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1.
1 引言。发展多年生饲料用灌木不仅可获得充足的饲料源,还可防止水土流失,保护生态环境。淀粉和果胶是饲料用灌木中的重要营养成分,其含量测定对饲料用灌木营养评价具有重要意义。为了快速准确地测定饲料用灌木中的淀粉和果胶,研究了用高效液相色谱法同时测定淀粉和果胶的方法;样品中淀粉和果胶在盐酸介质中被水解为葡萄糖和半乳糖醛酸,然后用高效液相色谱分离测定葡萄糖和半乳糖醛酸含量,再换算成淀粉和果胶含量。由于淀粉和果胶可同时测定,和常规方法相比,该方法更为简便快速。  相似文献   

2.
苧麻用草酸铵抽提果胶,用氢氧化钾和氢氧化钠抽提半纤维素。果胶和半纤维素水解成单糖,再制备成糖腈乙酰酯和二硫缩醛硅烷化衍生物,作气相色谱分析,研究其糖基组成。实验结果表明,苧麻果胶糖基以半乳糖醛酸及半乳糖醛酸甲酯为主,其次为鼠李糖、半乳糖和阿拉伯糖,还有少量的岩藻糖、葡萄糖和木糖等。苧麻半纤维素中存在着葡萄甘露聚糖和鼠李半乳糖醛酸聚糖等多糖,前者糖基组成以葡萄糖和甘露糖为主,后者则以鼠李糖、半乳糖及半乳糖醛酸为主,它与果胶的糖基组成相似,但中性糖基占主要成份,用草酸铵难以将其抽出,用碱抽提则比葡萄甘露聚糖容易。  相似文献   

3.
研究了在HCl-KSCN底液中用单扫描示波极谱法连续测定羊乳、黄芪、白鲜皮、蕨菜中铜和锌含量的方法。在此底液中,铜和锌分别在-0.42和-1.03 V(vs.SCE)处产生一敏锐的二阶导数波,检出限分别为0.005和0.01 mg·L-1,线性范围分别为0.01~8.00和0.01-10.00 mg·L-1。应用此法测定羊乳、黄芪、白鲜皮、蕨菜中铜和锌含量,回收率在97.0%~101.7%。  相似文献   

4.
抗坏血酸及L-半胱氨酸的流动注射动力学同时测定法   总被引:3,自引:0,他引:3  
pH2~9时,抗坏血酸与L-半胱氨酸均可与Fe3+-邻菲咯啉混合液反应,生成Fe2+-邻菲咯咻有色配合物,但两者反应速度相差极大。根据这个原理,采用流动注射分析停流技术,建立了抗坏血酸与L-半胱氨酸的动力学吸光光度同时测定法。两者测定的线性范围分别为0~24mg·L-1和0~280mg·L-1,相应的检出限为1mg·L-1和16mg·L-1,抗坏血酸与L-半胱氨酸浓度分别为12.0mg·L-1和160.0mg·L-1时,测定的相对标准偏差分别为0.9%和0.6%,采样频率为30样·h-1。该法灵敏、快速、准确,选择性较高,且流路及设备简单,实用性强,用于实际样品测定,抗坏血酸及L-半胱氨酸的加标回收率分别可达95.2%和92.8%。  相似文献   

5.
对当归多糖ASP3的水解特征及其水解产物的组成和红外光谱特征进行了研究。分别采用0.05、0.2和0.5mol/L三氟乙酸(trifluoroacetic acid,TFA)和内切-α-(1→4)-聚半乳糖醛酸酶对ASP3进行部分酸水解和酶水解,并研究其水解特征;结合GC、FT-IR等方法对其水解产物的组成和红外光谱特征进行分析。实验结果表明,ASP3是一种果胶多糖,主要由光滑区(半乳糖醛酸聚糖)和毛发区(富含中性糖侧链的鼠李半乳糖醛酸聚糖)两部分组成:GalA和Rha位于多糖分子的主链,由于Rha含量较低,大部分GalA相连形成半乳糖醛酸聚糖光滑区;Gal、Ara、Man及Glc位于多糖分子的支链,其中Gal以较高的聚合度(半乳聚糖)与主链相连,Ara以还原性末端或低聚寡糖的形式与主链相连或与半乳聚糖末端相连形成阿拉伯半乳聚糖。  相似文献   

6.
研究了4,5-二甲基-2-噻唑偶氮重氮氨基偶氮苯(DMTDAA)与银的显色反应,在pH 11.0的硼砂-氢氧化钠缓冲介质中,乳化剂-OP存在下,DMTDAA与银反应生成2:1稳定络合物,该络合物可用Waters XterraTM RP18固相萃取小柱富集,小柱上富集的络合物用乙醇(内含0.01 mol.L-1pH为11.0的四氢吡咯-乙酸缓冲盐)洗脱后用光度法测定,在洗脱剂介质中λmax =518 nm,ε=1.39×105L·mol-1·cm-1。银含量在0.01~2.0 mg·L-1范围内符合比耳定律。方法用于环境水样中银含量的测定,结果的RSD在2.2%~2.8%,回收率在96%~104%。  相似文献   

