ASTM-F86 PASSIVATION INCREASES TRACE-ELEMENT RELEASE FROM TI6AL4V INTO CULTURE-MEDIUM

There is growing concern regarding the possible effects of prolonged body exposure to trace amounts of metals. The high corrosion resistance of titanium and its alloys is resulting in their more widespread use. Passivation of these metals using HNO3 according to ASTM F86 is based on the assumption that this will produce an increased resistance to corrosion, but its effects do not appear to have been examined at the trace element level. We have used sensitive graphite furnace atomic absorption spectrophotometry to examine in vitro the influence of such passivation on the release of Ti, Al and V from Ti6Al4V and solid cpTi into serum-containing culture medium during incubation for 9 days. We detected a highly significant increase in the trace levels of Ti, Al and V in medium samples from passivated Ti6Al4V compared to those obtained from non-passivated Ti6Al4V; in addition, there was a significant time-related decrease in these levels, as well as in the levels observed in medium samples from the non-passivated Ti6Al4V controls and from passivated and non-passivated cpTi