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Abstract: There is increasing demand for automated cell reprogramming in the fields of cell biology, biotechnology and the biomedical sciences. Microfluidic-based platforms that provide unattended manipulation of adherent cells promise to be an appropriate basis for cell manipulation. In this study we developed a magnetically driven cell carrier to serve as a vehicle within an in vitro environment. To elucidate the impact of the carrier on cells, biocompatibility was estimated using the human adenocarcinoma cell line Caco-2. Besides evaluation of the quality of the magnetic carriers by field emission scanning electron microscopy, the rate of adherence, proliferation and differentiation of Caco-2 cells grown on the carriers was quantified. Moreover, the morphology of the cells was monitored by immunofluorescent staining. Early generations of the cell carrier suffered from release of cytotoxic nickel from the magnetic cushion. Biocompatibility was achieved by complete encapsulation of the nickel bulk within galvanic gold. The insulation process had to be developed stepwise and was controlled by parallel monitoring of the cell viability. The final carrier generation proved to be a proper support for cell manipulation, allowing proliferation of Caco-2 cells equal to that on glass or polystyrene as a reference for up to 10days. Functional differentiation was enhanced by more than 30% compared with the reference. A flat, ferromagnetic and fully biocompatible carrier for cell manipulation was developed for application in microfluidic systems. Beyond that, this study offers advice for the development of magnetic cell carriers and the estimation of their biocompatibility. [Copyright &y& Elsevier]

Two simple methods for the analysis of the total concentration of sulfur in CO2 by diode laser atomic absorption spectrometry of excited, metastable sulfur atoms in a direct current discharge are presented. In the first method, the CO2 sample gas is mixed with the plasma gas (Ar or He) while the second is based on reproducible measurements of the sulfur released from the walls in a helium discharge after being deposited as a result of operating the discharge in pure CO2 sample gas. The detection limits obtained satisfy the requirements for the control of sulfur compounds in CO2 used in the food and beverage industry. [Copyright &y& Elsevier]

Abstract: Transformation and surviving of E. coli C600 have been evaluated in dependence on the electric field strength and current density by changing the conductivity of the bacteria suspension. In this context the impact of making bacteria electrocompetent and the addition of NaCl solution was examined. Transformation efficiency declines with increasing conductivity of the suspension. When washing bacteria differently, the transformation efficiency correlates with the number of survivors. In contrary, adding different concentrations of NaCl has no effect on the surviving of E. coli C600. In dependence on the electric field strength, the transformation efficiency shows no effect on changing the conductivity. Regarding the transformation efficiency in dependence of the current density, a clear shift of the transformation maximum was observed. For higher conductivities, higher current densities are needed to reach the transformation maximum. [Copyright &y& Elsevier]

Specific analytical characteristics of near-infrared E´chelle microwave-induced plasma atomic emission spectrometry (NIR-E´chelle-MIP-OES) with respect to the quantification of organic compounds were examined. Matrices consisting of halogenated and sulfureous hydrocarbons were gas chromatographically separated and subsequently H-, C-, F-, Cl-, Br-, I- and S-selectively analyzed. For these purposes, a compact E´chelle spectrometer, designed for the high-repetitive, high-resolved and simultaneous spectra acquisition between 640 and 990 nm was used. Depending on the plasma gas applied and element considered, detection limits typically varied from 200–2200 pg/s for Ar to 70–660 pg/s for He. Furthermore, strategies to improve the over-all sensitivity are discussed. In this context, a concept, which rests on simultaneous multi-line analysis is described and experimentally proofed. [Copyright &y& Elsevier]

The capability of the small-sized dielectric barrier discharge as an element-selective diode laser atomic absorption detector for gas chromatography is investigated. Detection limits have been determined for halogenated and sulfured hydrocarbons in the low to the high pg/s-range dependent on the element measured. Furthermore, the effect of doping gas (oxygen) and make-up gas (argon, helium) on the chromatograms is studied. [Copyright &y& Elsevier]

Two small-size plasmas used as detectors of halogenated hydrocarbons and suitable for miniaturized instrumentation are discussed. A reduced pressure dielectric barrier discharge was integrated in a diode laser atomic absorption spectrometer and the already reported chlorine detection limits of 5 ppm (v/v) can be improved with one order of magnitude by spatially resolved measurements. A microstructured electrode discharge at atmospheric pressure was coupled with a miniaturized E´chelle spectrometer and detection limits were found to be 20 ppb for chlorine as well as for fluorine. [Copyright &y& Elsevier]

The present review reflects the importance of dielectric barrier discharges for optical spectrometric detection in analytical chemistry. In contrast to usual discharges with a direct current the electrodes are separated by at least one dielectric barrier. There are two main features of the dielectric barrier discharges: they can serve as dissociation and excitation devices as well as ionization sources, respectively. This article portrays various application fields of dielectric barrier discharges in analytical chemistry used for elemental and molecular detection with optical spectrometry. [ABSTRACT FROM AUTHOR]

