Eliminating surfactant interference in lateral flow immunoassay using separation strategy for the sensitive detection...

Coumaphos (CMP), an organophosphorus insecticide and acaricide widely used in agriculture for controlling pests, pose health and environment risks. However, no lateral flow immunoassays (LFIA) have been reported for its detection. Here, sensitive monoclonal antibodies with IC₅₀ values of 0.59 ng mL^-1, were developed. It was observed that surfactants interfere with antibody-antigen interactions, reducing sensitivity. To eliminate the interference, a surfactant interference-free LFIA (SF-LFIA) was developed by spatially separating the immunoreaction from the strip. The detection limit of the SF-LFIA was 0.016 ng mL^-1, which is 59.4 and 393.1 times more sensitive than that of the traditional LFIA and the optimized traditional LFIA, respectively. The SF-LFIA was applied to detect CMP in apple and cabbage demonstrating satisfactory recoveries (86.8 %-101.2 %) and coefficient of variations (<15 %). Additionally, the detection procedure took less than 30 min. The approach is essential and may provide guidance for the field.