Abstract: A method for detecting the presence of a specific analyte in a sample using an immunoassay format in which magnetic particles provide the solid phase and the signal is a dopant detectable by the change in conductivity of an electroconductive polymer coating an electrode. Additionally, magnetic devices for creating a strong force on the particles and the use of cacodylate to catalyze the production of a dopant, triiodide. Also, a gravure coating process for producing electroconductive polymer films.

Abstract: An electrochemical sensor cartridge with at least three reservoir cells, the floor of each cell in leakproof contact with the surface of an electrode assembly whose conductivity is affected by the presence of an analyte in that cell.

Abstract: Compounds useful as tracers in the radioimmunoassay of xanthine derivatives such as theophylline and pharmacologically related drugs: ##STR1## wherein at least one R.sub.1, R.sub.3, R.sub.7 or R.sub.8 is a radioiodinated radical and wherein, if not substituted by a radioiodinated radical, the remaining R.sub.1, R.sub.3, R.sub.7 or R.sub.8 groups are otherwise identical to the substituents at these positions in the xanthine derivative to be assayed. Ordinarily, R.sub.1 is hydrogen, acetate or methyl; R.sub.3 is methyl; R.sub.7 is hydrogen, acetate or methyl; and R.sub.8 is hydrogen. The tracers are made by linking radioiodinatable or preradioiodinated radicals to the xanthine derivative which is to be assayed. The tracers may be employed in known radioimmunoassay techniques.

Abstract: The binding of vitamin B-12 by natural substances in samples assayed for vitamin B-12 is reduced by heating the test sample in an alkaline buffer comprising thioglycerol and denaturing agent having the formula (R).sub.2 NC(A)N(R).sub.2, wherein R is hydrogen or lower alkyl and A is oxygen or hydroxyl.

Abstract: Compounds useful as tracers in the radioimmunoassay of xanthine derivatives such as theophylline and pharmacologically related drugs: ##STR1## Wherein at least one R.sub.1, R.sub.3, R.sub.7 or R.sub.8 is a radioiodinated radical and wherein, if not substituted by a radioiodinated radical, the remaining R.sub.1, R.sub.3, R.sub.7 or R.sub.8 groups are otherwise identical to the substituents at these positions in the xanthine derivative to be assayed. Ordinarily, R.sub.1 is hydrogen, acetate or methyl; R.sub.3 is methyl; R.sub.7 is hydrogen, acetate or methyl; and R.sub.8 is hydrogen. The tracers are made by linking radioiodinatable or preradioiodinated radicals to the xanthine derivative which is to be assayed. The tracers may be employed in known radioimmunoassay techniques.