液相色谱-氢化物发生原子荧光光谱法测定富硒酵母中硒的形态

建立了富硒酵母中硒酸Se(Ⅵ)、亚硒酸Se(Ⅵ)、硒代蛋氨酸(SeMet)和硒甲基硒代半胱氨酸(SeMeCys)4种硒形态的高效液相色谱-氢化物发生原子荧光光谱(HPLC-HG-AFS)分析方法。样品采用蛋白酶和胰蛋白酶酶解提取,20 mmol/L(NH4)2HPO4为流动相,经PRP-X100阴离子交换色谱柱分离后HG-AFS测定。结果显示,4种硒形态标准曲线的线性关系良好(R2≥0.9995),方法检出限为0.5~5.0μg/kg,平均回收率为82.5%~101.2%,日内相对标准偏差≤8.6%,日间相对标准偏差≤14.5%。本方法前处理简单、灵敏度高、设备便宜、运行费用低廉,适用于富硒饲料产品中硒的形态分析。     

高效液相色谱与电感耦合等离子体质谱联用技术用于胁迫富硒海带硒形态研究

通过对海带胁迫富硒培养, 研究了海带对硒的富集总量及硒化学形态转变. 建立了反相离子对缓冲盐等3个色谱系统的高效液相色谱与电感耦合等离子体质谱联用(RP-HPLC-ICP-MS)技术测定亚硒酸钠、硒甲基半胱氨酸(MeSeCys)、硒代蛋氨酸(SeMet)三种硒形态. 采用3种提取溶剂, 超声提取缩短提取时间, 分离检测富硒海带的主要硒形态为亚硒酸钠、硒甲基半胱氨酸和硒代蛋氨酸.     

超声辅助酶法提取-原子荧光光谱法测定富硒黑木耳中硒形态

建立了富硒黑木耳中硒代胱氨酸、硒代半胱氨酸、亚硒酸、硒蛋氨酸、硒酸5种硒形态的液相色谱-原子荧光光谱分析方法。通过链酶蛋白酶E酶解,结合超声提取后,选取Hamilton PRP-X100离子交换色谱柱(250 mm×4.1 mm,10μm),40 mmol/L的磷酸氢二铵为流动相,在16 min内,5种硒形态完全达到基线分离。5种硒形态在线性范围内相关系数R为0.9990~0.9999;加标回收率为76.1%~108%;检出限分别为硒代胱氨酸0.35μg/L、甲基-硒代半胱氨酸0.46μg/L、亚硒酸0.26μg/L、硒代蛋氨酸0.64μg/L、硒酸3.06μg/L;方法应用于富硒黑木耳中硒形态的分析,精密度高、重现性好、方法稳定、准确可靠,是测定富硒黑木耳中硒形态含量的有效方法。     

超声辅助酶法提取-液相色谱-原子荧光光谱法测定富硒黑木耳中硒形态

建立了富硒黑木耳中硒代胱氨酸、硒代半胱氨酸、亚硒酸、硒蛋氨酸、硒酸5种硒形态的液相色谱-原子荧光光谱分析方法.通过链酶蛋白酶E酶解,结合超声提取后,选取Hamilton PRP-X100离子交换色谱柱(250 mm×4.1 mm,10μm),40 mmol/L的磷酸氢二铵为流动相,在16 min内,5种硒形态完全达到基...     

高灵敏度原子荧光光谱系统应用于砷、硒形态分析的研究

将实验室自制的高灵敏度原子荧光光谱系统与色谱分离、在线紫外光前处理装置联用,实现了元素形态的液相色谱分离、在线紫外消解、蒸气发生及原子荧光光谱测定,并以砷、硒两元素为例对系统的分析性能进行研究。样品通过加热混旋提取、离心、过滤,使用反相色谱柱并以5.0 mmol/L磷酸氢二铵缓冲溶液(pH 5.7)-0.5 mmol/L四丁基溴化铵(TBAB)-1%甲醇为流动相进行分离;三价砷(AsO3-3)、二甲基砷(DMA)、一甲基砷(MMA)、五价砷(AsO3-4)可在7 min内进行分离和测定,硒代胱氨酸(SeCys)、硒代蛋氨酸(SeMet)、四价硒(SeO2-3)、六价硒(SeO2-4)的测定约需11 min。在优化实验条件下,方法检出限(DLs,S/N=3)为0.08~0.74μg/L;相对标准偏差(RSD,n=7)为1.4%~7.9%,实际样品的加标回收率为82.5%~116.5%;砷、硒各形态在0.28~40.0μg/L和0.38~80.0μg/L范围内线性良好。建立的联用系统稳定性好、检出限低,可实现样品中低浓度砷、硒形态的准确测定。     

