Determination cobalt

Concentration limits of the diphosphate-ion, admissible to determination of magnesium and cobalt, manganese and cobalt, zinc and cobalt by spectrophotometric method with application of the l-(2-pyridylazo)-resorcinol (PAR) are presented. Exceeding maintenance of the diphosphate-ion higher admissible supposes a preliminary its separation on the anionite in the H+-form. The optimum conditions of cobalt determination and amount of the PAR, necessary for its full fastening are established on foundation of dependence of optical density of the cobalt complex with PAR from concentration Co + and pH (buffer solutions citrate-ammoniac and acetate-ammoniac). 

A standard official method has been published for the determination of cobalt in plant material [8 ]. The samples are digested with 1 4 v/v perchloric acidmitric acid and the residue dissolved in nitric acid. Cobalt is then extracted into chloroform as the diethyldithiocarbonate. The latter complex is decomposed by bromine and cobalt extracted into dilute hydrochloric acid. Following the addition of a borate buffer, cobalt is then extracted as the o-nitrocresol complex [9]. Excess coupling agent is removed by repeated extraction with copper acetate solution and cobalt determined spectrophotometrically at 360 nm. See Sects. 7.34.1, 7.34.3 and 7.34.4. 

Sodium citrate solution for cobalt determination, 40% m/v Dissolve 400 g of sodium citrate dihydrate in water and dilute to 11. 

The surface conditions of the cobalt determines the maximum water contained in hydrogen-steam mixtures, without oxidizing the cobalt catalyst. 

A cobalt determination must be made on the cobalt carbonate used if an accurate check on the yield of the complex salt is desired. 

Cobalt determination with the graphite tube technique (Furnace method)... 

Nickel nickel/cobalt Determination of hypophosphite, orthophosphite, dtric acid, succinic... 

The procedure described here has a maximum concentration factor of =400 (volume ratio of sample to final extract). This is, for example, necessary for cobalt determinations in ocean samples. For other metals and sample origins (e.g., Zn in estuarine waters), the Hnal extracts may provide metal concentrations too high for direct ETAAS analysis. In this case, part of the acidic extract is diluted with 0.1 mol/LHNOs to bring the metal concentration into the proper working range. 

Boyle, E. A., B. Handy, and A. Geen. 1987. Cobalt determination in natural waters using cation-exchange liquid chromatography with luminol chemiluminescence detection. Anal. Chem. 59 1499-1503. 

Berton, P. Wuilloud, R.G. (2010) Highly selective hquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples. Anal Chim. Acta, 662 155-162. 

Gil EP, Ostapczuk P (1993) Nickel and cobalt determination by constant current stripping potentiometry 1. Method development 2. Modifications and check of the method. Eresenius J Anal Chem 346 952-956, 957-960... 

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