谷物样品中淀粉,非淀粉多糖和游离糖的流水序列测定法

谷物样品中各单糖及游离糖、淀粉、可溶性和不溶性ＮＳＰ流水序列测定方法：用８０％乙醇提取游离糖；而后用乙酸缓冲液、α－淀粉酶和葡萄糖苷酶分解淀粉，得到可溶和不可溶ＮＳＰ；用葡萄糖氧化酶／过氧化酶方法测定淀粉；ＮＳＰ和游离糖再经水解。与内标共同完成还原和酰化过程，用装有高级性毛细管柱的ＧＣ测定。该法不仅可给出构成ＮＳＰ各单糖含量，也可给出淀粉和游离糖的量值。     

高效液相色谱法测定果低聚糖中的糖含量

 以ＹＷＧ－ＮＨ２色谱柱和ＲＩＤ－６Ａ示差折光检测器对果低聚糖进行高效液相色谱法（ＨＰＬＣ）分析，获得了良好的分离效果。结果表明：果低聚糖糖浆中含有３０％～３５％的葡萄糖和５５％～５８％的果低聚糖（包括三糖、四糖和五糖），此外，还含有少量的果糖和蔗糖。ＨＰＬＣ能准确、快速地定性、定量果低聚糖中各组分糖，方法灵敏度高、重现性好，有理想的回收率，单糖和低聚糖的最低检出限在微克级。     

高效液相色谱法测定果低聚糖中的糖含量

以ＹＷＧ－ＮＨ２色谱柱和ＲＩＤ－６Ａ示差折光检测器对果低聚糖进行高效液相色谱法（ＨＰＬＣ）分析，获得了良好的分离效果。结果表明：果低聚糖糖浆中含有３０％～３５％的葡萄糖和５５％～５８％的果低聚糖（包括三糖、四糖和五糖），此外，还含有少量的果糖和蔗糖。ＨＰＬＣ能准确、快速地定性、定量果低聚糖中各组分糖，方法灵敏度高、重现性好，有理想的回收率，单糖和低聚糖的最低检出限在微克级     

低聚糖结构表达中应注意的问题

在书写低聚糖结构时易犯的错误是将D-型糖残基写成L-型糖残基。避免此错误的关键是需要对写出的低聚糖中的糖残基手性碳原子进行R、S构型标定和熟练掌握糖残基各Haworth式间的关系。     

利用差异衍生同步分析醛糖和酮糖

建立了一种可同时对醛、酮糖进行精确定性和定量分析的方法。以肌醇作为内标，用80％乙醇超声提取，利用醋酸酐和HMDS＋TMCS（1：3）进行差异衍生，在EI源下用SIM模式进行GC／MS分析。结果表明：11种标准单糖在1—4mg／L范围内线性良好；仪器检出限：醛糖在8．15—22．4μg／L之间；酮糖为2．32μg／L和3．47μg/L；高、中、低3个量的平均回收率在73．0％-95．7％，相对标准偏差在3．1％-10．0％。对枸杞游离单糖进行测定，各单糖含量分别在0．26—368．6mg／g。该方法弥补了以前单糖分析中的缺陷，对既含有醛糖又含有酮糖的样品可同时进行精确的定性定量分析。     

