PHASE-SELECTIVE AC ADSORPTIVE STRIPPING VOLTAMMETRIC ASSAY FOR AMINOPTERIN AND 10-EDAM IN HUMAN SERUM

Aminopterin was studied as a model compound for its analogues which ma intain the pteridine ring in their structure. Its adsorptive behaviour on mercury was studied and the DC adsorptive stripping and phase-sele ctive AC adsorptive stripping conditions were optimized. 10-Edam, an a minopterin analogue, was studied and shown to behave similarly to amin opterin. Phase-selective AC voltammetry provided the best signal and g ave a detection limit of 4 x 10(-12) M aminopterin in aqueous solution employing an accumulation time of 10 min. The optimized method was ap plied to the analysis of both aminopterin and 10-Edam respectively in human serum. After extraction with a C18 reversed-phase cartridge the detection limit of the method was 1 x 10(-8) M aminopterin and the ove rall assay percentage recovery was 73.5% (n = 5) at a concentration of 5 X 10(-7) M aminopterin in serum. The analysis of 10-Edam at the sam e concentration in serum yielded the higher percentage recovery of 94. 46% (n = 5) following the same procedure.