Carrier-Based Ion-Selective Electrodes and Bulk Optodes. 1. General Characteristics.

Quest for Nonaqueous Multivalent Secondary Batteries: Magnesium and Beyond

We review the current state of optical methods for sensing oxygen. These have become powerful alternatives to electrochemical detection and in the process of replacing the Clark electrode in many fields. The article (with 694 references) is divided into main sections on direct spectroscopic sensing of oxygen, on absorptiometric and luminescent probes, on polymeric matrices and supports, on additives and related materials, on spectroscopic schemes for read-out and imaging, and on sensing formats (such as waveguide sensing, sensor arrays, multiple sensors and nanosensors). We finally discuss future trends and applications and summarize the properties of the most often used indicator probes and polymers. The ESI† (with 385 references) gives a selection of specific applications of such sensors in medicine, biology, marine and geosciences, intracellular sensing, aerodynamics, industry and biotechnology, among others.

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Optical methods for sensing and imaging oxygen: materials, spectroscopies and applications

A new optical sensor based on covalent immobilization of a newly synthesized calcium-selective, long-wavelength, fluorescent indicator has been constructed, with a response dynamic range optimal for physiological measurements. Immobilization occurs via photoinitiated copolymerization of the indicator with acrylamide on the distal end of a silanized 125 μm diameter multimode optical fiber. The working lifetime of this sensor is limited only by photobleaching of the indicator. Due to the inherent hydrophilic nature of the acrylamide polymer, the response time of this new sensor is governed by simple aqueous diffusion of the ionic calcium. This results in sensor response times fast enough to monitor some concentration fluctuations at physiological rates. The ability to monitor calcium concentration fluctuations in a high background level of magnesium is also demonstrated with a calculated selectivity of 10-4.5.

Fluorescent fiber-optic calcium sensor for physiological measurements.

Since the discovery of perchlorate in the ground and surface waters of several western states, there has been increasing interest in the health effects resulting from chronic exposure to low (parts per billion [ppb]) levels. With this concern has come a need to investigate technologies that might be used to remediate contaminated sites or to treat contaminated water to make it safe for drinking. Possible technologies include physical separation (precipitation, anion exchange, reverse osmosis, and electrodialysis), chemical and electrochemical reduction, and biological or biochemical reduction. A fairly unique combination of chemical and physical properties of perchlorate poses challenges to its analysis and reduction in the environment or in drinking water. The implications of these properties are discussed in terms of remediative or treatment strategies. Recent developments are also covered.

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Perchlorate Chemistry: Implications for Analysis and Remediation

Determination of protein in human serum by high-performance liquid chromatography with semiconductor laser fluorometric detection.

Chlorophyll is fluorescent in the deep-red resign and is determined by semiconductor laser fluorometryn after its separation with capillary zone electrophoresis. The separation efficency is several hundred thousand in the theoretical plate. Methylene blue is used as a chromophore in indirect fluorometry. The detection limit achieved is 1-pmol levels. A new labelling reagent is synthesized, which consists of a thiazine chromophore for fluorescence detection and a succinimidyl ester for combination with an amino acid. The labeled amino acids are clearly resolved by capillary zone electrophoresis, the detection limit being 10-pmol levels

Determination of amino acids by capillary zone electrophoresis based on semiconductor laser fluorescence detection

Thermal lens spectrophotometry based on pulsed laser excitation

An intense and monochromatic laser beam consisting of more than 40 vibrational and rotational lines is generated by the stimulated Raman effect, when two-color laser beams separated by ∼590 cm−1 are tightly focused into pressurized hydrogen. This phenomenon is reasonably explained by four-wave mixing; one beam is used for two-step excitation (ω1+ω1) to an imaginary level and another beam (ω2) acts as a seed beam, generating a fourth beam (2ω1−ω2). Through cascade processes, so many laser emissions appear with a frequency difference of (ω1−ω2) in entire ultraviolet and visible regions.

Generation of more than 40 laser emission lines from the ultraviolet to the visible regions by two-color stimulated raman effect

A thermal lens spectrophotometric system, consisting of a pulsed dye laser source, a photomultiplier, and a wave memory controlled by a microcomputer, is used for a determination of atmospheric NO/sub 2/. The enhancement factor for the sample in various media is calculated by using the theoretical equation and the optical parameters and compared with the observed value for the gaseous and liquid phase samples. The agreement of the observed value with the theoretical value was fair. For a laser pulse energy of 1 mJ, a signal enhancement of 10/sup 3/ is expected in comparison with a conventional spectrophototmeter. The determination of NO/sub 2/ is carried out by using a dye laser with a pulse energy of 20-40 ..mu..J, and a detection limit of 0.8 ppm was achieved. Verification of the theorectical equation and advantages of a pulsed laser source for the determination of the gaseous sample are discussed in comparison with a CW laser excitation method. 3 tables, 2 figures.

Nobuhiko Ishibashi

Papers

Determination of protein in human serum by high-performance liquid chromatography with semiconductor laser fluorometric detection.

Determination of amino acids by capillary zone electrophoresis based on semiconductor laser fluorescence detection

Thermal lens spectrophotometry based on pulsed laser excitation

Generation of more than 40 laser emission lines from the ultraviolet to the visible regions by two-color stimulated raman effect

Determination of nitrogen dioxide by pulsed thermal lens spectrophotometry