高效液相色谱-氢化物发生-原子荧光光谱法测定富硒食品中5种形态硒的含量

提出了将高效液相色谱-氢化物发生-原子荧光光谱法应用于富硒食品中硒的形态分析。选择木瓜蛋白酶(PP)作为提取剂,在如下优化条件下对样品中5种形态硒进行提取:(1)料液比1g/40mL;(2)50.0g·L~(-1) PP溶液加入量20mL;(3)于60℃水浴中振荡提取8h。提取液冷却并离心后取其上清液,用Hamilton PRP-X100离子交换色谱柱作为固定相,35mmol·L~(-1)磷酸氢二铵溶液(pH 6.0)作为流动相进行高效液相色谱的分离,5种形态硒[Se(Ⅵ)、Se(Ⅳ)、硒代胱氨酸(SeCys_2)、甲基-硒代半胱氨酸(MeSeCys)和硒代蛋氨酸(SeMet)]在16 min内完全分离。将分离所得分别含有5种形态硒的溶液先后引入仪器进行氢化物发生-原子荧光光谱法测定。结果表明:5种形态硒的质量浓度均在5~100μg·L~(-1)内与其对应的峰面积呈线性关系,5种形态硒的检出限(3S/N)为0.39~1.18μg·L~(-1)。按所提出方法对富硒大米样品进行加标回收和精密度试验,测得回收率为80.2%~118%,测定值的相对标准偏差(n=6)为2.1%~8.2%。     

断续流动氢化物发生原子荧光法测定富硒食品中的微量硒

建立了断贯流动氢化物发生原子荧光法测定富硒食品中微量硒的方法。样品用硝酸高氯酸混酸消化，在优化的实验条件下，标准曲线的线性范围为0-100μg/L，相关系数为0.9999。检测限0.06545μg/L。应用于测定鸡蛋，富硒米和富硒盐中微量硒的测定。回收率分别为90.6%,98.5%和104.3%。     

微波水解-液相色谱-原子荧光光谱法测定硒蛋白中的硒代氨基酸

针对酶解法测定硒代氨基酸操作复杂,时间长,水解不完全且水解产物不稳定等问题,建立一种微波水解-液相色谱-原子荧光光谱仪测定硒蛋白中硒代氨基酸的方法。样品经HCl(6 mol/L)微波水解后,调节pH值至7.5,采用阴离子色谱柱,pH=6.0的(NH_(4))_(2)HPO_(4)(40 mmol/L)溶液为流动相,流速0.6 mL/min,等度洗脱12 min的条件对硒代胱氨酸(SeCys_(2))、甲基-硒代半胱氨酸(MeSeCys)和硒代蛋氨酸(SeMet)进行分离,用原子荧光光谱仪测定其含量。微波水解条件采用星点设计-响应面法进行优化,优选最佳水解条件为:称样量20 mg,水解温度150℃,水解时间40 min。SeCys_(2)、MeSeCys和SeMet均在0~100 ng浓度范围内呈线性关系,相关系数均大于0.999,检出限分别为0.07、0.03和0.14 mg/kg,RSD分别为5.6%、4.6%、3.7%(n=6)。用来测定硒代氨基酸,耗时短,成本低,水解完全,操作简单,水解产物稳定,能够科学评价硒蛋白中硒代氨基酸的组成,对硒蛋白产品的质量控制和溯源提供了科学方法,值得推广应用。     

高效液相色谱-电感耦合等离子体质谱（HPLC-ICP-MS）联用测定富硒小麦中硒代氨基酸

为科学补硒和促进富硒小麦的种植推广,建立了高效液相色谱-电感耦合等离子体质谱联用技术(HPLC-ICP-MS)检测富硒小麦中硒代氨基酸的方法。用蛋白酶XIV辅助微波振荡提取富硒小麦中硒代氨基酸,采用C18 分离柱分离,以30.0mmol/L磷酸氢二铵+1.0%甲醇+2.0mmol/L四丁基溴化铵溶液(pH=6.5)为流动相,能在10min内实现5种硒代氨基酸的分离。在高能氦气模式（HEHe）下,用78Se的色谱峰积分面积作为定量依据,5种硒代氨基酸在1.0～200.0μg/L范围内线性相关性良好,检出限在 0.11~0.29μg/L之间。以富硒小麦为基体进行加标回收试验,除硒代胱氨酸（SeCys2）可能不稳定,易分解造成回收率偏低外,其他4种硒代氨基酸的加标回收率在92.34～102.46%之间,相对标准偏差为 1.6 %~4.2 %（n=7）。用该方法测定了农业科技工作者种植推广的富硒小麦,结果发现小麦中的硒赋存形态多为硒代蛋氨酸（SeMet）,此外,小麦中还含有少量硒代胱氨酸（SeCys2）、硒代半胱氨酸（SeCys）、甲基硒代半胱氨酸（MeSeCys）和硒代乙硫氨酸（SeEt)。该方法具有良好的精密度和准确度,适用于富硒小麦中硒代氨基酸的形态分析。     

