离子色谱法测定茶叶中的无机阴离子

提出了离子交换色谱法分离测定茶叶中F-、Cl-、Br-、NO3-、H2PO4-和SO2-4 6种无机阴离子含量的方法.茶叶样品中6种阴离子用水在95℃超声萃取20 min后,经IonPac ASll-HC阴离子分离柱,AGll-HC阴离子保护柱,以氢氧化钾为淋洗液,浓度从15 mmol·L-1到30 mmol·L-1进行梯度淋洗.F-、Cl-和Soi2-4的峰面积与其质量浓度在0.01～150.0 mg·L-1范围内,H2PO-4、NO-3和Br-在0.05～150.0 mg·L-1范围内呈线性关系.6种离子的检出限(3S/N)均小于0.03 mg·L-1.该方法用于茶叶样品中F-、Cl-、Br-、NO-3、H2PO-4和SOi2-4的测定,加标回收率在90.9%～100.0%之间,测定值的相对标准偏差(n=5)小于3.5%.     

离子色谱阀切换快速测定六氟磷酸根及多种阴离子

建立了快速测定离子液体中六氟磷酸根(PF6-)及其它常规阴离子(F-,Cl-,NO-3,SO24-)的离子色谱阀切换方法。通过保护柱与分离柱的简单切换,使强保留离子PF6-仅通过保护柱,缩短其流通路径,在较短时间内出峰,其它离子既通过保护柱又通过分离柱,从而达到快速同时分离的目的。样品经稀释溶解后直接进样,淋洗液选用KOH,流速为1.0 mL/min,采用抑制型电导检测,外标法定量。PF6-,F-,Cl-,NO-3和SO24-的线性范围分别为1~200 mg/L,0.1~25 mg/L,0.1~5 mg/L,0.1~5 mg/L和0.1~5 mg/L,线性相关系数均大于0.9995;加标回收率在86.5%~112.2%之间;相对标准偏差在1.4%~4.1%之间,检出限分别为8.9,0.41,0.44,1.2和1.2 mg/L。本方法适用于一系列强弱保留离子同时分析的问题。     

离子色谱法测定大气降尘中四种阴离子

以流速 1.5ml·min- 1,0 .2 4mol·L- 1Na2 CO3和 0 .30mol·L- 1NaHCO3混合液为淋洗液 ,在YSA 4型阴离子分离柱上分离 ,采用带电导检测器的离子色谱仪对大气降尘中四种阴离子进行分离测定 ,F- 、Cl- 、NO- 3、SO2 - 4的检出限 (3S/N)分别为 0 .0 0 1,0 .0 0 1,0 .0 0 6 ,0 .0 0 4mg·L- 1,相关系数分别为 0 .9991,0 .9986 ,0 .9997,0 .9984 ,RSD分别为 0 .80 % ,0 .76 % ,1.80 % ,1 90 %。     

离子色谱法测定印刷电路板上痕量无机阴离子

将印刷电路板样品置于异丙醇及水(3 1)的混合溶液中浸泡以萃取板上的无机阴离子Cl-、Br-、NO-3及SO2-4,并经在线预处理除去异丙醇对测定的干扰.用离子色谱法测定所得溶液中4种阴离子,对影响上述阴离子分离条件(淋洗液浓度及样品溶液的在线转移时间等)进行了研究.在最优条件下,测得4种阴离子工作曲线的线性范围均为20.0～800.0 μg·L-1,以质量浓度为100.0,800.0μg·L-1的混合标准溶液对方法的精密度作了试验,测得Cl-、Br-、NO-3及SO2-4峰面积值的相对标准偏差(n=6)依次为0.7%,0.8%,0.7%,1.8%和0.1%和0.1%,1%,0.1%,0.7%.     

离子色谱法测定银杏叶中无机阴离子

应用离子色谱法测定了银杏叶中6种无机阴离子(F-,Cl-,NO-2,PO3-4,NO-3及SO2-4),测定中采用了Y5AB-8041A型阴离子分离柱及电导检测器,用含有5.0 mol·L-1碳酸钠溶液及5.4 mmol·L-1碳酸氢钠溶液的混合液作为洗脱液,以1.5 mL·min-1的流速通过分离柱.6种阴离子的峰高值与浓度值在一定范围内呈线性关系,其相关系数在0.999 1～0.999 7之间.测得6种阴离子的检出限(以μg·L-1表示)依次为2.75,4.71,9.43,11.1,30.0及22.4.用含6种阴离子的混合标准溶液,连续测定5次,检测方法的精密度,算得其相对标准偏差≤0.94%.用标准加入法测定了方法的回收率,测得结果在96.4%～102.3%之间.     

