Viscomagnetic Study of Bovine Serum Albumin and Egg Albumin Proteins in Aqueous Solutions

Intrinsic viscosities [η] for 0.2, 0.4, 0.6, and 0.8 mg% aqueous of each Bovine serum albumin (BSA) and egg albumin (EA) solutions under zero, 0.5 and 0.7 magnetic flux at 298.15 K and 1 atmosphere are reported. The [η] data for BSA are higher than EA and values of both increase with magnetic flux strengthening molecular interactions.     

分散固相萃取结合HPLC-MS/MS检测鸡蛋中16种全氟化合物

建立了分散固相萃取净化结合HPLC-MS/MS测定鸡蛋中16种全氟化合物(Perfluorinated compounds,PFCs)的方法。样品经乙腈40℃下超声萃取,氮吹浓缩,石墨化碳黑分散萃取净化后,采用HPLCMS/MS进行测定,基质曲线-内标法定量。结果显示,16种PFCs在0.50~10.0μg/L浓度范围内呈良好线性,相关系数(r)为0.996 2~0.999 9,检出限为0.001~0.093μg/kg,定量下限为0.003~0.310μg/kg。在0.5,1.0,2.0μg/kg 3个加标浓度水平下,16种PFCs的加标回收率为79%~125%,相对标准偏差(RSDs,n=6)为0.26%~14%。该方法具有净化效果好、定量准确、灵敏度高的特点,适用于鸡蛋样品中16种常见全氟化合物的快速确认和准确定量。     

Fluorescence of organic dyes in lipid membranes: Site of solubilization and effects of viscosity and refractive index on lifetimes

The fluorescence decay of several organic dye molecules intercalated in egg phosphatidylcholine lipid membrane vesicles is consistent with the existence of two or three prominent lifetime components rather than a single continuous distribution of lifetimes. The major lifetime components are identified with different sites of solubilization in the membrane. The variation of the lifetime of the membrane-bound dye was studied as a function of the sucrose concentration, which varied the viscosity and refractive index of the aqueous solution. The combined effect of viscosity and refractive index on the lifetime of the dye was used to identify the site of solubilization of the dye in the membrane. The study was useful to identify dye molecules on the surface which are exposed to the aqueous phase, for which the fluorescence lifetime increased systematically with sucrose (viscosity effect). More importantly, it was possible in a few cases to identify the dye molecules which are oriented in the membrane phase, and the fluorescence lifetime decreased systematically with sucrose (refractive index effect). Anomalous values of order parameters determined from the refractive index effect are explained in terms of an orientational distribution of the linear dye molecule weighted in favor of mutually orthogonal orientations.     

TSD based framework for mining the induction rules

Sex determination mainly encompasses two aspects: genotypic sex determination (GSD) and temperature-dependent sex determination (TSD). Genotypic sex determination performs its task by observing the presence of sex chromosomes. In many reptiles sex determination is greatly influenced by the environmental conditions such as temperature of the nest, weight and size of eggs. A nature inspired algorithm which mimics the mechanism of temperature dependent sex determination (TSD) has been introduced for mining the classification rules from datasets. A comparison of proposed TSD algorithm with other well known rule induction algorithms like PRISM, C4.5, 1-R, CN2, and NN has been evaluated on some bench mark datasets.     

高效液相色谱法测定禽蛋及其制品中的三聚氰胺

建立了高效液相色谱测定禽蛋类及加工品中三聚氰胺的检测方法．以经三聚氰胺标准添加的鸡蛋、咸鸭蛋和松花蛋为代表性样品,优化了提取溶剂的种类、用量和提取时间条件,探讨了直接过滤、正己烷反萃和固相萃取三种前处理方式的净化效果,并考察了测定时流动相比例和缓冲液的pH条件．实验结果表明：当添加浓度为0．20和10．0μg／g时,三聚氰胺的回收率分别为87．6％-101．5％,测量标准偏差为1．6％～2．8％,方法检出限为0．05μg／g．标准溶液在0．10～2．00μg／mL范围内,线性关系良好,相关系数r=0．9999．利用本方法对12个实际禽蛋样品进行测定,结果表明能够满足禽蛋及其制品中三聚氰胺残留的快速筛查要求．     