柱前衍生化-HPLC法测定恩施3种富硒蔬菜中硒氨基酸

采用HPLC与ICP-MS间隙联用的方法,以柱前衍生化-HPLC法进行定性定量分析,使用ICP-MS鉴定,建立一种富硒蔬菜中硒氨基酸的分离检测方法。结果表明:所测定的硒代氨基酸在其线性范围内呈现良好的线性关系(R2>0.999)。该方法中硒代蛋氨酸和硒代胱氨酸的检出限分别为0.204 mg/L和0.680 mg/L,加标回收率分别为97.4%和94.0%,RSD分别为2.1%和0.69%。检测恩施富硒蔬菜样品,白菜、萝卜叶和苋菜含有硒代蛋氨酸和硒代胱氨酸。此方法可用于富硒蔬菜中硒代氨基酸的含量检测。     

Observation in the Growth of Selenium Nanoparticles

A mild chemical reduction method was developed to synthesize selenium nanoparticles. The observation of the particle growth within a five‐minute time frame at an elevated temperature is achieved, and it was evidenced by analyzing the particle sizes from electron micrographs. The samples at individual growth stages were taken after the reaction was quenched by cooling to stop further particle growth. The nucleation and growth processes dominate different reaction time regimes under the experimental condition. We demonstrate the size evolution of the selenium nanoparticles from 30 nm to about 200 nm.     

Specific determination of selenoaminoacids in whole milk by 2D size-exclusion-ion-paring reversed phase high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP MS)

A procedure was developed for the quantitative recovery of selenomethionine (SeMet) and selenocysteine (SeCys) from whole milk. It was based on the protein unfolding, carbamidomethylation of the aminoacid residues using iodoacetamide and proteolysis using Protease XIV. The selenoaminoacids were specifically determined by ion-paring reversed phase HPLC-ICP MS after their isolation from the post-reaction mixture by size-exclusion LC. Se(IV) present in the sample was derivatized as well and was determined along with the selenoaminoacids. The origin and identity of species were identified by the co-elution with the Se(IV), isotopically labelled selenomethionine, and with the synthetic standard of carbamidomethylated selenocysteine. The method development for SeCys was assisted by using glutathione peroxidise as the SeCys standard. SeMet, SeCys and Se(IV) were quantified by the method of standard additions. The mass balance provided a measure of the method validation. The method was applied to monitoring selenium speciation during supplementation of cows (dose-effect study) with Se-rich yeast containing feed and during milk processing.     

阴离子交换色谱-电感耦合等离子体质谱法测定长期汞暴露人群硒干预后血清中的小分子硒形态

建立了阴离子交换高效液相色谱-电感耦合等离子体质谱联用测定不同形态硒的在线分离检测方法,并将其应用于长期汞暴露人群血清中小分子硒的形态研究.流动相A为0.5 mmol/L柠檬酸铵-2%(V/V)甲醇(pH 3.7),流动相B为100 mmol/L柠檬酸铵-2%(V/V)甲醇(pH 8.0);采用93%A-7%B时,硒代...     

Die Reaktion von SePh2 mit N‐Chlorsuccinimid. Kristallstrukturen von [SeCl2Ph2] und [SeCl2Ph2(Succinimid)2]

Reaction of SePh₂ with N‐Chlorosuccinimide. Crystal Structures of [SeCl₂Ph₂] and [SeCl₂Ph₂(succinimide)₂] SePh₂ reacts with N‐chlorosuccinimide in acetonitrile solution to give [SeCl₂Ph₂] ( 1 ) and [SeCl₂Ph₂(succinimide)₂] ( 2 ) as colourless crystals, which can be separated by fractional crystallization. According to X‐ray single crystal determinations both compounds contain [SeCl₂Ph₂] molecules with ψ‐trigonal‐bipyramidal coordination at the selenium atom, the chloro ligands being in apical positions. In 2 the dimeric unit (HNC₄O₂H₄)₂ is linked with its [SeCl₂Ph₂] unit via a weak C–H···O hydrogen bond. 1 : Space group Pbcn, Z = 4, lattice dimensions at 193 K: a = 1350.6(1), b = 573.3(1), c = 1503.3(2) pm, R₁ = 0.0326. 2 : Space group I2/a, Z = 4, lattice dimensions at 193 K: a = 1363.9(1), b = 557.7(1), c = 2781.3(1) pm, β = 101.01(1)°, R₁ = 0.0286.     

