Buffer for immunoassay, kit including same and immunoassay method using said buffer

摘要

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 --NC. 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,PPR.sub.3 is --NR.sub.1 R.sub.2, --NH.sub.2, -- CHY, cyclohexyl, or H,PPm is an integer of from 2 to 5, PPp is an integer of from 0 to 5, and PPn is 0 or 1,PPand the addition salts thereof.