Abstract: Among different applications of dielectric barrier discharge (DBD) plasma, the soft ionization ability is certainly one of the most interesting. In this paper the helium plasma jet, produced by a capillary DBD, penetrating in the ambient atmosphere, has been spectroscopically investigated in dependence on applied voltage and helium flow. It was found that the change of the applied voltage leads to different discharge modes. Based on the measurements of the emission spectra of atomic He and N2 + and N2 molecules in the capillary and in the plasma jet with high spatial resolution, it can be assessed in which mode, i.e. under which conditions the plasma jet is expected to be most effective for soft ionization of molecules. [Copyright &y& Elsevier]

Abstract: An atmospheric pressure microplasma ionization source based on a dielectric barrier discharge with a helium plasma cone outside the electrode region has been developed for liquid chromatography/mass spectrometry and as ionization source for ion mobility spectrometry. It turned out that dielectric barrier discharge ionization could be regarded as a soft ionization technique characterized by only minor fragmentation similar to atmospheric pressure chemical ionization (APCI). Mainly protonated molecules were detected. In order to characterize the soft ionization mechanism spatially resolved optical emission spectrometry (OES) measurements were performed on plasma jets burning either in He or in Ar. Besides to spatial intensity distributions of noble gas spectral lines, in both cases a special attention was paid to lines of N2 + and N2. The obtained mapping of the plasma jet shows very different number density distributions of relevant excited species. In the case of helium plasma jet, strong N2 + lines were observed. In contrast to that, the intensities of N2 lines in Ar were below the present detection limit. The positions of N2 + and N2 distribution maxima in helium indicate the regions where the highest efficiency of the water ionization and the protonation process is expected. [Copyright &y& Elsevier]

Abstract: This paper presents the characterization of a source for soft ionization of organic molecules. This source is based on a plasma jet established at the end of a capillary dielectric barrier discharge at atmospheric pressure. He, Ne and Ar as pure gas or with different concentrations of N2 are used as buffer gas for the plasma jet. Spectroscopic emission measurements are carried out along the plasma jet in and outside the capillary. The intensity variation of N2 + lines, for example emission at 391.4 and 427.8nm, can be associated with the protonation process which is the basis for the soft ionization. The mechanism of the N2 + production outside the capillary, which is relevant for the protonation of molecules and sustains the production of primary ions, is investigated. The response signal of the ions in a nitrogen atmosphere was measured with an ion mobility spectrometer (IMS). [Copyright &y& Elsevier]

Abstract: The paper reviews the past 11 years of literature on the application of diode lasers in atomic absorption spectrometry with graphite furnaces (GF), plasmas and flames as atomizers. Experimental arrangements and techniques for powerful absorption measurements as well as the theoretical background are covered. The analytical possibilities of high-resolution spectroscopy, including Doppler-free techniques for isotope selective measurements and isotope dilution analysis are discussed and various applications of element-selective detection by diode laser atomic absorption in combination with separation techniques, such as liquid (LC) and gas chromatography (GC), and with laser ablation of solid samples, are presented. [Copyright &y& Elsevier]

A small, low-pressure dielectric barrier discharge used as a detector for the analysis of halogenated hydrocarbons was studied by diode laser absorption spectroscopy of excited plasma atoms. The distribution, as well as diffusion of the excited atoms, was measured with high spatial and temporal resolution. The major part of the excited atoms was found in a very narrow discharge volume, where the maximum gas temperature and electron density, determined from broadening of the absorption line profiles, were approximately 1000 K and greater than 1015 cm−3, respectively. [Copyright &y& Elsevier]

Micro-Tube Plasmas (μTP) have been gaining attention for applications ranging from medicine to material science and analytical chemistry due to their small size, low cost of operation and flexibility. In the present work a specific μTP, known as the Flexible Micro Tube Plasma (FμTP) is investigated experimentally and, for the first time, numerically as well. The creation, propagation mechanisms and properties of the ionization waves inside the microtube are investigated during the positive and negative half cycle of a μs square wave applied voltage. A two-dimensional (2D) axi-symmetric numerical model is developed and compared with optical emission spectroscopy showing good agreement. During the positive half cycle the plasma propagates as an ionization wave (or streamer) depositing charges on the dielectric wall. During the negative half cycle the plasma propagates due to the neutralization of those surface charges on the walls. The different propagation mechanisms affect the accumulation of charges, the induced electric field, and the speed of the ionization waves. [Display omitted] • The microtube plasma is an efficient and low voltage ambient MS soft ionization source. • The discharge during the rising voltage resembles a plasma streamer. • The discharge during the falling voltage is much faster and is due to leftover charges on the wall. • There is a glow discharge from the electrode to the wall during the falling voltage. [ABSTRACT FROM AUTHOR]