o-Amino heterocyclic azo-dyes as analytical reagents-II Spectrophotometric determination of cobalt with 3-[(5-chloro-2-pyridyl)azo]-2,6-diaminopyridine.
Cobalt(II) and 3-[(5-chloro-2-pyridyl)azo]-2,6-diaminopyridine (5-Cl-PADAPy) in slightly acid, neutral or alkaline media form a blue complex which is very stable even in the presence of mineral acids. The complex has two absorption maxima, at 575 and 620 nm. in 1.2M hydrochlororic acid. The system conforms to Beer's law; the optimal range for a 1-cm cell is 0.2-1.2 ppm cobalt. Milligram amounts of common anions and cations do not interfere. The molar absorptivity is 3.69 x 10(4) 1.mole(-1).cm(-1) at 620 nm.
Shibata
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S
Government Industrial Research Institute Nagoya, Kita-ku, Nagoya, Japan.
Furukawa
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M
Goto
K
K