (i.e.

Direct nuclear magnetic resonance observation of odorant binding to mouse odorant receptor MOR244-3.

Mammals are able to perceive and differentiate a great number of structurally diverse odorants through the odorant's interaction with odorant receptors (ORs), proteins found within the cell membrane of olfactory sensory neurons. The natural gas industry has used human olfactory sensitivity to sulfur compounds (thiols, sulfides, etc.) to increase the safety of fuel gas transport, storage, and use through the odorization of this product.

Composition of the C+ Fraction of Natural Gas by Multiple Porous Layer Open Tubular Capillaries Maintained at Low Temperatures.

As the sources of natural gas become more diverse, the trace constituents of the C+ fraction are of increasing interest. Analysis of fuel gas (including natural gas) for compounds with more than 6 carbon atoms (the C+ fraction) has historically been complex and expensive. Hence, this is a procedure that is used most often in troubleshooting rather than for day-to-day operations.

Field portable low temperature porous layer open tubular cryoadsorption headspace sampling and analysis part II: Applications.

This paper details the sampling methods used with the field portable porous layer open tubular cryoadsorption (PLOT-cryo) approach, described in Part I of this two-part series, applied to several analytes of interest. We conducted tests with coumarin and 2,4,6-trinitrotoluene (two solutes that were used in initial development of PLOT-cryo technology), naphthalene, aviation turbine kerosene, and diesel fuel, on a variety of matrices and test beds. We demonstrated that these analytes can be easily detected and reliably identified using the portable unit for analyte collection.

Field portable low temperature porous layer open tubular cryoadsorption headspace sampling and analysis part I: Instrumentation.

Building on the successful application in the laboratory of PLOT-cryoadsorption as a means of collecting vapor (or headspace) samples for chromatographic analysis, in this paper a field portable apparatus is introduced. This device fits inside of a briefcase (aluminum tool carrier), and can be easily transported by vehicle or by air. The portable apparatus functions entirely on compressed air, making it suitable for use in locations lacking electrical power, and for use in flammable and explosive environments.

Modeling RP-1 fuel advanced distillation data using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry and partial least squares analysis.

Recent efforts in predicting rocket propulsion (RP-1) fuel performance through modeling put greater emphasis on obtaining detailed and accurate fuel properties, as well as elucidating the relationships between fuel compositions and their properties. Herein, we study multidimensional chromatographic data obtained by comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC × GC-TOFMS) to analyze RP-1 fuels. For GC × GC separations, RTX-Wax (polar stationary phase) and RTX-1 (non-polar stationary phase) columns were implemented for the primary and secondary dimensions, respectively, to separate the chemical compound classes (alkanes, cycloalkanes, aromatics, etc.

High-density biosynthetic fuels: the intersection of heterogeneous catalysis and metabolic engineering.

Biosynthetic valencene, premnaspirodiene, and natural caryophyllene were hydrogenated and evaluated as high performance fuels. The parent sesquiterpenes were then isomerized to complex mixtures of hydrocarbons with the heterogeneous acid catalyst Nafion SAC-13. High density fuels with net heats of combustion ranging from 133-141 000 Btu gal(-1), or up to 13% higher than commercial jet fuel could be generated by this approach.

Analysis of arson fire debris by low temperature dynamic headspace adsorption porous layer open tubular columns.

In this paper we present results of the application of PLOT-cryoadsorption (PLOT-cryo) to the analysis of ignitable liquids in fire debris. We tested ignitable liquids, broadly divided into fuels and solvents (although the majority of the results presented here were obtained with gasoline and diesel fuel) on three substrates: Douglas fir, oak plywood and Nylon carpet. We determined that PLOT-cryo allows the analyst to distinguish all of the ignitable liquids tested by use of a very rapid sampling protocol, and performs better (more recovered components, higher efficiency, lower elution solvent volumes) than a conventional purge and trap method.

Correlation of rocket propulsion fuel properties with chemical composition using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry followed by partial least squares regression analysis.

There is an increased need to more fully assess and control the composition of kerosene-based rocket propulsion fuels such as RP-1. In particular, it is critical to make better quantitative connections among the following three attributes: fuel performance (thermal stability, sooting propensity, engine specific impulse, etc.), fuel properties (such as flash point, density, kinematic viscosity, net heat of combustion, and hydrogen content), and the chemical composition of a given fuel, i.

Method and apparatus for pyrolysis--porous layer open tubular column--cryoadsorption headspace sampling and analysis.

