Trace metal determinations in blood obtained in evacuated collection tubes.

Using atomic absorption spectrophotometry, we determined levels of iron, copper and zinc in serum or plasma samples collected in acid-washed containers and in commercially available evacuated tubes including one model equipped with rubber stoppers prepared by a process which reduces zinc contamination of the rubber. Serum or plasma from all evacuated tubes yielded iron and copper values which were comparable to those from serum obtained in acid-washed glass. Zinc values were higher from all evacuated tubes than from acid-washed glassware. Values obtained from samples collected in the specially-prepared tubes were 10% higher than values obtained from samples collected in acid-washed glassware. Thus, the specially-prepared evacuated tubes may only be useful in large-scale clinical screening studies. Traditional blood collection methods for zinc determination should be used when accuracy is required.