Polychromatic analysis: new applications of an old technique.

As a means of correcting for many potential interferences, polychromatic analysis offers an effective alternative to either sample pretreatment or separate blank determinations. Because of the differing spectral characteristics of each interfering species, and the nature of these interferences (static vs. kinetic), the application of polychromatic analysis must be optimized for each analytical procedure to minimize all residual errors. Overall assay precision can be maximized by proper use of flagging procedure to minimize all residual errors. Overall assay precision can be maximized by proper use of flagging procedures (also based on polychromatic analysis). By using a second wavelength measurement, the analyst can also verify the accuracy of an analytical measurement in selected situations. These applications of polychromatic analysis are a departure from conventional analytical procedures in allowing for correction of various interferences in the actual reaction mixture, without making assumptions about the recovery of analyte during pretreatment or the equivalent absorptivity of interferent in both blank and assay solutions.