离子色谱法同时测定大气降水中的5种阴离子

以保留时间定性、峰面积外标法定量,建立了离子色谱同时测定大气降水中F–,Cl–,NO2–,NO3–,SO42–5种阴离子的分析方法。结果表明,5种阴离子标准曲线线性相关系数均大于0.999 8,检出限(3s/k)在0.000 3~0.006 6 mg/L之间。F–,Cl–,NO2–,NO3–,SO42–测定结果的相对标准偏差(n=10)分别为1.70%,2.46%,9.30%,0.73%,0.67%。用该方法对水样进行测定并进行加标回收试验,5种阴离子加标回收率在91.2%~102.7%之间。该方法灵敏度高,简便、快速,能满足大气降水中阴离子分析的要求。     

离子色谱法测定生活饮用水中的F~–,Cl~–,SO_4~(2–)和NO_3~–

建立了电导检测–离子色谱法同时测定生活饮用水中F–,Cl–,SO42–,NO3–的方法。选择30 mmol/L Na OH溶液为淋洗液,流量为1.40 m L/min,检测器电流为106 m A。F–的线性范围为0.15~2.0 mg/L,Cl–,SO42–,NO3–的线性范围为3.00~40.0 mg/L,4种离子的线性相关系数均大于0.999 5。F–,Cl–,SO42–,NO3–的方法检出限分别为0.02,0.13,0.14,0.02 mg/L,加标回收率在95.2%~103.0%之间。对环境标准204715进行了平行测试,各阴离子测定值均在标准值的不确定度范围内,测定结果的相对标准偏差小于2%(n=6)。该方法灵敏、准确、快速,可用于生活饮用水中F–,Cl–,SO42–,NO3–的同时测定。     

离子色谱法测定土壤中氯离子、硫酸根离子、硝酸根离子

建立离子色谱法测定土壤中Cl~–,SO_4~(2–),NO_3~–3种阴离子的含量。淋洗液为30 mmol/L KOH溶液,等浓度淋洗,流速为1.0 mL/min。Cl~–,SO_4~(2–),NO_3~–的线性范围均为0~20 mg/L,线性相关系数均大于0.999 9,检出限为0.051~0.082 mg/L,混合标准溶液测定结果的相对标准偏差为0.31~0.38%(n=10)。对土壤样品进行重复测定,3种离子测定结果的相对标准偏差均小于3%(n=7),加标回收率在95.0%~104.5%之间。该方法测定结果准确,操作简单、快速,适用于土遗址中Cl~–,SO_4~(2–),NO_3~–的测定。     

离子色谱法同时测定大气降水中7种阴离子

建立离子色谱法同时测定大气降水中F^-,Cl^-,NO2^-,Br-,NO3^-,SO4^2-和PO43^-7种阴离子的分析方法。选用IonPac■AS19型色谱柱(4 mm×250 mm),以KOH梯度淋洗,用抑制电导检测器进行测定。7种阴离子在各自的质量浓度范围内与色谱峰面积成良好的线性关系,相关系数均不小于0.997,方法检出限为0.002~0.004 mg/L。测定结果的相对标准偏差为0.80%~3.38%(n=6),样品加标回收率为75.0%~98.7%。该方法简便、快速,灵敏度高,适用于大气降水中F^-,Cl^-,NO2^-,Br^-,NO3^-,SO4^2-和PO43^-7种阴离子的同时测定。     

毛细管离子色谱法测定饮用水中的阴离子

研究了毛细管离子色谱法检测饮用纯净水、矿物质水及天然矿泉水中的7种无机阴离子(F–,Cl–,Br–,NO2–,NO3–,PO43–,SO42–)含量的方法。实验采用Ion Pac AS19 Capillary阴离子交换色谱柱(250 mm×0.4 mm,Thermo Fisher),以KOH溶液为淋洗液。测定7种阴离子的线性范围F–为10~1 000μg/L,Cl–为15~1 500μg/L,Br–,NO2–,NO3–为50~5 000μg/L,PO43–,SO42–为75~7 500μg/L,线性相关系数除PO43–为0.998外,均大于0.999,检出限为0.001~0.1μg/L,各离子加标回收率在94.53%~101.1%之间。用该法对实际水样进行测定,测定结果的相对标准偏差小于5%(n=3)。该方法简单实用,适用于饮用水中常见阴离子的分析测定。     

