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A workflow for the development of organometallic processes in flow was applied to synthesize 1-(5-bromopyridin-2-yl)-2-methylpropan-2-ol, a pharmaceutical intermediate. Key factors and correspondin...

This paper describes the development of an improved and scalable method for the manufacture of nemiralisib, a phosphatidylinositol-3-kinase delta inhibitor. Incorporation of three consecutive catal...

Imaging experiments are performed on a solution-cathode glow discharge. Laser scattering is used to observe droplet trails ejected at a range of angles from the solution surface. Interference filters are used to photograph a variety of analyte emission lines and background emission bands. The effects of low molecular weight organic compounds (HCOOH and CH3CH2OH) and non-ionic surfactants (Triton X-45 and Triton X-405) on the spatial distributions of emission are studied. Low molecular weight organic compounds are found to affect the degree of emission for some species, but do not detectibly change the plasma structure. The lighter surfactant affects the degree of emission for some background species, but does not noticeably affect analyte emission or plasma structure. The heavier surfactant (Triton X-405) is found to affect both the degree of emission from some species and the overall structure of the plasma.

Acetaldehyde is a major wine oxidation product. Here, three Cabernet Sauvignon wines, containing different levels of acetaldehyde from different micro-oxygenation (mOx) regimes, including yeast-mediated treatments, were aged under closures differing in oxygen ingress. Oxygen, phenolics, carbonyls and heterocyclic acetals were measured. Acetaldehyde levels at bottling was a significant factor in the phenolic compound profile after one year, with anthocyanins most affected, then flavonols, flavonoids and hydroxycinnamic acids, but there were negligible effects on benzoic acids. The effect of bottle closures with increased oxygen ingress had a similar trend. Increased acetaldehyde levels and oxygen ingress also yielded higher levels of the heterocyclic acetals from glycerol. These changes reflect aging, and suggest that managing mOx during production could be used to reduce the time needed to achieve some aged wine characteristics.

The liquid sampling – atmospheric pressure glow discharge (LS-APGD) microplasma was paired with a monochromatic imaging spectrometer (MIS) to interrogate relevant plasma species/elements. The coupling of the LS-APGD source to the MIS allows for the generation of spatial emission profiles at specific analyte and background species' wavelengths. A major goal of this work was to utilize these emission profiles to gain an understanding of the species' location in the plasma as well as the effects of plasma gas flow on these emission profiles. It was found that as sheath gas and counter gas flow rates were increased, there were visible differences in intensity and distribution of emission from the monitored species in the plasma. Silver was used as the representative (test) analyte for this work due to its good sensitivity, wavelength positioning, and ability to provide continuity for comparison to previous works. The majority of analyte emission was found to occur at the tip of the solution electrode, where solutes are introduced to the plasma, whereas various background species emitted throughout the plasma. In addition to aiding in the understanding of plasma operation based on spatial emission characteristics, these studies also aided in optimizing the gas flow parameters for analyte emission intensity, signal-to-background (S/B), and signal-to-noise (S/N) values. The optimized gas flow parameters were found to be 0.7 and 0.1 L min−1 for the sheath and counter gas respectively.

Several biocatalytic approaches for the preparation of optically pure methyl 3-oxocyclohexanecarboxylates (S)-, (R)-1 and 3-oxocyclohexanecarbonitriles (S)-, (R)-2 have been successfully demonstrated. Screening of reaction-focused enzyme collections was used to identify initial hits using three enzymatic strategies. Reaction optimization and scale-up enabled the production of chiral intermediates for route scouting efforts on scales of up to 100 g. The enzymes applied in these processes (lipases, enoate reductases, and nitrilases) have been shown to be robust catalysts for drug manufacturing and represent a green alternative to conventional methods to access these chiral cyclohexanone building blocks.

