亲水作用色谱法同时测定食品添加剂中D-异抗坏血酸、L-抗坏血酸和二氧化硫脲

食品添加剂样品用含1%(体积分数,下同)甲酸的100mmol·L~(-1)甲酸铵溶液溶解,经乙腈稀释后,用0.22μm微孔滤膜过滤,采用亲水作用色谱法同时测定滤液中D-异抗坏血酸、L-抗坏血酸和二氧化硫脲的含量。以InfinityLab Poroshell 120HILIC-Z色谱柱(3.0mm×100mm,2.7μm)为固定相,以含1%甲酸的100mmol·L~(-1)甲酸铵溶液和乙腈以体积比15∶85组成的混合液为流动相,用二极管阵列检测器测定。D-异抗坏血酸、L-抗坏血酸和二氧化硫脲的质量浓度均在1.0～100mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)均为1.0%。以空白样品为基体进行加标回收试验,所得回收率为94.7%～108%,测定值的相对标准偏差(n=6)小于8.0%。     

超高效液相色谱-串联质谱法同时测定豆芽中氟喹诺酮类和硝基咪唑类抗生素的残留量

取5 g豆芽样品,加入100μg·L^-1混合内标溶液40μL和含1%(体积分数,下同)乙酸的乙腈溶液10 mL,振荡3 min,超声20 min,离心3 min。重复提取一次,合并上清液,用含1%乙酸的乙腈溶液稀释至25 mL。分取10.00 mL,置于装有QuEChERS吸附剂[100 mg N-丙基乙二胺(PSA)、100 mg C₁₈、800 mg无水硫酸镁]的离心管中,离心3 min,静置5 min。分取5.00 mL上清液于40℃氮吹至近干,加入1.00 mL含0.1%(体积分数,下同)甲酸的30%(体积分数)乙腈溶液,复溶后过0.22μm滤膜,滤液进入超高效液相色谱-三重四极杆质谱仪分析。12种抗生素在ACQUITY UPLC HSS T₃色谱柱(100 mm×2.1 mm, 1.8μm)上用不同体积比的含2 mmol·L^-1甲酸铵的0.1%甲酸溶液和含0.1%甲酸的乙腈溶液的混合液为流动相进行梯度洗脱分离,以电喷雾离子源正离子(ESI⁺)模式电离,以多反应监测(M...     

超高效液相色谱串联质谱法测定木贼中4种吡咯里西啶生物碱

建立超高效液相色谱–串联质谱法测定木贼中4种肝毒性吡咯里西啶生物碱(石松胺、石松胺氮氧化物、蓝蓟定氮氧化物和蓝蓟定)的含量。采用ACQUITY UPLC HSS T3型色谱柱(100 mm×2.1 mm,1.8μm),以甲酸–甲酸铵缓冲液(10 mmol/L甲酸溶液–2.5 mmol/L甲酸铵溶液)–酸化乙腈(95%乙腈水溶液,含10 mmol/L甲酸溶液–2.5 mmol/L甲酸铵溶液)(体积比为85∶15)为流动相,流量为0.30 mL/min,进样体积为1μL,电喷雾离子源,正离子多反应监测模式,以外标法计算含量。石松胺、石松胺氮氧化物、蓝蓟定氮氧化物和蓝蓟定在各自的质量浓度范围内与色谱峰面积线性关系良好,线性系数均不小于0.999,检测限分别为0.20、0.21、0.20、0.20 ng/mL。测定结果的相对标准偏差分别为2.5%、3.2%、3.4%、2.9%(n=6),平均加标回收率为91.9%-97.1%。该方法可为木贼中吡咯里西啶生物碱的质量控制和安全性评价提供科学依据。     

QuEChERS/高效液相色谱-串联质谱法测定护肤品中的21种麻醉剂

建立了QuEChERS/高效液相色谱-串联质谱(HPLC-MS/MS)同时快速测定护肤品中21种麻醉剂的分析方法。样品用水分散后加入含1.0%(体积分数)甲酸的乙腈溶液超声提取,经无水硫酸镁、十八烷基键合硅胶(C₁₈)和N-丙基乙二胺(PSA)净化,采用具有反相(RP)、弱阳离子交换(WCX)和HILIC多种保留机制的Acclaim Mixed-Mode WCX-1色谱柱(150 mm×2.1 mm,3μm)分离,以20 mmol·L^-1甲酸铵溶液(用甲酸调至pH 4.0)和乙腈(含0.035%甲酸)为流动相。在电喷雾正离子模式下,多反应监测(MRM)模式测定,基质匹配标准溶液外标法定量。21种麻醉剂在0.5～100 ng·mL^-1质量浓度范围内线性关系良好,相关系数(r)均大于0.99,检出限和定量下限分别为0.1～3μg·kg^-1和0.3～10μg·kg^-1。在膏霜、乳液和凝胶3种基质中,3个不同加标水平下的平均回收率为84.3%～109%,相对标准偏差为0.70%～7.1...     

