反相离子对高效液相色谱-电感耦合等离子体质谱法测定富硒酵母中硒

Ion-Pair RP-HPLC-ICP-MS Determination of Selenium in Selenium-Enriched Yeast

富硒酵母样品用pH 7.5的Tris-盐酸缓冲溶液经超声破碎提取30min,于提取液中加链霉蛋白酶E在37℃搅拌18h,高速离心分离。取上清液经Millipore Corp超滤膜过滤,滤液中无机硒(Ⅵ及Ⅳ)和有机硒,即硒代半胱氨酸、硒代尿素和硒代蛋氨酸通过Waters Symmetry ShieldRP18色谱柱分离。用不同比例混合的甲醇-七氟丁酸溶液作流动相进行梯度洗脱,用电感耦合等离子体质谱法在线测定洗脱液中各种形态硒的含量。5种形态硒的质量浓度均在100μg·L-1以内呈线性。应用此法分析了富硒酵母样品,结果表明:无机硒占总硒量的1.63%,65%的硒以易被人体吸收的硒代蛋氨酸形式存在。

Sample of selenium-enriched yeast was extracted with Tris-HCl buffer solution of pH 7.5 by ultrasonic smashing for 30 min.Protein hydrolytic enzyme Pronase E was added to the extract,which was stirred at 37 ℃ for 18 h and separated by high speed centrifugation.The supernatant was taken and filtrated with Millipore Corp super-filtering membrane.Waters Symmetry Shield RP18 chromatographic column was used for separation of inorganic selenium（Ⅵ and Ⅳ） and organic selenium compounds of Selenocysteine,Selenourea and Seleno-methionine.Mixtures of methanol and heptafluoro-butanoic acid mixed in different ratios were used as mobile phase in gradient elution for the 5 species of selenium.The eluates were used for ICP-MS determination.Linear relationships of the 5 species of selenium were kept in the same range within 100 μg·L-1.The proposed method was applied to the analysis of sample of selenium-enriched yeast.It was found that： the amount of inorganic selenium was only amounting to 1.63% of the total selenium.The major species of selenium existed in yeast was selenomethionine,amounting to 65%,which was easily absorbed and utilized by the human body.