Separation and determination of bromophenols in Trachypenaeus curvirostris and Lepidotrigla microptera by capillary zone electrophoresis

Bromophenols have been identified as key off-flavor compounds found in seafood. In this report, a new method of capillary zone electrophoresis (CZE) was established for simultaneous assay of five bromophenols, 4-bromophenol (4-BP), 2,4,6-tribromophenol (2,4,6-TBP), 2,4-dibromophenol (2,4-DBP), 2-bromophenol (2-BP) and 2,6-dibromophenol (2,6-DBP), in seafood. The optimum buffer system was 20 mM borate-NaOH buffer (pH 10.00). Voltage was +30 kV and the ultraviolet absorbance detection at 280 nm. The column was an uncoated 50 mu m ID fused-silica capillary. Regression equations revealed linear relationships (correlation coefficients: 0.9990, 0.9998, 0.9997, 0.9999 and 0.9989) between the peak area of each compound and its concentration. Calibration curves were constructed in the range of 18.8 - 1200, 15 - 960, 9.4 - 600, 10.6 - 680 and 3.0 - 370 mg/mL for 4-BP, 2,4,6-TBP, 2,4-DBP, 2-BP and 2,6-DBP, respectively. The relative standard deviations of migration times and peak areas were <2.1% and 4.9% within one day, respectively. The recoveries of bromophenols were 91.5 - 103.4%. The detection limits (S/N = 3) of 4-BP, 2,4,6-TBP, 2,4-DBP, 2-BP and 2,6-DBP were 1.6, 1.9, 1.2, 0.9 and 1.4 mg/mL, respectively. The effects of several CE parameters on the resolution were studied systematically. Compared with liquid chromatography, the method described here is relatively rapid and can give symmetrical peaks. The contents of 5 bromophenols in seafood (Trachypenaeus curvirostris and Lepidotrigla microptera) were determined with satisfactory repeatability and recovery. The contents of 4-BP, 2,4,6-TBP, 2,4-DBP and 2,6-DBP in T curvirostris were 3.9, 2.5, 7.3 and 0.6 ng/g, respectively. The feasibility of this method for the determination of bromophenols in freshwater fish and crustaceans (Macrobrachium nipponense and Carassius auratus var. Pengzesis) also tested. The result indicated that these flavor compounds in freshwater fish and crustaceans were lower than the detection limits mentioned above.