Electrochemical Detection of TNT at Cobalt Phthalocyanine Mediated Screen‐Printed Electrodes and Application to Detection of Airborne Vapours

We describe the use of cobalt phthalocyanine as a mediator to improve the sensitivity for the electrochemical detection of TNT. Commercial screen‐printed electrodes containing cobalt phthalocyanine were employed for determination of TNT. Improved sensitivities compared to screen‐printed carbon electrodes without phthalocyanine were observed, current response for cyclic voltammetric measurements at modified electrodes being at least double that of unmodified electrodes. A synergistic effect between oxygen and TNT reduction was also observed. Correlation between TNT concentrations and sensor output was observed between 0–200 µM TNT. Initial proof‐of‐concept experiments combining electrochemical determinations, with the use of an air‐sampling cyclone, are also reported.     

Swelling Ratios and Rates of Sulfonation of Solvent Modified Copolymers of Styrene Cross-Linked with Pure m-and Pure p-Divinylbenzene

Solvent-modified (toluene) copolymers have been prepared from styrene cross-linked with commercial divinylbenzene, m-divinylbenzene, and p-divinylbenzene at divinyl monomer contents of 16 mole % and 32 mole % at F_M = 0.50. The resultant copolymers have been characterized by swelling-ratio determinations and rates of sulfonation at 60 and 80°C. The solvent-modified 16 mole % cross-linked copolymers sulfonated at rates slightly greater than those characterizing the 8 mole % cross-linked copolymers prepared in the absence of diluent. The order of decreasing sulfonation rates for both the conventional 8 mole % cross-linked systems and for the solvent-modified 16 mole % cross-linked copolymers is commercial divinylbenzene/styrene, p-divinylbenzene/styrene, m-divinylbenzene styrene. The 32 mole % cross-linked systems exhibit a different order of decreasing sulfonation rates: commercial divinylbenzene/styrene, m-divinylbenzene/styrene, p-divinylbenzene/styrene. The swelling ratios of the 32 mole % solvent-modified copolymers were comparable to those of the conventional 8 mole % cross-linked systems.     

Neuronal metabolomics by ion mobility mass spectrometry: cocaine effects on glucose and selected biogenic amine metabolites in the frontal cortex, striatum, and thalamus of the rat

We report results of studies of global and targeted neuronal metabolomes by ambient pressure ion mobility mass spectrometry. The rat frontal cortex, striatum, and thalamus were sampled from control nontreated rats and those treated with acute cocaine or pargyline. Quantitative evaluations were made by standard additions or isotopic dilution. The mass detection limit was ～100 pmol varying with the analyte. Targeted metabolites of dopamine, serotonin, and glucose followed the rank order of distribution expected between the anatomical areas. Data was evaluated by principal component analysis on 764 common metabolites (identified by m/z and reduced mobility). Differences between anatomical areas and treatment groups were observed for 53 % of these metabolites using principal component analysis. Global and targeted metabolic differences were observed between the three anatomical areas with contralateral differences between some areas. Following drug treatments, global and targeted metabolomes were found to shift relative to controls and still maintained anatomical differences. Pargyline reduced 3,4-dihydroxyphenylacetic acid below detection limits, and 5-HIAA varied between anatomical regions. Notable findings were: (1) global metabolomes were different between anatomical areas and were altered by acute cocaine providing a broad but targeted window of discovery for metabolic changes produced by drugs of abuse; (2) quantitative analysis was demonstrated using isotope dilution and standard addition; (3) cocaine changed glucose and biogenic amine metabolism in the anatomical areas tested; and (4) the largest effect of cocaine was on the glycolysis metabolome in the thalamus confirming inferences from previous positron emission tomography studies using 2-deoxyglucose.

Characterization of NIST food-matrix standard reference materials for their vitamin C content

The vitamin C concentrations in three food-matrix Standard Reference Materials (SRMs) from the National Institute of Standards and Technology (NIST) have been determined by liquid chromatography (LC) with absorbance detection. These materials (SRM 1549a Whole Milk Powder, SRM 1849a Infant/Adult Nutritional Formula, and SRM 3233 Fortified Breakfast Cereal) have been characterized to support analytical measurements made by food processors that are required to provide information about their products’ vitamin C content on the labels of products distributed in the United States. The SRMs are primarily intended for use in validating analytical methods for the determination of selected vitamins, elements, fatty acids, and other nutrients in these materials and in similar matrixes. They can also be used for quality assurance in the characterization of test samples or in-house control materials, and for establishing measurement traceability. Within-day precision of the LC method used to measure vitamin C in the food-matrix SRMs characterized in this study ranged from 2.7 % to 6.5 %.     

