Analytical methods using antibodies have made remarkable progress in the fields of medicine and life sciences. However, hydrophobic low molecular compounds, such as pesticides and mycotoxins in foods, have not been put into practical use because antibodies, which are proteins, are easily influenced by organic solvents using their extractions. In the authors team, antibodies for their compounds were prepared, and analytical methods were attempted to develop using them. As results, various monoclonal antibodies tolerated to organic solvents were prepared, and ELISAs for residue analyses of pesticides in garden crops and immunoaffinity columns for cleaning up mycotoxins in foods were developed. Next, surface plasmon resonance immunosensors were introduced to establish a simultaneous analysis method for several pesticides. One of the immunosensors was also applied to detect O antigen on Escherichia coli, but it was difficult to remove bacteria after signal detection because the O antigen binds to the antibody at multiple points. It was successfully removed by a physical method using a gel such as gelatin or agarose as the results of trial and error search. The sensor regeneration maintained the antibody function. This method could be applied to detection of animal cells as well as bacteria.
An ultra-compact elemental analyzer by liquid electrode plasma atomic emission spectrometry (LEP-AES) without Argon gas has been developed. LEP is generated at narrow channel on electrolyte filled micro flow channel by charging a high voltage. The emission produced by LEP is analyzed with a micro spectrometer. The instrument is portable and suitable for on-site analysis because it does not need Argon gas, an exhaust system, and a specified electrical power source, which are indispensable for inductively coupled plasma atomic emission spectrometry (ICP-AES). The first model is a small and light mobile instrument. The second model is a desktop instrument improved in usability and functionality. Instantaneous analysis method is provided. Sample volume, reagent volume, sample preparation time and wastewater volume are reduced. It contributes to green chemistry. LEP-AES developing process, performance, and applications are reported.
“Flow analysis” is a generic term for continuous flow analysis (CFA) and flow injection analysis (FIA), which has been evolving into sequential injection analysis (SIA), stopped-in-loop flow analysis (SILFA), simultaneous injection effective mixing flow analysis (SIEMA) etc. Among them, CFA and FIA have been adapted into the Japanese Industrial Standard (JIS) K 0170 “Testing methods for water quality by flow analysis” in 2011. The JIS K 0170 consists of 9 parts, e.g. “part 1: Ammonium nitrogen”, “part 3: Total nitrogen”, “part 5: Phenol index”. The Japanese Ministry of the Environment has adopted the JIS K 0170 as several national official methods in 2014. In addition, SIA has been finally adopted into the JIS K 0126 “General rules for flow analysis” in 2019, which eventually contains FIA, CFA and SIA. The recent movement toward standardization proves that flow analysis has been recognized as an analytical technique that can support industry. In the present paper, recent progress in the development of flow analysis methods (FIA, SIA, SILFA, SIEMA) for the determinations of several substances as environmental index in wastewater, drinking water and/or environmental water is reviewed.
Although the Nobel Prize was awarded for the development of lithium-ion batteries, there is an urgent need to develop next-generation storage batteries with even higher energy densities for use in electric vehicles and power storages for renewable energy. Lithium-sulfur batteries are expected to be one of them. The development of electrolyte solutions plays a key role for the realization of lithium-sulfur batteries. The local structure of lithium ions in the electrolyte and the liquid structure of the electrolyte solution directly affect the battery parformance, such as the electromotive force and the charging speed. In other words, not only thermodynamics, but also kinetics the and dynamics of the electrolyte solutions dominate the battery performance. Recently, a new lithium-sulfur battery using a cathode material active insoluble electrolyte solution has been proposed, and clarifying the electrolyte solutions at the atomic and molecular level is a key. This article outlines the liquid structure, the speciation analysis and a new ionic conduction mechanism specific to the solvate ionic liquids that are the electrolyte solutions for the cathode active material insoluble a new lithium-sulfur battery.
We studied the chemical structure of polyesterimide in insulating varnish, which influences the surface hardness of an enamel wire coating. Magnet wires having equal synthesis and enameling processes, and mechanical and thermal properties, such as flexibility, show different surface hardness upon using a nanoindentation. Acetonitrile soluble parts and insoluble parts of polyesterimide varnishes were analyzed by using a liquid chromatograph-mass spectrometer (LC-MS) and a nuclear magnetic resonance (NMR). We find that the surface hardness of an enamel wire coating may depend on the amount of low-molecular-weight components, including esterimides in acetonitrile soluble parts and that of ethylene glycols at the end of polyesterimides in acetonitrile insoluble parts. These results indicate that controlling the surface hardness of an enamel wire coating requires chemical analysis of insulating varnishes.
