Fluphenazine decanoate given in low dosage has proven to be a major analytical chemistry problem in terms of plasma level monitoring. Utilizing a newly developed high affinity, specific antisera to fluphenazine we propose to develop an HPLC-RIA combined procedure which will enable us to quantitate less than 200 pg/ml. This reference procedure will then be used to evaluate direct and solvent extraction RIA procedures developed at this institute. Finally a large number of samples will be analyzed simultaneously by the above methods and the neuroleptic radioreceptor assay. It is anticipated that a combination of two or more of these assays may help determine plasma level clinical efficacy relationships.