离子液体-K_2HPO_4超声双水相萃取预富集-高效液相色谱法测定水产品中组胺含量

样品经高氯酸溶液提取,丹磺酰氯衍生化,于离子液体1-丁基-3-甲基咪唑溴盐和磷酸氢二钾组成的双水相体系中进行萃取。待测物在XDB C_(18)色谱柱上分离,以0.02mol·L~(-1)乙酸铵-乙腈混合液为流动相进行梯度洗脱,于波长254nm处进行紫外检测。组胺的质量浓度在0.10~2.0mg·L~(-1)范围内呈线性,测定下限(10S/N)为0.05mg·L~(-1)。加标回收率在95.0%~103%之间,日内和日间相对标准偏差(n=6)分别在2.8%~6.1和4.8%~7.7%之间。     

气相色谱-质谱法快速测定食品接触用塑料中2,2,4-三甲基-1,3-戊二醇双异丁酸酯的特定迁移量

采用气相色谱-质谱法快速测定从食品接触用塑料中迁移至水、4%(体积分数,下同)乙酸溶液、20%(体积分数,下同)乙醇溶液、50%乙醇溶液、异辛烷和橄榄油等6种食品模拟物中2,2,4-三甲基-1,3-戊二醇双异丁酸酯的含量。在气相色谱分离中采用DB-5MS色谱柱(30m×0.25mm,0.25μm),在质谱分析中采用选择离子监测模式。食品模拟物为水、4%乙酸溶液、20%乙醇溶液和50%乙醇溶液时,萃取溶剂为正己烷,萃取次数为1,萃取时间为10min;食品模拟物为异辛烷时无需萃取;食品模拟物为橄榄油时,萃取溶剂为甲醇,萃取次数为3,萃取时间为10min。TXIB的质量浓度在0.03～1.00mg·L~(-1)(食品模拟物为橄榄油:0.10～2.00mg·kg~(-1))内与其对应的峰面积呈线性关系,检出限(3S/N)为0.01mg·kg~(-1)(食品模拟物为橄榄油:0.03mg·kg~(-1)),测定下限(10S/N)为0.03mg·kg~(-1)(食品模拟物为橄榄油:0.10mg·kg~(-1))。以空白食品模拟物为基体进行加标回收试验,所得回收率为82.7%～110%,测定值的相对标准偏差(n=6)为2.3%～10%。     

线性扫描极谱法测定消旋山莨菪碱

用线性扫描极谱法和循环伏安法研究了消旋山莨菪碱在0.3mol·L~(-1)磷酸氢二钠-磷酸二氢钾缓冲溶液(pH 6.70)中的电化学行为。消旋山莨菪碱于-1.095V(vs.SCE)处产生一灵敏的吸附波,消旋山莨菪碱质量浓度在0.10～10.0mg·L~(-1)范围内与其一次微分线性扫描峰电流i_p呈线性关系,检出限(3S/N)为0.06mg·L~(-1)。对5.0mg·L~(-1)消旋山莨菪碱溶液进行6次平行试验,相对标准偏差为0.34%,该方法用于片剂中消旋山莨菪碱含量的测定,测定值与标示值相符。     

高效液相色谱法测定联苯菊酯悬浮剂中联苯菊酯

提出了高效液相色谱法测定联苯菊酯悬浮剂中联苯菊酯含量的方法。样品用甲醇超声提取20min,分取部分提取液用流动相溶液,即甲醇与水(87+13)的混合溶液定容为100mL。用针头过滤器净化并取出此溶液,通过Agilent Eclipse XDB-C_(18)色谱柱,并用上述流动相溶液进行分离,流量为1.4mL·min~(-1),于206 nm波长处用二极管阵列检测器检测。联苯菊酯的质量浓度在3.0～50.0mg·L~(-1)范围内与其峰面积呈线性关系,方法的检出限(3S/N)为0.67mg·L~(-1)。在11.1,15.5,24.4mg·L~(-1)三个添加水平下,回收率在99.2%～104.5%之间,相对标准偏差(n=6)在0.8%～2.9%之间。     

超高效液相色谱法同时测定膨胀烟丝中3种糠醛类化合物

粉碎后的膨胀烟丝样品(约1g)用乙腈-二氯甲烷(1+1)混合液20 mL超声提取40min,取适量上清液在10 000r·min~(-1)转速下离心15min,过0.22μm的滤膜。采用超高效液相色谱法同时测定滤液中3种糠醛类化合物的含量。以ACCQ-TAG~(TM)ULTRA C_(18)色谱柱为分离柱,以乙腈(1+9)溶液为流动相,在检测波长284nm处进行测定。3种糠醛类化合物的质量浓度在一定范围内与其对应的峰面积呈线性关系,检出限(3s)为0.012～0.015 mg·L~(-1),测定下限(10s)为0.040～0.050mg·L~(-1)。方法用于膨胀烟丝样品的分析,加标回收率为76.1%～102%,测定值的相对标准偏差(n=5)为3.2%～4.9%。     

