Milk quality evaluation is essential for dairy industry and each country establishes its own directives, based on international standards, to evaluate and standardize milk parameters. In Brazil, all milk produced must be monthly submitted to analysis in one of 12 laboratories of Brazilian Network for Milk Quality (BNMQ). Due to the Brazilian large territorial extension, conservation by refrigeration and preservatives of samples are necessary, because samples will be analyzed after several days of being collected. Among substances used for milk preservation, IDF recognizes only boric acid, potassium dichromate, bronopol and sodic azide. We evaluated all 3 kinds of bronopol-based preservatives available on Brazilian market to use on milk samples destined to analyses on laboratories of BNMQ. Preservative tablets have the following composition: 8 mg bronopol, 0.30 mg natmicin and 10 mg inert carrier (P1); 8 mg bronopol, 12.5% natmicin, 20.76% yellow dye, NaCl, PVP solution (P2); 8 mg bronopol, 0.4 mg natmicin, 0.5 mg yellow dye (P3), according to manufacturers. Raw milk samples were collected in vials containing different microtablets of bronopol-based preservatives, stored at 4°C and analyzed during 14 d for Somatic Cell Count (SCC) and chemical composition through flow citometry and FTIR spectroscopy respectively. The entire experiment was repeated 8 times. Results were evaluated by ANOVA and Tukey’s test mean comparison (P < 0.05). All results obtained were according to standards for raw milk. There were no differences in fat, protein, casein, lactose, total solids, milk urea-nitrogen and SCC between preservatives.The 3 bronopol-based preservatives were used during 14 d of refrigerated storage and did not affect milk evaluated parameters. However, in practice P3 leads to analytical disorders, considering tablets dissolution time and interruptions on equipment operation, making its usage more difficult. Therefore, we recommend evaluation of bronopol-based preservatives and its convenience before electronic analysis.