The determination method of trace anions in high-concentration sodium hydroxide solutions by in-line neutralization-ion chromatography equipped with a neutralization device packed with a strongly acidic cation exchange resin was developed. The removal rate of sodium ions on the neutralization device determined by injecting 20 μL of 25 %w/v sodium hydroxide was 99.99 % or more. The passed solution from the neutralization device was measured by ion chromatography using the anion concentration column method. The detection limit (S/N = 3) for chloride ions in the presented method was 0.19 μg L−1, and the quantification limit (S/N = 10) was 0.63 μg L−1. Chloride ion, chlorate ion and sulfate ion were detected in reagent-grade of sodium hydroxide solutions (concentration; 48 %w/v). The repeatability (RSD, n = 3) for each anion detected was less than 1 %. The proposed method was applied to the determination of anions in an industrial sodium hydroxide solution (concentration; 48 %w/v), and chloride ion, chlorate ion and sulfate ion were quantified with good accuracy. The repeatability (RSD, n = 3) for each anion was also less than 1 %, and the recovery rates for spiked three anions were from 101.1 to 102.6 %.
The precise dispensing of droplets is a crucial step for acquiring reliable diagnostic results. When a source sample volume is limited, the need for precise dispensing of submicroliter and nanoliter quantities is especially important. In this study, we developed a positive-displacement high-precision dispensing technique using a nickel electroformed tube with an inner diameter accuracy of ±0.7 μm. The dispensing variation of 0.1 μL was evaluated using a photometric method. To reduce liquid retention on the edge of the electroformed tube, the outside surfaces of the tube were hydrophobically treated with self-assembled monolayers on a gold surface. Regarding the results, the most stable coefficients of variation (CV) was 0.70 %, i.e. 0.70 nL. Furthermore, the glucose and cholesterol concentrations in 0.2 μL of animal-based control serum were colorimetrically measured with enzymatic reactions. The CV value of the analysis was approximately 2.38 % and 1.45 %, respectively, suggesting that several biochemical panels can be precisely measured even from one drop of whole blood (∼10 μL). The present positive-displacement dispenser ensures zero contamination and an almost-zero dead volume, and therefore would be useful for multi-panel clinical blood diagnosis.
The determination of anions in heavy metal salt reagents using an ion chromatograph coupled with a metal removal device packed with a cation-exchange resin was examined. The present system was applied to the determination of some anions in cobalt chloride hexahydrate and zinc acetate dihydrate. The bromide, nitrate and sulfate ion were detected from the reagent-grade cobalt chloride hexahydrate, and the quantified values were 14.4 μg L−1, 8.35 μg L−1 and 20.0 μg L−1, respectively. Also, the relative standard deviations (RSD, n = 5) for the quantitative values were 1.51 %, 1.85 % and 1.09 %, respectively. On the other hand, the anions in zinc acetate dihydrate could not be quantified because of its low anion concentration, but good spiked recovery rates for the anions were obtained except for the chloride ion. The presented system will be applied as a method for the determination and testing of anions in the samples containing heavy metal ions at high concentration, such as metal salt reagents and plating solutions.
An on-site analytical technique for the colorimetric determination of sulfate ion in a water sample was developed based on the formation of purple precipitates as mixed crystals composed of barium sulfate with permanganate. Potassium permanganate solution and acidic barium chloride solution with hydrochloric acid were added in sequence into 1.5 mL of the sample, then the mixed crystals precipitated and suspended. The residual excess of permanganate ion remaining in the mother solution was reduced with ascorbic acid to turn it colorless. At that time, colors of the suspended precipitates became observable. The intensity of purple color tone of the suspension varied depending on the concentration of sulfate ion. The concentration was determined semi-quantitatively by visual comparison of the intensity with standard color charts. The proposed colorimetry permitted us to determine sulfate ion at the range of 50 to 2000 mg L−1. The time required for the on-site analysis was less than one minute. We applied the colorimetry to the real drainage samples taken from biological desulfurization systems and obtained good results useful for maintenance of them.