The availability of a buffer that prevents false positives due to the presence of lectins has implications affecting all LFDs and immunoassays. The mechanism by which 50% PBSTM prevented false positives or ‘nonspecific’ binding between the capture and detector antibodies that comprise LFDs is not understood. The explanation that the lectin coupled the two antibodies via their glycosyl groups does not explain why 100 mM lactose failed to suppress false positives. The modest increases in the LOD values for ricin with LFDs were acceptable considering the sensitivity of the assays and elimination of a potential source of false positives.