Determination of carbofuran in water by homogeneous immunoassay using selectively conjugate mastoparan and terbium/dipicolinic acid fluorescent complex

Homogeneous immunoassay (LITRFIA) for carbofuran (CF) determination was performed using liposomes and mastoparan (Mast) conjugate as cytolitic agent. Mast was conjugated to the 5-(2-2-dimethyl-2,3-dihydro-benzofuran-7-yloxy)-pentanoic acid (CPCF) both randomly and selectively to a single (V1- or K4-) amino-group. The conjugated compounds have been tested for the cytolytic activity on liposomes trapping Tb/citrate complex. Dipicolinic acid (DPA) was used as fluorescent chelating agent. The CPCF-V1-Mast derivative (retaining almost the same lytic activity as Mast) was used in the immunoassay in competition with standard CF. Liposome lysis was proportional to the standard concentrations in a dynamic range between 10 pg and 10 ng. Assay has been performed for tap water analysis and for 10 real samples taken from an agricultural area to the south of Milan. Recovery in samples spiked with two different CF concentrations was between 92.5 and 105%.