This paper describes the discovery and development of a flexible route to two candidate drug molecules by a common intermediate approach. Key reactions include Negishi and Suzuki couplings to form biaryl bonds. Conditions for a Miyaura borylation of heteroaryl bromides were also developed. Heteroaryl trifluoroborates and aryl chlorides were used as coupling partners in the Suzuki reaction, thereby minimizing detrimental side reactions such as protodeboronation and oxidative homocoupling. A complementary set of reaction conditions using pinacolboronates with potassium bifluoride as an additive were also developed and used to make 5 kg of drug substance for use in early-phase clinical trials.

Solution-cathode glow discharge was studied in an attempt to further elucidate the processes involved in the plasma. Spectroscopic and electrical properties were measured with and without the influence of three organic modifiers: formic acid, acetic acid, and ethanol. Degradation products (CO, C2, and CH) of the modifiers were detected in the plasma spectroscopically. Properties of solutions before and after exposure to the discharge were compared. The effects of organic additives on these solution properties were measured. A single, simple mechanism was not consistent with the data, so a multi-part mechanism is proposed for solution and analyte transport into the plasma. Evaporation from the cathode surface, droplet generation, and chemical generation of volatile species may each play a role.

A modified design of a chromatically resolved optical microscope (CROMoscope), a grating-based spectral imaging microscope, is described. By altering the geometry and adding a beam splitter, a twisting aberration that was present in the first version of the CROMoscope has been removed. Wavelength adjustment has been automated to decrease analysis time. Performance of the new design in transmission–absorption spectroscopy has been evaluated and found to be generally similar to the performance of the previous design. Spectral bandpass was found to be dependent on the sizes of apertures, and the smallest measured spectral bandpass was 1.8 nm with 1.0 mm diameter apertures. Wavelength was found to be very linear with the sine of the grating angle (R 2 = 0.9999995), and wavelength repeatability was found to be much better than the spectral bandpass. Reflectance spectral imaging with a CROMoscope is reported for the first time, and this reflectance spectral imaging was applied to blue ink samples on white paper. As a proof of concept, linear discriminant analysis was used to classify the inks by brand. In a leave-one-out cross-validation, 97.6% of samples were correctly classified.

The development of a hydrogenation process and subsequent isolation for an intermediate in the manufacture of an active pharmaceutical ingredient is described. In-line process analytical technology (PAT) approaches were applied to gain process understanding and control. First, a calibration-free, qualitative, scale-independent approach using in situ mid-infrared (MIR) spectrometry to determine the end point of a hydrogenation reaction in real time is described. A curve-fitting algorithm was developed using MATLAB software to allow the reaction rate to be calculated at any given time during the reaction on the basis of the consumption of an intermediate species. The algorithm, coupled with understanding of the process, allowed the end point to be correctly identified in triplicate during scale-up of the process from 0.2 to 20 L scale. Second, a quantitative partial least-squares (PLS) regression model was developed using near-infrared (NIR) spectrometry to determine the solvent composition during the subse...

HCOOH, CH 3 COOH, and CH 3 CH 2 OH were used as chemical modifiers in a solution-cathode glow discharge. Emission was measured directly from the discharge, without a gas–liquid separator or a secondary excitation source. Emission from Ag, Se, Pb, and Hg was strongly enhanced, and the detection limits (DL) for these elements were improved by up to an order of magnitude using a combination of HCOOH and HNO 3 compared to using HNO 3 alone. The DL was measured for Mg (1 μg/L), Fe (10 μg/L), Ni (6 μg/L), Cu (6 μg/L), Pb (1 μg/L), Ag (0.1 μg/L), Se (300 μg/L), and Hg (2 μg/L). Coefficients of determination (R 2 ) were between 0.9986 and 0.9999. A voltage of 1 kV was used, which produced a current of approximately 70 mA.

