| abstract |
Chemical analysis of a sample with reagents spotted on a fibrous or porous medium employs a medium pretreated both with reagents and with conditioning agent. The conditioning agent increases the degree to which the liquid reactants wet the medium. One form of pretreated medium has different reagents located predominantly within different selected zones. Liquid is applied to the medium, typically as diluted sample, at a rate selected to enhance formation of repeatable spots. In one embodiment the liquid is applied by flowing it onto a wick element seated on the medium. The wick is disc-like and small relative to the spot which the reactants form on the medium. The disc can be pretreated to carry reagent, which the liquid transfers to the medium. The analysis instrument receives a reaction medium between selectively recessed upper and lower surfaces aligned in opposition at the reaction spot being analyzed. The analysis can, depending on the analytical reaction, the medium and the precision required, proceed while the reactants are wet or can measure a reaction product after the reactants are dry. A single point analysis can also be made. |