Tosylation of endocrine-disruptive alkylphenolic compounds in a solid-phase reaction system consisting of C18-modified silica gel and aqueous buffer solution

The tosylation reaction of endocrine-disruptive alkylphenolic compounds in a solid-phase aqueous system was investigated with the aim of developing an environment-friendly and efficient derivatization method for HPLC analyses of environmental samples. The phenols were rapidly and efficiently converted to the tosyl derivatives on a commercially available ODS solid-phase cartridge by passing an aqueous buffer solution through it. The solid-phase aqueous tosylation system has been incorporated into a preconcentration step performed by solid-phase extraction from environmental water.     

Electrophoretic analysis of quinone anion radicals in acetonitrile solutions using an on-line radical generator

We have investigated analysis of anion radicals of phenanthrenequinone (PhQ) and anthraquinone (AQ) using acetonitrile-capillary electrophoresis (CE) under anaerobic conditions. PhQ and AQ have relatively high negative reduction potentials meaning that their anion radicals are re-oxidized quite readily by the surrounding O(2) to disappear during analysis and we failed to detect them with our previous system. In this work, we have developed an on-line system combining a unique electrolysis cell for generation of the radicals and a CE unit to keep the analysis system free from external O(2) molecules and to reduce analysis time remarkably. As a result, electrophoretic detection of the anion radicals of PhQ and AQ has been achieved. Furthermore, we have observed hydrogen-bonding interaction between the anion radicals and dimethylurea (DMU) using the present system and have indicated a characteristic interaction of the anion radical of PhQ as an ortho-quinone with DMU.     

Determination of cadmium by an improved double chamber electrothermal vaporization inductively coupled plasma atomic emission spectrometry

An improved double chamber electrothermal vaporization (ETV) system was designed. A new inner chamber and its bottom plate made of quartz glass were attached with carrier support gas inlet port for the determination of cadmium by inductively coupled plasma atomic emission spectrometry (ICP-AES). The use of the inner chamber in combination with the plate played important roles to transport the metal vapor efficiently into argon ICP. Ten-μl sample aliquots were dried at 100 °C and subsequently heated at 1000 °C on the tungsten boat furnace. The evolved vapor was swept into the ICP source through PTFE tubing and the inner chamber by a 0.8 l/min H₂ (7%)-Ar carrier gas. The performance parameters of ETV-ICP-AES such as temperature program and gas flow rate were evaluated using cadmium standard solution. Under the optimized experimental conditions, the best attainable detection limit at Cd II 214.438 nm line was 0.2 ng/ml with linear dynamic ranges of 50 to 10,000 ng/ml for cadmium. The instrumental precision expressed as the relative standard deviation (RSD) from ten replicate measurements of 10,000 ng/ml for cadmium by ETV-ICP-AES was 0.85%. The present method has been successfully applied to the determination of cadmium in zinc-base materials.     

Absolute Positioning of Scanning Probe Microscope Tip by Two-Wavelength Synthetic Method

In this paper, we describe the absolute positioning of a probe tip in a scanning Wiener fringe optical microscope (SWOM) using a synthetic wavelength method. Two laser beams with different wavelengths are superimposed and are incident on a sample surface. A synthetic fringe which has a longer period than that of the Wiener fringe obtained with a single wavelength is formed on the surface. The order of Wiener fringe which is utilized as a feedback signal in the microscope can be determined by the synthetic fringe. A sample with known structure was observed for various defined fringe orders using the SWOM.     

Human liver dihydrodiol dehydrogenase 1-catalyzed reaction generating 9alpha,11beta-prostaglandin F2 from prostaglandin D2 followed by micellar electrokinetic chromatography

An enzyme reaction converting prostaglandin D2 (PGD2) into 9alpha,11beta-prostaglandin F2 (9alpha,11beta-PGF2) by a human liver-originated recombinant dihydrodiol dehydrogenase 1 (DD1) has been studied using CE. Four prostaglandins, viz. PGD2, 9alpha,11beta-PGF2, PGE2, and PGF2a (see Fig. 1, the latter two major PGs are possibly coexisting compounds in the assay mixtures), were completely separated by using SDS or PEG as buffer additives. Because analysis times in the SDS system were shorter than in the PEG system, SDS was employed in measurements of the enzyme activity of DD1. The pH dependence and the reaction temperature dependence of enzyme activity have been studied. The present method enabled us to detect all of the participants in the enzyme reaction: PGD2, 9alpha,11beta-PGF2, nicotinamide adenine dinucleotide phosphate (NADPH), and NADP+. Thus, direct, comprehensive, and reliable analysis of the enzyme reaction becomes possible. Enzyme activity has hitherto been estimated indirectly from the decrease of fluorescence derived from NADPH as an index of progress of the enzyme reactions in batch methods employed in conventional studies. In addition, the low sample consumption characteristic of CE should be a significant advantage of the present method in characterization of less commonly available enzymes such as the recombinant species used in this work.     

Development of a compact supersonic jet/multiphoton ionization/time-of-flight mass spectrometer for the on-site analysis of dioxin, part II: Application to chlorobenzene and dibenzofuran.

A compact supersonic jet/multiphoton ionization/mass spectrometer (SSJ/MPI/MS) equipped with a single pump system was developed for use in the analysis of dioxin. A mass spectrum and multiphoton ionization spectrum were obtained for chlorobenzene and dibenzofuran using an optical parametric oscillator (OPO) for excitation and subsequent ionization. The detection limit for chlorobenzene (S/N = 3) was 0.3 ppb, which corresponds to an absolute amount of 0.1 pg. The rotational temperature was 35 K. This slightly high temperature can be attributed to the long nozzle throat used in the instrument.     

Anthraquinone-2-sulfonyl chloride: a new versatile derivatization reagent-synthesis mechanism and application for analysis of amines

A new sulfonating agent, anthraquinone-2-sulfonyl chloride, has been synthesized. The reagent consists of three important moieties: a cyclic conjugation system (with 18 pi-electrons), a p-quinone system and a group of sulfonyl chloride and is thereby a versatile derivatization reagent for analytical chemistry. The mechanism about the synthetic reaction was first elucidated in aid of mass spectrometry. Several primary and secondary amines were selected to evaluate the new reagent and their standard derivatives were prepared via a facile pathway. Analytical derivatization carried on through a one-step procedure at room temperature within 3 min. The new reagent reacts quantitatively with amines to form stable sulfonamides, which are readily amenable to analysis by normal-phase and reversed-phase HPLC. Compared with standard derivatives, excellent response linearity is demonstrated over the concentration range 0.4-400 muM at 320 nm for normal-phase HPLC and 4 nM to 4 muM at 256 nm for reversed-phase HPLC. Detection limits are 0.8 nmol and 8 pmol, respectively.