HPLC determination of ethoxyquin and its major oxidation products in fresh and stored fish meals and fish feeds

✍ Scribed by He, Ping; Ackman, Robert G

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 104 KB
• Volume: 80
• Category: Article
• ISSN: 0022-5142
• DOI: 10.1002/(sici)1097-0010(20000101)80:1<10::aid-jsfa478>3.0.co;2-t

✦ Synopsis

A new method was developed to determine 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline (EQ, ethoxyquin), 2,6-dihydro-2,2,4-trimethyl-6-quinolone (QI) and 1,8'-di(1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline) (DM) in ®sh meals or ®sh feeds, QI and DM being the oxidation products of EQ. The sample was ®rst extracted with hexane. After the removal of hexane the three analytes were extracted from the resulting oil with acetonitrile and determined by C 18 reverse phase highperformance liquid chromatography with a UV detector set at l = 280 nm. The mobile phase was acetonitrile±0.01 M ammonium acetate (80:20 v/v). The recoveries for EQ, QI and DM from the samples spiked at different levels varied in the ranges 90±100 per cent, 75±85 per cent and 90±100 per cent respectively. At room temperature, QI and DM were the major oxidation products of EQ in stored ®sh meals and ®sh feeds. Loss of EQ from ®sh meals is faster than that from feeds, resulting in relatively higher accumulations of QI and DM in the ®sh meals. Both QI and DM, especially the former, were not stable during storage of either and could be further oxidised to unidenti®ed compounds. The residue levels of these two compounds were thus unpredictable during storage intervals. When the storage temperature was increased to 50 °C, EQ disappeared more rapidly, but neither QI nor DM accumulated.