Phase-selective AC adsorptive stripping voltammetric assay for aminopterin and 10-Edam in human serum

Abstract Aminopterin was studied as a model compound for its analogues which maintain the pteridine ring in their structure. Its adsorptive behaviour on mercury was studied and the DC adsorptive stripping and phase-selective AC adsorptive stripping conditions were optimized. 10-Edam, an aminopterin analogue, was studied and shown to behave similarly to aminopterin. Phase-selective AC voltammetry provided the best signal and gave a detection limit of 4 × 10 −12 M aminopterin in aqueous solution employing an accumulation time of 10 min. The optimized method was applied to the analysis of both aminopterin and 10-Edam respectively in human serum. After extraction with a C 18 reversed-phase cartridge the detection limit of the method was 1 × 10 −8 M aminopterin and the overall assay percentage recovery was 73.5% ( n = 5) at a concentration of 5 × 10 −7 M aminopterin in serum. The analysis of 10-Edam at the same concentration in serum yielded the higher percentage recovery of 94.46% ( n = 5) following the same procedure.