Vanadium speciation by chromatographic separation of V(IV) and V(V) in acidic solution followed by ICP-OES determination

Abstract

A new method for vanadium speciation has been developed. The method is based on chromatographic separation of vanadium(IV) and vanadium(V) in acidic medium followed by the determination with ICP-OES. Vanadium species exist in acidic solution (pH < 3) as VO 2+ for vanadium(IV) and VO 2 + for vanadium(V). The two vanadium species were chromatographically separated using a cation exchange column, Dionex IonPack CG10, and eluant (120 mmol/ℓH 2 SO 4 ) at a flow rate of 1.5 mℓ/min. The detection limits for vanadium(IV) and vanadium(V) are 40 µg/ℓand 30 µg/ℓ, respectively. Among common anions, only nitrite, NO 2 -which may act as oxidant for vanadium(IV) and reductant for vanadium(V) can cause interference. Interference from common cations has not been observed for concentration levels not exceeding 40 mg/ℓ. The developed method has been successfully applied to the determination of vanadium(IV) and vanadium(V) in synthetic and minerals processing samples.

Ternary complexes of vanadium(IV) with 4-(2-pyridylazo)-resorcinol (PAR) and ditetrazolium chlorides (DTC)

“…These comparisons will be useful for better understanding the chemistry of V(IV) and V(V) -the two most important vanadium oxidation states, and can help in [35,36]. Since V(IV) is oxidized by atmospheric oxygen in slightly acidic and neutral media [7][8][9][10]35] it has been concluded that the V(V)-complex has formed at pH 6.0 [35] or 5.2 [37], independent of the original vanadium oxidation state.…”

“…2+ ) is the most common V(IV)-form in acidic aqueous solutions [7][8][9][10]. At pH values higher than 3.2 -3.5 (if C V(IV) is in the interval from 10 -5 mol L -1 to 10 -4 mol L -1 ) a neutral V(IV)-form VO(OH) 2 prevails [39].…”

“…There has been much recent research interest in vanadium connected with a number of developments concerning industry, the environment, and medicine [1][2][3][4][5][6][7][8][9][10][11]. Vanadium has dual character depending on its concentration; it easily switches between the oxidation states +5 and +4 (which, along with +3, are the oxidation states of naturally occurring vanadium compounds) [1].…”

“…Vanadium has dual character depending on its concentration; it easily switches between the oxidation states +5 and +4 (which, along with +3, are the oxidation states of naturally occurring vanadium compounds) [1]. Vanadium(V) can be almost as toxic as lead, cadmium, and mercury [9], but it also has beneficial biological functions. The roles of vanadium in physiological systems include normalization of sugar levels, participation in various enzyme systems as an inhibitor and a cofactor, and catalysis of the oxidation of various amines [6].…”

“…Vanadium compounds are well recognized occupational hazards in boiler cleaning and V 2 O 5 production and usage. Presence of vanadium in excess of the Threshold Limit Values (0.5 mg m -3 of air, 0.1 mg m -3 of fume and 0.1 mg L -1 of drinking water) is reported to cause anemia, cough, emaciation, irritation of mucous membrane, Ternary complexes of vanadium(IV) with 4-(2-pyridylazo)-resorcinol (PAR) and ditetrazolium chlorides (DTC) the development of better procedures for V(IV)/V(V) speciation -an important task for many present day researchers [3,[6][7][8][9][10][11] …”