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Each year thousands of wildland fires blaze across the United States causing secondary (“smoke”) damage to numerous businesses and personal property. Currently there are no specific industry standards or guidelines for determining wildfire combustion residues. Remediation decisions often rely on anecdotal evidence from occupants. A variety of particulate methods are used to assess surface contamination but there are few methods for evaluating organic chemical residues that encompass the wide range of chemical classes produced during wildland fires. A new method was developed employing a thermal desorption gas chromatography mass spectrometry (TD-GCMS). TD-GCMS using novel sorbent beds decreases the sample preparation substantially and enables sampling of bulk materials by off-gassing. Furthermore, the method developed is specific to wildland fire events. Results from a simulated wildland fire event are also provided.

Motivating students in analytical chemistry can be challenging, in part because of the complexity and breadth of topics involved. Some methods that help encourage students and convey real-world relevancy of the material include incorporating environmental issues, research-based lab experiments, and service learning projects. In this paper, we describe an approach that combines all three of these methods by integrating environmental research-based activities into the second-year undergraduate analytical chemistry course. We discuss the development, implementation, and preliminary evaluation of the research-based labs employed during the new summer analytical chemistry course. Students perform environmental investigations of sites on Beaver Island, Michigan, and prepare reports to contribute to an ongoing research project analyzing these locations that began in the 1970s. Preliminary impacts on analytical students were examined using pre- and postsurveys, including the Chemistry Attitudes and Experiences Qu...

Succinate-based plasticizer mixtures have potential use as nontoxic and sustainable plasticizers and as replacements for commonly used phthalate plasticizers. Synergistic effects occur when the interaction between two materials is enhanced by the addition of a third component. This concept was applied to plasticizers within a polymer matrix. Three newly synthesized succinate-based plasticizers (di-ethylhexyl succinate, di-decyl succinate, and di-dodecyl succinate) were tested for their plasticizing ability. Then, di-decyl succinate and didodecyl succinate were blended with the previously reported succinate di-esters (di-ethyl succinate, di-hexyl succinate, and di-octyl succinate) to study their plasticizing efficiency. Mixtures of these higher molecular weight (MW) succinate di-esters and previously reported lower MW ones were found to be more effective at plasticizing poly(vinyl chloride) compared to the individual succinate plasticizers alone.

Phthalates pose adverse health effects due to their propensity to leach and the most common, di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DOP), are petroleum-based. Conversely, di-esters, succinates are biobased (produced from fermentation of biomass), biodegradable, and therefore potential sustainable replacements for phthalates. A series of succinates, di-octyl succinate (DOS), di-hexyl succinate (DHS), di-butyl succinate (DBS), and di-ethyl succinate (DES), were mixed with poly(vinyl chloride) (PVC). The interaction of the plasticizer ester carbonyl with PVC shows an average −5 cm−1 shift of the carbonyl absorbance peak energy. The glass transition temperatures (T g), were monitored by differential scanning calorimetry and dynamic mechanical analyses. The T gs of DOS and DHS plasticized PVC were significantly lower than DOP plasticized PVC at a lower percent mass. On the other hand, PVC plasticized with either DBS or DES exhibited a similar trend in lowering the T g as that of DOP plasticized PVC.

A series of polyhedral oligosilsesquioxane (POSS) nanosensors functionalized with fluorophores that change their wavelength of emission in response to their chemical environment has been synthesized and characterized by IR, NMR, UV, one- and two-dimensional fluorescence spectroscopy, MALDI-TOF MS, and electrospray MS. When each nanosensor in an array of n nanosensors is functionalized with a different wavelength shifting fluorophore, the array can generate a unique fingerprint comprised of n emission wavelength data points in response to a given chemical warfare agent (CWA) simulant or toxic industrial chemical (TIC). One-photon fluorescence fingerprints were constructed by measuring the fluorescence spectra of nanosensor-analyte pairs in solution. Two-photon fluorescence fingerprints were then generated by remotely interrogating nanosensor-analyte pairs using a femtosecond IR laser and a stand-off fluorimeter. Two-photon fingerprints were obtained for analytes in solution, on a surface, and in cloud form. A four-component nanosensor array could differentiate a homologous series of alcohols and distinguish G and VX classes of nerve agent simulants.

