高效液相色谱法同时测定蔬菜中有机酸与磺胺类抗生素

建立了同时提取和测定蔬菜中有机酸与磺胺类抗生素的方法。通过对液相色谱分析条件的优化,建立了以Penomenex C18为分析柱,以0.5%(NH_4)_2HPO_4-H_3PO_4溶液(pH 3.0)为流动相,柱温30℃,流速1.0 m L/min,紫外检测器检测波长为210 nm和270 nm的检测方法。并比较了水提取,0.1%H_3PO_4,0.5%(NH_4)HPO_4,0.5%KH_2PO_44种不同溶液对有机酸和磺胺的提取效果。结果表明:4种提取方法下,乙酸、柠檬酸提取率无显著性差异,草酸、苹果酸、富马酸、磺胺(SA)、磺胺二甲基嘧啶(SM2)均以水提的效果较好。7种有机酸和2种磺胺类抗生素线性关系良好,检出限为0.21~1.95 ng/g,样品的加标回收率81.2%~96.2%,相对标准偏差(RSD)小于8.6%,方法适用于蔬菜中有机酸和磺胺类抗生素快速、高效的分离。     

高效液相色谱法测定食品中有机酸

前言 有机酸是食品重要的组成成分之一,它与食品加工、贮存、质量评价等密切相关,因此越来越受到人们的重视。近年来,高效液相色谱(多采用离子色谱和离子交换色谱)已广泛应用于食品中有机酸的分析。 本文采用反相色谱,以0.6％KH_2PO_4(pH 2.65)为流动相,测定了酱油、黄酒、豆奶中的八种有机酸,取得了很好的分离效能。此法具有灵敏度高、重现性和回收率好、流动相价格便宜等特点。     

卷烟主流烟气气相物和总粒相物中有机酸的分析研究

以二氯甲烷-甲醇为萃取溶剂,N,O-双(三甲基硅基)三氟乙酰胺(BSTFA)为硅烷化试剂,采用配备氢火焰离子化检测器(FID)的气相色谱仪分别对卷烟主流烟气中气相物和总粒相物中甲酸、乙酸、硬脂酸等21种有机酸进行了定量分析。对样品主流烟气中气相物前处理硅烷化条件及有机酸萃取条件进行了优化,并采用气相色谱法对卷烟主流烟气中气相物和总粒相物中有机酸的含量进行了定量分析。该方法用于实际样品中挥发性有机酸分析时,回收率为88.12%～98.63%,相对标准偏差(RSD)为1.51%～8.38%。     

离子色谱法测定合成气制烯烃产物中的C_1~C_6有机酸

采用离子色谱建立了合成气制烯烃(SGTO)水相产物和油相产物中C1~C6有机酸的测定方法。对分离条件进行了优化,使用标准样品测定了线性范围和工作曲线,考察了方法的精密度和准确度,确定了SGTO油相产物样品的碱洗条件,并对SGTO水相产物和油相产物样品进行了测定。结果表明:C1~C6有机酸的质量浓度在各自配制的质量浓度范围内呈现良好的线性关系,相关系数均大于0.99。标准溶液的回收率测定表明回收率在95.6%~104.3%之间,5次重复测定的相对标准偏差(RSD)在0.4%~3.6%之间,表明该方法具有良好的准确性和精密度。SGTO油相产物中的加标回收率在91.1%~96.8%之间,5次重复测定的RSD为0.7%~2.3%,准确性可以满足实际分析的需要。实际SGTO水相产物和油相产物中C1~C6有机酸的分析结果表明,SGTO水相产物中C2~C4有机酸含量较高,而SGTO油相产物中C4~C6有机酸含量较高。本研究对SGTO反应研究、催化剂制备、工艺优化以及设备材料的选择具有重要意义。     

