Yoshikazu Fujita

Selective and sensitive fluorometric determinations of cobalt(II) and hydrogen peroxide with fluorescein-hydrazide

Fluorophotometric determinations of cobalt(II) and hydrogen peroxide were investigated by using the fluorescence reaction between fluorescein-hydrazide (fl-NHNH(2)), and/or hydrogen peroxide, cobalt(II), respectively. The calibration graphs were liner in the range of 0-6.0 ng cobalt(II) and 0-1000 ng hydrogen peroxide per 10 ml at an emission wavelength (E(m)) of 530 nm with an exicitation wavelength (E(x)) of 508 nm, respectively. These proposed methods were selective and simple, and the effect of foreign ions was negligible in comparison with conventional reported methods such as nitroso R,4-(2-pyridylazo)resorcinol(PAR), alizarin, pyridine-2-aldehyde-2-pyridinehydrazone, stilbazo-cobalt(II), etc.

Sensitive spectrophotometric determination of human serum albumin(HSA) with (2-(5-bromo-2-pyridylazo)-5-(N-phenyl-N-sulfopropylamino)phenol) (5-Br.PAPS)-cobalt(II)) complex

Abstract A sensitive and selective spectrophotometric determination of human serum albumin(HSA) was proposed by using the ternary complex-formation reaction among 2-(5-bromo-2-pyridylazo)-5-(N-phenyl-N-sulfopropylamino)phenol (5-Br.PAPS) as a pyridylazo derivative, cobalt(II) and HSA in the presence of poly(N-vinylpyrrolidone) (PVA) as a dispersion agent. The calibration curve was linear in the range of 0 - 7.0 μg/ml HSA by measuring the difference of absorbances at 636 nm between ((5-Br.PAPS)-cobalt(II)-HSA) and (5-Br.PAPS-cobalt(II)) solutions. The sensitivity was > 6-fold over the (Pyrogallol Red(PR)-molybdenum(VI)) method, and the recovery test in urine was satisfactory (97.5 ± 2.8%).

Selective and sensitive spectrophotometric determination of copper(II) and benzoylperoxide with N-ethyl-2-naphthylamine☆

Spectrophotometric determinations of benzoylperoxide (BPO) and copper(II) were, respectively, investigated by using the colour reaction for N-ethyl-2-naphthylamine (NENA), BPO and copper(II) as a metal ion in various concentrations of acetonitrile-water mixed solution as acidic media. The calibration graphs were linear in the range of 0-200 mug BPO with apparent molecular coefficient (epsilon) of 8.5 x 10(3)M(-1) cm(-1) at 530 nm, and 0-2.4 mug per 10 ml copper(II) with epsilon = 1.72 x 10(5)M(-1) cm(-1) at 533 nm, respectively. Additionally, the FIA method for copper(II) was proposed with NENA-BPO. The calibration graph for FIA was linear in the range of 0-7.9 ng copper(II) per 5 mul at 533 nm. These proposed methods were selective and simple in comparison with previous methods such as cuproin kinetic reactions, especially the spectrophotometry for copper(II) with NENA-BPO was very specific, and the effect of foreign ions was negligible.

Detection of pharmaceuticals and phytochemicals together with their metabolites in hospital effluents in Japan, and their contribution to sewage treatment plant influents

The occurrence of 41 pharmaceuticals and phytochemicals (PPs) including their metabolites was surveyed in hospital effluent in an urban area of Japan. A detailed survey of sewage treatment plant (STP) influent and effluent, and river water was also conducted. Finally, mass balances with mass fluxes of the target PPs through the water flow were evaluated and the degree of contribution of hospital effluent to the environmental discharge was estimated. The results indicate that 38 compounds were detectable in hospital effluent over a wide concentration range from ng/L to μg/L, with a maximum of 92μg/L. The contributions of PPs in the hospital effluent to STP influent varied widely from <0.1% to 14.8%. Although almost all of the remaining components could be removed below 1.0ng/L at STPs by the addition of ozone treatment, a number of PPs still remained above 10ng/L in STP effluent. These findings suggest the importance of applying highly developed treatments to hospital effluents and at STPs in the future to reduce the environmental risks posed by PPs. To our knowledge, this is the first demonstration of the presence of two conjugated metabolites of acetaminophen, acetaminophen glucuronide and acetaminophen sulfate, as well as of loxoprofen and loxoprofen alcohol, in hospital effluent, STP, and river waters.

Spectrophotometric determination of hydrogen peroxide with osmium(VIII) and m-carboxyphenylfluorone.

