Mass spectral characterization of the Intact chromophore of organic dyestuffs, frequently prepared as salts, Is relatively facile with desorption Ionization. The mass spectra obtained, however, may show the presence of chemically altered forms of the chromophore. Comparison of the fission fragment (FF)

Dual-Discharge Ionization SourceSir: In recent years, the glow discharge has been studied as a possible alternative source to the pulsed rf spark ion source in mass spectrometry (1-4) and to electrothermal atomization in atomic absorption (5, 6). Others have investigated glow discharges and low pressure plasmas as surface analysis probes (7)(8)(9). For trace element analysis by mass

A microfluidic assay was developed for screening botulinum neurotoxin serotype A (BoNT-A) by using a fluorescent resonance energy transfer (FRET) assay. Molded silicone microdevices with integral valves, pumps, and reagent reservoirs were designed and fabricated. Electrical and pneumatic control hardware were constructed, and software was written to automate the assay protocol and data acquisition. Detection was accomplished by fluorescence microscopy. The system was validated with a peptide inhibitor, running 2 parallel assays, as a feasibility demonstration. The small footprint of each bioreactor cell (0.5 cm2) and scalable fluidic architecture enabled many parallel assays on a single chip. The chip is programmable to run a dilution series in each lane, generating concentration-response data for multiple inhibitors. The assay results showed good agreement with the corresponding experiments done at a macroscale level. Although the system has been developed for BoNT-A screening, a wide variety of assays can be performed on the microfluidic chip with little or no modification.

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Magnetic field coupling to a gas discharge finds practical employment in several types of present-day low-pressure discharge assemblies, for example, in the duoplasmatron ion source and in commercial sputter atomization units serving to deposit coatings or films of sputtered material on selected substrates. To date, gas discharge ionization sources for glow discharge mass spectrometry (GDMS) (1), an analytical technique developed by researchers for inorganic solids analysis (2-5) and thin film process control (6), and which