梯度洗脱高效液相色谱法快速检测厌氧菌代谢物中的有机酸

提出了一种快速分析厌氧细菌代谢物中5种有机酸的高效液相色谱方法。该方法采用乙腈-0.02mol/L磷酸二氢钾缓冲溶液(pH 2.8)作为流动相,流速和流动相中两种组分的比例均采用四元泵程序梯度洗脱方法控制,检测波长为215 nm,柱温30℃时,能够快速、准确地分离和测定细菌培养基中的甲酸、乙酸、乳酸、琥珀酸和丙酸等5种有机酸,总分析时间只需4 m in。方法的相对标准偏差为0.26%~1.26%,回收率95.0%~100.8%,各种有机酸的线性相关系数r≥0.99981,具有较高的精密度和准确度,可以用于细菌代谢物中有机酸的分析。     

固相萃取-超高效液相色谱法同时测定乳制品中6种有机酸

建立了固相萃取-超高效液相色谱(UPLC)同时测定乳制品中苹果酸、酒石酸、乳酸、乙酸、柠檬酸、富马酸等6种有机酸的分析方法。样品用体积分数1%氨水溶液提取,调节至中性后经MAX柱净化,用Acquity UPLC HSS T3色谱柱(2.1 mm×100 mm,1.8μm)分离,以乙腈和0.02 mol/L KH2PO4缓冲溶液(pH 2.0)作为流动相进行梯度洗脱,二极管阵列检测器检测。6种有机酸在其相应范围内(0.05~5000 mg/L)线性关系良好(r2≥0.999),方法的定量限(信噪比为10)为0.05~25.0 mg/kg,3个不同水平的添加浓度回收率为80.1%~103.2%,相对标准偏差(n=8)在1.9%~11%之间。方法适合于乳制品中6种有机酸的同时检测。     

结冰过程对溶解性有机质典型组分还原Cr(Ⅵ)的影响

研究了结冰过程对溶解性有机质(DOM)的4种典型组分草酸、酒石酸、苹果酸和柠檬酸还原Cr(Ⅵ)的影响.结果表明,在低浓度下Cr(Ⅵ)在水溶液中不能被4种有机酸所还原;而在冰中,不同的有机酸对Cr(Ⅵ)的去除均有促进作用,且去除效果随着有机酸浓度的增大逐渐增强.4种有机酸的作用效果强弱顺序为草酸酒石酸苹果酸柠檬酸.通过使用不同浓度的无机盐和无机酸可以改变冰表面上类似液体层的厚度来抑制Cr(Ⅵ)的还原,作用效果与无机盐种类无关.溶液的初始pH值和有机酸结构是影响Cr(Ⅵ)还原的重要因素.实验条件下冷冻浓缩效应的富集倍数至少可达10~3,对冰中草酸去除Cr(Ⅵ)有明显的促进作用.     

HPLC法检测丁二酸发酵液中的有机酸和水溶性维生素

采用高效液相色谱法(HPLC)同时检测丁二酸发酵液中的有机酸和水溶性维生素。以RP-HPLC为分离模式,选用Hedera ODS-2色谱柱(5μm,4.6×250 mm),20 mmol/L的磷酸盐缓冲溶液(pH2.9)和乙腈为流动相,梯度洗脱,检测波长为210 nm,建立了同时测定分析8种水溶性维生素和3种有机酸的方法,15 min内所有组分都洗脱完全。8种水溶性维生素和3种有机酸在线性范围内峰面积与浓度呈良好的线性关系,相关系数为0.9989~0.9997;加标回收率在92.5%~100.3%之间;RSD(n=5):0.9%~1.9%。本方法采用同一种流动相既可以测定发酵液中的有机酸又可以测定水溶性维生素的含量。     

烟气中有机酸的分析

 应用甲酯衍生化试剂对卷烟烟气粒相物中有机酸进行甲酯衍生化 ,经固相微萃取 (SPME)后通过气 质联用仪分离鉴定。分析了 4个品牌的卷烟烟气 ,共鉴定了 60多种挥发及半挥发性有机酸。对丁酸、己酸、糠酸、辛酸、壬酸、苯甲酸、苯乙酸、十四酸、十六酸进行了定量分析。该方法用于烟气中有机酸的定性、定量分析 ,灵敏度较高 ,快速简便。     

