Mitsubishi Chemical Corporation

Mitsubishi Kasei Corporation

Atsushi Yanagida

Michio Ito

Satoshi Sugawa

A non-specific reaction suppressor for immunoassays having the formula: ##STR1## where R.sub.1, R.sub.2, Y, X, and R.sub.3 are defined in the specification.

Non-specific reaction suppressor

The invention relates to immunoassay reagents that are both sensitive and specific and which require no sample pretreatment. The invention reagents are particularly useful for assaying digoxin concentrations in patient sera. More particularly, the invention relates to methods and kits comprising (A) an immunoreactant immobilized on a support; and, (B) a buffer agent comprising (i) a buffering agent, (ii) sodium chloride, (iii) choline chloride, (iv) a polysaccharide, (v) fatty-acid-free serum albumin, and (vi) a non-specific reaction suppressor of the formula: ##STR1## wherein X is --NH--(CO)--NH--, --NH--(CS)--NH--, or --N.dbd.C.dbd.N--, R.sub.1 and R.sub.2, which may be the same or different, are C.sub.1 -C.sub.5 linear or branched alkyl groups, or R.sub.1 and R.sub.2, together with nitrogen, is ##STR2## or the metho-p-toluenesulfonate salt thereof, Y, which may be the same or different, is any of H, OH and halogen,

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Carmel, IN, United States of America

Atsushi Yanagida