[High performance liquid chromatography for simultaneous determination of 2-amino-6-methoxybenzothiazole and two raw...

Objective: To establish a high-performance liquid chromatography method for the simultaneous determination of 2-amino-6-methoxybenzothiazole and its raw materials, namely p-anisidine and (4-methoxyphenyl) thiourea, in workplace air. Methods: In May 2024, high-performance liquid chromatography was employed with a C(18) column. The mobile phase was methanol-pure water (volume ratio 60∶40) at a flow rate of 0.9 ml/min. The detection wavelength was 242 nm, injection volume was 20 μl, and quantification was performed by the external standard method for the detemination of 2-amino-6-methoxybenzothiazole, p-anisidine and (4-methoxyphenyl) thiourea in the samples. Results: Good linearities were obtained for 2-amino-6-methoxybenzothiazole, (4-methoxyphenyl) thiourea and p-anisidine in the ranges of 0-100 μg/ml, 0-40 μg/ml and 0-100 μg/ml, with correlation coefficients (r) of 0.9997, 0.9995 and 0.9997, respectively. The limits of detection were 0.15, 0.05 and 0.15 μg/ml, respectively. The intra-batch precisions were 2.0%-2.8%, 2.3%-3.6% and 2.1%-4.1%, and the inter-batch precisions were 3.2%-3.8%, 4.3%-6.1% and 4.0%-5.8%, respectively. The sampling efficiency using silica gel tubes was higher than 95%. Samples could be stored for at least 7 days at room temperature. Conclusion: This method has high sampling efficiency, simple operation, high precision and sensitivity, and can meet the simultaneous determination of 2-amino-6-methoxybenzothiazole, (4-methoxyphenyl) thiourea and p-anisidine in workplace air.