Enzyme immunoassay of testosterone in plasma, with use of polyethylene glycol to separate antibody-bound and free hormone.

We describe an enzyme immunoassay for testosterone in which we use a testosterone-3-(carboxymethyl)oxime horseradish peroxidase conjugate as the label and an antiserum, raised in rabbits, to testosterone-3-(carboxymethyl)oxime-bovine serum albumin conjugate. Polyethylene glycol (Carbowax 6000) is used to separate antibody-bound and free steroid. The assay has a sensitivity of 12 pg/assay tube and satisfies the usual criteria of specificity, precision and accuracy. The results agree well with those obtained with a comparable radioimmunoassay.

Enzyme immunoassay of estrogen-like substances in plasma, with polyethylene glycol as precipitant.

We devised an enzyme immunoassay for plasma estrogen-like substances in pregnancy, using estriol covalently linked to horseradish peroxidase. Free and bound steroid were separated by use of polyethylene glycol reagent. The assay satisfies the normal criteria of specificity and precision. Results obtained by radioimmunoassay and enzyme immunoassay agreed well. Our assay is particularly applicable in smaller clinical laboratories to routine determination of plasma estriol in pregnancy.