Micro-oxygenation (MOx) is a common winemaking treatment used to improve red wine color development and diminish vegetal aroma, amongst other effects. It is commonly applied to wine immediately after yeast fermentation (phase 1) or later, during aging (phase 2). Although most winemakers avoid MOx during malolactic (ML) fermentation, it is often not possible to avoid because ML bacteria are often present during phase 1 MOx treatment. We investigated the effect of common yeast and bacteria on the outcome of micro-oxygenation.Compared to sterile filtered wine, Saccharomyces cerevisiae inoculation significantly increased oxygen consumption, keeping dissolved oxygen in wine below 30 µg LThe production of acetaldehyde is a key outcome of MOx and it is dramatically increased in the presence of yeast, although it is possibly counteracted by the metabolism of O. oeni bacteria. Additional controlled experiments are necessary to clarify the interaction of yeast and bacteria during MOx treatments. Analysis of the glycerol acetals may be useful as a proxy for acetaldehyde levels. © 2017 Society of Chemical Industry.

A formal synthesis of neooxazolomycin is described via the preparation of Kende’s key intermediate in a longest linear sequence of 23 steps. This work is founded upon the union of three fragments: Moloney’s lactam-derived triflate, a vinyl stannane and a Julia–Kocienski sulfone and encompasses three key steps: (i) a Stille cross-coupling to combine the triflate and vinyl stannane, (ii) a base-promoted enone deconjugation to derive the dihydroxylation precursor and (iii) our previously reported Julia–Kocienski methodology to assemble the pentadienyl amine side chain with the sulfone precursor.

The chromatically resolved optical microscope (CROMoscope) is capable of spectral imaging with tunable spectral and spatial resolutions. Because of its remarkably simple design, the CROMoscope can be easily assembled and aligned. Spectral resolution as low as 2.5 nm full width at half maximum (fwhm) was measured using an atomic emission line of Hg. Absorption spectra of different parts of a micrograph can readily be compiled using white-light illumination. Chloroplast absorption from an Elodea plant leaf was used to demonstrate this capability. Spectral imaging is widely applicable to many areas of science, and the CROMoscope is particularly simple to adapt to conventional microscopes and should enable detailed spectroscopic information to be obtained from microscopy.

Anthocyanins and their aglycone anthocyanidins are pigmented flavonoids found in significant amounts in many commonly consumed foods. They exhibit a complex chemistry in aqueous solution, which makes it difficult to study their chemistry under physiological conditions. Here we used a gel electrophoresis assay employing supercoiled DNA plasmid to examine the ability of these compounds (1) to intercalate DNA, (2) to inhibit human topoisomerase I through both inhibition of plasmid relaxation activity (catalytic inhibition) and stabilization of the cleavable DNA-topoisomerase complex (poisoning), and (3) to inhibit or enhance oxidative single-strand DNA nicking. We found no evidence of DNA intercalation by anthocyan(id)ins in the physiological pH range for any of the compounds used in this study-cyanidin chloride, cyanidin 3-O-glucoside, cyanidin 3,5-O-diglucoside, malvidin 3-O-glucoside and luteolinidin chloride. The anthocyanins inhibited topoisomerase relaxation activity only at high concentrations (> 50 muM) and we could find no evidence of topoisomerase I cleavable complex stabilization by these compounds. However, we observed that all of the anthocyan(id)ins used in this study were capable of inducing significant oxidative DNA strand cleavage (nicking) in the presence of 1 mM DTT (dithiothreitol), while the free radical scavenger, DMSO, at concentrations typically used in similar studies, completely inhibited DNA nicking. Finally, we propose a mechanism to explain the anthocyan(id)in induced oxidative DNA cleavage observed under our experimental conditions.

The Stille coupling between a common oxazole vinyl iodide and stereodefined stannyl-diene units is described as the cornerstone of a unified synthetic route to the inthomycin family of bioactive Streptomyces metabolites. This procedure has been utilised to prepare (+)-inthomycin B and (+)-inthomycin C for the first time; in these examples the stereogenic centre was introduced using the Kiyooka ketene acetal/amino acid-derived oxazaborolidinone variant of the Mukaiyama aldol reaction. In addition, a convenient preparation of rac-inthomycin A is described based on the same strategy.

