Vanadium pentoxide

1.1.4

Technical products and impurities

Vanadium pentoxide is commercially available in the USA in purities between 95% and

99.6%, with typical granulations between 10 mesh [~ 1600 

µm] and 325 mesh [~ 35 µm]

× down (Reade Advanced Materials, 1997; Strategic Minerals Corp., 2003). Vanadium pen-

toxide is also commercially available as a flake with the following specifications: purity,

98–99%; silicon, < 0.15–0.25%; iron, < 0.20–0.40%; and phosphorus, < 0.03–0.05%; and

as a powder with the following specifications: purity, 98%; silicon dioxide, < 0.5%; iron,

0.3%; and arsenic, < 0.02% (American Elements, 2003).

Vanadium pentoxide is commercially available in Germany as granules and powder

with a minimum purity of 99.6% (GfE mbH, 2003), and in the Russian Federation as a

powder with the following specifications: purity, 98.6–99.3%; iron, < 0.05–0.15%;

silicon, < 0.05–0.10%; manganese, < 0.04–0.10%; chromium, < 0.02–0.07%; sulfur,

< 0.005–0.010%; phosphorus, < 0.01%; chlorine, < 0.01–0.02%; alkali metals (sodium

and potassium), < 0.1–0.3%; and arsenic, < 0.003–0.010% (AVISMA titanium-magne-

sium Works, 2001).

Vanadium pentoxide is also commercially available in South Africa as granular and

R-grade powders with a minimum purity of 99.5% and grain sizes of > 45 

µm and

< 150

µm, respectively (Highveld Steel & Vanadium Corporation Ltd, 2003). 

1.1.5

Analysis

Occupational exposure to vanadium pentoxide is determined by measuring total vana-

dium in the workplace air or by biological monitoring.

(a)

Monitoring workplace and ambient air 

Respirable fractions (< 0.8 

µm) of airborne vanadium pentoxide are collected by

drawing air in a stationary or personal sampler through a membrane filter made of poly-

carbonate, cellulose esters and/or teflon. The filter containing the collected air particulates

can be analysed for vanadium using several methods. In destructive methods, the filter is

digested in a mixture of concentrated mineral acids (hydrochloric acid, nitric acid, sulfuric

acid, perchloric acid) and the vanadium concentration in the digest determined by

GF–AAS (Gylseth et al., 1979; Kiviluoto et al., 1979) or ICP–AES (Kawai et al., 1989).

Non-destructive determination of the vanadium content on a filter can be performed using

INAA (Kucera et al., 1998).

Similar methods can be used for the measurement of vanadium in ambient air.

X-ray powder diffraction allows quantification of vanadium pentoxide, vanadium tri-

oxide and ammonium metavanadate separately on the same sample of airborne dust

(Carsey, 1985; National Institute for Occupational Safety and Health, 1994).

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(b)

Biological monitoring 

(i)

Tissues suitable for biomonitoring of exposure

Vanadium concentrations in urine, blood or serum have been suggested as suitable

indicators of occupational exposure to vanadium pentoxide (Gylseth et al., 1979;

Kiviluoto et al., 1979, 1981; Pyy et al., 1984; Kawai et al., 1989; Kucera et al., 1998).

The concentration of vanadium in urine appears to be the best indicator of recent expo-

sure, since it rises within a few hours after the onset of exposure and decreases within a

few hours after cessation of exposure (Kucera et al., 1998). Table 2 presents data of vana-

dium concentrations in urine from workers exposed to vanadium.

Detailed information on the kinetics of vanadium in human blood after exposure is

still lacking. Kucera et al. (1998) regarded vanadium concentrations in blood as the most

suitable indicator of the long-term body burden (see Section 4.1.1). However, in a study

of vanadium pentoxide exposure in rats, blood concentrations showed only marginal

increases. This seems to indicate that there was limited absorption of vanadium (National

Toxicology Program, 2002).

(ii)

Precautions during sampling and sample handling 

Biological samples are prone to contamination from metallic parts of collection

devices, storage containers, some chemicals and reagents; as a result, contamination-free

sampling, sample handling and storage of blood and urine samples prior to analysis are of

crucial importance (Minoia et al., 1992; Sabbioni et al., 1996). There is also a great risk

of contamination during preconcentration, especially when nitric acid is used (Blotcky

et al., 1989). 

(iii)

Analytical methods

Several reviews are available on analytical methods used for the determination of

vanadium concentrations in biological materials (Seiler, 1995) and on the evaluation of

normal vanadium concentrations in human blood, serum, plasma and urine (Versieck &

Cornelis, 1980; Sabbioni et al., 1996; Kucera & Sabbioni, 1998). Determination of vana-

dium concentrations in blood and/or its components and in urine is a challenging

analytical task because the concentrations in these body fluids are usually very low

(below the 

µg/L level). A detection limit of < 10 ng/L is therefore required and only a few

analytical techniques are capable of this task, namely GF–AAS, isotope dilution mass

spectrometry (IDMS), ICP–MS and NAA. Furthermore, sufficient experience in applying

well-elaborated analytical procedures is of crucial importance for accurate determination

of vanadium concentrations in blood, serum and urine.

Direct determination of vanadium concentrations in urine or diluted serum by GF–AAS

is not feasible because the method is not sufficiently sensitive and because the possibility of

matrix interferences; however, GF–AAS with a preconcentration procedure has been

applied successfully (Ishida et al., 1989; Tsukamoto et al., 1990).

IDMS has good potential for the determination of low concentrations of vanadium. This

technique has been applied for the determination of vanadium concentrations in human

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