The generation of ammonium hydrogen sulfate from ammonium sulfate is of current interest because of its potential as a process component of bio-based organic acid production from biomass. An organic acid, for example succinic acid, is a chemical product that is used in food, cosmetics, deicing applications, etc. and a potential key carbon building block for numerous other materials. Its production from biomass (corn, etc.) makes it a renewable chemical resource, and the regeneration process described here minimizes the use of additional acid and base value reagents and byproduct (low value salt) waste. In the present work ammonium hydrogen sulfate (acid) and ammonia (base) were regenerated from ammonium sulfate using a thermal cracking method. Raman spectroscopy was used for primary analysis of the ammonium hydrogen sulfate product formed to determine the optimal reaction rate (80 °C/min) and to study the role of ammonium pyrosulfate in this reaction.

Ordered carbonaceous growth typically requires high-energy methods such as arc discharge [1] or decomposition of hydrocarbon-based precursors using laser [2–4], plasma [3], or thermolytic techniques [4]. For the latter technique, temperature regimes on the order of 600–1000° C are most common, with a few recent reports citing lower temperatures using halogenated precursors [5–7], or through alkali-metal catalyzed transformation of bulk carbon allotropes [8,9]. Sailor etal. have reported the first growth of non-amorphous carbon deposits at room temperature [10]. However, their electrochemical synthesis did not produce nanostructural carbon; due to the absence of nanosized catalytic seeds, the diameters of their fibers were > 5μm, and contained copious amounts of Cl, H, N, and O impurities.

Two-beam fluorescence cross-correlation spectroscopy (FCCS) was used to resolve the bound and unbound fractions of fluorescently labeled single-stranded DNA (ssDNA) in a ssDNA-protein complex as the analyte solution flowed continuously through an electrophoresis capillary. Cross-correlation of the single molecule fluorescence from two spatially separate excitation laser beams resulted in cross-correlation functions that consisted of well-resolved peaks characteristic of the different electrophoretic flow velocities of the bound and unbound ssDNA. This decoupled the molecular parameters of the bound and unbound ssDNA used to model the cross-correlation function, which enabled the relative concentrations to be determined without prior knowledge of the pure-component cross-correlation functions, as would be required in an analogous autocorrelation analysis. The relative concentrations of the bound and unbound ssDNA were determined by two-beam FCCS within 2-6% precision, even for samples that contained as little as 5% unbound ssDNA, and were consistent with the results obtained by capillary electrophoresis (CE) separation of the same samples. Data sufficient to obtain these results was acquired in 10-15 s per sample. Fluorescently labeled poly(dT)39 complexed with the single stranded DNA binding protein of Escherichia coli served as the model system. The measured dissociation constant of 2.5+/-0.9 nM agreed with the literature value for this complex within experimental error. The CE/two-beam FCCS experiment described here is part of a family of techniques that use single molecule fluorescence detection to resolve different components in an electrophoresis system. Advantages of these methods relative to separations-based CE include enhanced sensitivity, the potential for higher speed analyses, elimination of the sample plug injection step, and the ability to carry out the analysis in shorter flow channels.

The nonlinear optical technique of second harmonic generation (SHG) is introduced as a novel technique for monitoring particle formation in batch crystallizations. SHG is more sensitive and is less prone to interference than turbidometric methods. The studies presented show the applicability of SHG as a method for in situ measuring the induction time of a number of noncentrosymmetric crystal systems.

A capillary electrophoresis-based electrophoretic mobility shift assay is described wherein fluorescence correlation spectroscopy is used to resolve the bound and unbound fractions of a DNA-protein complex on the basis of their characteristic electrophoretic flow velocities.

A high-speed capillary electrophoresis mobility shift assay (CEMSA) for determining the binding ratios of DNA–protein complexes in solution is demonstrated. Single molecule fluorescence correlation spectroscopy (FCS) was used to resolve the bound and unbound fluorescently labeled DNA molecules as they flowed continuously through a fused silica capillary under the influence of an applied electric field. Resolution of the bound and unbound complexes was based on the difference in their electrophoretic mobilities, and was accomplished without the need to perform a chemical separation. Data sufficient to perform the analysis was acquired in less than 10 s, compared to the minutes that are normally needed to carry out such measurement via CE separation. The binding ratios were determined with 5 to 10% precision and agreed with the results obtained by CE separation within experimental error. The resolution of the CEMSA based FCS analysis (CEMSA-FCS) was significantly higher than for the analysis performed by conventional diffusional FCS, due to the higher mass sensitivity of the electrophoretic mobility compared to the translational diffusion coefficient. Fluorescently labeled 39-mer single stranded DNA (ssDNA) and the single stranded binding protein (SSB) from Escherichia coli was used as the model system. The dissociation constant of the ssDNA–SSB complex was estimated to be ≈2 nM based on the CEMSA-FCS analysis.