The flowing afterglow-atmospheric pressure glow discharge (APGD) ionization source described in part 1 of this study (in this issue) is applied to the direct analysis of condensed-phase samples. When either liquids or solids are exposed to the ionizing beam of the APGD, strong signals for the molecular ions of substances present on their surfaces can be detected without compromising the integrity of the solid sample structure or sample substrate. As was observed for gas-phase compounds in part 1 of this study, both polar and nonpolar substances can be ionized and detected by mass spectrometry. The parent molecular ion (or its protonated counterpart) is usually the main spectral feature, with little or no fragmentation in evidence. Preliminary quantitative results show that this approach offers very good sensitivity (detection limits in the picogram regime are reported for several test compounds in part 1 of this study) and linear response to the analyte concentration. Examples of the application of this strategy to the analysis of real-world samples, such as the direct analysis of pharmaceutical compounds or foods is provided. The ability of this source to perform spatially resolved analysis is also demonstrated. Preliminary studies of the mechanisms of the reactions involved are described.

The large-scale preparation of 2-methyloxazole-4-carboxaldehyde presents a significant challenge due to the physical characteristics of the molecule. A method for the preparation of 10-kg batches of 2-methyloxazole-4-carboxaldehyde is described. The key reaction is the reduction of the corresponding N-methoxy-N-methyl amide using lithium aluminium hydride, followed by workup and isolation by crystallization.

The phage T4 UvsW protein has been shown to play a crucial role in the switch from origin-dependent to recombination-dependent replication in T4 infections through the unwinding of origin R-loop initiation intermediates. UvsW also functions with UvsX and UvsY to repair damaged DNA through homologous recombination, and, based on genetic evidence, has been proposed to act as a Holliday junction branch migration enzyme. Here we report the purification and characterization of UvsW. Using oligonucleotide-based substrates, we confirm that UvsW unwinds branched DNA substrates, including X and Y structures, but shows little activity in unwinding linear duplex substrates with blunt or single-strand ends. Using a novel Holliday junction-containing substrate, we also demonstrate that UvsW promotes the branch migration of Holliday junctions efficiently through more than 1000 bp of DNA. The ATP hydrolysis-deficient mutant protein, UvsW-K141R, is unable to promote Holliday junction branch migration. However, both UvsW and UvsW-K141R are capable of stabilizing Holliday junctions against spontaneous branch migration when ATP is not present. Using two-dimensional agarose gel electrophoresis we also show that UvsW acts on T4-generated replication intermediates, including Holliday junction-containing X-shaped intermediates and replication fork-shaped intermediates. Taken together, these results strongly support a role for UvsW in the branch migration of Holliday junctions that form during T4 recombination, replication, and repair.

Glow discharge sources have shown impressive analytical performance, cost effectiveness, and versatility but have traditionally been ill-suited for the analysis of liquids or solutions. However, in recent years, glow discharges operated at atmospheric pressure have shown progress in this direction. In particular, glow discharges have been operated with the solution to be analyzed acting as one of the electrodes (most typically, and most successfully, the cathode). These sources exhibit many of the traditional advantages of glow discharges (such as low power requirements) and possess the additional benefit of not requiring vacuum equipment. In the present study, a modified design is introduced and its analytical performance is evaluated. The modification from the most similar source is primarily a reduction in discharge volume (nearly 5-fold, to 2 mm(3)) and a corresponding increase in power density. With the new design, detection limits for a range of metals are greatly improved, with most now in the single and sub-part per billion range.

A glow discharge optical-emission spectrometry source was evaluated for use in imaging elemental surface distributions. A 1.8 cm 2 area of a nickel–chromium alloy was sampled and copper emission was observed directly above the surface of a copper inclusion. By pulsing the glow discharge, the resolution was improved greatly over measurements using direct-current powering. Ranges of gas flows, pulse frequencies, pulse potentials, pulse widths, and pressures were explored to determine their effects on spatial resolution and were related to atom transport in the glow discharge cell. Pressure, pulse width, and pulse frequency were all found to have a significant effect on resolution.

