Abstract:

A high-performance liquid chromatography method was established for the simultaneous determination of nine preservatives in food-grade detergents, including methylisothiazolinone, in food-grade detergents. The preservatives were extracted from the detergent using ethanol, solvent-exchanged to methanol using a parallel concentrator, and then subjected to ultrasonication and filtration. Gradient elution was performed using methanol and 0.05% aqueous formic acid solution as the mobile phase. Chromatographic separation was achieved on a ZORBAX Eclipse XDB-C₁₈ column （250 mm×4.6 mm, 5 µm） with an injection volume of 10 µL and a flow rate of 0.9 mL/min. The detection wavelength was set at 280 nm for methylisothiazolinone, methylchloroisothiazolinone, and phenoxyethanol; 254 nm for 1, 2-benzisothiazol-3-one, methylparaben, ethylparaben, propylparaben, and butylparaben; and 230 nm for sodium benzoate. Method validation demonstrates good linearity for all nine preservatives within the range of 0.5-20.0 µg/mL, with correlation coefficients greater than 0.999. The limits of detection range from 0.12 to 1.0 mg/kg, and the limits of quantification range from 0.40 to 3.0 mg/kg. Spiked recovery tests at low, medium, and high concentration levels yield recoveries between 87.6% and 108.5%, with relative standard deviations ranging from 3.4% to 7.8%. The method is accurate, reliable, and suitable for the quantitative determination of the nine preservatives in food-grade detergents.

Key words: detergent for food use, preservative, high performance liquid chromatography