Colorimetric assay based on arginine-functionalized gold nanoparticles for the detection of dibutyl phthalate in Baijiu samples

In this paper, a simple and innovative colorimetric method is established, which is based on DBP-induced aggregation of arginine functionalized gold nanoparticles (ARG-AuNPs), and can be used for the sensitive determination of dibutyl phthalate (DBP) in Baijiu samples. The morphological characteristics and the color changes of ARG-AuNPs caused by aggregation show good sensitivity, and can be observed through ultraviolet-visible spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential technology. The color change of ARG-AuNPs from red to blue is due to the strong non-covalent interactions between DBP and ARG-AuNPs (electrostatic, van der Waals force and hydrogen bonding), which leads to the reduction of the electrostatic repulsion between the nanoparticles and aggregation. A two-stage linear equation was established between the absorption ratio (A690/A530) and the DBP concentration (0.0-2.8 mg L-1); the correlation coefficient (R2) was 0.9914-0.9940, and the detection limit (LOD) was estimated at 0.05 mg L-1. The designed ARG-AuNPs acting as a dependable sensor for the detection of Baijiu samples equally acquired satisfactory recoveries. When the concentration of DBP in the solution is more than 1.0 mg L-1, the color change can be clearly observed by the naked eye; so there is no need for sample preparation techniques and tedious operations to quickly and semi-quantitatively detect DBP. The successful application of the proposed method in Baijiu samples indicates its potential to detect DBP in more complex environment samples.