超高效液相色谱-串联质谱法测定减肥类保健品中的西布曲明

采用超高效液相色谱-串联质谱法测定减肥类保健品中的西布曲明。样品经甲醇超声提取后,使用Phenomenex Kinetex C18色谱柱分离,以乙腈-10mmol·L-1乙酸铵溶液(含0.1%甲酸)为流动相进行梯度洗脱,质谱中选择多反应选择离子监测模式检测,以西布曲明-D6作为同位素内标进行定量。西布曲明的质量浓度在5.00~400μg·L-1范围内呈线性,测定下限(10S/N)为10ng·g-1。加标回收率在97.0%~104%之间,相对标准偏差(n=9)为1.1%~3.0%。     

液相色谱-串联质谱法测定黄瓜中霜霉威残留

黄瓜样品经乙腈超声波提取后,用活性炭固相萃取小柱净化,用乙腈洗脱,将洗脱液旋转蒸发至近干,用乙腈-水(1+1)溶液1.0 mL溶解测定。采用Hypersil GOLD C18色谱柱(2.0mm×150mm,3μm)分离,用不同比例配成的10mmol.L-1乙酸铵溶液(含甲酸φ0.1%)和乙腈为流动相梯度洗脱。质谱测定中采用正离子电离方式,选择离子监测模式。霜霉威的质量浓度在1.02～1 020μg.L-1范围内与峰面积呈线性关系,测定下限(10S/N)为0.2μg.kg-1。用标准加入法做回收试验,测得回收率在88%～96%之间,测定值的相对标准偏差(n=6)在4.7%～6.4%之间。     

高效液相色谱法测定食品添加剂中水杨酸

提出了高效液相色谱法测定食品添加剂中水杨酸含量的方法。样品采用含0.1%(体积分数)甲酸的甲醇-水(9+1)混合溶剂溶解,超声提取后经0.22μm滤膜过滤,滤液供高效液相色谱荧光仪测定。采用ZORBAX SB-C18色谱柱(4.6mm×250mm,3.5μm)分离,用不同配比的(A)甲酸-乙腈(0.1+99.9)和(B)甲酸-水(0.1+99.9)的混合溶液为流动相梯度洗脱,在激发波长为290nm、发射波长为400nm处检测。水杨酸的质量浓度在41.60～1 664μg·L-1范围内与其对应的峰面积呈线性关系,检出限(3S/N)为1.55μg·L-1,方法的回收率在90.4%～101.7%。     

HPLC-MS/MS同时检测人血液中佐匹克隆、唑吡坦、扎来普隆和褪黑素

建立液相色谱串联质谱同时检测全血中佐匹克隆、唑吡坦、扎来普隆和褪黑素的方法。采用液液萃取进行提取,提取物以Inersil ODS(2.1×100 mm,3.5μm)色谱柱分离,以10 mmol/L的甲酸铵水溶液(体积分数0.1%甲酸)-乙腈(体积分数0.1%甲酸)为流动相梯度洗脱,流速为0.3 m L/min,液相色谱串联质谱检测。全血中佐匹克隆、唑吡坦和褪黑素的线性范围为0.20~100.0ng/m L,检出限为0.20ng/m L;扎来普隆的线性范围为0.50~100.0ng/m L,检出限0.50ng/m L。     

基于UPLC-Q-TOF MS的广佛手指纹图谱建立及炮制前后成分差异分析

采用超高效液相色谱-四极杆串联飞行时间质谱(UPLC-Q-TOF MS)建立生、制广佛手的指纹图谱,并通过化学模式识别方法分析两者的差异成分.采用Agilent Poroshell 120 EC-C18(3.0 mm×150 mm×2.7μm)色谱柱进行分离,以0.1％甲酸+5 mmol/L乙酸铵水溶液-乙腈为流动相进...     

超高效液相色谱-四极杆-飞行时间质谱快速筛查蔬菜中18种农药残留

建立蔬菜中18种农药残留的超高效液相色谱-四极杆-飞行时间质谱(UPLC-Q-TOF MS)快速筛查方法。样品经1%乙酸乙腈提取,QuEChERS法净化,经C_(18)色谱柱(100 mm×3.0 mm, 1.8μm)分离,以乙腈与含0.1%甲酸的2 mmoL/L甲酸铵溶液为流动相,梯度洗脱,UPLC-Q-TOF MS检测,建立18种农药的一级精确质量数据库以及二级谱图库,通过化合物的精确质量数、保留时间定性确证,外标法定量。18种农药均能准确定性,且在1.0～200.0μg/kg范围内线性关系良好(r≥0.9908),各组分检出限范围为0.0006～0.005 mg/kg,回收率范围为73.56%～103.2%,相对标准偏差(RSDs,n=6)范围为0.23%～9.85%。该方法快速、简便、准确,可用于蔬菜中18种农药残留的快速筛查。     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

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.