Experimental study of copper leveling additives and their wafer and pattern-scale effect on copper planarization

The impact of Cu leveling additives on electrodeposited Cu topography and subsequent planarization behaviour was studied on both the pattern and wafer scales. The leveling agent significantly reduces as-deposited Cu topography, especially “mounding”. The reduction in topography results in a higher effective Cu removal rate during subsequent Cu planarization, both at the pattern and wafer scales. On the wafer scale, this effect is more evident for lower overburdens as the topography must be eliminated in a shorter total polish time. For Cu electrodeposited from leveler additive-free chemistries, significant pattern-scale topography persists throughout almost the entire planarization process, whereas for Cu deposited using a leveling agent only very wide features (～ > 100 μm) show any significant topography evolution during Cu polish. It is shown that excess electrodeposited Cu topography can lead to poor in-plane Cu wiring leakage performance.     

Studies on the Synthesis of Eremophilane Sesquiterpenes. A Novel Entry into the Aristolane Ring System

Readily available tricyclo[3.2.2.0^2,4]non-6-en-8-one is converted into the tricyclo ring system of the aristolane sesquiterpenes via an alkoxide accelerated [3, 3]-sigmatropic rearrangement.     

An Experimentally Convenient Preparation of Highly Substituted Pyridines

A four step sequence is described for the conversion of α,β-unsaturated carboxylic acids into highly substituted pyridines.     

Fully Protected Glycosylated Zinc (II) Phthalocyanine Shows High Uptake and Photodynamic Cytotoxicity in MCF‐7 Cancer Cells

Phthalocyanine photosensitizers are effective in anticancer photodynamic therapy (PDT) but suffer from limited solubility, limited cellular uptake and limited selectivity for cancer cells. To improve these characteristics, we synthesized isopropylidene‐protected and partially deprotected tetra β‐glycosylated zinc (II) phthalocyanines and compared their uptake and accumulation kinetics, subcellular localization, in vitro photocytotoxicity and reactive oxygen species generation with those of disulfonated aluminum phthalocyanine. In MCF‐7 cancer cells, one of the compounds, zinc phthalocyanine {4}, demonstrated 10‐fold higher uptake, 5‐fold greater PDT‐induced cellular reactive oxygen species concentration and 2‐fold greater phototoxicity than equimolar (9 μm ) disulfonated aluminum phthalocyanine. Thus, isopropylidene‐protected β‐glycosylation of phthalocyanines provides a simple method of improving the efficacy of PDT.     

Gas chromatographic retention of alkyl phosphates on ionic liquid stationary phases

Retention behaviors of alkyl phosophates were studied on a series of ionic liquid gas chromatography columns. The selectivity of the IL columns for alkyl phosphates were compared with a 5% phenyl column as a route to evaluating the potential use of IL columns in the analysis of alkyl phosphates in petroleum samples in both one- and multi-dimensional GC. Most interestingly, we demonstrate for the first time the dependence of elution order on separation temperature for members of a homologous series of compounds. At low temperatures it was found that trihexyl phosphate eluted before trioctyl phosphate, while at higher temperatures this pattern was reversed.     

Substituted 4‐Oxo‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic Esters by a Tandem Imine Addition‐SNAr Reaction

A tandem imine addition‐S_NAr annulation reaction has been developed as a new approach to the synthesis of 4‐oxo‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic esters. A series of these structures has been generated by reacting selected imines with tert‐butyl 2‐fluoro‐5‐nitrobenzoylacetate. Structural variations in the final products are accomplished by changing the substituents on the imine and the alkyl group of the ester. The title compounds are isolated as their enols in 55–97% yield without the need for added base or catalysts. The synthesis of the starting materials as well as mechanistic studies and further synthetic conversions of the products are presented.