Flavonoids and other polyphenolic compounds have been shown to inhibit human topoisomerase IB (topo I) through both inhibition of relaxation activity and through stabilization of the cleavable complex (poisoning). Some flavonoids have also been shown to intercalate DNA, and an association of topoisomerase inhibition with intercalation has been noted. We surveyed 34 polyphenolic compounds, primarily flavonoid glycones and aglycones, for their ability to inhibit topo I and to intercalate DNA using an in vitro gel electrophoresis method. We show that the most potent topo I poisons are the flavones and flavonols, and that these generally, but not always, are found to be DNA intercalators. There was no clear correlation, however, of topo-I-poisoning activity with the degree of DNA unwinding. Surprisingly, both DNA intercalation and topo I poisoning were shown to occur with some flavone glycones, including the C-glycosylflavone orientin. Inhibition of relaxation activity by flavonoids was found to be difficult to quantify and was most likely to be due to non-specific inhibition through flavonoid aggregation. As part of a structure–activity analysis, we also investigated the acid–base chemistry of flavonoids and determined that many flavonoids show acid–base activity with a pKa in the physiological pH region. For this reason, subtle pH changes can have significant effects on solution activity of flavonoids and their concomitant biological activity. In addition, these effects may be complicated by pH-dependent aggregation and oxidative degradation. Finally, we develop a simple model for the intercalation of flavonoids into DNA and discuss possible consequences of intercalation and topoisomerase inhibition on a number of cellular processes.

The DNA maintenance enzyme, topoisomerase I, is thought to play crucial roles in all living cells and for this reason inhibitors of this enzyme have been much studied. In this paper we describe a gel electrophoresis method capable of characterizing and quantifying inhibition of topoisomerase I by selected compounds. Inhibitors of topoisomerase I are often associated with intercalative binding to DNA and the method can simultaneously determine intercalative binding (as DNA unwinding) except in the cases where inhibition is prohibitively strong. The method uses closed circular (plasmid) DNA and can separate single-strand nicked, linearized (double-strand nicked), fully relaxed, partially relaxed (topoisomers), and supercoiled forms of the plasmid so that topoisomerase-dependent DNA cleavage (poisoning) can also be determined. By quantifying poisoning, inhibition, and intercalation simultaneously and separately in relation to reference compounds it is possible to make quantitative determinations of these phenomena for comparative purposes. Data for the topoisomerase I inhibitor, luteolin, are presented.

Still-Gennari reactions have been carried out on a range of E- and Z-3-substituted propenals. In all cases, with the exception of Z-3-stannyl systems, good Z-stereoselectivity was observed. By contrast, the Ando procedure gives reasonable Z-stereoselectivity with all systems studied, including those with a cis-disposed stannyl substituent. © 2003 Elsevier Ltd. All rights reserved.

BACKGROUND Evidence exists that red wine, which contains a large array of polyphenols, is protective against cardiovascular disease and possibly cancer. OBJECTIVE We tested the hypothesis that catechin, the major monomeric polyphenol in red wine, can delay tumor onset in transgenic mice that spontaneously develop tumors. DESIGN Mice were fed a nutritionally complete amino acid-based diet supplemented with (+)-catechin (0-8 mmol/kg diet) or alcohol-free solids from red wine. Mice were examined daily; the age at which a first tumor appeared was recorded as the age at tumor onset. Plasma catechin and metabolite concentrations were quantified at the end of the study. RESULTS Dietary catechin significantly delayed tumor onset; a positive, linear relation was observed between the age at tumor onset and either the amount of dietary catechin (r(2) = 0.761, P < 0.001) or plasma catechin and metabolite concentrations (r(2) = 0.408, P = 0.003). No significant effects on tumor onset were observed when mice consumed a diet supplemented with wine solids containing

