Analytical systems ranked by freedom from interferences

We determined the effect of hemolysis, lipemia, and bilirubinemia on clinical-chemical analytical results under standardized conditions, for serum specimens prepared by us. Our purpose was to assess results obtained with 22 commonly available analytical systems. The quantitative rating scheme described is derived from the observed interference(s) divided by the number of analytical methods evaluated. The combined ranking reveals which chemistry analyzers are least affected and which are most affected by the added substances. Generally, systems that incorporate physical barriers or protein-separation steps perform better than those without thin-film layers, glass-fiber barriers, or dialysis membranes. Among the "direct" analyzers, fewer interferences are seen if appropriate "blanking" wavelengths are used, especially if a "specimen blank" absorbance is used appropriately in the analytical system. Centrifugal analyzers tended to perform poorly, according to the criteria presented here.