Development of lateral flow immunoassay for rapid control and quantification of the presence of the colorant Sudan I in spices and seafood

- The lateral flow immunoassay for selective Sudan I detection was developed.
- Monoclonal antibody to Sudan I was conjugated with gold nanoparticles.
- Highly colored spices and seafood do not influence on the assay efficiency.
- The limit of detection of Sudan I is 2.5 ng/mL in extracts and 10 μg/kg in food.

The lateral flow immunoassay for colorant Sudan I detection was developed using the monoclonal antibody to Sudan I conjugated with gold nanoparticles. Conditions of the assay were optimized for both qualitative control and quantification of Sudan I in food matrixes with minimal dilution of the extracting media (final content of methanol - 50%). In the case of photometric registration, the limit of Sudan I detection in extracts was 2.5 ng/mL (which corresponds to 10 μg/kg of food and spices), and the working range of determined concentrations was 13-240 ng/mL. The average error of measurements varied from 5.5 to 16.9%. The visual limit of detection, which is the minimum concentration causing absence of visible coloration at the test zone, was 1 μg/mL. The assay efficiency was confirmed by its application to determine Sudan I content in highly colored spices (turmeric, curry) and seafood (caviar, mussels, fish). Thus, the developed assay is suitable as a rapid, inexpensive tool for revealing Sudan I quantification by mobile laboratories and in out-of-laboratory conditions.