高效液相色谱法同时测定化工废水中乙醇酸、乙醛酸和草酸的含量

水样经0.22μm亲水针筒式过滤器过滤,根据需要进行稀释后,在Acclaim MixedMode WAX-1色谱柱(4.6mm×150mm,5μm)上进行分离,以90mmol·L~(-1)磷酸盐缓冲溶液[pH 6.0,溶剂为10%(体积分数)乙腈溶液]为流动相进行等度洗脱,在波长210nm处进行紫外检测。结果表明:乙醇酸、乙醛酸和草酸的质量浓度分别在3.51～2 500,4.20～8 000,18.0～800mg·L~(-1)内与对应的峰面积呈现线性关系,检出限(3S/N)分别为1.00,1.24,4.82mg·L~(-1),测定下限(10S/N)分别为3.32,4.15,16.1mg·L~(-1)。对实际样品进行加标回收试验,乙醇酸、乙醛酸和草酸的回收率分别在98.2%～101%,99.6%～103%,99.2%～101%之间,测定值的相对标准偏差(n=6)分别为0.77%,0.65%,1.1%。     

高效液相色谱法测定造影剂碘普罗胺中的相关杂质

提出采用高效液相色谱法测定一种非离子型碘造影剂碘普罗胺中5种杂质含量的方法。以Eclipse C18Plus色谱柱为分离柱,以不同体积比混合的水和体积比为55∶40∶5的水-乙腈-2-丁醇混合溶液为流动相进行梯度洗脱,在检测波长245nm处对5.0g·L~(-1)的样品溶液中的5种杂质进行测定。结果显示:杂质1～5标准曲线的线性范围分别为2.57～51.4 mg·L~(-1),5.05～101mg·L~(-1),2.56～51.2mg·L~(-1),1.01～20.2mg·L~(-1),0.51～10.2mg·L~(-1)。检出限(3S/N)分别为0.10,0.20,0.15,0.12,0.10mg·L~(-1)。对实际样品进行3个浓度水平的加标回收试验,杂质1～5的回收率分别为105%,93.7%,95.2%,97.8%,112%,重复性和中间精密度试验结果显示,杂质1～5测定值的相对标准偏差(n=6)均在15%以内。     

反相高效液相色谱法测定保健品中反式维生素K1的含量

建立了反相高效液相色谱法测定保健品中维生素K_1反式构体含量的方法。将维生素K_1补充片剂研磨成粉后,称取0.25 g样品,用异丙醇溶解后,定容至50 mL棕色容量瓶中,用0.45μm滤膜过滤,取上清液,采用Phenyl柱,以不同体积比的甲醇和50 mmol·L~(-1)乙酸溶液的混合液为流动相进行梯度洗脱。结果显示:在上述色谱条件下,顺、反式维生素K_1的分离度(R_S)为1.76,线性范围分别为0.01～2 mg·L~(-1)和0.04～8 mg·L~(-1),检出限(3S/N)分别为0.032 mg·L~(-1)和0.074 mg·L~(-1)。对空白样品进行3个浓度水平的加标回收试验,反式维生素K_1的回收率为92.0%～95.2%,测定值的日内相对标准偏差(RSD,n=6)为1.6%～2.2%,日间RSD(n=5)为2.4%～4.8%;顺式维生素K_1的回收率为90.0%～101%,测定值的日内RSD(n=6)为1.4%～2.3%,日间RSD(n=5)为2.6%～4.6%。方法用于实际样品分析,反式维生素K_1的检出量为75.36～80.12μg·g~(-1)。     

微波消解试样-火焰原子吸收光谱法测定茶叶中铅和铜

采用浓硝酸-过氧化氢(体积比5比1)混合酸对茶叶试样进行消解,用火焰原子吸收光谱法测定其中铅和铜的含量。对消解酸体系、仪器工作条件进行了优化。铅的质量浓度在0.95～3.80mg·L~(-1)、铜的质量浓度在0.108～0.864mg·L~(-1)范围分别与其吸光度呈线性关系,检出限(3σ)分别为18.3,15.9μg·L~(-1)。方法用于分析茶叶试样,铅和铜加标回收率分别为98.8%～102.4%和93.3%～100.0%之间。     

反相高效液相色谱法测定花椒的3种黄酮苷元的含量

提出了反相高效液相色谱法测定花椒的3种水解黄酮苷元槲皮素、山柰酚、异鼠李素的含量。采用Zorlbax Eclipse C_(18)色谱柱(4.6mm×150mm,5μm),以甲醇-0.4%(体积分数)磷酸溶液(1+1)混合溶液为流动相,在360nm波长处进行测定。槲皮素的质量浓度在2.19～109.6mg·L~(-1),山柰酚的质量浓度在2.28～114.0mg·L~(-1),异鼠李素的质量浓度在2.80～140.0mg·L~(-1)时分别与其峰面积呈线性关系。槲皮素、山柰酚和异鼠李素的加标回收率分别为95.6%,104.4%,103.8%,相对标准偏差(n=5)分别为2.98%,3.97%,4.30%。     

