Development of immunoaffinity restricted access media for rapid extractions of low-mass analytes

Preparation and application of an immunoaffinity column based on an antibody with strong affinity and packing material with good stability

This article describes the production of an anti-citrinin antibody that showed a high affinity constant (Ka) of 6.28 × 10⁹ and good tolerance to organic solvent and low pH, the synthesis of a Cu (II)-embedded polymer that showed strong binding with this antibody and the preparation of packing material for an immunoaffinity column (IAC) that show good stability. Most of the IACs reported either use harsh elution conditions and are used only once or use gentle elution conditions and are reused many times. Here, through the combined use of a strong-affinity antibody and packing material with good stability, high recoveries during clean-up and yet simultaneously good stability of the IAC were successfully achieved. Under optimised conditions of 80% methanol (pH 3), the IACs were used to clean-up the extracts of Monascus colour and red yeast rice samples, followed by HPLC detection. The recoveries of citrinin from spiked samples at levels of 50-200 μg kg⁻¹ were in the range of 84-97%.

Preparation of an immunoaffinity column for the clean-up of fermented food samples contaminated with citrinin

An immunoaffinity column (IAC) for the clean-up of citrinin-contaminated food samples was prepared by using silica gel immobilised with a anti-citrinin antibody. Antibodies produced against citrinin-bovine serum albumin (BSA) were covalently immobilised onto a silica-based solid support to prepare the IAC. The selective extraction and clean-up ability of the IAC was evaluated by capillary zone electrophoresis coupled with ultraviolet detection. Clean-up conditions such as eluting solutions kind, concentrations, pH and volumes were optimised for citrinin by using the IAC. IACs were applied to citrinin-contaminated foods such as red yeast rice and monascus colour. The method's performance was acceptable in terms of recoveries, which ranged from 80.4% to 97.1% for citrinin-spiked samples at levels of 50, 100 and 200 µg kg(-1), and the relative standard deviation ranged from 5.3% to 10.5%.