Fourier-transform infrared spectroscopic study of the interactions of selenium species with living bacterial cells

A study of the interactions of several selenium species with living bacterial cells was carried out by Fourier-transform infrared (FT-IR) spectroscopy. Bacterial cells consisted of an Escherichia coli strain (K-12) cultivated in a growth medium based on glucose contaminated with selenium species. Equilibrium between the analyte in the solution and the extraction medium was established, and then the effects of selenium species upon the external membrane of the living bacterial cells were characterized by performing FT-IR spectroscopy of whole cells. The presence of the toxicants at various concentrations in the culture medium had an effect on the FT-IR spectra, and the concentration of the selenium species was determined directly in the biomass by FT-IR spectroscopy. The intensity ratios between several absorption lines, which varied as a function of the concentration of the selenium species, were used as the analytical signal.Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

硒的土壤化学及其生物有效性

硒是重要的生命元素。高硒和低硒均会引起动物发生各种疾病，硒由土壤进入植物体，通过食物链控制着动物的硒营养状况，因此研究硒的土壤化学及其对生物的有效性对维护人类健康和牲畜生产是十分有意义的，本文拟就土壤中硒的含量、形态、有效性影响因素，硒的保健作用和调节措施等方面作一综述。     

Determination of trimethylselenonium iodide, selenomethionine, selenious acid, and selenic acid using high-performance liquid chromatography with on-line detection by inductively coupled plasma mass spectrometry or flame atomic absorption spectrometry

An analytical method has been developed for the determination of selenious acid, selenic acid, trimethylselenonium ion, and selenomethionine. The four selenium compounds were separated by HPLC on a column (25 cm×4 mm I.D.) of the anion-exchanger ESA Anion III with a mobile phase (1.5 ml/min) of 0.0055 M ammonium citrate (pH 5.5). Detection was carried out using an on-line inductively coupled plasma mass spectrometer (ICP-MS) or a flame atomic absorption spectrometer (FAAS) as the selenium-specific detector. The chromatographic parameters and the chemical factors affecting the separation of the selenium species were optimized. The four selenium compounds could be separated within 8 minutes. The detection limits of the coupled HPLC–FAAS system were approximately 1 mg Se/l for each compound (100 μl injection), estimated as three times the base-line noise of the chromatograms. More powerful selenium detection was achieved with an ICP-MS. Selenium was measured at m/z 78. To increase the nebulization efficiency, the Meinhard concentric glass nebulizer was replaced by an ultrasonic nebulizer. The ICP-MS signal intensity was increased with the ultrasonic nebulization by a factor of 7 times for selenious acid and 24 to 31 times for trimethylselenonium ion, selenomethionine, and selenic acid compared to that with the Meinhard nebulization. The detection limits achieved by the HPLC–ICP-MS with the ultrasonic nebulization were 0.08 μg Se/l for trimethylselenonium ion, 0.34 μg Se/l for selenious acid, 0.18 μg Se/l for selenomethionine, and 0.07 μg Se/l for selenic acid, respectively.     

Measurement of total selenium and selenium(IV) in seawater by stripping chronopotentiometry

We developed a stripping chronopotentiometric method (constant current stripping analysis, CCSA) with a mercury film electrode for selenium quantification in seawater. A sensitivity and detection limit of 222 ms ng^–1 l and 4 ng l^–1 (50 pM), respectively, were accomplished for a 3-min electrolysis time. Compared to the other chronopotentiometric methods available for a single selenium measurement only in natural waters, our procedure exhibits a ten times better sensitivity. It, therefore, allows one to reach the current concentration thresholds found in coastal and oceanic waters (30–200 ng l^–1). Moreover, a simple change in operating conditions enables one to also quantify Se(IV), a toxic dissolved species. With respect to the other electrochemical methods of current use, our procedure is beneficial because of its ease-of-use: it needs neither degassing step, nor catalyser.     

The first example of α-organoseleno arsonium ylides and its Wittig-type reaction

α-Organoseleno arsonium ylide 3 was synthesized for the first time by a phenylselenenylation-transylidation reaction. It has sufficient activity to carry out the Wittig-type reaction, affording a novel method for the stereoselective synthesis of (Z)-α-phenyl-seleno-α, β-unsaturated esters 6.     

Effects of interfering elements and chemical modifier on the activation energy of electrothermal atomization of selenium

In order to obtain additional insight into the mechanism of stabilization of selenium by palladium modification and to investigate the interference mechanism of Na, K, Mg and Ca on selenium atomization, the appearance temperature and the activation energy of atomization of selenium with or without the presence of the modifier and with or without the presence of the concomitant element, have been evaluated and discussed.