在线渗析-离子色谱法测定蔬菜中无机阴离子

采用在线渗析技术与离子色谱法联用测定蔬菜等样品中多种阴离子.样品提取后,取上层清液经渗析后进入分离柱,采用Metrosep A Supp 4-250阴离子交换柱,以1.8 mmol·L-1Na2CO3与1.7 mmo·L-1NaHCO3混合溶液为流动相,化学抑制电导检测.方法中各阴离子检出限(3S/N)为1-18ug·L-1.方法用于复杂基质蔬菜样品中F-、Cl-、NO-2、Br-、NO-3、PO3-4和SO2-4等阴离子的测定,加标回收率均大于78%,相对标准偏差(n=6)在1.8%～6.1%之间.     

离子色谱法测定选矿废水中4种阴离子

采用离子色谱法测定选矿废水中微量F-、Cl-、NO3-、SO42-的含量。以SH-AC-1型阴离子分离柱为离子交换柱,以2.5 mmol.L-1碳酸钠-3.5 mmol.L-1碳酸氢钠溶液为淋洗液,采用抑制电导器检测。F-、Cl-、NO3-、SO24-4种阴离子分别在0.01~4.0,0.01~15.0,0.01~15.0,0.01~30.0 mg.L-1范围内呈线性关系,检出限(3S/N)分别为6.13,3.89,5.86,8.49μg.L-1。方法用于选矿废水试样中4种阴离子的测定,加标回收率分别为97.5%,104.0%,102.0%,98.3%,相对标准偏差均小于4.0%。     

离子交换色谱法测定间苯二甲酸生产工艺中间物料及产品中的阴离子

建立了用离子交换色谱法同时测定间苯二甲酸生产工艺中中间物料及产品中F-、Cl-、Br-、OAc-、NO3-、PO43-和SO42-等7种阴离子的分析方法。采用A SUPP 5-250阴离子交换柱,以2.8 mmol.L-1Na2CO3和1.2 mmol.L-1NaHCO3混合溶液为流动相,在20 min内有效地分离和测定了样品中上述7种阴离子。采用抑制型电导检测,以S/N=3计算,F-、Cl-、Br-、OAc-、NO3-、PO43-和SO42-等离子的检出限分别为0.10,0.40,0.35,0.25,2.50,0.25和0.90μg.L-1,相关系数在0.999 1~0.999 7范围内;峰面积的相对标准偏差小于1.3%,加标回收率在98.2%~100.3%之间。     

离子色谱法测定麻黄中的无机阴离子

建立了用单柱阴离子色谱测定麻黄中阴离子的方法。采用Shim Pack IC AI阴离子交换柱、2.5 mmol/L 邻苯二甲酸和2.4 mmol/L 三羟甲基氨基甲烷混合溶液为流动相、电导检测器在10 min内完成麻黄草中F-,Cl-, NO-2,Br-,NO-3, SO 2- 4的测定。该法具有良好的线性（相关系数为 0.999 2 ～ 0.999 7 ）和重复性（相对标准偏差小于1.92%）,回收率为96.6%～100.4%。方法简便实用,用于实际样品分析,所得结果令人满意。     

离子色谱法测定农村饮用水中阴离子

采用离子色谱法测定农村饮用水中F-、Cl-、NO2-、Br-、NO3-和SO42-等6种阴离子的含量。水样经Ion Pac AG19保护柱及Ion Pac AS19分离柱分离,以20.00mmol·L-1氢氧化钾溶液为淋洗液,采用抑制电导器检测。F-、NO2-和Br-在4mg·L-1以内,Cl-、NO3-和SO42-在40mg·L-1以内呈线性关系,检出限(2S/N)在0.002～0.012mg·L-1之间。方法用于水样中6种阴离子的测定,加标回收率在98.0%～101.3%之间,相对标准偏差(n=6)在0.83%～2.7%之间。     

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.     

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.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

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.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.