Abstract: In this research, an analytical method for simultaneous determination of thiourea, kojic acid, thiabendazole, thiadiazole and tetracycline in wheat flour by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established. Samples were extracted with 80% ethanol-acetonitrile (1:1, V/V), and then subjected to centrifugation and nitrogen blowing concentration before being quantitatively analyzed by using the multi-reaction monitoring (MRM) mode. The results showed that the developed method exhibited a good linear relationship in the concentration range of 100–5 000 ng/mL for thiourea, kojic acid and tetracycline, 1–50 ng/mL for thiabendazole and 1–50 μg/mL for thiadiazole, with correlation coefficients of higher than 0.999. The limits of detection (LOD) and limits of quantitation (LOQ) were 25 and 50 μg/kg for thiourea, kojic acid and tetracycline; 0.5 and 1 μg/kg for thiabendazole; 0.5 and 1 mg/kg for thiadiazole. The recoveries from spiked samples ranged from 88.6% to 102.2%, and the precision expressed as relative standard deviation (RSD) ranged from 0.7% to 5.6% (n = 6). This method, with simple and rapid pretreatment, can be used for the rapid determination of thiourea, kojic acid, thiabendazole, thiadiazole and tetracycline in wheat flour.

Key words: wheat flour; illegal additives; liquid chromatography-tandem mass spectrometry