Flame atomic absorption determination of trace cobalt in steel samples using a flow-injection on-line separation system

✍ Scribed by M. C. Yebra-Biurrun

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 150 KB
• Volume: 10
• Category: Article
• ISSN: 0895-7533
• DOI: 10.1002/(sici)1098-2728(1998)10:5<299::aid-lra6>3.0.co;2-#

✦ Synopsis

A flow-injection on-line system was developed for the trace determination of cobalt by flame atomic absorption spectrometry (FAAS) with separation and preconcentration on a minicolumn packed with a poly(aminophosphonic acid) chelating resin (PAPhA). This resin allows the selective separation of cobalt at pH 2 because Co(II) and Fe(III) are the only metal ions retained quantitatively at this pH level, and Co(II) presents a greater selectivity coefficient than Fe(III); therefore, Co(II) is preferentially complexed over Fe(III) on the active groups of the chelating resin. Elution was performed by using a small volume of 0.2 M nitric acid. At a consumption of 7 mL sample volume, the procedure resulted in an enhancement factor of 83 and yielded a detection limit of 0.15 lg/L (3r) at a sampling frequency of 32 h ‫1מ‬ . The precision (coefficient of variation, n ‫ס‬ 11) was in the range 0.5-1.0% at the 1-15 lg/L level. The procedure was applied to the determination of cobalt in steel samples with high tolerance to interferences, and results obtained for a standard reference material were in good agreement with the certified value.