超高效液相色谱-串联质谱法测定饲料中氨苯胂酸和洛克沙胂

采用超高效液相色谱-串联质谱法测定饲料中氨苯胂酸和洛克沙胂的含量。粉碎过筛后的样品用乙腈(1+1)溶液超声提取30min,离心后,上清液用二氯甲烷净化,取水层(上层)过0.22μm水系滤膜。以Thermo HYPERCARB色谱柱为固定相,以不同体积比的0.05%(体积分数)甲酸溶液和乙腈混合液为流动相进行梯度洗脱,串联质谱分析中采用电喷雾负离子源和多反应监测模式。氨苯胂酸和洛克沙胂的质量浓度均在0.05～10.0mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)为0.01～0.05mg·kg~(-1)。以空白样品为基体进行加标回收试验,所得回收率为82.0%～106%,测定值的相对标准偏差(n=6)为1.0%～7.9%。     

固相萃取净化-气相色谱-质谱法测定记号笔油墨中8种挥发性苯系物的含量

称取记号笔笔芯中油墨0.200 0g,加入乙酸乙酯至体积为5.0mL,涡旋提取2min,将提取液流经HLB固相萃取柱进行净化处理。经净化的流出液用乙酸乙酯定容至10.0 mL,经0.22μm滤膜过滤,取滤液按仪器工作条件进行气相色谱-质谱法分析。选择HP-INNOWax毛细管色谱柱,在35～220℃之间按程序升温模式对8种挥发性苯系物(苯、甲苯、乙苯、对二甲苯、间二甲苯、异丙苯、邻二甲苯和苯乙烯)进行分离,并在电子轰击离子源(EI)和选择离子监测(SIM)模式下进行质谱测定。8种挥发性苯系物均在0.1～5.0mg·L~(-1)内与其相应的峰面积呈线性关系,其检出限(3S/N)为0.06～0.18mg·kg~(-1)。在阴性样品的基础上,在3个浓度水平上进行加标回收试验,测得8种化合物的回收率为79.8%～114%,测定值的相对标准偏差(n=5)为0.20～11%。应用此方法分析了116支记号笔中不同颜色的油墨样品,苯系物的检出率为76.9%,其质量分数为0.33～3.49×10~4 mg·kg~(-1)。     

超高效液相色谱-串联质谱法测定茶叶中百草枯

采用超高效液相色谱-串联质谱法测定茶叶中百草枯的含量。均质茶叶样品(2±0.02)g用硫酸(7+13)溶液提取,提取液5mL通过固相萃取柱净化,再用5mol·L~(-1)氯化铵溶液15mL洗脱。在洗脱液中加入12mol·L~(-1)氢氧化钠溶液12mL,10g·L~(-1)铁氰化钾溶液1mL后,用二氯甲烷提取两次(每次20mL),合并二氯甲烷层,并将其蒸干。用乙腈(1+9)溶液2 mL溶解残渣,并过0.22μm有机系滤膜。以Waters BEH UPLC C_(18)色谱柱为分离柱,以不同体积比的乙腈和乙腈(5+95)溶液的混合液为流动相进行梯度洗脱,采用电喷雾正离子源和多反应监测模式检测。百草枯的质量浓度在0.001~0.1mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)为0.5μg·L~(-1)。在10,100μg·kg~(-1)等2个浓度水平进行加标回收试验,回收率依次为71.0%,89.2%,测定总量的相对标准偏差(n=6)依次为11%,1.1%。     

高效液相亲水作用色谱-串联质谱法同时测定婴幼儿配方乳粉中胆碱和左旋肉碱的含量

称取乳粉样品1.000g,加入1.0mol·L~(-1)的盐酸溶液25mL,涡旋混匀5min,于70℃水浴中水解3h(每隔30min振摇混匀一次),冷却后加入20mL乙醚,涡旋振荡30s,然后于4℃下以6 000r·min~(-1)冷冻离心10min。取上清液0.10mL,加入1mol·L~(-1)的乙酸铵溶液50μL,用水定容至10.0 mL,涡旋混匀,吸取1～2 mL上清液,经0.22μm水系针式滤膜过滤后,采用Hypersil GOLDTMAQ色谱柱(2.1mm×100mm,1.9μm)分离,以乙腈-乙酸铵溶液为流动相进行梯度洗脱。质谱选择电喷雾正离子源和多反应监测模式。胆碱和左旋肉碱的质量浓度分别在0.05～1.0mg·L~(-1),0.01～0.20mg·L~(-1)内与其定量离子峰面积呈线性关系,检出限(3S/N)分别为0.003,0.005mg·kg~(-1)。方法用于测定质控样品中的胆碱和左旋肉碱,测定值与认定值的相对误差在10%以内。采用本方法测定婴幼儿配方乳粉样品中的胆碱和左旋肉碱,测定结果和国家标准方法的测定结果相符,测定值的相对标准偏差(n=6)小于9.0%     

反相高效液相色谱法测定花椒的3种黄酮苷元的含量

提出了反相高效液相色谱法测定花椒的3种水解黄酮苷元槲皮素、山柰酚、异鼠李素的含量。采用Zorlbax Eclipse C_(18)色谱柱(4.6mm×150mm,5μm),以甲醇-0.4%(体积分数)磷酸溶液(1+1)混合溶液为流动相,在360nm波长处进行测定。槲皮素的质量浓度在2.19～109.6mg·L~(-1),山柰酚的质量浓度在2.28～114.0mg·L~(-1),异鼠李素的质量浓度在2.80～140.0mg·L~(-1)时分别与其峰面积呈线性关系。槲皮素、山柰酚和异鼠李素的加标回收率分别为95.6%,104.4%,103.8%,相对标准偏差(n=5)分别为2.98%,3.97%,4.30%。     

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.     

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.     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.