Microdetermination of Cobalt Colorimetrically as the 1-Nitroso-2-Naphthol Complex

Abstract

An advantage of determining cobalt with 1-nitroso-2-naphthol is that the reagent is relatively stable and forms a very stable cobalt complex. Also this cobalt complex has maximum absorption in the visible spectrum which allows determination visually or with ordinary calorimeters. ,The procedure is based on decreasing the iron interference by the removal of part of the iron as phosphate and on a simple purification of the carbon tetrachloride solution of the 1-nitroso-2-naphthol cobalt conlples which eliminates traces of palladium, iron, etc.The method has the same order of accuracy as the o-nitrosocresol method but preparation of reagents and the analysis in general require less time.

Microdetermination of Cobalt in Biological Materials

“…The purified cobalt complex was then ashed and determined photometrically with the same reagent. In a similar procedure which Nichol (12) claimed was more rapid, iron was removed by a preliminary precipitation as ferric phosphate. Other impurities and excess reagent were removed from the carbon tetrachloride extract of the cobalt complex by a series of six washes with concentrated hydrochloric acid, alcoholic sodium hydroxide, and water.…”

Light Absorption Spectrometry

“…A number of unrelated papers deal wdth individual organic compounds. Included are salicylaldehyde for several colorless cations (52); ß-diketones for copper (299); -diimines for iron(II) (259); sulfosalicylic acid for aluminum and nickel (271); ethylenediaminetetraacetic acid for seven lanthanon metals (468); chloranilic acid for zinc (4J7); nitroso R salt (70) and l-nitroso-2naphthol (337) for cobalt; nitroso R salt for iron(II) (117); thymol for titanium (180); 2,4-pentanedione for manganese(III) (79); 4,5-dihydroxv-2,7-naphthaIenedisulfonic acid (chromotropic acid) for titanium (59); alizarin for six metals (129); four reagents for iron (425); several reagents for ruthenium (479); and triphenylarsonium thiocyanate for iron (135).…”