Carbonyl compounds are produced during fermentation and chemical oxidation during wine making and aging, and they are important to wine flavor and color stability. Since wine also contains these compounds as α-hydroxysulfonates as a result of their reaction with sulfur dioxide, an alkaline pre-treatment requiring oxygen exclusion has been used to release these bound carbonyls for analysis. By modifying the method to hydrolyze the hydroxysulfonates with heating and acid in the presence of 2,4-dinitrophenylhydrazine (DNPH), the carbonyl compounds are simultaneously and quickly released and derivatized, resulting in a simpler and more rapid method. In addition, the method avoids air exclusion complications during hydrolysis by the addition of sulfur dioxide. The method was optimized for temperature, reaction time, and the concentrations of DNPH, sulfur dioxide and acid. The hydrazones were shown to be stable for 10 h, adequate time for chromatographic analysis by HPLC-DAD/MS. This method is demonstrated for 2-ketoglutaric acid, pyruvic acid, acetoin and acetaldehyde, wine carbonyls of very different reactivities, and it offers good specificity, high recovery and low limits of detection. This new rapid, simple method is demonstrated for the measurement of carbonyl compounds in a range of wines of different ages and grape varieties.

The SmI2–H2O reagent system mediates challenging 5-exo/6-exo lactone radical cascade cyclisations that deliver carbo[5.4.0]bicyclic motifs in a diastereoselective, one-pot process that establish two new carbocyclic rings and four stereocentres.

Unsaturated, differentially substituted Meldrum's acid derivatives undergo cascade cyclizations upon ester reduction with SmI(2)-H(2)O. The cascade cyclizations proceed in good yield and with high diastereocontrol and convert simple, achiral starting materials to complex molecular architectures, bearing up to four stereocenters, in a single operation. The cascades are triggered by the generation and trapping of unusual radical-anions formed by electron transfer to the ester carbonyl.

(±)-Polysiphenol (1), an atropisomerically stable 4,5-dibrominated 9,10-dihydrophenanthrene from Polysiphonia ferulacea, was prepared by a biomimetically inspired highly regioselective intramolecular oxidative coupling of a dibrominated dihydrostilbene. The installation of the two bromine atoms prior to oxidative coupling prevents further oxidation to a planar aromatized phenanthrene. By this strategy, the synthesis of (±)-polysiphenol was achieved in four steps in 70% overall yield. Synthesis of the naturally occurring 5,5'-(ethane-1,2-diyl)bis(3-bromobenzene-1,2-diol) (2) (the likely biogenetic precursor of polysiphenol) and 5,5'-(ethane-1,2-diyl)bis(3,4,6-tribromobenzene-1,2-diol) (9) are also reported. The origins of the regioselectivity in the oxidative coupling are explored.

Bacteriophage T4 provides an important model system for studying the mechanism of homologous recombination. We have determined the crystal structure of the T4 UvsX recombinase, and the overall architecture and fold closely resemble those of RecA, including a highly conserved ATP binding site. Based on this new structure, we reanalyzed electron microscopy reconstructions of UvsX-DNA filaments and docked the UvsX crystal structure into two different filament forms: a compressed filament generated in the presence of ADP and an elongated filament generated in the presence of ATP and aluminum fluoride. In these reconstructions, the ATP binding site sits at the protomer interface, as in the RecA filament crystal structure. However, the environment of the ATP binding site is altered in the two filament reconstructions, suggesting that nucleotide cannot be as easily accommodated at the protomer interface of the compressed filament. Finally, we show that the phage helicase UvsW completes the UvsX-promoted strand-exchange reaction, allowing the generation of a simple nicked circular product rather than complex networks of partially exchanged substrates.

This article describes a self-powered system that uses chemical reactions—the thermal excitation of alkali metals—to transmit coded alphanumeric information. The transmitter (an “infofuse”) is a strip of the flammable polymer nitrocellulose patterned with alkali metal ions; this pattern encodes the information. The wavelengths of 2 consecutive pulses of light represent each alphanumeric character. While burning, infofuses transmit a sequence of pulses (at 5–20 Hz) of atomic emission that correspond to the sequence of metallic salts (and therefore to the encoded information). This system combines information technology and chemical reactions into a new area—“infochemistry”—that is the first step toward systems that combine sensing and transduction of chemical signals with multicolor transmission of alphanumeric information.

