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Importance of Preanalytical Factors in Measuring Cr and Co Levels in Human Whole Blood: Contamination Control, Proper Sample Collection, and Long-Term Storage Stability.

A number of errors with potentially significant consequences may be introduced at various points in the analytical process which result in skewed, erroneous analytical results. Precautionary procedures such as contamination control, following established sample collection protocols, and having a complete understanding of the long-term stability of the elements of interest can minimize or eliminate these errors. Contamination control is critical in quantification of Cr and Co in human whole blood. Cr and Co levels in most biological samples are low, but these elements occur naturally in the environment and are often found in commercial and consumer products, which increases the risk of contamination. In this paper, we demonstrated that lot screening process in which we pre-screen a sub-set of manufactured lots used in collecting, analyzing, and storing blood samples is a critical step in controlling Cr and Co contamination. Stainless steel needles are often utilized in blood collection but are considered a potential source of introducing metal contamination to the patient sample. We conducted two studies to determine if there is a possibility of Cr or Co leaching into the human whole blood from the needles during blood collection. We analyzed blood collected from 100 donors and blood collected in-vitro in the laboratory from designated vessel containing spiked blood with higher levels of Cr and Co. Two blood tubes were consecutively collected through one needle. In both studies, Cr and Co concentration levels in the two consecutively collected tubes were compared. Based on the results from donor and in-vitro blood collection studies, we concluded there was no Cr and Co leaching from the limited sets of stainless steel needles used in these studies. Further, we demonstrated that Cr and Co human whole blood samples are stable for one year stored at temperatures of -70 °C, -20 °C, and 4 °C, and six months at room temperature.