柱前衍生-高效液相色谱法测定巴戟天中氨基酸含量及营养价值评价

建立柱前衍生-高效液相色谱法测定巴戟天中氨基酸含量,采用氨基酸比值系数法评价其营养价值。采用盐酸水解法制得巴戟天氨基酸供试品溶液,以异硫氰酸苯酯和三乙胺为柱前衍生化试剂,采用高效液相色谱法,使用Ultimate Amino Acid色谱柱(4.6 mm×250 mm,5μm)以0.1 mol/L无水乙酸钠-乙腈为流动相,梯度洗脱,柱温40℃,检测波长为254 nm,测定氨基酸含量;通过氨基酸比值、氨基酸比值系数、氨基酸比值系数分等评价其营养价值,并采用系统聚类和主成分分析对其进行分类分析。结果表明,15种氨基酸线性关系良好,相关系数r≥0.9996。16份巴戟天氨基酸总含量为17.87~102.15 mg/g,均检测到15种氨基酸,其中包含6种必需氨基酸,占总氨基酸含量的14.15%~32.06%;8种药用氨基酸,占总氨基酸含量的45.20%~56.31%。限制氨基酸为苏氨酸和亮氨酸,氨基酸比值系数分为33.87~61.31。不同巴戟天样品氨基酸组成相关性显著;主成分分析提取2个主成分,累计方差贡献率为97.085%,可将16批巴戟天分为三类。该实验测定方法简单有效,可同时分离测定15种氨基酸,精密度与重复性良好,有较高的药用价值,可为巴戟天的品质分析和资源开发利用提供参考。

柱前衍生-高效液相色谱法测定化妆品中16种氨基酸的含量

提出了2,4-二硝基氟苯(DNFB)柱前衍生-高效液相色谱法测定化妆品中甘氨酸、亮氨酸、组氨酸、缬氨酸、甲硫氨酸、脯氨酸、半胱氨酸、苏氨酸、谷氨酸、赖氨酸、酪氨酸、精氨酸、异亮氨酸、色氨酸、苯丙氨酸、丙氨酸等16种氨基酸含量的方法。取化妆品样品5 g置于50 mL离心管中,加入5 mL水,超声10 min,加热煮沸15 min,冷却后加入15 mL 35 g·L^(−1)磺基水杨酸溶液,以转速10500 r·min^(−1)离心20 min。取全部上清液,用35 g·L^(−1)磺基水杨酸溶液定容至25 mL。取1 mL样品溶液,加入0.5 mol·L^(−1)碳酸氢钠溶液(pH 9.0)1 mL和1%(体积分数)DNFB衍生溶液1 mL,混匀,于60℃加热10 min,冷却后用0.01 mol·L^(−1)磷酸二氢钾溶液(pH 7.0)定容至5 mL,所得溶液中16种氨基酸经X Bridge C_(18)色谱柱分离,以不同体积比的含1%(体积分数)N,N-二甲基甲酰胺的0.05 mol·L^(−1)乙酸钠缓冲液(pH 6.5)-体积比1∶1的乙腈-水混合溶液为流动相进行梯度洗脱,在360 nm处检测。结果表明:16种氨基酸标准曲线的线性范围均为0.004~40.0 mg·L^(−1),检出限(3S/N)为0.1~0.2 mg·kg^(−1);对空白样品进行3个浓度水平的加标回收试验,回收率为89.0%~105%,测定值的相对标准偏差(n=7)均不大于10%。方法用于11种市售化妆品分析,检出的氨基酸成分多为组氨酸、甘氨酸、甲硫氨酸、谷氨酸。

柱前衍生法-HPLC测定化妆品中甲醛的不确定度评定

分析柱前衍生法-HPLC测定化妆品中甲醛的不确定度。根据《化妆品安全技术规范》(2015年版)第四章理化检验4.12方法甲醛测定和JJF1059.1-2012《测量不确定度评定与表示》,建立分析柱前衍生法-高效液相色谱法测定甲醛的不确定度数学模型,通过对整个测定过程中的不确定度来源进行分析和合成,运用最小二乘法对甲醛标准曲线拟合不确定度进行评定。取样量为0.2 g时,置信区间为95%时,K=2,化妆品中甲醛含量为(14.9±0.072104)mg/g。

