A facile, highly selective and sensitive
spectrophotometric method has been developed for
the determination of manganese (II) in different foods.
The method is based on the formation of the binary
complexes of manganese with Mordant brown 33 (MB33)
2, 4-diamino-5-(2-hydroxy-5-nitrophenylazo) benzene
sulfonic acid sodium salt at pH 9.0 with Tween 20 at
wavelengths 575 nm with molar absorbtivity 0.75×104
l mol-1 cm-1. Manganese was thus determined in the
ranges 1.1–4.4 μg mL-1 in the presence of Tween 20.
The detection limits were found to be 0.046 μg mL-1.
The effect of foreign ions was elucidated .The relative
standard deviations were in all instances less than 1.2
%. The proposed method was successfully applied for
the determination of manganese in different kinds of
foods.

A facile, highly selective and sensitive
spectrophotometric method has been developed for
the determination of manganese (II) in different foods.
The method is based on the formation of the binary
complexes of manganese with Mordant brown 33 (MB33)
2, 4-diamino-5-(2-hydroxy-5-nitrophenylazo) benzene
sulfonic acid sodium salt at pH 9.0 with Tween 20 at
wavelengths 575 nm with molar absorbtivity 0.75×104
l mol-1 cm-1. Manganese was thus determined in the
ranges 1.1–4.4 μg mL-1 in the presence of Tween 20.
The detection limits were found to be 0.046 μg mL-1.
The effect of foreign ions was elucidated .The relative
standard deviations were in all instances less than 1.2
%. The proposed method was successfully applied for
the determination of manganese in different kinds of
foods.

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 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 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.