A new LC-MS method has been established for determination of momoiodotyrosine(MIT) and diiodotyrosine(DIT) in the hydrolysate of premix feeds.Samples was hydrolyzed with 4.0 mol·L-1 NaOH for 16 h at 110 ℃,then the hydrolysate was cleaned up with a SPE cartridge and injected directly for LC-MS analysis.Chromatographic separation was performed on a 2.1 mm×150 mm,5 μm particle,C18 column with a mixture of acetonitrile and 0.1%(by volume) acetic acid as mobile phase at a flow rate of 0.2 mL· min-1.ESI+ mass spectrometry detection was run on SIR mode with m/z 308,262 for MIT,and m/z 434,388 for DIT.Quantification was carried out with external standard method.Validation data indicated the method was linear in the concentration ranges investigated with regression coefficients(R2) of more than 0.99.The limits of detection(LOD) were 8 μg·L-1 and limits of quantification(LOQ) were 30 μg·L-1.The recoveries were range of 93%-110% with relative standard deviations of 6.5%-13.2%.The method was sensitive,accurate,and was applied in the determination of MIT and DIT in real sample with satisfactory results.
本试验旨在研究三氧化二铬和氧化钛2种指示剂对测定玉米干酒糟及其可溶物(D D G S)生长猪标准回肠氨基酸消化率的影响。试验选用6头安装简单T型瘘管的三元杂交(杜洛克×大白×长白)去势公猪,初始体重为(35.1±2.1)kg,应用6×6拉丁方试验设计,分为6期,6种日粮,分别以三氧化二铬和氧化钛配制4种含D D G S日粮,2种无氮日粮。结果表明:玉米D D G S的赖氨酸和色氨酸标准回肠消化率最低;除组氨酸和苯丙氨酸外,2种指示剂对测定其他必需氨基酸和非必需氨基酸标准回肠消化率均无显著影响(P>0.05)。结果提示,三氧化二铬和氧化钛均可用于测定玉米D D G S氨基酸消化率。
