The specificity of the extraction fluorescence assay for serum or plasma quinidine.

A series of 26 randomly selected serum samples from patients receiving long-term antiarrhythmic therapy with oral quinidine preparation were assayed by both a modification of the extraction fluorescence technique and high-pressure liquid chromatography, with highly comparable results (r = 0.98). A review of the literature on comparing the extraction fluorescence technique's results with other methods indicates a high degree of agreement. However, because variations from study to study exist, investigators using the extraction fluorescence technique should assess the specificity of the method in their own laboratory.