Molecular Recognition of Aflatoxin M1 in Water and Milk Samples

Two stochastic microsensors based on diamond paste modified with 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) were proposed for the molecular recognition of aflatoxin M1 in water and milk samples. Two types of diamond were used: a monocrystalline diamond powder (1 μm) (DP) and a nanopowder of monocrystalline diamond (10 nm) (nDP) for the design of the stochastic microsensors. The microsensors were incorporated as combined stochastic microsensors (a microcell containing the stochastic microsensor and the Pt wire, and a Ag/AgCl sensor) in a platform used for monitoring of waste waters and milk samples. The platforms were used for the fast screening of water and milk samples for the qualitative and quantitative analysis of aflatoxin M1 at very low concentration levels (up to 0.001 fg/L). The linear concentration ranges were wide, being able to cover concentrations between 0.001 fg/L to 20 μg/L. The highest sensitive microsensor (sensitivity of 4.74×10¹⁰ s mg^?1 L) was the one based on nDP. The results provided by the platforms were in agreement with those obtained by utilization of standard method (ISO certified methods (HPLC/fluorescence method)), recoveries being higher than 99.00 % and RSD lower than 1.00 % proving that the method can be reliable used for molecular recognition of aflatoxin M1 in water and milk samples.