固相萃取-高效液相色谱法测定蜂蜜中的有机酸

建立了固相萃取-高效液相色谱(SPE-HPLC)同时测定蜂蜜中5种有机酸(L-苹果酸、马来酸、琥珀酸、柠檬酸、D-苹果酸)含量的方法。蜂蜜经制样后过Bond Elutes SAX固相萃取(SPE)小柱净化,用C18-MS-II反相色谱柱(250 mm×4.6 mm, 5 μm)进行分离,流动相为2%偏磷酸溶液,流速为0.7 mL/min,检测波长为210 nm。在此条件下5种有机酸在相应的线性范围内其线性相关系数均大于0.9967;方法的回收率为86.0%～103.9%,相对标准偏差为5.7%～9.8%(n=6),检出限为0.06～9.4 mg/kg。所建立的方法可用于蜂蜜样品中有机酸的测定。     

Spectrophotometric study of the interaction of tetraphenylporphyrin tetrasulfonate (TPPS4) with proteins

The interaction of water-soluble porphyrin TPPS(4) (tetraphenylporphyrin tetrasulfonate) with proteins in acidic solution was studied by spectrophotometry. The absorption spectra of TPPS(4)-protein complexes, the aggregation of TPPS(4) in acidic solution, and comparison of the absorption spectra of TPPS(4)-protein conjugate with that of the TPPS(4)-protein complex was investigated in detail. The effects of denaturants including urea and SDS were also examined. A mechanism was proposed that TPPS(4) would be distributed between microphase of protein and the aqueous solution and then aggregated in the microphase.     

9,9-二[4-(4-羧基苯氧基)苯基]呫吨的合成

在碘化亚铜、四丁基溴化铵和磷酸钾存在下,9,9-二(4-羟基苯基)呫吨(1)和4-甲基碘苯(2)于N,N-二甲基甲酰胺溶剂中发生Ullmann偶联反应,加热回流反应24 h,以95%的产率合成了中间体--9,9-二[4-(4-甲基苯氧基)苯基]呫吨(3),继而加入催化量的N-溴代丁二酰亚胺并在光照条件下,将中间体3氧化得到一种新型芳香族二羧酸--9,9-二[4-(4-羧基苯氧基)苯基]呫吨(4),其产率为84%,二步反应总收率为79.8%。 目标化合物4经1H NMR、13C NMR、IR和元素分析测试技术确定了其结构。 该法具有原料易得,操作简单,反应条件温和,收率高等优点。     

脂蛋白脂酶激活剂艾溴利平类似物的合成

合成了两个新型的艾溴利平类似物——N-2 -硝基-4-氯苯基-4-[(膦酸二乙酯基)甲基]苯甲酰肼(5,总收率28.1％)和N-2-四氮唑基-4-氯苯基-4-[(膦酸二乙酯基)甲基]苯甲酰胺(7,总收率30.5％).以对氯甲基苯甲酸为原料,经酯化、水解和酰氯反应制得中间体4-[(膦酸二乙酯基)甲基]苯甲酰氯(4);4与2-硝基-4-氯苯肼盐酸盐反应合成了5.4先与2-氨基-5-氯苯腈反应制得N-2-氰基-4-氯苯基-4-[(膦酸二乙酯基)甲基]苯甲酰胺(6);6再与叠氮化钠反应合成了7.其结构经1 H NMR和IR表征.     

4-(4-溴丁基)苯乙烯的合成

4-(4-溴丁基)苯乙烯的合成;溴丁基苯乙烯;对氯苯乙酮;对氯苯乙烯;合成     

Synthesis and Characterization of Poly(ether amide)s Containing Phthalazinone Moieties

Soluble aromatic polyamides containing phthalazinone moieties were prepared. Those polymers were obtained from the solution polymerization of a new diacid containing phthalazinone moieties with various diamines. The new monomer, 2-(4-carboxyphenyl)-4-(4-carboxyphenoxy)phenyl-1(2H)phthalazinone(Ⅳ) was synthesized in a two-step reaction sequence. 2-(4-Cyanophenyl)-4-(4-cyanophenoxy)phenyl-1(2H)phthalazinone (Ⅲ) was prepared via the condensation reaction of 4-(4-hydroxyphenyl)-1(2H)phthalazinone (Ⅰ) with p-chlorobenzonitrile (Ⅱ). After (Ⅲ) was hydrolyzed, (Ⅳ) was acquired. The synthesized polyamides were characterized by means of viscosimetry, DSC, FT-IR, 1H NMR and EA. The polyamides have a high glass transition temperature which can be as high as 316 ℃. The polyamides also have good solubilities in some organic solvents.     