The Stille coupling between a common oxazole vinyl iodide and stereodefined stannyl-diene units is described as the cornerstone of a unified synthetic route to the inthomycin family of bioactive Streptomyces metabolites. This procedure has been utilised to prepare (+)-inthomycin B and (+)-inthomycin C for the first time; in these examples the stereogenic centre was introduced using the Kiyooka ketene acetal/amino acid-derived oxazaborolidinone variant of the Mukaiyama aldol reaction. In addition, a convenient preparation of rac-inthomycin A is described based on the same strategy.

“Science off the air” (Random Samples, 28 March, p. [1741][1]) analyzes a survey's results without paying attention to the actual question asked. The article discusses whether Americans “can” or “cannot” name living scientists. You would expect, then, that the survey question actually

A novel chemical ionization source for organic mass spectrometry is introduced. This new source uses a glow discharge in the flowing afterglow mode for the generation of excited species and ions. The direct-current gas discharge is operated in helium at atmospheric pressure; typical operating voltages and currents are around 500 V and 25 mA, respectively. The species generated by this atmospheric pressure glow discharge are mixed with ambient air to generate reagent ions (mostly ionized water clusters and NO+), which are then used for the ionization of gaseous organic compounds. A wide variety of substances, both polar and nonpolar, can be ionized. The resulting mass spectra generally show the parent molecular ion (M+ or MH+) with little or no fragmentation. Proton transfer from ionized water clusters has been identified as the main ionization pathway. However, the presence of radical molecular ions (M+) for some compounds indicates that other ionization mechanisms are also involved. The analytical capabilities of this source were evaluated with a time-of-flight mass spectrometer, and preliminary characterization shows very good stability, linearity, and sensitivity. Limits of detection in the single to tens of femtomole range are reported for selected compounds.

A miniaturized version of an atmospheric-pressure glow discharge using a solution as the cathode was recently evaluated for elemental analysis of continuously sampled aqueous solutions. Although continuous sampling is useful, transient analysis is required for certain applications, including chromatographic or similar separations, small-volume sampling, high-throughput sampling, and on-line preconcentration. The miniaturized solution-cathode glow discharge seems particularly well suited to transient analysis by virtue of its low dead volume and high sensitivity. Two benefits of transient analysis were exploited here: high throughput and small sample volume. Sampling 25-microL volumes at 1000 samples/h, the discharge achieved detection limits ranging from 5 pg (0.2 ppb) for Li to 6 ng (270 ppb) for Hg.

Glow discharge optical emission spectrometry has cemented itself as an important surface elemental analysis technique in part because of its superb depth resolution (on the order of single nanometers). However, very few studies have explored the ability of the glow discharge to provide laterally resolved elemental information. In the present study, an end-on-viewed pulsed radio frequency glow discharge is coupled to a monochromatic imaging spectrometer to provide lateral surface imaging. The performance of the technique is demonstrated with etched copper circuits on fiber-glass substrates, and it is shown how several operating parameters including pressure, pulsed mode operation, and time-resolved detection affect the lateral surface resolution. In addition, because a pulsed radio frequency glow discharge offers elemental information on nonconducting samples, the technique is applied to the three-dimensional elemental analysis of proteins on blotting substrates. Several alternative sample types are also examined, including photographic film and glass.

A concise, convergent and stereocontrolled synthesis of (+)-inthomycin B, based on the Stille coupling of a stannyl-diene with an oxazole vinyl iodide unit, is described. The asymmetric centre was introduced using the Kiyooka ketene acetal/amino acid-derived oxazaborolidinone procedure.

