Direct extraction/analysis of Dried Blood Spots(DBS): A fully automated system including spot localization, internal standard (IS) application and multiple batch analysis

摘要

Our tests with semi-automated and automated DBS systems confirmed that with increasing automation of the DBS analysis the three factors addressed in this project gain in importance and should be considered as key issues: (1) In practice we observed positioning variations of the blood spots relative to the DBS card boundaries of up to 3mm due to the blood spotting procedure and card tolerances. An automated system which does not detect those variations will miss part of the spot in such a situation. This would be unacceptable in routine analysis and accurate spot localization seems to be a must. (2) All parts in contact with the DBS sample are potentially contributing to carryover. We experienced that for critical applications an automated wash system can be used efficiently to significantly reduce or eliminate the remaining carryover after every sample. (3) Normalization of data by an internal standard has been found to be one of the key issues. Furthermore the application of the internal standard to the DBS card after blood spotting but prior to extraction seems to be favoured logistically and will have the potential to correct for extraction efficiencies. More details on the homogeneity of the application of solvent containing an internal standard are addressed in a separate poster [4]. We have shown that all the above-mentioned processes can be automated and coupled with a fully automated card handling system, and that an inte-grated fully automated DBS system using direct extraction of blood spots can be built constructed?. Additional steps such as punching, eluting, centrifuging etc. were substituted by the direct extraction process and the amount of manual work was minimized to the process of spotting blood onto DBS cards.