柱前衍生-超高效液相色谱-串联质谱测定茶叶中草甘膦、草铵膦及主要代谢物氨甲基膦酸残留

采用柱前衍生-超高效液相色谱-串联质谱测定茶叶中草甘膦、草铵膦及其主要代谢物氨甲基膦酸残留。利用正交试验方法,系统研究了提取与净化等前处理条件对茶叶中草甘膦、草铵膦和代谢物氨甲基膦酸检测的影响。实验结果表明,最优的前处理方案为茶叶样品经纯水旋涡提取,阳离子交换柱净化,0.5%（v/v）甲酸水溶液洗脱和9-芴甲基氯甲酸酯衍生,C₁₈色谱柱分离,超高效液相色谱-串联质谱定量分析（电喷雾正离子）。结果表明：在1~100 μ g/L范围内,草甘膦、草铵膦和氨甲基膦酸呈现良好的线性关系,相关系数（R²）均大于0.991,该方法检出限为0.0160~0.0300 mg/kg,定量限为0.0530~0.100 mg/kg。在0.0500、0.400和1.20 mg/kg 3个添加水平下,草甘膦、草铵膦和氨甲基膦酸的平均回收率为78.3%~108%,相对标准偏差为5.46%~9.63%。利用该方法检测837份茶叶中草甘膦、草铵膦和氨甲基磷酸残留,检出率分别为3.46%、0.24%和4.42%,超标率为0.24%。该方法简单、快速、灵敏、准确,能够满足大批量茶叶中草甘膦、草铵膦和氨甲基膦酸残留的检测需要。     

超高液相色谱-三重四极杆质谱法快速测定水中9种极性农药残留量

建立了一种超高效液相色谱-三重四极杆质谱(UPLC-MS/MS)快速测定水中草甘膦、氨甲基膦酸、N-乙酰草甘膦、N-甲基草甘膦、草铵膦、N-乙酰氨甲基磷酸、3-甲基磷酸亚基丙酸、N-乙酰草铵膦及乙烯利共9种极性农药残留的方法。样品经0.22μm滤膜过滤或PLS固相萃取小柱净化后0.22μm滤膜过滤,滤液无需衍生化直接进样定性、定量分析。9种目标物通过Dikma Polyamino HILIC色谱柱(150 mm×2.0 mm, 5μm)分离,以甲酸铵-氨水缓冲溶液(pH=11)和乙腈为流动相进行梯度洗脱,在电喷雾离子源负离子模式下,采用MRM方式进行测定。结果表明,9种目标物在0.20～50.00μg/L范围内线性关系良好,相关系数均大于0.999,方法检出限为0.04～0.08μg/L,方法测定下限为0.12～0.24μg/L。在高、中、低3个浓度水平进行加标回收实验,回收率在88.9%～105%之间,相对标准偏差(n=6)在2.8%～8.2%之间。与传统的衍生化方法比较,该方法操作简便、重现性好、准确性高且不受基体干扰,适用于环境水样中草甘膦、氨甲基膦酸、N-乙酰草甘膦、N-甲基草...     

柱后加碱-高效阴离子交换色谱-脉冲安培检测法测定农田土中草铵膦、氨甲基膦酸和草甘膦残留

应用柱后加碱-高效阴离子交换色谱-脉冲安培检测法同时测定了农田土中草铵膦、氨甲基膦酸和草甘膦的残留。土壤样品用2 mmol/L氢氧化钠振荡提取，混匀后依次用0.22 μm滤膜、IC-C₁₈和IC-Na柱处理。滤液中的3种目标物和共存离子经IonPacAS11-HC离子色谱柱分离，柱后加碱-脉冲安培检测器检测。结果表明，草铵膦和草甘膦质量浓度在20.0~1000 μg/L、氨甲基膦酸质量浓度在5.0~400 μg/L范围内线性关系良好，相关系数均大于0.999。草铵膦、氨甲基膦酸和草甘膦的检出限分别为0.08、0.02和0.04 mg/kg，回收率为80.2%~106%，相对标准偏差为0.7%~5.0%（n=6）。该方法抗干扰性强、灵敏度和准确度高，操作简便快捷，适用于农田土中草铵膦，氨甲基膦酸和草甘膦残留量的检测。     

高效液相色谱-串联质谱法测定血液中草铵膦及其代谢物3-甲基膦基-丙酸的含量

利用两份口服草铵膦中毒死者提取的心血样本,分析了人体内草铵膦代谢物的存在情况,明确了草铵膦中毒死者血液的检测目标物为草铵膦及其主要代谢物3-甲基膦基-丙酸,并提出了高效液相色谱法-串联质谱法测定血液中草铵膦及其代谢物3-甲基膦基-丙酸含量的方法。在血液、水、乙腈的体积比为1∶0.5∶3条件下沉淀蛋白,获取上清液后添加与乙腈体积相同的二氯甲烷,涡旋、离心,上层水相经0.22μm水相滤膜过滤,所得滤液注入高效液相色谱仪。以价格低廉的Dikma Polyamino HILIC色谱柱(150 mm×2.0 mm, 5μm)为固定相,以含5 mmol·L^-1乙酸铵的1.25%(体积分数)氨水溶液-乙腈为流动相体系进行梯度洗脱;分离后的目标物经电喷雾离子源负离子模式扫描,多反应监测模式检测,以基质匹配法定量。结果显示：草铵膦和3-甲基膦基-丙酸工作曲线的线性范围均为0.2～10.0 mg·L^-1,检出限(3S/N)均为0.1 mg·L^-1;对空白心血进行3个浓度水平的加标回收试验,草铵膦和3-甲基膦基-丙酸的回收率分别为35.6%～...     