离子色谱法测定瓶装水中阴离子

采用离子色谱法测定瓶装水中7种阴离子的含量。水样经Ion Pac AG14保护柱及IonPac AS14分离柱分离,以3.5mmol·L~(-1)碳酸钠-1.0mmol·L~(-1)碳酸氢钠溶液为淋洗液,采用抑制电导器检测。F~-和PO_4~(3-)分别在0.05～1.20mg·L~(-1)和0.80～3.00mg·L~(-1)范围内,Cl~-、NO_2~-、Br~-、NO_3~-和SO_4~(2-)均在0.20～4.80mg·L~(-1)范围内呈线性关系,检出限(3S/N)在0.025～0.126mg·L~(-1)之间。方法用于瓶装水中7种阴离子的测定,加标回收率在92.8%～102.0%之间,相对标准偏差(n=7)均小于4.0%。     

高效液相色谱法同时测定刺三加叶中芦丁和没食子酸含量

刺三加叶样品先后经沸水和石油醚浸泡,所得滤渣再经60%(体积分数)乙醇溶液超声提取,提取液经高效液相色谱法测定其中芦丁和没食子酸含量。以ZORBAXSB-C_(18)色谱柱(250 mm×4.6 mm,5μm)为固定相,以体积比为 44:55.6:0.4 的 CH_2 OH-H_2O-CH_3COOH 混合溶液为流动相,以260 nm和272 nm分别作为芦丁和没食子酸的检测波长。芦丁和没食子酸的质量浓度分别在0.55～11.00,0.26～5.18 mg·L~(-1)内与其对应的峰面积呈线性关系,芦丁和没食子酸的检出限(3S/N)分别为0.04,0.03 mg·L~(-1);芦丁和没食子酸的测定下限(10S/N)分别为0.11,0.08 mg·L~(-1)。芦丁和没食子酸的的平均加标回收率分别为99.7%,99.4%,相对标准偏差(n=6)分别为 0.81%,0.97%。     

流动注射-催化光度法测定痕量草酸根

在1.8×10~(-2)mol·L~(-1)硫酸介质中,于30℃加热160s时,草酸根对重铬酸钾、碘化钾和罗丹明6G之间的褪色反应具有显著的催化作用。结合流动注射技术,提出了一种催化光度法测定痕量草酸根的方法。草酸根的线性范围为0.10～1.20mg·L~(-1),检出限(3s/k)为0.03mg·L~(-1),进样频率18次·h~(-1)。对0.30及0.80mg·L~(-1)草酸根标准溶液进行平行测定,其相对标准偏差(n=11)分别为2.7%和1.6%。该方法用于菠菜、尿液中草酸根含量的测定,并以此样品为基体进行回收试验,测得回收率在93.3%～96.7%之间。     

超高效液相色谱-串联质谱法测定灵芝红茶中灵芝酸A和灵芝酸B

样品经40%(体积分数)甲醇溶液15.0mL超声提取20min。以Ultimate UPLC XBC18色谱柱(150mm×2.1mm,1.8μm)分离,用乙腈-水(45+55)溶液洗脱,采用负离子模式监测。以氯霉素为内标物。灵芝酸A、B的线性范围分别为0.051 3~0.513 mg·L~(-1)和0.020 8~0.125mg·L~(-1),方法的检出限(3S/N)分别为0.15,0.062mg·L~(-1)。方法用于灵芝红茶样品的分析,加标回收率在96.0%~104%之间,测定值的相对标准偏差(n=9)在1.1%~2.8%之间。     

离子色谱法测定皂粒中葡萄糖酸钠含量

建立了离子色谱检测皂粒中葡萄糖酸钠含量的分析方法。样品经METROSEP CARB 1糖分析色谱柱(150 mm×4.0 mm,5μm)分离,以150 mmol·L~(-1) NaOH+20 mmol·L~(-1)NaAc水溶液为流动相进行等度洗脱,流速1.0 mL·min~(-1),采用瑞士万通850型离子色谱仪,选择脉冲安培检测器进行测定,外标法定量。结果显示:葡萄糖酸钠在0.5～200 mg·L~(-1)质量浓度范围内呈良好的线性,相关系数(r~2)为0.999 6,检出限为0.25 mg·L~(-1),定量下限为0.63 mg·L~(-1)。葡萄糖酸钠在1～20 mg/g加标范围内的回收率为80.7%～104%。该方法无需衍生化处理,操作简单方便,灵敏度高,可用于皂粒产线葡萄糖酸钠含量的监控与测定。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

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.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.