Detection of thiabendazole applied on citrus fruits and bananas using surface enhanced Raman scattering

Thiabendazole (TBZ) is a chemical fungicide and parasiticide largely used in food industry against mold and blight in vegetables and fruits during transportation and long term deposit. We investigated the possibility to detect and monitor the TBZ from the chemically treated bananas and citrus fruits available on Romanian market, using surface enhanced Raman spectroscopy (SERS) with a compact, portable, mini-Raman spectrometer. To assess the potential of the technique for fast, cheap and sensitive detection, we report the first complete vibrational characterization of the TBZ in a large pH and concentration range in conjunction with the density functional theory (DFT) calculations. From the relative intensity of the specific SERS bands as a function of concentration, we estimated a total amount of TZB as 78 mg/kg in citrus fruits, 13 times higher than the maximum allowed by current regulations, whereas in banana fruit the value was in the allowed limit.