Facile synthesis of LiMnPO4 olivines with a plate-like morphology from a dittmarite-type KMnPO4·H2O precursor

Dittmarite-type compound KMnPO(4)·H(2)O was used as a new precursor for the synthesis of nanostructured LiMnPO(4) phospho-olivines with a plate-like morphology at low temperature (about 200 °C) and a short reaction time (90-180 min). The dehydration of KMnPO(4)·H(2)O was studied by DTA and TG analysis. Structural and morphological characterization of both KMnPO(4)·H(2)O and LiMnPO(4) was performed by powder XRD, SEM and TEM analyses. The formation of nanostructured LiMnPO(4) was examined by electron paramagnetic resonance spectroscopy and TEM. It was found that the reaction between KMnPO(4)·H(2)O with the LiCl-LiNO(3) mixture includes a fast ionic exchange of K(+) with Li(+) in the framework of the dittmarite structure, followed by H(2)O release and the formation of the olivine-type structure. The morphology and texture of the dittmarite-type precursor results in a plate-like morphology of LiMnPO(4) with a preferred orientation along the [100] direction. The plate-like morphology of LiMnPO(4) is stable after annealing at 500 °C. The plates are composed of nanocrystallites, with various sizes in the range 10-20 nm. The EPR signal of LiMnPO(4) is due to the exchange-coupled Mn(2+) ions. It was demonstrated that the EPR line-width correlates with the Scherrer crystallite size.     

Hexasubstituted donor-acceptor benzenes as nonlinear optically active molecules with multiple charge-transfer transitions

The synthesis of three novel nonlinear optical (NLO) chromophores with threefold symmetry, namely 1,3,5-tris(4-N,N-diethylaminophenyl)-2,4,6-tris(4-nitrophenyl)benzene (3), 1,3,5-tris(4-N,N-dihexylaminophenylbutadiynyl)-2,4,6-tris(4-nitrophenyl)benzene (13) and 1,3,5-tris(4-N,N-dihexylaminophenylethynyl)-2,4,6-tris(4-nitrophenylethynyl)benzene (4 b), is reported. We used the [Co(2)(CO)(8)]-catalysed trimerisation of 4-N,N-diethylamino-4'-nitrotolane (5) to prepare 3. The trimerisation experiment carried out with 1-(4-N,N-diethylaminophenyl)-6-(4-N,N-nitrophenyl)hexatriyne (6) and [Rh(PPh(3))(3)Cl] afforded 13. A stepwise approach was used to prepare 4 b. 1,3,5-Trichloro-2,4,6-triiodobenzene (8 b) was coupled with 4-nitrophenyl-acetylene (14) under Pd(0) catalysis to yield 1,3,5-trichloro-2,4,6-tris(4-nitrophenylethynyl)benzene (15). The coupling reaction of 15 with 4-N,N-dihexylaminophenylethynyltributylstannane (21) led to 4 b. X-ray investigations on 3, 4 b and 13 confirmed the structural assignments and revealed that the peripheral aryl rings in 4 b are less twisted around the connecting bonds than in 3 and 13. A large second-order polarisability (beta) of 4 b relative to 3 and 13 was determined by hyper-Rayleigh scattering (HRS). Compound 4 b represents an NLO chromophore with second-order polarisabily among the highest obtained so far for two-dimensional nondipolar NLO chromophores.     

