超高效液相色谱-串联质谱分析蓝藻中微囊藻毒素的总量

建立了超高效液相色谱-串联质谱对蓝藻中微囊藻毒素总量的测定方法。样品采用乙酸及甲醇溶液进行抽提后离心,上清液经浓缩用固相萃取柱进行富集、纯化,洗脱液经0.025 mol/L KMnO4和饱和NaIO4溶液在pH 9条件下氧化1h。以BEH C18色谱柱进行梯度洗脱分离,采用离子监测质荷比(m/z 131.10)定量分析。微囊藻毒素总量的回收率在82.0%～98.6%之间。微囊藻毒素总量的检出限为0.80μg/L。该方法适用于测定蓝藻中的微囊藻毒素总量分析。     

固相萃取-高效液相色谱-二极管阵列检测器法同时测定湖水中10种蓝藻毒素

建立了固相萃取-高效液相色谱-二极管阵列检测器法测定湖水中10种蓝藻毒素(MC-RR、MC-YR、MC-Hty R、MC-LR、MC-WR、MC-LA、MC-LY、MC-LW、MC-LF和NOD)的方法。水样经固相萃取净化后,用Waters PAH C_(18)(250 mm×4.6 mm,5μm)色谱柱,以乙腈和含0.05%三氟乙酸为流动相梯度洗脱,流速为0.8 m L/min,柱温为30℃,进样量为20μL,二极管阵列检测器检测范围190~300 nm,检测波长为238 nm。根据保留时间、二极管阵列检测器全扫描光谱和色谱峰纯度分析等进行定性分析。10种蓝藻毒素在0.05~2.00 mg/L浓度范围内线性关系良好,线性系数R为0.9998~0.9999,方法检出限为0.005~0.020μg/L。3个浓度加标水平(0.1、1.0和1.8 mg/L)的回收率为85.1%~105.3%,相对标准偏差为0.8%~9.2%。本方法适用范围广、操作简单、分析速度快、灵敏度高、重现性和回收率好,采用多重定性增强了定性分析的准确性,可用于实际湖水中10种蓝藻毒素的测定。     

多功能柱净化-柱后光化学衍生-高效液相色谱法同时检测玉米和花生中9种真菌毒素

建立了同时检测玉米和花生中黄曲霉毒素B1、B2、G1、G2、M1、M2、玉米赤霉烯酮、呕吐毒素和展青霉素的多功能柱净化-柱后光化学衍生-高效液相色谱检测方法。样品经乙腈-水(体积比为86∶14)提取,多功能净化柱净化,采用C18柱分离,以甲醇、乙腈和水为流动相进行梯度洗脱,在线光化学衍生,以荧光和二极管阵列测器同时检测。黄曲霉毒素B1、B2、G1、G2、M1、M2、玉米赤霉烯酮、呕吐毒素和展青霉素的检出限分别为0.02μg/kg、0.01μg/kg、0.03μg/kg、0.05μg/kg、0.08μg/kg、0.04μg/kg、0.09μg/kg、0.20mg/kg和0.04 mg/kg,在相应浓度范围内线性相关系数均大于0.999,平均加标回收率为80.0%~101.5%,相对标准偏差在1.3%~5.6%之间。该方法简便快速、灵敏度高、重现性好,可满足玉米、花生中9种黄曲霉毒素的检测。     

液相色谱-串联质谱法测定宠物食品中赭曲霉毒素A和B

建立了同时测定宠物食品中赭曲霉毒素A和B的液相色谱-串联质谱分析方法。样品经乙腈/水(1∶1,V/V)提取,HLB固相萃取柱净化。采用Agilent ZOBRAX C_(18)柱(150×2.1mm,5μm)分离,以0.1%甲酸水溶液-乙腈作为流动相,梯度洗脱。目标化合物在多反应监测模式(MRM)下进行检测,外标法定量。在优化的条件下,赭曲霉毒素A和B在0.1~10.0ng·mL~(-1)范围内呈良好的线性关系,相关系数均不低于0.9993,方法定量限分别为0.1μg·kg~(-1)和0.05μg·kg~(-1)。方法平均回收率为78.3%~107.5%,相对标准偏差不大于9.5%。该方法前处理简单、选择性好、灵敏度高,可用于宠物食品中赭曲霉毒素A和B的测定。     

在线固相萃取–液相色谱法测定水中3种微囊藻毒素

建立了在线固相萃取–液相色谱法测定水中3种微囊藻毒素的方法。采用Acclaim PA Cartridge在线固相萃取小柱(10 mm×4.3 mm,5μm),以KH2PO4缓冲溶液–甲醇为富集流动相,进样体积为10 m L。以KH2PO4缓冲溶液–乙腈为洗脱流动相,采用二极管阵列检测器进行检测,检测波长为238 nm。微囊藻毒素MC–LR,MC–RR在0.1~10.0μg/L范围内线性关系良好,MC–YR线性范围则为0.1~5.0μg/L,相关系数r2不小于0.998,3种微囊藻毒素MC–LR,MC–RR,MC–YR的检出限均为0.1μg/L(S/N=3),水源水加标回收率为96.9%~105.4%,测定结果的相对标准偏差为3.55%~6.46%(n=12)。该方法适用于水源水及饮用水中3种微囊藻毒素的快速测定。     

