Minako Toyoda

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.

Fluorescence Reaction Among N-(Phenyl)-N-(4-Methylquinolinyl) Amine Derivatives, Hydrogen Peroxide and Cobalt(II), and its Application

Abstract The fluorescence reactions among seven N-(phenyl)-N-(4-methylquinolinyl)amine derivatives, hydrogen peroxide as a redox agent and cobalt (II), in the presence or absence of various surfactants, were systematically investigated. The order of the relative fluorescence intensities (R. fl. Int.) of these fluorescence products were N-(4′-hydroxyphenyl)-N-(4-methylquinolinyl)amine (IV), N-(2′-hydroxyphenyl)-N-(4-methyl quinolinyl)amine(11) > 3′-hydroxy-4 ′-carboxyphenyl)-N-(4- methylquinolnyl)amine(MQAB)(VII))> N-(3′-hydroxyphenyl)-N-(4 methylguinolinyl)amins(III) > N-(phsnyl)-N-(4-methylquinolinyl)amine(I)) >N-(4′-carboxyphenyl)-N-(4-methylquinolinyl)amine(V) >N-(3′-carboxyphenyl)-N-(4-methylquinolinyl)amine(VI)- fluorescence products. Especially, the R.fl.Int. using (IV) in the presence of cationic surfactants inbssic media was most large and stable, and asimple, rapid and eensitive spect- rofluorometric method for the determination of cobalt(II) using (IV) and hydrogen peroxide in the presence of tr...

Alternative spectrophotometric determination of niobium and tantalum with o-hydroxyhydroquinonephthalein in cationic surfactant micellar media

SummaryThe alternative and simultaneous spectrophotometric determination of niobium and tantalum was examined by using the colour development between o-hydroxyhydroquinonephthalein (Qnph) and niobium or tantalum in the presence of hexadecyltrimethylammonium chloride (HTAC) in strong acidic media. Beers law was obeyed up to 10.0 μg of niobium and up to 18.0 μg of tantalum in a final volume of 10.0 ml. The apparent molar absorption coefficients for niobium and tantalum were 2.18×105 and 2.09×105 l mol−1 cm−1 with Sandells sensitivities of 0.00042 μg/cm2 niobium at 520 nm and 0.00085 μg/cm2 tantalum at 510 nm, respectively. The alternative assay of niobium and tantalum was possible by using two methods: Method A — masking method with oxalic acid, Method B — acid adjusting-method using 50% sulfuric acid. These methods were 2–6-times more sensitive than other methods.

Improved spectrophotometric determination of osmium(VIII) with 4-(2-pyridylazo) resorcinol in mixed surfactants

The colour development between 4-(2-pyridylazo)-resorcinol(PAR) and osmium(VIII) in the presence of cationic and nonionic surfactants in a weakly acidic medium was more stable and reproducible than in the absence of surfactant (PAR-alone method). An improved spectrophotometric determination of osmium(VIII) with PAR was investigated in the presence of mixed surfactants of N-hexadecyltrimethylammonium chloride (HTAC) and Brij 58 [poly(oxyethylene)lauryl ether] as cationic and nonionic surfactants at pH 6.0-7.2. The calibration graph was linear in the range 0-110 microg/10 ml osmium(VIII), and the apparent molar absorptivity was 2.4 x 10(4) l.mole(-1).cm(-1) with a Sandell sensitivity of 0.0079 microg/cm(2) osmium(VIII).

Highly sensitive spectrophotometric determination of osmium(VIII) with pyrogallolphthalein and hydrogen peroxide in the presence of Brij 35

SummaryA highly sensitive determination of osmium(VIII) is based on the decolouring reaction with pyrogallolphthalein (gallein) and hydrogen peroxide in the presence of Brij 35. Beers law was obeyed in the range of 0–0.5 ng of osmium(VIII) per 10 ml and the apparent decomposed absorption coefficient was 2.5×109 l mol−1 cm−1 at 535 nm.

Spectrophotometric Determination of Gadolinium(III) With O-Hydroxyhydroqoinonephthalein in Mixed Micelles of N-Hexadecylpyridinilm Chloride and Brij 35

Abstract A sensitive, simple and selective spectrophotometric method for the determination of gadolinium(III) is proposed using o-hydroxyhydroquinonephthalein(Qnph), by analogy with phenylfl-uorone(Phfl), in the presence of N-hexadecylpyridinium chlo-ride(HPC)-Brij 35 mixed surfactants. The calibration curve is rectilinear in the range of 0 – 16.0 μg per 10 ml at 590 nm with an apparent absorption coefficient(∊) of 1.2 × 105 1 cm−1 mol−1 and Sandell sensitivity of 0.0013 μg/cm2 gado-linium(III).

Spectrophotometric determination of antimony with vanillylfluorone in the presence of poly(vinyl alcohol)

Antimony in the range up to 2.5 mug/ml in the final solution is determined spectrophotometrically with vanillylfluorone in the presence of poly(vinyl alcohol) in acidic media. The method is compared with that using o-hydroxyhydroquinonephthalein (Qnph). It is simple, rapid and sensitive, without need for heating or solvent extraction, and the apparent molar absorptivity () is 5.0 x 10(4) 1.mole(-1).cm(-1) at 545 nm; for the Qnph method is 2.8 x 10(4) 1.mole(-1).cm(-1) at 520 nm. Tests with an artificial wastewater gave 99-103% recovery.

Zero-Order and Third-Derivative Spectrophotometric Determination of Iron(III) with 4-(2-Pyridylazo)-Resorcinol in the Presence of N-Hexadecylpyridinium Chloride

Abstract The complex formation reaction between iron(III) and 4-(2-pyridylazo) resorcinol(PAR) in the presence of various water soluble surfactants((N-hexadecylpyridinium chloride (HPC), poly(vinylalcohol)(PVA), sodium dodecylsulfate(SDS), sodium N-lauroylsarcosine(SL)) alone or in combination at weakly acidic media was systematically investigated. An improved and more sensitive spectrophotometric method for the determination of iron was proposed by zero-order and third-derivative spectrophotometry using the PAR-iron(III)-HPC ternary complex system at about pH 5.2. The calibration curve was rectilinear in the ranges of 0 – 15.0 μg iron(III) in a final 10-ml on the zero-order spectrophotometry. Also, upon the third-derivative spectrophotometry, Beers law was obeyed in the range of 0 – 8.0 μg iron(III)/10 ml by measuring the distance between the absorbance peak(λ1 = 527 nm) and the valley (λ2 = 560 nm). The apparent molar absorptivity was 4.8 × 104 1 mol−1 cm−1 in zero-order spectrophotometry, and 1.36 × 1...

Improved spectrophotometric determination of dysprodium(III) with 4-(2-pyridylazo)resorcinol in the presence of Triton X 305 - hexadecylpyridinium chloride

Abstract An improved spectrophotometric determination of dysprodium(Dy(III)) as a rare earth element with 4-(2-pyri-dylazo)resorcinol(PAR) was proposed in a mixed micellar medium(cationic- and nonionic- surfactants mixed) of hexadecylpyridinium chloride(HPC) and Triton X 305(octylphenol (polyethylene)glycol). The calibration graph was linear in the range 0–20 μg/10 ml Dy(III) with a Sandell sensitivity of 0.0023 μ/cm2 at 540 nm. The proposed method was more sensitive and reproducible in comparison with that in the absence or presence of HPC or Triton X 305 alone.