Makoto Otomo

Solvent extraction and spectrophotometric determination of iron(II) with di-2-pyridyl ketone benzoylhydrazone

Di-2-pyridyl ketone benzoylhydrazone (DPKBH) was used for the spectrophotometric determination of trace amount of iron(II) in connection with the extraction process. The green iron(II) complex with a maximum absorbance at 379 and 686 nm is quantitatively extracted into benzene from aqueous solution buffered to pH 4.7 – 6.0. Beers law is obeyed over the range 0–30 μg of iron in 10 ml of benzene at 686 nm. The molar absorptivity of the complex is 1.59 × 104 liters mol−1 cm−1. The relative standard deviation for 16.8 μg of iron was 0.48% at this wavelength. The proposed method is relatively selective for iron(II) and is satisfactorily applied to the determination of the total iron in natural waters. The proton dissociation constants of the ligand determined spectrophotometrically were pKa1 = 3.18 and pKa2 = 10.87 at 25 °C and μ = 0.1.

2,2'-Dipyridyl-2-quinolylhydrazone as a reagent for the spectrophotometric determination of metals: The extractive spectrophotometric determination of palladium(II)

Abstract 2,2-Dipyridyl-2-quinolylhydrazone, DPQH, is proposed as a Spectrophotometric reagent for certain metal ions. The composition, extractability and Spectrophotometric characteristics of the complexes formed with 7 metal ions are reported. DPQH appears to be promising especially for palladium(II) and cobalt(II) in selectivity and for zinc(II) and cadmium(II) in sensitivity. A detailed study has been made for the extractive spectrophotometric determination of palladium(II) in the presence of chloride ions.

Solvent extraction and spectrophotometric determination of palladium(II) with some nitrogen-containing heterocyclic hydrazones in the presence of chloride ions

Abstract Three terdentate hydrazones, all containing the 1-phthalazino grouping in the hydrazine moiety but differing in the heterocyclic substituent in the aldehyde moiety, have been used as analytical reagents for palladium(II), the optimal conditions for the extractive spectrophotometric determination of palladium(II) in the presence of chloride ions being deduced. These compounds are highly selective and sensitive reagents for palladium(II), since they are not extracted into chloroform from sulfuric acid solutions and do not react with other platinum group metals. The desirable spectral properties of the palladium(II) complex of benzothiazole-2-aldehyde-1-phthalazinohydrazone (BAPhH) have also been discussed with respect to preference of the ue5f8C ue5fb Nue5f8 structural form in the heterocyclic ring on the aldehyde moiety of the ligand.

Benzothiazole-2-aldehyde-2-quinolylhydrazone as a reagent for the extractive spectrophotometric determination of copper (II)

Benzothiazole-2-aldehyde-2-quinolylhydrazone (BTAQH) was used for the spectrophotometric determination of trace amounts of copper(II) after the extraction process. Copper(II) reacts with BTAQH at pH 8.3–12.6 to form a water-insoluble 1:2 complex, which can be extracted with many kinds of organic solvent. The extracted species with benzene has an absorption maximum at 523 nm and obeyed Beers law over the range 0.09 to 0.75 ppm of copper. The molar absorptivity is 7.50 × 104 M−1 cm−1 at 523 nm. The spectral properties of the copper(II) complexes with some tridentate hydrazones containing benzothiazole ring as a functional group were also discussed.

Solvent extraction and spectrophotometric determination of iron(II) with 2,2′-dipyridyl-2-quinolylhydrazone

Abstract 2,2′-Dipyridyl-2-quinolylhydrazone (DPQH) was used for the spectrophotometric determination of trace amount of iron(II) after the extraction process. Iron(II) reacts with DPQH at pH 3.4–4.5 to form a water-insoluble 1:2 complex, which can be extracted with many kinds of organic solvent. The extracted species with benzene has absorption maxima at 473, 504, and 644 nm and obeyed Beers law over the range 0–14 μg of iron at 504 nm and 0–33 μg at 644 nm. The molar absorptivities at 504 and 644 nm are 3.14 × 10 4 and 1.30 × 10 4 M −1 cm −1 , respectively. DPQH is one of the most sensitive reagents for iron(II) and trace amount of iron(II) can be determined in the presence of fairly large amounts of other ions. Possible equilibria involved in the extraction process were also studied.

Extractive—spectrophotometric determination of trace iron(II) with di-2-pyridylmethanone 2-(5-nitro)pyridylhydrazone

The optimum conditions for the extractive-spectrophotometric determination of trace iron(II) with di-2-pyridylmethanone 2-(5-nitro)pyridylhydrazone have been established. Iron(II) reacts with this reagent at pH 2.0-7.5 to form an uncharged 1:2 (metal-to-ligand) complex, which can be extracted with toluene. Beers law is obeyed over the range up to 0.84 mug/ml of iron(II) at 505 nm. The molar absorptivity of the extracted species is 5.83 x 10(4) 1.mole(-1).cm(-1). The proposed method is extremely sensitive and reproducible, and has been satisfactorily applied to the determination of total iron in freshwater samples by adding ascorbic acid to reduce iron(III).

Solvent extraction and spectrophotometric determination of iron(II) with 2,2′-dipyridyl-2-furancarbothiohydrazone

Abstract 2,2′-Dipyridyl-2-furancarbothiohydrazone (DPFTH) was used for the spectrophotometric determination of trace amount of iron(II) after the extraction process. Iron(II) can be quantitatively extracted with DPFTH in benzene from aqueous solution buffered to 3.0–8.0. The extracted species has absorption maxima at 440, 477, and 738 nm and obeyed Beers law over the range 0–40 μg of iron in 10 ml at 738 nm. The molar absorptivity at this wave length is 1.17 × 104 liters mole−1 cm−1. The proposed method is relatively selective for iron(II) and is satisfactorily applied to the determination of the total iron in natural waters. The proton dissociation constants of the ligand determined spectrophotometrically were pKa1 = 2.88 and pKa1 = 6.70 at 25 °C and μ = 0.1.

Solvent extraction and spectrophotometric determination of vanadium(V) with 2,2′-dipyridyl-2-quinolylhydrazone

2,2′-Dipyridyl-2-quinolylhydrazone (DPQH) has been used for the extractive spectrophotometric determination of vanadium(V) after the cation-exchange separation of this ion from metal ions. Vanadium(V) reacts with DPQH in weakly acidic solution to form a 1 : 1 metal to ligand complex that is extractable into many organic solvents. The species when extracted with chloroform has an absorption maximum at 572 nm and obeyes Beers law over the range up to 1.5 µg ml–1 of vanadium. The method has been satisfactorily applied to the determination of vanadium in three standard alloy steel samples. A possible structure for the extracted species is postulated.

Extraction-spectrophotometric determination of palladium(II) with thiazole-2-carbaldehyde 2-quinolylhydrazone

Thiazole-2-carbaldehyde 2-quinolylhydrazone (TAQH) was prepared as a reagent specifically for the spectrophotometric determination of trace amounts of palladium(II) following an extraction process. In the presence of chloride ions, palladium(II) reacts with TAQH in the wide acidity range to form a 1:1 metal to ligand complex extractable into benzene. The extracted species has absorption maxima at 588 and 625 nm with a molar absorptivity of 1.93 × 104 l mol–1 cm–1 at the latter wavelength and obeyed Beers law over the range 0–4.2 µg ml–1 of palladium at 625 nm. The method is reasonably selective and sensitive for palladium(II) and was satisfactorily applied to the determination of palladium in some palladium catalysts.