Solvent Dependence of the Hydrolysis Products of Mn2Sb4(OEt)16

The hydrolysis-condensation pathways of Mn2Sb4(OEt)16 in various ethanol-toluene solvents have been studied for h < 1.5 (h = H2O/Mn2Sb4(OEt)16). The hydrolysis was performed by slow addition of H2O diluted with the ethanol-toluene solvent. Mn2Sb4(OEt)16 and its hydrolysis products were studied by FT-IR spectroscopy, SEM-EDS and single-crystal X-ray diffraction. The hydrolysis pathway for a given h-value was found to depend on the solvent composition. In ethanol-rich solvent mixtures, Mn7Sb4O4(OEt)18(HOEt)2 was obtained in maximum yield at h = 1.14, and in toluene-rich solvents, Mn8Sb4O4(OEt)20 was obtained in maximum yield at h = 1.0. In both cases, the remaining Sb was found as nonhydrolyzed Sb(OEt)3. The structures of the heterometallic ethoxides Mn2Sb4(OEt)16, Mn7Sb4O4(OEt)18(HOEt)2 and Mn8Sb4O4(OEt)20 have been determined earlier by single-crystal X-ray diffraction. According to FT-IR evidence the molecular structures of the latter two are retained almost intact in solution, whereas the first one changes appreciably. The hydrolysis products of Mn2Sb4(OEt)16 are compared with those of Ni2Sb4(OEt)16, and the structural and compositional changes in different solvents and at different h-values are discussed.     

Lewis Acid-Catalyzed Hydrostannation of Acetylenes. Regio- and Stereoselective Trans-Addition of Tributyltin Hydride and Dibutyltin Dihydride

Lewis acids such as ZrCl(4) or HfCl(4) catalyze the hydrostannation of acetylenes 1 by tributyltin hydride to produce the cis vinylstannanes 2 by regio- and stereoselective anti-hydrostannation. The hydrostannation of acetylenes using dibutyltin dihydride was also catalyzed by ZrCl(4) to give the stereodefined Z-Z divinyltin derivatives 4 by an anti-hydrostannation pathway. The use of nonpolar solvents such as toluene or hexane was essential for obtaining high stereoselectivity and chemical yield. Since ZrCl(4) and HfCl(4) are not soluble in such solvents, the hydrostannations were carried out in a heterogeneous system. The reactions of internal acetylenes with Bu(3)SnH proceeded smoothly, although the use of stoichiometric amounts of ZrCl(4) gave better results. The ZrCl(4)-catalyzed hydrostannation at 0 degrees C gave better yields and stereoselectivities than the reaction at room temperature. To help clalify the reason, the reaction of Bu(3)SnH with ZrCl(4) was monitored by (1)H and (119)Sn NMR spectroscopy, and it was found that Bu(3)SnH reacted with ZrCl(4) at room temperature to afford a mixture of tributyltin hydride, dibutyltin dihydride, and tetrabutyltin.     

合成聚对苯二甲酸丙二醇酯负载型催化剂钛酸四丁酯/纳米二氧化硅的制备

以钛酸酯偶联剂(TMC-201)为改性剂,采用超声波分散方法对亲水性纳米二氧化硅(nano-SiO2)进行了表面改性。采用浸渍法将钛酯四丁酯(Ti(OC4H9)4)负载于表面改性的nano-SiO2上,制备了纳米级Ti(OC4H9)4/nano-SiO2负载型催化剂。考察了偶联剂用量、温度、时间对纳米SiO2表面改性的影响,研究了负载时间、负载温度和Ti(OC4H9)4用量对表面改性后纳米SiO2负载Ti(OC4H9)4的影响。结果表明,当TMC-201质量分数为35%、反应温度为90℃、反应时间为3.5 h时,纳米SiO2粒子表面接枝的偶联剂量最大;在室温下,负载48 h,Ti(OC4H9)4用量为表面改性纳米SiO2量的1/2时得到的Ti(OC4H9)4/nano-SiO2负载型催化剂负载Ti(OC4H9)4量最大;运用ICP-AES、FESEM等测试技术对修饰后的纳米SiO2及Ti(OC4H9)4/nano-SiO2负载型催化剂进行了表征;将Ti(OC4H9)4/nano-SiO2负载型催化剂用于聚对苯二甲酸丙二醇酯(PTT)聚酯合成的结果表明,与均相Ti(OC4H9)4催化剂相比,Ti(OC4H9)4/nano-SiO2负载型催化剂催化合成PTT聚酯过程中酯化时间177 min,与均相催化剂催化酯化时间相近,在缩聚2 h后得到PTT的特性粘度高达1.05,证明该负载型催化剂具有高的催化活性,既可催化酯化反应又可催化缩聚反应。