Flow-injection spectrophotometric determination of trace cobalt with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N sulphopropylamino) aniline: use of the rate-enhancing effect of copper(II) on the complex formation reaction of cobalt

✍ Scribed by Takeshi Yamane; Kazuo Koshio

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 609 KB
• Volume: 261
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(92)80192-a

✦ Synopsis

A flow-mJectlon spectrophotometrlc method IS presented for the determloatlon of traces of cobalt utdlzmg Its complex formatlon with 2-(5-bromo-2-pyndylao)-5-~N-propyl-N-sulphopropylam~no)an~l~ne (PSAA) Copper(H) enhances the rate of the slow complex formatlon reaction and this provides high sensltlvlty in cobalt determmatlons m a flow system In order to ehmmate Interferences from copper and nickel (which form PSAA complexes that have overlapping absorption spectra wth the Co-PSAA complex), a hgand substitution reaction urlth EDTA was coupled on-line The detection limit IS 1 ng ml-' and the relative standard devlatlon is 14% (n = 10) for 50 ng ml-' cobalt Results obtained for the analysis of the blologlcal sample pepperbush (NIES-CRM No 1) after nucrowave dlgestlon were m good agreement with the certlfled value for cobalt