含N-乙酰化肝素寡糖的制备及序列分析

建立了含N-乙酰化肝素寡糖的分离提纯及其序列结构分析方法.首先应用肝素酶Ⅰ深度酶解低分子量肝素来富集含N-乙酰化结构寡糖,通过Bio-Gel P10凝胶色谱法分离制备了包括二糖至十四糖的系列肝素寡糖粗样品,ProPac PA-1强阴离子高效液相色谱(SAX-HPLC)等方法对粗样品进一步分离,提纯得到4种六糖和3种八糖片段.其次应用肝素酶Ⅰ,Ⅱ和Ⅲ复合酶解与HPLC法分析各纯化寡糖的二糖组分,并结合肝素酶Ⅰ底物特异性,初步推断4种六糖和3种八糖的序列结构.在寡糖的糖链两端均含有N-硫酸化二糖,而N-乙酰化二糖分布在糖链当中.应用电喷雾离子阱-飞行时间质谱(ESI-IT-TOF-MS)在负离子模式下进一步表征寡糖并分析其裂解规律.结果表明,各寡糖中均出现大量因SO32-丢失形成的碎片离子峰,六糖中主要有双电荷和三电荷碎片离子峰;在八糖中出现了一系列从双电荷至五电荷的离子峰.各寡糖的双电荷离子峰质荷比进一步确定了上述寡糖的序列结构.六糖的裂解规律表明,裂解主要存在于糖苷键,N-乙酰葡糖胺和糖醛酸上的裂解方式分别为0,2X和0,2Z.本研究提供了切实有效的分离、分析未知结构肝素寡糖序列的新方法.     

在汞电极上酮糖还原的电化学行为

用极谱法及恒电位电解法研究了酮糖中的单糖、果糖、塔格糖、二糖、拉克杜糖的电还原行为，由酮糖的电还原行为从理论上导出了相应的极谱电流－电压方程，该方程被实验所证实，成功地解释了实验现象。恒电位电解后电解的分析结果表明，电解选择性为１００％，电解产物为由酮糖还原成相应的多元醇。     

高效液相色谱法在双酶协同作用酶解淀粉制取麦芽低聚糖工艺研究中的应用

介绍了高效液相色谱在双酶协同作用酶解制取麦芽低聚糖工艺研究中的应用。以C18柱为分离柱,水作流动相,利用折光检测器来检测麦芽低聚糖产品中的7种糖,同时评估了补加酶量与麦芽低聚糖中麦芽三糖至六糖含量的关系,并测定了二次确认实验中麦芽低聚糖产品中各糖的含量。     

探秘无糖饮料的甜

市面上的无糖饮料日渐增多，但人们关于无糖饮料中的甜味还知之甚少。简要介绍甜味剂及其分类、无糖饮料中甜味剂的使用情况、甜味剂对人体的影响等，以期提升人们对无糖饮料中甜味剂的理解。其中对人体的影响方面主要针对无糖饮料中常用的7种甜味剂。     

以氧化糖为原料的氨基糖衍生物的合成

首次报道了以氧化糖为原料的氨基糖衍生物的合成方法。以2位氧化糖为原料 与芳胺反应得到羰基转至3位的2位脱氧2位胺基糖，此胺基糖径NaBH_4立体选择性 还原及AcOH脱去4，6位保护基，合成了新型的D－阿洛糖胺。X射线单晶衍射分析表 明其晶体中有多种氢键，由于氢键作用，晶体呈现三维超分子结构。对2位氧化糖 与H_2NC_6H_4COOEt反应生成α，β－不饱和酮糖的机理进行了探讨。以5位氧化糖 为原料通过基转位反应合成了新型的二氢－1，4－苯并二嗪氨基糖。     

手性螺-环丙烷双内酯化合物的合成与结构

本文进一步研究了5-(l-孟氧基)-3-溴-2(5H)-呋喃酮(1)与氧的亲核试剂,如二苯甲醇、苯甲醇、α-甲基苯甲醇、薄荷醇、冰片醇发生新颖的串联不对称双Michael加成/分子内亲核取代反应,合成了一般方法难以合成的含有多个手性中心的螺[1-溴-4-l-孟氧基-5-氧杂-6-氧代双环[3.1.0]己烷-2,3'-(4'-亲核基-5'-孟氧基丁内酯)](4a-4e)。通过元素分析,IR,UV,^1HNMR,^1^3CNMR,MS,[α]~D^2^0波谱分析数据以及X四圆衍射确定了4a-4e的化学结构和绝对构型。     