碱化底液消除水负峰离子色谱法测定水中F~–,Cl~–等7种阴离子

在研究消除水负峰的基础上,建立离子色谱法测定水中F–,Cl–,NO2–,H2PO4–,Br–,NO3–,SO42–7种阴离子的方法。经实验确定淋洗液为4.5 mmol/L NaHCO3–4.0 mmol/L Na2CO3,淋洗液流量为1.0 mL/min,柱箱温度为35℃。在底液中加入与淋洗液同浓度的Na2CO3–NaHCO3可有效消除水负峰。该方法对7种阴离子的检出限为0.004~0.034 mg/L,测定结果的相对标准偏差为0.69%~3.57%(n=6),加标回收率为95%~105%。该法能有效消除水负峰及其对F–测定的影响,操作简便、测定结果准确可靠,适用于水中F–、Cl–等7种阴离子的测定。     

离子色谱法测定纯净水中6种阴离子

建立离子色谱法测定纯净水中F–,Br O3–,Cl–,NO2–,Br–,NO3–等6种阴离子的方法。淋洗液为1.2mmol/L Na HCO3–1.0 mmol/L Na2CO3混合溶液,流量为1.5 m L/min,柱箱温度为35℃。在底液中加入与淋洗液同浓度的Na2CO3–Na HCO3碱化底液可有效消除水负峰。6种阴离子的检出限为1.0~21.0μg/L,加标回收率在90.0%~106.0%之间,相对标准偏差为1.43%~4.49%(n=5)。该方法测定结果准确、可靠,操作简便快速,适用于纯净水中F–,Br O3–,Cl–,NO2–,Br–,NO3–的测定。     

离子色谱法同时测定大气可吸入颗粒物PM10中14种水溶性离子

采用离子色谱法同时测定了大气可吸入颗粒物PM10中的多种水溶性阴阳离子。样品采用超纯水超声萃取各种水溶性离子,优化的萃取溶液体积为40mL,萃取时间为15 min,萃取液用0.45μm纤维滤膜过滤,阴、阳离子分别采用响应的离子色谱柱分离,流动相分别采用3.6 mmol/L Na2CO3溶液+0.6 mmol/L NaHCO3溶液,2 mmol/L HNO3溶液,其中阳离子检测未使用抑制器,电导检测器检测。14种离子在一定浓度范围内线性关系良好,相关系数r都>0.999,F-,BrO3-,Cl-,NO2-,Br-,NO3-,PO42-,SO42-等8种阴离子的检出限分别为1.5,7.5,1.6,4.2,6.5,12.5,10.4,3.3μg/L,Li+,NH4+,Na+,K+,Mg2+,Ca2+等6种阳离子的检出限分别为4.6,12.3,8.5,19.8,12.4,17.9μg/L,平均回收率为92.3%~99.7%,标准偏差小于5%。方法适用于同时测定PM10中的多种水溶性离子。     

离子色谱法测定电厂水中的有机酸和无机阴离子

建立离子色谱梯度淋洗抑制电导法测定电厂水中有机酸和无机阴离子的方法。选用Ion Pac AG11–HC(50 mm×4 mm)阴离子保护柱和Ion Pac AS11–HC(250 mm×4 mm)阴离子分析柱对样品进行分离,以氢氧化钾溶液梯度淋洗,自再生抑制电导检测器检测,同时测定电厂水中的有机酸和无机阴离子。F–,Cl–,NO2–,Br–,NO3–的线性范围为0.005~2 mg/L,CH3COO–,HCOO–,SO42–,PO43–的线性范围为0.01~5 mg/L,各组分线性相关系数为0.998 9~0.999 3,检出限为0.122~0.989 ng/m L,测定结果的相对标准偏差小于2.0%(n=7),样品加标平均回收率为97.9%~101.7%。该方法操作简便,实用性强,可以用于电厂水中有机酸和无机阴离子的检测。     

在线超滤-离子色谱法测定降水中4种阴离子

建立在线超滤–离子色谱法测定降水中4种阴离子。采用在线超滤技术,以Metrosep A Supp 5–150色谱柱为分析柱,3.2 mmol/L Na_2CO_3–1.0 mmol/LNaHCO_3溶液为淋洗液,流量为0.7 mL/min,0.5%H_2SO_4为抑制器再生液,用离子色谱法对降水中4种阴离子进行测定。氟离子、氯离子、硝酸根离子、硫酸根离子质量浓度在各自范围内与色谱峰面积呈良好的线性关系,相关系数均大于0.999,方法检出限为0.005～0.015 mg/L。测定结果的相对标准偏差为0.7%～2.2%(n=6),样品加标回收率为97.0%～103.0%。该法操作简单、成本低,适于大气降水中阴离子的测定。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.