RADIOIMMUNOASSAY, ENZYME IMMUNOASSAY, SPECTROPHOTOMETRY, AND GAS-LIQUID-CHROMATOGRAPHY COMPARED FOR DETERMINATION OF PHENOBARBITAL AND DIPHENYLHYDANTOIN
Sera from epileptic patients were assayed for phenobarbital and diphenylhydantoin by 4 different analytical procedures. Quantitative results obtained by radioimmunoassay (I) and enzyme immunoassay (II) were compared to each other and to the results obtained on aliquots of the same sample by GLC (III) and UV spectrophotometry (IV). For phenobarbital the correlation coefficients were I vs. II, 0.909; I vs. III, 0.947; II vs. III, 0.917; I vs. IV, 0.950; II vs. IV, 0.953. For diphenylhydantoin the correlation coefficients were I vs II, 0.953; I vs. III, 0.951; II vs. III, 0.957; I vs. IV, 0.862; II vs. IV, 0.898. The immunoassays can be substituted for liquid chromatography or UV spectrophotometry without changing the resulting clinical interpretations.