液相色谱串联质谱法快速测定牛奶与鸡蛋中的维吉霉素M_1残留量

建立了牛奶和鸡蛋样品中维吉霉素M_1残留的液质联用确证方法.用乙腈萃取样品中的维吉霉素M1残留,水稀释后,正己烷脱脂,以YMC-Pack Pro C_(18)色谱柱为分离柱,在正离子模式下以电喷雾电离串联质谱仪进行测定.方法的线性范围为2.5 ～25 μg/L,定量下限为50 μg/kg.在50、100、200 μg/kg 3个浓度水平进行加标回收实验,回收率为72% ～99%,相对标准偏差为2.7% ～6.1%.该方法简便、快速、准确,各项技术指标满足国内外法规的要求,可用于牛奶和鸡蛋样品中维吉霉素M1残留的快速确证检测.     

一种用于鸡蛋中氯霉素残留测定的吡啶类离子液体双水相体系

建立了由亲水性离子液体N-乙基吡啶溴化盐([Epy]Br)和K2HPO4形成的双水相体系对鸡蛋中痕量氯霉素(CAP)检测的高效液相色谱方法.优化了离子液体[Epy]Br和K2HPO4成相的条件,研究了萃取CAP的最佳体系.采用混合溶液(pH=7磷酸盐溶液,NaCl溶液,甲醇)提取样品,离子液体双水相体系富集,V(甲醇):V(水)=30:70为流动相,流速1.0 mL/min,UV检测器,检测波长278 nm,柱温25 ℃,进样量20 μL.对鸡蛋中氯霉素残留进行了测定,在0.05～15 mg/L范围内,CAP的响应峰面积与其相应浓度呈良好相关性(r=0.9994).不同浓度的回收率为90.3%～101.7%,相对标准偏差为1.7%～2.6%.本该法检测鸡蛋中氯霉素残留具有干扰小、速度快、灵敏度高等优点.最低检出限为1 μg/kg.     

高效液相色谱同时测定鸡蛋中4种氟喹诺酮类药物残留

建立了固相萃取—反相高效液相色谱同时分析鸡蛋样品中4种氟喹诺酮类药物残留量的方法。对鸡蛋样品的提取及其在C18固相萃取柱上的净化条件进行了研究,采用高效液相色谱分离,荧光检测器检测(λex=280nm,λem=450nm),外标法定量。4种沙星标准曲线的线性回归系数均在0．9999以上,环丙沙星、恩诺沙星、沙拉沙星的线性范围为2．5～500μg／L;达诺沙星为0．5～100μg/L。鸡蛋样品中4种沙星的加标回收率为78．1％～95．7％;相对标准偏差为4．1％～16．2％。环丙沙星、恩诺沙星、沙拉沙星的最低检出限为10μg／kg;达诺沙星的最低检出限为2μg/kg。     

喂食鸡蛋的清洁级KM小鼠血清中微量元素含量的变化

在屏障系统内 ,给清洁级KM小鼠在日粮中添加鸡蛋 ,用原子吸收光谱法测定了血清中 5种微量元素 ,进行了统计学分析。结果表明 ,实验组的Fe显著高于对照组 (P <0 0 1 ) ,实验组的Zn显著低于对照组 (P <0 0 1 ) ,而Cu、Ca、Mg含量与对照组比较无统计学意义 (P >0 0 5 )。结果提示 ,经常食用鸡蛋等天然食品 ,可提高体内一些必需微量元素的含量     

QuEChERS-超高效液相色谱-串联质谱法测定鸡蛋中125种兽药残留

采用冷冻脂质过滤,结合分散固相萃取净化的QuEChERS方法,建立了超高效液相色谱-串联质谱法测定鸡蛋中125种兽药残留的检测方法。样品中的11类兽药（硝基咪唑类、苯并咪唑类、磺胺类、喹诺酮类、四环素类、大环内酯类、雄激素类、孕激素类、糖皮质醇类、雌激素类、氯霉素类）用70%（v/v）乙腈-水溶液（含0.1 mol/L EDTA）提取后,提取液在-20℃冷冻处理2 h,再经分散固相萃取法净化,净化液经稀释后,以超高效液相色谱-串联质谱法测定,外标法定量。结果显示125种兽药的线性相关系数R²≥0.99,定量限范围为2.0~60 μg/kg,回收率在60.4%~119.3%之间,相对标准偏差在0.3%~16.1%之间。该方法前处理简单、准确、成本较低,适用于鸡蛋中兽药残留的高通量快速检测分析。