反相高效液相法测定血浆及尿液中的异烟肼

 建立了血浆及尿液中异烟肼的高效液相快速测定方法 ,以满足临床药物分析和法医学鉴定的需要 ,提高对血浆及尿液中异烟肼浓度检测的准确性。以香草醛为衍生化试剂 ,将异烟肼经柱前衍生为异烟肼 香草醛腙 ,直接对处理后样品中的腙进行定性、定量分析。以在空白人体液样本中定量添加标准异烟肼的方法考察了样品的前处理方法、仪器条件、线性范围、精密度、回收率等 ,并对健康受试者血液中的异烟肼浓度进行了监测。结果表明 ,方法的线性范围为 0 2mg/L～ 1 2 0mg/L ;检测限为 0 2mg/L ;日内、日间精度均小于 4 0 % (n =5) ;回收率在96 3 %以上。     

Analysis of non-conducting powders by direct current glow discharge atomic emission spectrometry and application to the determination of rare earth elements

Some characteristics for the analysis of non-conducting powders by direct current glow discharge atomic emission spectroscopy (dc-GD-AES) were investigated. Copper powder was chosen as a suitable host conducting material for the analysis of mixtures of rare earth oxides. The influences of sample preparation and discharge parameters on the sputtering rate, discharge stability and emission intensity of the analyte were investigated systematically. The sample-to-sample reproducibility was discussed, and the average RSDs were in the range from 4% to 5%. The proposed method was applied to the analysis of a mixture of rare earth oxides and the results obtained were in good agreement with those obtained by ICP-AES. Received: 4 June 1999 / Revised: 21 July 1999 / Accepted: 24 July 1999     

枸杞子糖缀合物LbGp4糖链的结构及其免疫活性的研究

枸杞子糖缀合物LbGp4经β--消除、柱层析分离后得到一条分子量高达180800的分支多糖化合物LbGp4-OL.LbGp4-OL糖基组成为n(Rha):n(Ara):n(Gal)=0.05:1.33:1.根据甲基化、部分酸水解及¹HNMR、¹³CNMR分析,确定了其主要的结构,并对LbGp4和LbGp4-OL的免疫活性进行了研究.     

Hydrophilic interaction liquid chromatographic analysis of aminohydroxyphenylalanines from melanin pigments

Malignant melanomas are more often seen in subjects with light colored skin who tan poorly than in persons who tan more rapidly. This has been attributed to the structure of their pigment, pheomelanin, which differs markedly from the eumelanin of persons with darker skin. To study the hydrolysis products of pheomelanin pigments a new method was developed for analysis of 4-amino-3-hydroxyphenylalanine (4-AHP) and 3-amino-4-hydroxyphenylalanine (3-AHP). Pheomelanin samples were hydrolyzed and extracted with solid-phase extraction columns using strong cation-exchange (SCX) cartridges. Separation of 4-AHP and 3-AHP was achieved on a ZIC-HILIC column (150 mm x 2.1mm I.D.) with a mobile phase consisting of acetonitrile: 0.1 M ammonium acetate buffer, pH 4.5 (82:18, v/v). Detection was performed with an electrochemical detector at +400 mV. Run time was 30 min. The limits of detection were 73 pg and 51 pg for 4-AHP and 3-AHP respectively, using 2 microl injections. Good linearity was found within the range 0.05-5.0 microg/ml. Absolute recovery was 70% and relative recovery was 100%. The AHPs were stable for 1 year in the hydrolyzed samples, for 4 days in the eluates from solid-phase sorbents stored in the refrigerator, and for 2 days diluted with mobile phase and stored in the autosampler at 10 degrees C. The within-day imprecision was <5% and the between-day imprecision was <7% for the two analytes. The method, applied to the analysis of pheomelanin in urine from human melanoma patients, allows the analysis of 30 samples in one set and is suitable for routine work with human hair and melanoma cells. By using the ZIC-HILIC stationary phase, ion-pairing reagents could be avoided, which makes the method suitable to further analysis of degradation products from pheomelanins using mass spectrometric detection.     

气体传感器阵列信号的盲分离研究

本文在使用一个四单元微热板式集成气体传感器阵列测试煤矿中的两种主要易燃易爆气体一氧化碳和甲烷的基础上, 将气体传感器阵列与盲信号分离技术相结合, 讨论了混合气体分析的盲可辨识性, 并使用盲信号分离中的一种主要方法独立分量分析法(ICA)进行了分析和验证.     