Determination of Sparfloxacin in Human Urine by Reversed-Phase High Performance Liquid Chromatography With Nitrous Acid and Hydroiodic Pre-Column Derivatization

Sparfloxacin can be oxidized by nitrous acid, then react with hydroiodic acid to form a fluorescent derivative. Based on this, a reversed-phase high performance liquid chromatographic pre-column derivatization new method is described for the determination of sparfloxacin in human urine. The linear range is 0.05 mg/L to 4.0 mg/L, the recoveries are 91.5%similar to 95.7% and the RSD is 1.2%similar to4.2%. The results showed that this method is suitable for the determination of sparfloxacin in human urine.

Determination of 18 Kinds of Amino Acids in Fresh Tea Leaves by HPLC Coupled with Pre-column Derivatization

A rapid and accurate quantitative method of high performance liquid chromatography( HPLC) with fluorescence detector has been developed for the analysis of 18 kinds of amino acids in fresh tea leaves. The samples were minced and mixed,and extracted with ultra pure water at 90℃ for 20 min. The 6-aminoquinolyl N-hydroxy-succinimidyl carbamate( AQC) was used as pre-column derivatization reagent. Gradient HPLC separation was performed on a C_(18) column( Symmetry C_(18),3. 9 mm × 15 cm,4 μm). Good linearity between concentrations and peak areas was achieved in the concentration range of 5. 0-250 μmol/L for 18 kinds of amino acids. The method was validated by the analysis of five replicates. The 18 kinds of amino acid standards were spiked in fresh tea leaf samples and the average recovery rate was 86. 25%-109. 05% with relative standard deviations( n = 5) ranging from 6. 03% to 10. 56%. The limit of detection( LOD) for the analytes was0. 05-1. 27 μmol/L. The method was successfully applied to the analysis of the 18 kinds of amino acids in fresh tea leaves from east Dongting and west Dongting mountains in Suzhou. The results indicate that the method is simple,rapid,precise and reliable.

Experimental study on seismic behavior of circular RC columns strengthened with pre-stressed FRP strips

Bonding fiber reinforced polymer （FRP） has been commonly used to improve the seismic behavior of circular reinforced concrete （RC） columns in engineering practice. However, FRP jackets have a significant stress hysteresis effect in this strengthening method, and pre-tensioning the FRP can overcome this problem. This paper presents test results of 25 circular RC columns strengthened with pre-stressed FRP strips under low cyclic loading. The pre-stressing of the FRP strips, types of FRP strips and longitudinal reinforcement, axial load ratio, pre-damage degree and surface treatments of the specimens are considered as the primary factors in the tests. According to the failure modes and hysteresis curves of the specimens, these factors are analyzed to investigate their effect on bearing capacity, ductility, hysteretic behavior, energy dissipation capacity and other important seismic behaviors. The results show that the initial lateral confined stress provided by pre-stressed FRP strips can effectively inhibit the emergence and development of diagonal shear cracks, and change the failure modes of specimens from brittle shear failure to bending or bending-shear failure with better ductility. As a result, the bearing capacity, ductility, energy dissipation capacity and deformation capacity of the strengthened specimens are all significantly improved.