离子色谱-质谱法测定生活饮用水中草甘膦和氨甲基磷酸

草甘膦(GLY)是一种广泛使用的除草剂[1-2],生活饮用水国家标准GB 5749-2006中规定,草甘膦的限值为0.7mg·L-1。草甘膦的主要代谢产物为氨甲基磷酸(AMPA)[3],因为草甘膦和氨甲基磷酸亲水性极强,不易挥发,所以采用气相色谱-串联质谱法(GC-MS/MS)[4-5]进行测定时,必须进行衍生,但是衍生法操作条件苛刻、重现性差。另外,草甘膦和氨甲基磷酸在C18柱上没有保留,采用高效液相色谱-质谱法进行测定时,极易受到干扰[6-11]。     

分散固相萃取净化液质联用测定茶叶中的草铵膦、草甘膦和氨甲基膦酸残留

建立了分散固相萃取净化非衍生-超高液相色谱-串联质谱快速检测茶叶中的草铵膦、草甘膦及其代谢物氨甲基膦酸残留的方法。样品用乙腈-水溶液提取后采用多壁碳纳米管净化,多反应监测(MRM)模式测定,基质外标法定量。结果表明:草铵膦、草甘膦、氨甲基膦酸的线性范围为分别为2. 5～100,5. 0～200,5. 0～200μg/L,相关系数(R~2)均大于0. 995,方法的检出限分别为10,20,20μg/kg,定量限为25,50,50μg/kg,回收率在80. 6%～98. 1%之间,相对标准偏差(RSDs)在4. 4%～9. 4%之间。该方法可用于茶叶中草铵膦、草甘膦和氨甲基膦酸的快速检测。     

柱前衍生-固相萃取-高效液相色谱法测定饮用水中草甘膦和氨甲基膦酸

提出了柱前衍生-固相萃取-高效液相色谱法测定饮用水中草甘膦和氨甲基膦酸。水样经9-芴基甲基三氯甲烷衍生和C18固相萃取小柱净化后,洗脱液采用Waters Atlantis T3色谱柱分离,流动相为甲醇-0.02mol·L-1乙酸铵溶液(60+40),荧光检测器激发波长为266nm,发射波长为315nm。草甘膦和氨甲基膦酸的质量浓度在5.00~500μg·L-1范围内与其峰面积呈线性关系,检出限均为0.002μg·L-1。对水样进行加标回收试验,草甘膦和氨甲基膦酸的回收率分别在84.4%~92.0%和87.8%~96.8%之间,相对标准偏差(n=6)分别在1.2%~4.3%和1.1%~4.0%之间。该方法适用于水厂出水水样中草甘膦和氨甲基膦酸的同时测定。     

离子色谱-串联质谱法测定地下水中草甘膦、草铵膦和氨甲基膦酸

采用离子色谱-串联质谱法测定了地下水中草甘膦、草铵膦和氨甲基膦酸,水样用0.22μm滤膜过滤后进样100μL,经Ionpac AS11-HC离子色谱柱分离,采用电喷雾串联四极杆质谱仪负离子多反应监测模式检测,外标法定量。结果表明,草甘膦、草铵膦和氨甲基膦酸分别在质量浓度为0.05～2.00μg/L,0.30～12.0μg/L,2.00～80.0μg/L范围内线性相关系数均大于0.999。草甘膦、草铵膦和氨甲基膦酸检出限分别为0.01,0.08,0.50μg/L,相对标准偏差为4.3%～15%,8.0%～10%,5.9%～7.7%,实际样品加标回收率为60.0%～100.0%,80.0%～118.3%,80.5%～109.0%。方法适用于地下水中草甘膦、草铵膦和氨甲基膦酸的测定。     

固相萃取净化-超高效液相色谱-三重四极杆质谱法测定土壤中草铵膦、草甘膦及其代谢物氨甲基膦酸

建立了固相萃取净化-超高效液相色谱-三重四极杆质谱法测定土壤中草铵膦、草甘膦及其代谢物氨甲基膦酸含量的方法.将土壤样品与水、二氯甲烷混合后,高速匀浆1 min后离心,取上清液3 mL过Oasis HLB固相萃取小柱,收集最后1 mL的流出液,过0.22μm滤膜.用超高效液相色谱-三重四极杆质谱测定滤液中的草铵膦、草甘膦...     

高效液相色谱-串联质谱法检测茶叶中痕量草胺膦、草甘膦及其代谢物氨甲基膦酸残留

建立高效液相色谱–串联质谱法测定茶叶中除草剂草胺膦、草甘膦及其代谢物氨甲基膦酸残留的方法。以纯水提取茶叶中的草胺膦、草甘膦、氨甲基膦酸,用二氯甲烷、阴离子交换固相萃取柱净化、富集,以0.25 mol/L碳酸氢钠溶液洗脱,然后直接采用1%芴甲氧羰酰氯进行衍生,衍生时间为5 min,用反相液相色谱柱分离,以电喷雾正离子模式,多反应模式(MRM)检测。草胺膦、草甘膦、氨甲基膦酸的质量浓度在0～20μg/L范围内均具有良好的线性,线性相关系数大于0.995,方法定量限为0.01 mg/kg。在不同茶叶基质中,0.01,0.025,0.05 mg/kg三水平的平均添加回收率为94.0%～116.0%,测定结果的相对标准偏差为3.5%～7.1%(n=6)。该方法操作简便,灵敏度与准确度高,满足茶叶样品中草胺膦、草甘膦及其代谢物氨甲基膦酸低残留的检测要求。     

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.