In previous work, dynamic headspace vapor collection on short, porous layer open tubular (PLOT) capillary columns maintained at low temperature was introduced. In this paper, that metrology is extended with the introduction of a small in situ pyrolysis platform that provides for rapid heating and rapid vapor capture for a wide variety of samples. The new approach is referred to as pyro-PLOT-cryo.

Weathering Patterns of Ignitable Liquids with the Advanced Distillation Curve Method.

One can take advantage of the striking similarity of ignitable liquid vaporization (or weathering) patterns and the separation observed during distillation to predict the composition of residual compounds in fire debris. This is done with the advanced distillation curve (ADC) metrology, which separates a complex fluid by distillation into fractions that are sampled, and for which thermodynamically consistent temperatures are measured at atmospheric pressure. The collected sample fractions can be analyzed by any method that is appropriate.

Findings and Recommendations From the Joint NIST-AGA Workshop on Odor Masking.

Since the days of the alchemist, the observation that some substances have a smell while other substances do not has been a source of fascination. The sense of smell, or olfaction, is our least understood sense, however it is important for many human functions, including digestion, food selection and hazard avoidance. The detailed explanation of why individual chemicals (called odorants) might have a particular smell is still elusive.

Chromatographic sample collection from two-phase (gas+liquid) flows.

A particularly challenging sample presentation in analytical chemistry is a flowing stream that consists of both a gas and liquid phase, combined with the common situation in which a reliable analysis is needed for both phases, separately. In these cases, the vapor and liquid must be physically separated (without change to either), before the individual phases can be collected and analyzed. It is not possible to analyze two-phase flows otherwise.

Enthalpy of adsorption for hydrocarbons on concrete by inverse gas chromatography.

Enthalpies of adsorption, ΔH(a), are reported for several light hydrocarbons on normal construction concrete. ΔH(a), which are a measure of the adhesion strength of a molecule on a surface, were determined by gas-solid chromatography with a packed column containing 60-80 mesh concrete particles. With this approach, the specific retention volume for a compound is measured as a function of temperature, and these data are used to calculate ΔH(a).

Prediction and preliminary standardization of fire debris constituents with the advanced distillation curve method.

The recent National Academy of Sciences report on forensic sciences states that the study of fire patterns and debris in arson fires is in need of additional work and eventual standardization. We discuss a recently introduced method that can provide predicted evaporation patterns for ignitable liquids as a function of temperature. The method is a complex fluid analysis protocol, the advanced distillation curve approach, featuring a composition explicit data channel for each distillate fraction (for qualitative, quantitative, and trace analysis), low uncertainty temperature measurements that are thermodynamic state points that can be modeled with an equation of state, consistency with a century of historical data, and an assessment of the energy content of each distillate fraction.

Novel reduced pressure-balance syringe for chromatographic analysis.

When withdrawing a fluid sample (for additional chromatographic analyses) from an apparatus operated at a reduced pressure, a typical syringe proves to be ineffective (even if it is equipped with a gas tight plunger). It simply does not create enough pressure differential to remove a fluid sample from a reduced pressure environment. We encountered such a situation as part of efforts to extend the operation of the advanced distillation curve protocol to reduced pressures.

Detecting gravesoil with headspace analysis with adsorption on short porous layer open tubular (PLOT) columns.

Victims of crimes are often buried in clandestine graves. There are several techniques for finding buried bodies or the scattered remains of a victim; however, none of these methods are very reliable or work in all scenarios. One way to detect gravesoil is to detect the biochemical changes of the surrounding soil due to cadaver decomposition, for example, the release of nitrogenous compounds.

Trace headspace sampling for quantitative analysis of explosives with cryoadsorption on short alumina porous layer open tubular columns.

Quantitative headspace (HS) measurements have been performed on the practical industrial and military plastic bonded explosives (PBX) tagged-C-4, Semtex-1A, Semtex-H, detonating cord (detcord), and sheet explosive (Detaflex). The measurements were made by a modified purge and trap technique developed in our laboratory on the basis of cryoadsorption on short alumina-coated porous layer open tubular (PLOT) columns. Trace compounds (of both high and low volatility) were identified and quantitated as a function of HS collection temperature.

Complex fluid analysis with the advanced distillation curve approach.

An improved method for measuring distillation curves reveals the physicochemical properties of complex fluids such as fuels.

The composition-explicit distillation curve technique: Relating chemical analysis and physical properties of complex fluids.

The analysis of complex fluids such as crude oils, fuels, vegetable oils and mixed waste streams poses significant challenges arising primarily from the multiplicity of components, the different properties of the components (polarity, polarizability, etc.) and matrix properties. We have recently introduced an analytical strategy that simplifies many of these analyses, and provides the added potential of linking compositional information with physical property information.