柱前衍生-高效液相色谱-荧光检测法测定白酒中的甜蜜素

白酒中甜蜜素(化学名为环己基氨基磺酸钠)是我国食品安全监督抽检计划中的重点关注项目,生产企业亟需简单、经济、灵敏度高而且可靠的检测方法。本研究建立了柱前衍生-高效液相色谱-荧光检测法测定白酒中甜蜜素的方法。在酸性条件下,通过脱磺酸基反应将样品中的环己基氨基磺酸钠转化为氨基化合物,然后加入400 g/L的氢氧化钠溶液中和样品处理液,再加入邻苯二甲醛衍生试剂与样品溶液中的氨基化合物进行反应,产生具有荧光信号的吲哚取代衍生物。以反相C18色谱柱(250 mm×4.6 mm,5μm)为分析柱,乙腈和磷酸盐缓冲液为流动相进行等度洗脱,荧光检测器检测,外标法定量。结果表明,甜蜜素在0.1~2.0 mg/L范围内呈良好的线性关系,其相关系数(r^(2))大于0.999。基于白酒样品,在0.1~1.0 mg/kg含量范围内进行3个浓度水平的加标回收试验(n=6),平均回收率为90.7%~100.9%,相对标准偏差为3.5%~5.6%,方法的检出限为0.03 mg/kg,定量限为0.10 mg/kg。应用本方法对市售9种白酒样品进行检测,结果与GB 5009.97-2016(第三法)液相色谱-串联质谱法所得结果一致。本方法具有成本低、灵敏度高、专属性强、定量结果准确的特点,适用于大批量白酒中甜蜜素的定量检测,可为生产企业或相关机构进行白酒中甜蜜素的日常监测提供有力的技术支持。

Enantioresolution of a Series of Chiral Benzyl Alcohols by HPLC on a Dinitrobenzoylphenylglycine Stationary Phase after Achiral Pre-Column Derivatization

High performance liquid chromatography method for the separation of a series of chiral benzyl alcohols on N-(3,5-dinitrobenzoyl)-D-phenylglycine stationary phase (Macherey Nagel, Chiral-2) after pre-column achiral derivatization was developed. Cheap and easy available aromatic acid chlorides were used as derivatization agents. Good to excellent separations of the enantiomers were achieved in all cases in relatively short analytical runs. It was shown that the enantiorecognition depends on the substituents both in the starting alcohol and in the acid chloride. The method presents an efficient alternative to the direct analyses on polysaccharide and cyclodextrine-derived stationary phases.

Coupling of on-Line Pre-Column Oxidative Cleavage and Solid-Phase Enrichment with Liquid Chromatography Using an Eco-Friendly Analytical Procedure to Determine Low Levels of Methotrexate

A simple, sensitive and precise green high-performance liquid chromatographic method including on-line pre-column oxidation combined by column switching with a short Hypersil ODS analytical column (100 mm × 4.0 mm i.d.) for enrichment and separation was developed and validated to determine low levels of methotrexate (MTX). The method was based on oxidative cleavage of MTX into highly fluorescence products, 2,4-diaminopteridine-6-carboxaldehyde and the corresponding 2,4-diaminopteridine-6-carboxylic acid, during the flow of phosphate buffer (0.04 M, pH 3.4) containing the analyte through the packed reactor of cerium (IV) trihydroxyhydroperoxide (CTH) at a flow-rate of 0.2 mL/min and 40℃. The fluorescent products were enriched on the head of ODS analytical column for the final separation. The separation was performed at room temperature using an environmentally friendly mobile phase consisting of ethanol and phosphate buffer (0.04 M, pH 3.4) in the ratio of 10:90 (v/v). The eluent was monitored at emission and excitation wavelengths of 463 and 367 nm, respectively. The method was successfully applied, without any interference from the excipients, for the determination of drug in tablets and vials with a detection limit of 0.06 ng/mL from 500 ?L of sample MTX.

