A highly selective and sensitive derivative spectrophotometric method has been developed for the determination of Fe(II) and Ni(II) in different mineral vitamins. The method is based on the formation of binary complexes of Fe(II) and Ni(II) with 2,4-diamino-5-(2-hydroxy-5-nitrophenylazo) benzenesulfonic acid sodium salt (Mordant Brown 33) at pH 5.6 with Tween 20. At lmax 512 and 493 nm, the molar absorbtivity was 2.09 ´ 104 and 0.58 ´ 104 L/mol cm for Fe(II) and Ni(II), respectively. Fe(II) can be determined in the range 0.55–2.79 mg/mL in the presence of 2.92 mg/mL Ni, and Ni(II) can be determined in the range 1.17–3.5 mg/mL in the presence of 2.79 mg/mL Fe(II) in the presence of Tween 20 (4%). The detection limits were 9.0 and 15.0 ng/mL for Fe(II) and Ni(II), respectively. The effect of foreign ions was elucidated. The RSD values were, in all instances, less than 1.3%. The proposed method was successfully applied for the simultaneous determination of Fe(II) and Ni(II) in different mineral vitamins.

A facile, highly sensitive, and selective spectrophotometric method has been developed for the determination of aluminum and copper in different alloys. The method is based on the formation of the binary complexes of aluminum and copper with Alizarin yellow R (AYR) [5-(4-nitrophenylazo) salicylic acid] at pH 2.0 and 6.2, respectively, at wavelengths 422 and 445 nm with molar absorbtivity 1.1
104 l mol1 cm1 for each one. Aluminum and copper were thus determined in the ranges 0.4–2.0 lgml1 and 1.9–3.6 lgml1, respectively, in the presence of one to another. The detection limits were found to be 1.4 ng ml1 of aluminum and 0.015 lgml1 for copper. The relative standard deviations were in all instances less than 1.3%. The proposed method was successfully applied for the simultaneous determination of aluminum and copper in certified reference aluminum-copper alloys.

A facile, highly sensitive, and selective spectrophotometric method has been developed for the determination of aluminum and copper in different alloys. The method is based on the formation of the binary complexes of aluminum and copper with Alizarin yellow R (AYR) [5-(4-nitrophenylazo) salicylic acid] at pH 2.0 and 6.2, respectively, at wavelengths 422 and 445 nm with molar absorbtivity 1.1
104 l mol1 cm1 for each one. Aluminum and copper were thus determined in the ranges 0.4–2.0 lgml1 and 1.9–3.6 lgml1, respectively, in the presence of one to another. The detection limits were found to be 1.4 ng ml1 of aluminum and 0.015 lgml1 for copper. The relative standard deviations were in all instances less than 1.3%. The proposed method was successfully applied for the simultaneous determination of aluminum and copper in certified reference aluminum-copper alloys.

A facile, highly sensitive, and selective spectrophotometric method has been developed for the determination of aluminum and copper in different alloys. The method is based on the formation of the binary complexes of aluminum and copper with Alizarin yellow R (AYR) [5-(4-nitrophenylazo) salicylic acid] at pH 2.0 and 6.2, respectively, at wavelengths 422 and 445 nm with molar absorbtivity 1.1
104 l mol1 cm1 for each one. Aluminum and copper were thus determined in the ranges 0.4–2.0 lgml1 and 1.9–3.6 lgml1, respectively, in the presence of one to another. The detection limits were found to be 1.4 ng ml1 of aluminum and 0.015 lgml1 for copper. The relative standard deviations were in all instances less than 1.3%. The proposed method was successfully applied for the simultaneous determination of aluminum and copper in certified reference aluminum-copper alloys.

A facile, highly sensitive, and selective spectrophotometric method has been developed for the determination of aluminum and copper in different alloys. The method is based on the formation of the binary complexes of aluminum and copper with Alizarin yellow R (AYR) [5-(4-nitrophenylazo) salicylic acid] at pH 2.0 and 6.2, respectively, at wavelengths 422 and 445 nm with molar absorbtivity 1.1
104 l mol1 cm1 for each one. Aluminum and copper were thus determined in the ranges 0.4–2.0 lgml1 and 1.9–3.6 lgml1, respectively, in the presence of one to another. The detection limits were found to be 1.4 ng ml1 of aluminum and 0.015 lgml1 for copper. The relative standard deviations were in all instances less than 1.3%. The proposed method was successfully applied for the simultaneous determination of aluminum and copper in certified reference aluminum-copper alloys.

Spectrophotometric evidence for the formation of hypomanganate(V), [CAR-MnVO4 3], and manganate( VI), [CAR-MnVIO4 2], intermediate complexes has been confirmed during the oxidation of iotaand lambda-carrageenan-sulfated polysaccharides (CAR) by alkaline permanganate at pHs P12 using a conventional spectrophotometer. These short-lived intermediate complexes were identified and characterized. A reaction mechanism in good consistence with the experimental results is suggested.

Spectrophotometric evidence for the formation of hypomanganate(V), [CAR-MnVO4 3], and manganate( VI), [CAR-MnVIO4 2], intermediate complexes has been confirmed during the oxidation of iotaand lambda-carrageenan-sulfated polysaccharides (CAR) by alkaline permanganate at pHs P12 using a conventional spectrophotometer. These short-lived intermediate complexes were identified and characterized. A reaction mechanism in good consistence with the experimental results is suggested.

Spectrophotometric evidence for the formation of hypomanganate(V), [CAR-MnVO4 3], and manganate( VI), [CAR-MnVIO4 2], intermediate complexes has been confirmed during the oxidation of iotaand lambda-carrageenan-sulfated polysaccharides (CAR) by alkaline permanganate at pHs P12 using a conventional spectrophotometer. These short-lived intermediate complexes were identified and characterized. A reaction mechanism in good consistence with the experimental results is suggested.

Spectrophotometric evidence for the formation of hypomanganate(V), [CAR-MnVO4 3], and manganate( VI), [CAR-MnVIO4 2], intermediate complexes has been confirmed during the oxidation of iotaand lambda-carrageenan-sulfated polysaccharides (CAR) by alkaline permanganate at pHs P12 using a conventional spectrophotometer. These short-lived intermediate complexes were identified and characterized. A reaction mechanism in good consistence with the experimental results is suggested.

Single phase MnPS3 powder was prepared by solid state reaction between Mn. S and P carried out at 650 ˚C in evacuated silica tube. The structure, morphology and sorption characteristics of the prepared solid were investigated. The results revealed that the obtained MnPS3 compound was capable of adsorbing 3.5 wt% hydrogen at – 193 ˚C and a pressure of 30 bar. Little amount of hydrogen (0.07 wt %) was adsorbed at room temperature. The hydrogen adsorption/desorption cyclesat various temperatures did not result in irreversible chemical structural changes of the MnPS3 compound, but the microstructure after hydrogen cycling diminished and became finer.