Rapid Determination of Ochratoxin A in Black Tea Using Terahertz Ultrasensitive Biosensor

Ochratoxin A (OTA), which is highly toxic and carcinogenic, is easily produced in cereal crops, dry herbs, and other foods under improper storage. Traditional detection methods, including high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA), can detect OTA accurately, but there are many problems such as long period, high cost, and poor reproducibility. Therefore, developing a rapid, non-destructive, and highly sensitive method for OTA detection is essential. In this paper, we used a surface plasmon resonance (SPR) biosensor combined with terahertz (THz) spectroscopy to quantify OTA. As a result, the concentration range of OTA in acetonitrile solution was up to 0–20 pg/μL, with a detection limit of 1 pg/μL, which can meet the requirements for OTA detection in most foods. Further, we applied this method to black tea, and the detection limit was up to 1 pg/mg, which is 500 times higher than UV spectrophotometry, and completely meets the EU regulations. This study shows that the combination of terahertz spectroscopy and an SPR biosensor is a promising approach to achieve a simple, rapid, and low-cost method for trace substance quantification in foods and drugs.