Still–Gennari reactions have been carried out on a range of E- and Z- 3-substituted propenals. In all cases, with the exception of Z -3-stannyl systems, good Z -stereoselectivity was observed. By contrast, the Ando procedure gives reasonable Z -stereoselectivity with all systems studied, including those with a cis -disposed stannyl substituent.

A solution–cathode glow discharge is coupled to a compact spectrograph. Such a coupling results in a small, potentially portable instrument that can simultaneously detect a range of metals by optical emission spectrometry. Detection limits were calculated for Ag (1 ppb), Cd (2 ppb), Cu (8 ppb), Fe (40 ppb), Hg (20 ppb), Mg (3 ppb), Ni (12 ppb), Pb (10 ppb) and Se (3 ppm). These values are similar to those for an earlier, monochromator-based solution–cathode glow discharge system. All calibration curves showed good linearity (R2 ≥ 0.9994). Short-term precision ranged from 0.6–7%.

We describe a setup for addressable optical trapping in which a laser source is focused on a digital micromirror device and generates an optical trap in a microfluidic cell. In this paper, we report a proof-of-principle single beam/single micromirror/single three-dimensional trap arrangement that should serve as the basis for a multiple-trap instrument.

A recent trend in plasma spectrochemistry, and in analytical chemistry in general, has been towards miniaturization. Miniaturized plasma sources often have properties leading to low cost, potential portability, and simplified integration with separation instrumentation such as chromatographs. However, these discharges have not often performed well with solution samples. To address this shortcoming, we have developed a new, small-scale (5 × 2 mm) plasma, maintained in atmospheric-pressure helium between a tubular cathode and a rod-shaped anode (both made of steel). The discharge extends between the two electrodes and an annular glow is visible within the cathode tube. An aerosol is introduced into the plasma through the cathode, and atomic emission is observed in the near-cathode region. In this study, we observe the effects of solvent addition on the plasma in terms of its electrical and spectroscopic characteristics and how they change with solution flow rate. Given that even a robust source such as the inductively coupled plasma is different under wet and dry conditions, it is not surprising that the discharge introduced here is affected by the presence of an aerosol. However, the discharge is stable even with significant solvent loading. In this preliminary investigation, flow injection has been used to establish detection limits for several metals between 7 ppb (0.7 ng absolute) for Cd and 111 ppb (11 ng absolute) for Cu.

Use of an electrolyte-cathode glow discharge (ELCAD) with complex samples is explored. The present state of knowledge in this regard is briefly reviewed and several previously undocumented effects are examined. Remedies to various interferences are proposed and evaluated. The implications of the results to the mechanistic understanding of ELCAD are discussed.

The ion and electron populations of a glow discharge that uses an electrolytic solution as the cathode (an electrolyte-cathode discharge or ELCAD) were investigated. This paper presents the first determinations of electron number density, ionization temperature, and degrees of ionization in the ELCAD. Spectroscopic techniques were used to keep from perturbing the plasma, a range of conditions was explored, and two regions (the negative glow and the positive column) were observed. By using the Stark broadening of the hydrogen beta line, electron number densities near 8.5 × 1014 cm−3 for the negative glow and 2.5 × 1014 cm−3 for the positive column were found. From those results and measurements of the relative strengths of Mg neutral and ionic lines, ionization temperatures of 5000 K for the negative glow and 4600 K for the positive column were calculated. From these results, the degrees of ionization and norm temperatures were estimated for a variety of elements. Analytical implications of the study are discussed.

A novel direct current glow discharge sustained in helium at atmospheric pressure has been developed. Current–voltage behavior and spectroscopic characteristics strongly suggest that the system operates in the glow regime, in spite of the high pressure. The diffuse and extremely stable discharge is typically operated within a voltage range of 300–900 volts (in the current-controlled mode) and at currents ranging over tens to hundreds of milliamps. Spatially resolved spectroscopic measurements of some selected species are presented. Rotational temperature profiles were calculated using the OH emission spectrum, yielding values in the positive column ranging from 1300 to 1600 K.