Trace-element analysis in biological fluids: evaluation of contamination in samples collected with metallic needles Original Research Article

The present study refers to the determination of trace elements in biological fluids, specially copper in cerebrospinal fluid (CSF) from animals and it assesses the possible contamination of the samples with copper originating from the systems (metallic needles) employed for their extraction from the animals. The results show that there is a significant incorporation of copper originating from the material (stainless steel) with which the needles have been manufactured. The influence of numerous variables on the quantity of the contamination has been evaluated; a very simple and practical procedure has been developed which minimises the contamination and introduces the necessary correction in the analytical results so that these can be used to diagnose certain diseases. The electroanalytical techniques employed were anodic stripping potentiometry with mercury film electrode and square wave voltammetry (SWV) with static mercury drop. The recommended procedure is valid for any other sample and any other metallic component present in the material used to manufacture the needle employed in the sample extraction.