含葑基的缩氨基硫脲、噻二唑的合成、表征与晶体结构

以(－)-葑酮为原料经中间体葑胺合成4-葑基氨基硫脲(4), 4与醛缩合得到11个未见文献报道的葑基缩氨基硫脲(5), 5用六氰合铁(III)酸钾氧化成环得到相应的2,5-二取代-1,3,4-噻二唑类化合物(6); 产物的结构经IR, NMR和元素分析确认, 并用X射线衍射法测定化合物6d的晶体结构. 化合物6d属单斜晶系, P2(1)空间群, 晶胞参数 a＝1.18719(10) nm, b＝1.48814(18) nm, c＝1.21629(12) nm, β＝118.113(2)°, Mr＝343.48, V＝1.8953(3) nm3, Dc＝1.204 Mg/m3, Z＝4, λ＝0.071073 nm, μ(Mo Kα)＝0.181 mm－1, F(000)＝736.     

Oxidation of 4-Nitrotoluene by Ozone in Acetic Anhydride in the Presence of Manganese Sulfate

The reaction of 4-nitrotoluene oxidation with ozone in acetic anhydride in the presence of MnSO₄and sulfuric acid was studied. The main reaction product is 4-nitrobenzyl acetate, the yield of which is 63.2%. Based on an analysis of the experimental data, a mechanism of the catalytic ozonation of 4-nitrotoluene in acetic anhydride was proposed.     

Synthesis and emission spectra of anionic para-substituted polyacrylophenones

Polyacrylophenone (aPAP), poly-4′-ethylacrylophenone (aP4EAP), poly-4′-methoxyacrylophenone (aP4MAP) and poly-4′-phenylacrylophenone (aP4PAP) were prepared by anionic polymerization initiated by lithium tert-butoxide. ¹H NMR analysis revealed higher content of isotactic dyads for aPAP (86%) and aP4MAP (88%) compared with polymers rPAP (60%) and rP4MAP (60%) prepared by radical polymerization. ¹H NMR spectra of a aP4EAP and a P4PAP were too complicated for analysis and ¹³C NMR spectra were not sensitive to stereostructure. The molecular weights of anionic polyacrylophenones were about 5000. In emission spectra, a bathochromic shift was observed in going from model compound to anionic and radical polymer doped in poly(methyl methacrylate) film at 77°K. The emission decay of rP4PAP and aP4PAP is non-exponential in comparison with model 4′-phenyl-3-chloropropiophenone. The bathochromic shift in the emission spectra and the non-exponential emission decay of polymers depends on molecular weight suggesting that the number of structural perturbations (triplet excimers) increases with molecular weight.     

CCl4 对左旋氧氟沙星超声降解的影响

研究了CCl4对超声降解喹诺酮类抗生素左旋氧氟沙星(Levofloxacin)的影响, 考察了CCl4添加量、 超声功率、 溶液初始pH值及左旋氧氟沙星初始浓度等影响因素, 并采用HPLC和LC-MS/MS对超声降解产物进行了初步分析. 结果表明, CCl4增强了左旋氧氟沙星的超声降解, 当反应液体积为50 mL, 超声35 min时, 随着CCl4体积分数的增大(0~0.06%), 左旋氧氟沙星的降解率由1.9%增至69.2%; 超声功率为100~200 W时, 降解率随着功率的升高而增大, 功率为200~400 W时降解率有所降低; pH值对左旋氧氟沙星的超声降解影响很大, pH =7.14时容易超声降解, pH过低或过高均导致降解率显著减小; CCl4的体积分数一定时, 左旋氧氟沙星的降解率随其初始浓度的增大而降低; 左旋氧氟沙星的降解率在33~49 ℃时最大. CCl4强化超声降解左旋氧氟沙星过程主要是由·OH和一系列氯自由基参与的反应. HPLC分析发现, 降解过程中同时生成了2个产物, 并通过LC-MS/MS对其进一步鉴定.