Abstract: Aim A novel method has been developed for evaluation of the levels of total residual protein in antibiotics produced by fermentation using gel filtration chromatography (GFC) combined with Bradford assay based on determination of residual protein in lincomycin hydrochloride. Methods The chromatographic conditions were Superdex^TM peptide column, 0.01 mol·L^-1 phosphate buffer solution as mobile phase, and flow rate of 1 mL·min^-1. Five hundred microliters of lincomycin hydrochloride solution (3 g of lincomycin hydrochloride dissolved in 10 mL of mobile phase) was injected into the chromatograph and the eluted solution was collected between 6 min and 14.5 min (protein eluted from column within this period), and the residual content of total protein in the eluted solution was assayed using Bradford assay method. Results The average recovery was more than 90% for bovine serum albumin, the calibration equation for the range of 0-12 μg·mL^-1 of protein was y = -0.0024x² + 0.0642x + 0.0029, r²＝0.9999, RSD = 0.1%-0.9%, and the LOD and LOQ were 3 and 10 ng·mL^-1 of protein, respectively. Conclusion The novel method for determining the residual protein in ferment antibio-tics is simple, rapid, and precise.

Key words: Gel filtration chromatography, Gel filtration chromatography, bradford assay, bradford assay, residual protein, residual protein, ferment antibiotics, ferment antibiotics, lincomycin hydrochloride, lincomycin hydrochloride