HBV PreS2+S/IFN-α融合基因真核表达载体的构建及其表达

构建含HBVPrdS2 +S和IFN α融合基因的真核表达载体pcDNA3.1.S2S/IFN α并在真核细胞中进行表达。应用重叠延伸剪切技术 (splicingbyoverlappingextension ,简称SOE)经两次PCR获得嵌合基因片段S2S/IFN α ,回收后直接克隆到 pcDNA3.1V5 /HisTOPOTA克隆载体 ,得到真核重组载体pcDNA3.1.S2S/IFN α。然后用脂质体法转染VeroE6细胞。对重组载体进行了限制性酶切及PCR鉴定 ,证明连接正确 ;经间接免疫荧光检测证实该重组载体能在真核细胞中表达插入的外源性基因编码的融合蛋白。真核表达载体pcDNA3.1.S2S/IFN α的成功构建及在VeroE6细胞中的有效表达 。

Preβ-1高密度脂蛋白与心血管疾病关系的研究进展

动脉粥样硬化是心血管疾病重要的病理生理基础,延缓和防治动脉粥样硬化对于减少和降低心血管疾病的发病率及病死率具有重要意义。高密度脂蛋白(high density lipoprotein,HDL)通过参与介导胆固醇逆向转运(reverse cholesterol transport,RCT)在抗动脉粥样硬化的形成和进展中发挥了重要作用。Preβ-1高密度脂蛋白(prebeta-1 high density lipoprotein,Preβ-1HDL)作为HDL的一种亚类,是外周细胞移出胆固醇的最初接受体,直接参与了RCT的起始步骤,并在随后的胆固醇酯化及转运中起着重要作用。本文就Preβ-1HDL的结构、代谢及其与心血管疾病的关系作一简要综述。

基于柱前衍生化GC-MS技术探究紫苏叶与白苏叶的质量差异

为比较紫苏叶与白苏叶化学成分差异,采用柱前衍生化气相色谱-质谱联用技术(GC-MS)对紫苏叶与白苏叶的氨基酸、有机酸、糖类、酚酸类等多种成分进行了定性和定量分析。进一步结合主成分分析(principal component analysis,PCA)和正交偏最小二乘判别分析(orthogonal partial least squares discrimination analysis,OPLS-DA)等多元统计分析方法筛选得到8个显著性差异化合物,分别为D-阿拉伯糖醇、D-果糖、D-半乳糖、D-葡糖醇、D-山梨糖醇、咖啡酸、麦芽糖、迷迭香酸,其中D-果糖、D-葡糖醇、咖啡酸、麦芽糖、迷迭香酸在紫苏叶中的相对含量均显著高于白苏叶。上述结果表明紫苏叶与白苏叶中的多种类型非挥发性成分含量存在显著差异,同时为不同种质紫苏叶的应用与开发提供了数据参考。

PITC柱前衍生-高效液相色谱法测大米肽中的16种氨基酸含量

为了建立一种以高效液相色谱检测大米肽中氨基酸含量的方法,以异硫氰酸苯酯(Phenyl isothiocyanate,PITC)为柱前衍生剂,实现大米肽中16种氨基酸(天冬氨酸(Asp)、谷氨酸(Glu)、丝氨酸(Ser)、甘氨酸(Gly)、组氨酸(His)、精氨酸(Arg)、苏氨酸(Thr)、丙氨酸(Ala)、脯氨酸(Pro)、酪氨酸(Tyr)、缬氨酸(Val)、蛋氨酸(Met)、异亮氨酸(Ile)、亮氨酸(Leu)、苯丙氨酸(Phe)、赖氨酸(Lys))能同时、快速、有效地分析检测。采用Athena AAA色谱柱为分析柱,以甲醇:乙腈:水=20:60:20和50 mmol/L乙酸钠(pH6.5)为流动相,进行梯度洗脱,流速为1.0 m L/min,柱温35℃,紫外检测器波长为254 nm。结果表明,16种氨基酸在0.125~2.5μmol/m L范围内具有良好的线性关系,14种氨基酸线性关系的决定系数R2≥0.9999,另外2种氨基酸的决定系数R^(2)分别为0.9998和0.9994,检出限为0.003%~0.018%,定量限为0.010%~0.059%,加标回收率在82.21%~103.59%,RSD均小于5%。该方法使得大米肽中16种氨基酸很好地分离,其中含量最高的氨基酸是谷氨酸(Glu),含量范围为13.11%±0.39%~21.38%±0.48%,含量最低的氨基酸是组氨酸(His)或蛋氨酸(Met),含量范围为1.59%±0.05%~2.27%±0.03%或1.26%±0.05%~2.32%±0.06%,其准确度和精密度佳,灵敏度和回收率高,适用于大米肽的氨基酸含量分析。

