Development of determination of di-n-octyl phthalate (DOP) residue by an indirect enzyme-linked immunosorbent assay

Abstract

In this research, the hapten di-n-octyl 4-aminophthalate (DOAP) was designed and synthesised successfully. It was used to couple with carrier proteins, bovine serum albumin (BSA) and ovalbumin (OVA) by diazotization reaction for immunogen (DOP-BSA) and coating antigen (DOP-OVA), respectively. Rabbits were immunised with DOP-BSA; polyclonal antiserum was raised and determined by competitive indirect enzyme-linked immunosorbent assay (ciELISA). After optimisation, a ciELISA was established. The quantitative working range for DOP was 5-75 ng/mL with the detection limit of 1.9±0.1 ng/mL and the IC50 of 19.2±1.1 ng/mL. The optimised ELISA had cross-reactivity of 22.6%, 17.6% and 21.2% with di-iso-octyl phthalate (DIOP), di-n-butyl phthalate (DBP) and di-hexyl phthalate (DHP), respectively. The result of the detection of polyvinyl chloride (PVC) samples showed that the immunoassay we developed had high-accuracy contrast with high-performance liquid chromatography electrospray ionisation tandem mass spectrometry analysis and it could be qualified to determine di-n-octyl phthalate (DOP) residue in PVC samples. © 2010 Taylor & Francis.