Spectrophotometric determination of hydrogen peroxide was accomplished with osmium(VIII) and m-carboxyphenylfluorone (MCPF) in the presence of cetyltrimethylammonium chloride (CTAC). In the determination of hydrogen peroxide based on the fading of the color of osmium(VIII)-MCPF complex, Beers law was obeyed in the range 20-406 ng mL(-1), with an effective molar absorption coefficient (at 580 nm) of 5.21×10(4) L mol(-1) cm(-1) and a relative standard deviation of 0.33% (n=6). Further, we performed the characterization of MCPF and obtained the crystal structure.

Design and synthesis of regioisomerically pure unsymmetrical xanthene derivatives for staining live cells and their photochemical properties

We have demonstrated the synthesis of regioisomerically pure unsymmetrical xanthene derivatives consisting of three units which can be independently modified to control their physical properties. The photochemical properties of the synthetic unsymmetrical xanthene derivatives were investigated in solution by UV-vis absorption and fluorescence measurements, and their cell imaging properties were examined by confocal laser-scanning microscopy.

Selective spectrophotometric determination of palladium(II) with 2(5-nitro-2-pyridylazo)-5-(N-propyl-N-3-sulfopropylamino) phenol(5-NO2.PAPS) and tartaric acid with 5-NO2.PAPS-niobium(V) complex

Spectrophotometric determinations of palladium(II) and tartaric acid were respectively investigated by using the color reactions between 2(5-nitro-2-pyridylazo)-5-(N-propyl-N-3-sulfopropylamino)phenol(5-NO(2).PAPS) and palladium(II) in strong acidic media, and between 5-NO(2).PAPS, niobium(V) tartaric acid in weak acidic media. The calibration graphs were linear in the range of 0-25 microg/10 ml palladium(II), with an apparent molecular coefficient (epsilon) of 6.2 x 10(4) l mol(-1) cm(-1) at 612 nm, and 0-23 microg/10 ml tartaric acid with epsilon=1.08 x 10(6) l mol(-1) cm(-1) at 612 nm, respectively. The proposed methods were selective and sensitive in comparison with other chelating pyridylazo dyes-palladium(II) or metavanadic acid-tartaric acid method, and the effect of foreign ions such as copper(II) was negligible for the assay of palladium(II) with 5-NO(2).PAPS.

Highly sensitive spectrophotometric determination of cobalt using o-hydroxyhydroquinonephthalein and hydrogen peroxide in the presence of mixed surfactants

SummaryThe effects of cobalt(II) and surfactants on the decomposition of various xanthene dyes by hydrogen peroxide have been systematically investigated. A simple and highly sensitive spectrophotometric determination of cobalt(II) (0.05 ∼ 1.2 Μg/10 ml) is proposed. The method is based on the catalytic effect of cobalt(II) on the oxidation of o-hydroxyhydroquinonephthalein (Qnph) by hydrogen peroxide. The proposed catalytic spectrophotometric determination was sensitive, selective, reproducible and virtually unaffected by the presence of other ions; the effective molar “desorptivity” was 4.2×108 l/mol per cm, Sandell sensitivity was 0.15 pg/cm2, and the relative standard deviation was 3.2% at 0.6 ng/10 ml (n=5). The selective assays of cobalt(II) in water samples were also investigated with satisfactory results (95% ∼ 101%).

Preconcentration of 1-(2-pyridylazo)—2-naphthol—iron(III)-capriquat on a membrane filter, and third-derivative spectrophotometric determination of iron(III)

Iron(III) was preconcentrated by collection on an organic solvent-soluble membrane filter (nitrocellulose (NC)) of the iron(III)-1-(2-pyridylazo)-2-naphthol (PAN) complex in the presence of capriquat as an oily quaternary ammonium salt. Third-derivative spectrophotometry was used for measurement of the third-derivative distance (d(3)A/dlambda(3)) between lambda(1) = 520 nm and lambda(2) = 590 nm or lambda(3) = 660 nm and lambda(4) = 724 nm of the iron(III)-PAN-capriquat complex or PAN-capriquat in dimethylsulfoxide (DMSO) following preconcentration. The calibration curve was linear in the range of 1-10 mug iron(III)/5.0 ml DMSO solution. The proposed method was about five-fold more sensitive and more selective than using zero-order spectrophotometry.

Simple fluorophotometric determination of cobalt(II) with p-hydroxy-2-anilinopyridine and hydrogen peroxide

SummaryA simple and sensitive determination of cobalt(II) is based on its fluorescence reaction with p-hydroxy-2-anilinopyridine and hydrogen peroxide. The relative standard deviation is 2.5% (n=5). An application to pharmaceutical preparations is recommended.