超高效液相色谱–串联质谱法测定饮用水中微囊藻毒素

建立饮用水中微囊藻毒素(MC–RR,MC–LR)的超高效液相色谱–串联质谱检测方法。样品经PVDF针式过滤头过滤后直接进样,采用喷雾正离子源(ESI~+)和多重反应监测模式(MRM)测定。MC–RR的质量浓度在0.02~10.00μg/L范围内与色谱峰面积呈良好的线性,线性相关系数r~2=0.998 9,检出限为0.096μg/L,测定结果的相对标准偏差为6.6%~9.1%(n=7),加标回收率为99.0%~103.0%。MC–LR的质量浓度在0.1~20μg/L范围内与色谱峰面积呈良好的线性,线性相关系数r~2=0.999 2,检出限为0.188μg/L,测定结果的相对标准偏差为4.3%~10.0%(n=7),加标回收率为93.0%~114.0%。该方法灵敏度高、重现性好,可用于饮用水中微囊藻毒素的检测。     

超高效液相色谱-串联质谱法检测螺旋藻保健品中7种微囊藻毒素

采用固相萃取净化结合超高效液相色谱-串联质谱法(UPLC-MS/MS)测定了螺旋藻保健品中7种微囊藻毒素(MCs)。螺旋藻保健品经70%(体积分数)的甲醇超声提取,冷冻离心沉淀杂质后,经HLB柱净化。在Waters ACQUITY UPLCBEH C18色谱柱上以乙腈和0.2 mmol/L乙酸铵水溶液为流动相进行梯度洗脱分离,采用电喷雾离子源正离子模式进行多反应离子监测,外标法定量。7种MC在线性范围内线性关系良好(相关系数(r)不小于0.995);检出限为6.7～33.3 μg/kg,定量限为20.0～100.0 μg/kg。各分析物在阴性螺旋藻保健品中的加标回收率在87.5%～97.9%之间,相对标准偏差(RSD)在1.6%～6.9%之间。该方法准确可靠,灵敏度高,可用于螺旋藻保健品中MC污染的确证定性、定量检测。     

固相萃取-超高效液相色谱-质谱联用技术检测大鼠血浆中T-2毒素及其主要代谢产物

应用固相萃取-超高效液相色谱-三重四极杆-线性离子阱串联质谱技术,建立了高灵敏度的大鼠血浆中单端孢霉烯族(T-2)毒素及其5种主要代谢物的分析方法。在优化的固相萃取条件下,大鼠血浆经HLB固相萃取柱净化富集后,以XDB-C18色谱柱(50 mm×4.6 mm,1.8μm)分离,以5 mmol/L乙酸铵溶液和甲醇溶液为流动相进行梯度洗脱,以玉米赤霉酮为内标,在正离子多反应监测模式下对各分析物进行定性和定量分析。各分析物在0.1～500.0μg/L范围内线性良好(R2>0.997);检出限介于0.02～0.3μg/L之间;加标回收率为93.5%～120.3%;相对标准偏差均小于13%。本方法快速、重现性好、灵敏度高,已成功应用于T-2毒素中毒的溯源性研究。     

固相萃取/高效液相色谱-串联质谱法快速测定饲料中的3种伏马毒素

建立了饲料中伏马毒素B1、B2、B3的高效液相色谱-串联质谱(HPLC-MS/MS)分析方法。样品经乙腈-水-甲酸(50∶49∶1,体积比)提取,PRIME HLB固相萃取柱净化后,采用Agilent Zorbax SB-C18色谱柱(150 mm×2.1 mm,3.5μm)分离,以乙腈-5 mmol/L乙酸铵溶液(含0.1%甲酸)为流动相梯度洗脱,采用电喷雾正离子(ESI+)源多反应监测(MRM)模式进行检测,基质校正曲线外标法定量。结果表明,3种化合物在5.0~250.0μg/L范围内线性关系良好,相关系数(r2)均大于0.995,方法的检出限(LOD)和定量下限(LOQ)分别为3μg/kg和10μg/kg。在10、20、50μg/kg 3个加标水平下,伏马毒素的平均回收率为80.3%~93.7%,相对标准偏差(RSD)为7.5%~13.4%。该方法简单、快速、稳定,适用于饲料中伏马毒素的检测。     

QuEChERS提取-高效液相色谱-高分辨质谱法测定水产品中3种蓝藻毒素的含量

取水产品样品2.00g与2g无水硫酸钠混匀后加入提取剂10 mL甲醇,涡旋振荡5min后超声提取5 min,再离心5 min,取其上清液。在上清液中加入500 mg中性氧化铝和15mg石墨化碳黑(GCB)涡旋振荡1min,离心5min,取上清液,于40℃下吹氮至近干,用体积比为1∶1的流动相A-流动相B混合溶液溶解残渣并定容至2.0mL,经0.22μm滤膜过滤,取其滤液按高效液相色谱-高分辨质谱法测定其中3种蓝藻毒素的含量。色谱分离中用Hypersile Gold C8色谱柱(150mm×2.1mm,3μm)为固定相,用不同比例的流动相A和流动相B两溶液的混合液作为流动相进行程序梯度洗脱。质谱测定中采用电喷雾离子源,正、负离子切换模式。由于3种蓝藻毒素均产生基质减弱效应,制作工作曲线需用基质标准溶液以消除基质效应。结果表明:所测3种蓝藻毒素均在10~200μg·L^-1内与其峰面积之间呈线性关系,其检出限(3S/N)均为5μg·kg^-1。通过标准加入法进行回收试验,测得回收率为68.3%~104%,测定值的相对标准偏差(n=6)为7.7%~17%。     

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.     

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.     

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.     

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.