Guidelines for pattern recognition using differential receptors and indicator displacement assays.

A colorimetric sensor array consisting of designed receptors and metal salts was utilized for discrimination of structurally similar carboxylic acid analytes (25-31). For the discrimination, the receptors do not need to have a 1:1 guest-receptor binding stoichiometry. More than 1:1 stoichiometry, such as 1:2 or 2:1, affords useful information for the discrimination. The importance of data preselection and data preprocessing methods prior to principal component analysis is discussed. These methods change a score plot of principal components in a manner that enhances discrimination. Using the higher order stoichiometry, and the preselection as well as preprocessing discussed herein, we found that an addition of only one designed receptor to an array of metal salts can discriminate the structurally similar analytes.