A lateral flow immunoassay for measuring ochratoxin A: Development of a single system for maize, wheat and durum wheat

A quantitative lateral flow immunoassay for the detection of ochratoxin A (OTA) in cereals has been developed. The ready-to-use device includes a nitrocellulose membrane on which capturing reagents are immobilized in spatially confined zones and a conjugate pad on which the antibody labelled with gold nanoparticles is pre-adsorbed. Stabilization of gold labelled antibodies and blocking of non-specific interactions of the nitrocellulose membrane were obtained by using 1% ovalbumin. This, combined with the use of PEG in the extraction of OTA from cereal samples, allows us to level the matrix effects caused by various cereals (maize, wheat and durum wheat). The immunochromatographic assay developed includes a rapid and very simple treatment of samples, which, in addition, does not involve the use of organic solvents and allows the quantitative determination of OTA with limits of detection as low as 1.5 μg kg−1. The coefficients of inter–assay variations are below 20%, with recoveries which ranged from 87 to 119%. Fifteen maize samples, four wheat and six durum wheat samples were extracted with the aqueous medium and analysed by the developed assay. A good correlation was observed (y = 0.99 x + 0.18, r2 = 0.982, n = 25) when data was compared with that obtained through a reference method