Determination of 1-nitropyrene in herbs after selective enrichment by a sol–gel-generated immunoaffinity column

Using the determination of 1-nitropyrene as an example the paper demonstrates the advantages of including a highly selective sol–gel-generated immunoaffinity column in the sequence of clean-up steps necessary to determine haptens in complex matrices. The sol–gel method to immobilise antibodies enlarges the variety of immunoaffinity columns available and leads to mechanically stable columns with constant retention characteristics. The sample preparation scheme proposed combines acetonitrile extraction, size-exclusion and immunoaffinity chromatography. 1-Nitropyrene is then separated by reversed-phase HPLC from interfering compounds and determined after catalytic on-line reduction to the corresponding amine by spectrofluorimetry. Concentrations in the range from 0.1 to 1.4 μg/kg 1-nitropyrene were detected in herbs.