柱前衍生-高效液相色谱法测定冷饮中的甜蜜素

本文建立了一种测定冷饮中甜蜜素含量的高效液相色谱法。在酸性条件下,甜蜜素和次氯酸钠反应,经正庚烷萃取后,采用高效液相色谱法检测。结果显示,甜蜜素在进样量10μL、流速1.0 mL·min^(-1)、波长314 nm、流动相乙腈-水=70∶30的仪器条件下,在线性范围内线性关系良好,加标回收率为96.33%~99.83%,RSD为0.73%~0.96%。该方法操作简单、抗干扰能力强、定量准确,适用于检验冷饮中的甜蜜素。

柱前手性衍生化-HPLC法测定科立内酯二醇对映异构体含量

基于柱前手性衍生化-HPLC法,以联苯-4-甲酰氯为衍生化试剂,采用硅胶表面涂覆有直链淀粉-三(s)-α-甲基苯基氨基甲酸酯手性色谱柱(AS-H,4.6 mm×250 mm,5μm),以正己烷-无水乙醇(V∶V=80∶20)为流动相,流速1 mL/min,柱温30℃,检测波长275 nm,外标法计算科立内酯二醇对映异构体超量值。结果显示,科立内酯二醇对映异构体衍生物分离度为2.8,(+)-科立内酯二醇衍生物在2.07~41.40μg/mL、(-)-科立内酯二醇衍生物在1.95~39.06μg/mL范围有良好线性关系(R2=0.9991、R2=0.9991)。(+)-科立内酯二醇衍生物低、中、高浓度平均加样回收率(RSD)分别为99.36%(0.51%)、99.24%(0.89%)、100.24%(0.65%);(-)-科立内酯二醇衍生物低、中、高浓度平均加样回收率(RSD)为99.74%(0.89%)、100.02%(0.31%)、98.81%(0.63%)。方法简便、快速,能准确测定科立内酯二醇对映异构体超量值,为前列腺素药物手性中间体提供新的分离和检测方法。

柱前衍生化顶空-气相色谱-质谱法测定坚果和梅类食品中氰化物的含量

提出了柱前衍生化顶空-气相色谱-质谱法测定坚果和梅类食品中氰化物(以CN-计,下同)含量的方法。取样品2.0000 g,加1.0 g·L^(-1)氢氧化钠溶液约60 mL,混匀,超声提取20 min,冷却至室温后用1.0 g·L^(-1)氢氧化钠溶液定容至100 mL,过滤。取5 mL续滤液置于顶空瓶中,加入17%(体积分数)磷酸溶液200μL,混合后加入10 g·L^(-1)氯胺T溶液200μL,于55℃衍生30 min。以DB-624UI毛细管色谱柱为固定相,采用气相色谱-质谱法测定所得溶液中氰化物的含量。结果显示:CN-的质量浓度在200μg·L^(-1)以内与对应的氰化物衍生物的峰面积呈线性关系,检出限(3S/N)为0.01 mg·kg^(-1)。按照标准加入法进行回收试验,回收率为96.8%~103%,测定值的相对标准偏差(n=6)均小于4.0%。方法与国家标准方法GB 5009.36-2016中分光光度法进行对比,两种方法所得测定结果基本一致,无显著性差异。方法用于实际样品分析,结果显示坚果和梅类食品中都检出氰化物,建议将氰化物添加到GB 2762-2022的食品中污染物限量名录中,对其进行严格控制。

