Influence of Storage Conditions on Aluminum Concentrations in Serum, Dialysis Fluid, Urine, and Tap Water

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Abstract
The Influence of storage temperature, vessel type, and treatment on alterations of aluminum (AI) concentrations in serum, urine, and dialysis fluid samples was studied at three different concentrations for each sample over an 18-month period. Furthermore, the influence of acidification on AI levels in tap water, urine, and dialysis fluid samples was studied over a four-month period. AI was measured by atomic absorption spectrometry. Sample storage in glass vessels was unsuitable, whereas only minor alterations of AI levels were observed with storage in polypropylene tubes, polystyrene tubes, and Monovettes. By using appropriate plastic containers, acid washing of the vessels showed no improvement. Frozen storage was superior compared with 4°C whereas storage at −80°C offered no advantage compared with storage at −20°C. Acidification of tap water samples was necessary to stabilize AI levels during storage. No striking effect of acidification on AI levels in urine and dialysis fluid samples was found. It is concluded that long-term storage of serum, urine, tap water, and dialysis fluid samples is possible if appropriate conditions are used.