Rapid quantification of thiocyanate in milk samples using a universal paper-based SERS sensor

Sodium thiocyanate (NaSCN) is a naturally antibacterial component in milk, but excessive consumption of thiocyanate may cause potential risks to human health. Currently available methods for the detection of thiocyanate have some disadvantages such as poor sensitivity and high price. Here, we report a robust and cost-effective method to detect NaSCN based on paper substrates deposited with in situ reduced Ag nanoparticles by surface-enhanced Raman spectroscopy (SERS). Densely packed multilayer AgNPs provide uniform narrow nanogaps, which exponentially enhance the Raman signals. Moreover, these homogeneous narrow hotspots ensure that this method has high sensitivity (the limit of detection is 10(-12) mol L-1), a wide linear range (from 10(-9) mol L-1 to 10(-4) mol L-1), and remarkable reproducibility (the coefficient of variation within a SERS sensor is 6.5%). Spiked milk samples were detected and the recovery rates of NaSCN were in the range of 95.1%-108.0%. This paper-based SERS sensor offers great potential for sensitive NaSCN detection and milk analysis.

Automated summary

Sodium thiocyanate is a naturally antibacterial component in milk, but excessive consumption may pose potential risks to human health. In this study, a robust and cost-effective method based on surface-enhanced Raman spectroscopy (SERS) was developed for NaSCN detection using paper substrates deposited with in situ reduced Ag nanoparticles. The proposed method exhibited high sensitivity, a wide linear range, and good reproducibility, making it suitable for NaSCN detection and milk analysis.