Kinetic immunoturbidimetry of human choriomammotropin in serum

The sensitivity of kinetic immunoturbidimetry as a method for the measurement of specific proteins has been shown previously to be equivalent to 1 mg of analyte per liter. We confirm this in the method for human choriomammotropin described here. A relatively large sample volume is required, which results in other components of serum influencing the immunoprecipitin reaction. The technique is shown to be precise, and results compare well with those by a commonly available radioimmunoassay. The method performs well, as judged from results obtained for assayed quality control materials and in an external quality assurance program. The method is rapid (instrument assay time 120 s per sample), automated, and economical for routine use.