The MECTEST Opiate Radioimmunoassay is a solid-phase
radioimmunoassay wherein 125-I-labeled morphine competes
for a fixed time with opiates extracted from meconium
for antibody sites. The antibody is immobilized to
the wall of a polypropylene tube; hence decanting
the supernatant suffices to terminate the competition
and to isolate the antibody-bound fraction of the
radiolabeled morphine, which is then counted in a
gamma counter. A comparison of the counts to a standard
curve yields a measure of the opiate present in the
sample, expressed as nanograms of morphine-3-glucoronide
per milliliter (ng/mL).
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