柱前衍生-气相色谱质谱法检测食用油中缩水甘油及其酯

采用柱前衍生-气相色谱质谱法,建立同时测定食用油中缩水甘油及其酯含量的分析方法,并研究暴露在空气中不同时间对食用油中缩水甘油及其酯含量的影响。结果表明:该方法在10~800ng范围内线性良好(r>0.999),缩水甘油与缩水甘油酯的检出限分别为0.01、0.02mg/kg,定量限分别为0.03、0.06mg/kg,加标回收率分别为81.3%~103.8%、83.8%~92.2%,相对标准偏差均小于5%。随着食用油暴露在空气中时间的延长,缩水甘油酯含量变化幅度较小,而缩水甘油含量在10d后逐渐增加。方法灵敏、准确、重现性好,能满足食用油中缩水甘油及其酯的同时测定。

High－Performance Liquid Chromatographic Determination Of N－Nitrosoamines by Pre－Column Fluorescence Derivatization with 9－Phenanthrene Chloride

A sensitive high-performance chromatographic method for the detection of N-nitrosoamines with pre-column fluorescence derivatization has been developed.Eight representative N-nitrosoamines, which were separated on a reversed-phase C18column with methanol - Water-triethylamine as eluent, were used as model compounds to optimize the derivathation and the chromatographic conditions. The relative standard deviations(n=7) at an analytical concentration of 4×10-6 mol/L are less than 5%. The detection limits (signal-to-noise ratio=3) for the N-nitrosoamines compounds are in the range of 0.02～0. 14 nmol per injection volume(10μl).

高效液相色谱法测定复方氨基酸胶囊(8-11)中氨基酸的含量

以1-(5-氟-2,4-二硝基-苯基)-4-甲基哌嗪(PPZ)为衍生化试剂,建立了一种测定氨基酸含量的柱前衍生化的高效液相色谱法(HPLC).色谱条件:采用Cica-reagent Mightysil RP-18 GP (3μm, 150 mm×4.6 mm)色谱柱,流动相为甲醇和水的混合液(甲醇和水的体积比为1∶1且混合液中含体积分数为0.2%的甲酸),流速为0.3 mL/min,紫外检测波长为354 nm,进样体积为2μL.衍生化条件:温度为40℃,反应时间为3 h,氨基酸与衍生化试剂的摩尔比为1∶10.对复方氨基酸胶囊(8-11)中的8种氨基酸进行测定显示,在0.5~1 000μmol/L浓度范围内工作曲线呈良好线性关系,且最低检测限为0.5~5.0μmol/L,加标平均回收率为90.0%~104.3%,相对标准偏差为0.57%~2.29%.由此表明该方法具有良好的灵敏度、重复性和准确度,可用于测定药物中氨基酸的含量.

衍生化-液相色谱-串联质谱法同时测定益生菌发酵液中3种短链脂肪酸和乳酸含量

建立一种结合柱前衍生技术液相色谱-三重四级杆质谱联用同时测定益生菌发酵液中乙酸、丙酸、丁酸和乳酸含量的方法。在吡啶作为催化试剂和碳二亚胺盐酸盐做偶联试剂条件下,目标物与3-硝基苯肼缩合反应生成3-硝基苯腙,优化确定衍生反应的温度、时间以及试剂用量;采用BEH C18(100 mm×2.1 mm,1.7μm)液相色谱柱,以甲酸水-甲醇异丙醇为流动相,5 min内较好的分离了3种短链脂肪酸和乳酸;采用ESI离子源,多反应监测负离子模式采集质谱信号,以丁酸-D7为内标进行定量。最佳反应条件为30 mmol/L EDC作为偶联试剂和50 mmol/L 3-NPH·HCl作为衍生试剂,40℃反应30 min;4种目标物在各自的浓度线性范围内线性关系良好(R^(2)>0.999),方法检出限为0.5~2 mg/kg,加标回收率在81.8%~105.3%之间,重复性测试相对标准偏差1.3%~5.1%。该方法灵敏度高,结果可靠,操作简便,适用于各类益生菌发酵液中3种短链脂肪酸和乳酸的同时快速测定。