Evaluation of an automated radioimmunoassay system: the ARIA II

The ARIA II is an automated instrument for the quantitation by radioimmunoassay of the following constituents: digoxin, cortisol, thyroxine, T3 uptake, T3 RIA, estriol, and progesterone, its methodology uses a specific antibody covalently bonded to a solid support in a reusable antibody chamber. We evaluated the assay system for the first three constituents listed above. Coefficients of correlation with conventional manual methods were: thyroxine-0.9797; digoxin-0.9871; and cortisol-0.9727. Inter-assay variations using a commercially available tri-level control serum were as follows: thyroxine-5.4 to 10.3%; digoxin-3.7 to 6.3%; cortisol-5.2 to 8.4%. The ARIA II is not a discrete analyzer, and an estimate of carryover was significant only on low-to-high for the thyroxine assay. ARIA II assays are approximately one-half the cost of manual assays. Time studies indicate the ARIA II to be most suited to laboratories of low or moderate volume.