Continuous-flow determination of dialyzable calcium in serum.

We describe a procedure for measuring dialyzable calcium in 60 sera per hour with use of AutoAnalyzer (Technicon) modules. The serum is buffered, then dialyzed in a regular 6-inch (15-cm) dialysis block. A constant proportion of the dialyzable calcium is fluorometrically measured. Analysis of samples containing protein, prepared by an equilibrium dialysis technique, shows that protein-bound calcium is not detected. The method requires less than 0.4 ml of serum, and is accurate, precise, and durable. No unusual care or special techniques are required during sample collection or analysis.