Vanadium-hydroxyquinoline complex

The following review presents the selective, but rather insensitive methods based on the use of BPHA and 8-hydroxyquinoline, a moderately sensitive method involving 4-(2-pyridylazo)resorcinol (PAR), and a very sensitive method based on the ion-associate of a vanadium chelate complex with Brilliant Green... 

The lUPAC (International Union for Pure and Applied Chemistry) reference method for the determination of nickel in serum and urine [43], for example, recommends an acid digestion followed by extraction with APDC-MIBK prior to ETAAS determination. Similar procedures were described for molybdenum in blood plasma which was extracted as the 8-hydroxyquinoline complex prior to its determination by ETAAS [44] and for vanadium in serum and urine [45]. There is no question, however, that these procedures require skilled operators. As multistage manual procedures they also bear the risk of analyte loss and/or contamination, so that the final result may not always reflect the analyte concentration in the original sample. 

The use of the complex with A -substituted-phenylstyrylacrylohydroxamic acid and Aliquat 336 for the determination of V in alloys, rock, environmental and clinical samples has recently been reported [1]. Studies on the complexation of V(V) with PAR on the solid phase of a fibrous sorbent filled with an anion exchanger were described [2]. The DL of of 3-4 ng ml V was achieved. The effect of modification of a solid support with 8-hydroxyquinoline and 8-hydroxyquinoline-5-sulfonic acid on analytical characteristics of the reaction of vanadium(V) with PAR on a solid phase was studied [3]. Extraction of V with the use of 3-hydroxy-2-(4-methoxyphenyl)-6-methyl-4//-chromen-4-one was employed to detect V in flue dust and steel [4]. 

Hydroxyquinoline (oxine) reacts with numerous metal ions, in neutral, ammoniacal, or acetic acid solution, to produce inner complex salts of the coordination structure (II). Anions of metallo acids (molybdic, tungstic, vanadic) react in acetic acid solution to form insoluble compounds of a different structure probably the oxine esters of the particular metallo acid are formed. The vanadium compound is represented by (III). ... 

In a further spectrophotometric method, the polyester is reacted with a dimethyl formamide monochlorbenzene solution of vanadium 8-hydroxyquinolinate (V8HQ). A coloured complex is formed according to Tanaka and Kojima [9]. 

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