7.
分根法研究镧对水稻生长及其生理参数的影响   总被引:11,自引:1,他引:10  
用分根营养液培养法研究了镧对水稻生长及其促进作用的生理机制。结果表明:低浓度镧(0 05~1 5mg·L-1)提高水稻产量,增加实粒数;随着镧浓度从0 05增加到0 75mg·L-1,镧降低第一片完全展开叶和根中过氧化氢酶(CAT)活性;当镧浓度为0 75~9mg·L-1时,镧显著降低叶和根中超氧化歧化酶(SOD)活性;0 75mg·L-1镧增加叶中赤霉素(GA)和吲哚乙酸(IAA)含量,0 75和3mg·L-1镧增加根中细胞分裂素(iPAs)和IAA含量,但降低脱落酸(ABA)含量;秧苗移栽后46d,0 25~6mg·L-1镧显著增加叶片气孔导度;秧苗移栽后59和83d,当镧浓度分别为15和6mg·L-1时,镧显著降低叶片气孔导度;镧对叶片叶绿素(Chl)含量、叶和根中蛋白质,脂质过氧化产物丙二醛(MDA)含量没有发现显著作用。还讨论了镧促进水稻生长和消除超氧阴离子(·O2-)的可能机制。  相似文献   

8.
在线渗析-离子色谱法直接测定面粉及面制品中溴酸盐   总被引:3,自引:0,他引:3  
建立一种简单快速检测面粉中溴酸盐的在线渗析-离子色谱法。选用Metrosep A Supp 5250和Metrosep A Supp 1 Guard分离柱,碳酸钠-碳酸氢钠淋洗液,流速为0.65 mL·min-1,进样体积为100μL,并采用抑制型电导检测器。峰面积与溴酸盐质量浓度在0.005~10.0 mg·L-1之间呈线性关系,相关系数为0.999 9,在1.0,50.0及100.0 mg·kg-1三个浓度水平作精密度试验,所得相对标准偏差依次为1.75%,0.55%和0.85%,样品加标平均回收率在80.8%~95.2%之间;取面粉10 g溶于100 mL超纯水中,检出限为0.10 mg·kg-1。  相似文献   

9.
本文建立了1-苯基-3-甲基-5-吡唑啉酮(PMP)柱前衍生高效液相色谱-紫外检测法结合离子色谱-脉冲安倍法测定泽泻中10种单糖含量的测定方法,并比较了不同产地泽泻多糖中的单糖组成差异。经测定泽泻多糖中含有葡萄糖、半乳糖、半乳糖醛酸和阿拉伯糖,其中葡萄糖含量最高,说明泽泻多糖是以葡聚糖为主的杂多糖。不同产地泽泻多糖中葡萄糖、半乳糖、半乳糖醛酸含量差异显著(P<0.05),葡萄糖含量由高到低依次为广泽泻(166.940~264.724 mg/g)、川泽泻(82.647~155.019 mg/g)和建泽泻(51.148~97.746 mg/g);广泽泻多糖中半乳糖含量(3.511~3.840 mg/g)显著高于川泽泻(1.193~1.797 mg/g,P<0.01)和建泽泻(低于定量限);仅有广泽泻中半乳糖醛酸含量(1.342~1.823 mg/g)高于方法定量限。广泽泻中葡萄糖、半乳糖、半乳糖醛酸摩尔比为60.13∶1∶0.40,川泽泻中葡萄糖、半乳糖摩尔比为1545.05∶1,建泽泻多糖中几乎都是葡萄糖,葡萄糖占比在上述产地多糖中依次增加,三种单糖的杂合程度依次减弱。研究结...  相似文献   

10.
流动注射停流法快速测定环境水样中COD   总被引:8,自引:0,他引:8  
应用流动注射停流分析技术 ,对环境水样中的COD进行测定。采用KMnO4 作氧化剂和光度分析指示剂 ,葡萄糖作基准物质 ,在反应温度为 95℃ ,停流 5min时 ,COD测定范围为 0~10 0mg·L- 1,检出限为 2mg·L- 1,相对标准偏差为 0 .8% (n =9) ,回收率为 85 %~ 95 %。Cl-<15 0mg·L- 1时不干扰测定  相似文献   

11.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

12.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

13.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

14.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

15.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

16.
17.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

18.
Quercetin, the polyphenolic compound, which has the highest daily intake, is well known for its protective effects against aging diseases and has received a lot of attention for this reason. Both quercetin 3-O-β-d-glucuronide and quercetin 3′-O-β-d-glucuronide are human metabolites, which, together with their regioisomers, are required for biological as well as physical chemistry studies. We present here a novel synthetic route based on the sequential and selective protections of the hydroxyl functions of quercetin allowing selective glycosylation, followed by TEMPO-mediated oxidation to the glucuronide. This methodology enabled us to synthesize the five O-β-d-glucosides and four O-β-d-glucuronides of quercetin, including the major human metabolite, quercetin 3-O-β-d-glucuronide.  相似文献   

19.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

20.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

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