LIAISON hCG--an automated chemiluminescent immunoassay for the determination of human chorionic gonadotropin (hCG).

An immunoassay utilizing chemiluminescence and paramagnetic particles has been developed for the new fully automated, random access LIAISON immunoanalyzer. The LIAISON hCG assay is a two-site immunolouminometric one-step assay using two highly specific monoclonal antibodies. Total incubation time is only 10 min. A specially designed unique Reagent Integral contains all specific reagents; the on-board stability of these reagents is given over a very long period (> 4 weeks). The assay works with a 2-point calibrated master curve. 30 microliters sample is added to 200 microliters tracer and 20 microliters antibody-coated magnetic particles. After 10 min incubation the particles are separated, washed and the chemiluminescent signal is generated. The time to first result is only 15 min. The assay with a unique extended standard range up to 5,000 ng/ml shows no high dose hook effect up to 500,000 mlU/ml (spiked sera). The assay detects both the intact molecule and the free beta subunit. The cross-reactivity to FSH, LH and TSH is less than 0.1%. Precision (within-run < 3%; between-run < 5%), linearity, recovery and sensitivity (< 0.5 mlU/ml) are excellent. The assay shows a very good correlation to the LIA-mat hCG (r = 0.996). In summary the LIAISON hCG assay together with the new LIAISON immunoanalyzer is a very rapid and accurate method for the quantitative determination of hCG/beta-hCG in serum.