固相萃取-HPLC法测定蜂蜜中残留的10种磺胺类药物

研究了用固相萃取-高效液相色谱法同时测定蜂蜜中10种磺胺类药物残留量的方法。样品经三氯甲烷溶液提取,过Oasis HLB C18固相萃取柱净化,用乙腈洗脱10种磺胺,反相高效液相色谱-紫外检测器测定。检测波长为270nm,柱温45℃．流动相：磷酸水溶液-乙腈梯度洗脱．该方法前处理简单,梯度洗脱分离效果和重现性好,在0．010～1．0mg／kg添加水平,10种组分的回收率在86．5％～100．8％之间,室内相对标准偏差在3．5％～8．1％之间,线性范围为0．010～10μg／mL,检出限为0．005mg／kg。该方法快速、灵敏、专属,可用于食品中磺胺类药物残留量的常规检测。     

高效液相色谱同时测定鸡蛋中4种氟喹诺酮类药物残留

建立了固相萃取—反相高效液相色谱同时分析鸡蛋样品中4种氟喹诺酮类药物残留量的方法。对鸡蛋样品的提取及其在C18固相萃取柱上的净化条件进行了研究,采用高效液相色谱分离,荧光检测器检测(λex=280nm,λem=450nm),外标法定量。4种沙星标准曲线的线性回归系数均在0．9999以上,环丙沙星、恩诺沙星、沙拉沙星的线性范围为2．5～500μg／L;达诺沙星为0．5～100μg/L。鸡蛋样品中4种沙星的加标回收率为78．1％～95．7％;相对标准偏差为4．1％～16．2％。环丙沙星、恩诺沙星、沙拉沙星的最低检出限为10μg／kg;达诺沙星的最低检出限为2μg/kg。     

测定鸡肉、水产品中四种硝基呋喃类药物残留量的固相萃取-液相色谱法

采用固相萃取(SPE)前处理净化技术，高效液相色谱(HPLC)法快速测定鸡肉、鱼、虾中呋喃它定(furaltadon)、呋喃西林(furacilin)、呋喃妥因(titrofurantoine)、呋喃唑酮(furazolidonum)药物残留量；通过对待测成分的提取、净化、定性、定量的液相色谱条件研究，建立了HPLC法测定鸡肉、鱼、虾中4种硝基呋喃类药物残留量的准确、可靠的方法；4种硝基呋喃类药物在鸡肉、鱼、虾样品中3个不同水平的添加回收率(n=7)为87％-102％；相对标准偏差(RSD)为2．0％～7．8％；工作曲线的线性范围为5—100μg／kg；呋喃它定、呋喃西林、呋喃妥因、呋喃唑酮的检出限分别为5、2、3、2μg／kg。     

反相高效液相色谱／质谱法同时测定鸡肉中5种喹诺酮药物残留

采用反相高效液相色谱／四级杆串联质谱（RP-HPLC／MS／MS）同时测定鸡肉中的5种喹诺酮药物（quinolones，QNs）。均质后的鸡肉样品采用磷酸盐缓冲溶液和乙腈的混和溶液提取。提取液经正己烷液-液分配（LLP）去除脂肪后，用C18固相萃取（SPE）柱净化，氨化甲醇洗脱，洗脱液用氮气吹干，流动相定容后，分析物采用LC／MS／MS电喷雾电离（ESI），正离子，多反应监测（MRM）模式检测，外标法定量。在添加浓度2．5～10μg/kg范围内，5种QNs的回收率在79．8％～95．1％之间；相对标准偏差（RSD）均小于11．7％。环丙沙星、丹诺沙星、恩诺沙星检出限（LOD）为0．5μg／kg，沙托沙星为1．0μg／kg，氟甲喹为0．1μg／kg。     

固相萃取-高效液相色谱法同时测定牛奶中13种磺胺残留

建立了固相萃取-高效液相色谱同时测定牛奶中13种磺胺类药物残留的方法。样品经乙腈溶液漩涡超声提取后,采用自制碱性氧化铝固相萃取小柱(SPE)净化,洗脱液减压浓缩至近干后用流动相溶解并定容,过PTFE滤膜后在Thermo Fisher Scientific ODS hypersil色谱柱上,以乙腈-20 mmol/L H3PO4溶液为流动相进行梯度洗脱,检测波长为270 nm。13种磺胺在50~5000μg/L范围内具有良好的线性,相关系数≥0.999,检出限为2.0~4.2μg/L,定量限为8.9~14.2μg/L。在20,50,100μg/L添加水平的加标回收率为79.0%~118.2%,相对标准偏差在2.7%~6.9%之间。方法能对牛奶中13种磺胺类药物残留实现准确定量分析。     

多功能柱净化-高效液相色谱法检测谷物中的玉米赤霉烯酮

建立了玉米和小麦中玉米赤霉烯酮（ZEN）的多功能柱净化-高效液相色谱检测方法。样品经乙腈-水混合溶剂（V（乙腈）：V（水）=84：16）提取，通过多功能净化柱（MFC）进行一次性净化，以Symmetry^R C18柱为分离柱，甲醇-水（V（甲醇）：V（水）=68：32）为流动相进行高效液相色谱分离和检测。玉米赤霉烯酮的质量浓度在0．01～4．0μg／mL范围内呈良好线性，相关系数为0．9996。检出限为0．04μg／g，在0、04—5．0mg／kg添加范围内的回收率为87．5％～98．6％，相对标准偏差为1．5％～8．3％。     

高效液相色谱-电喷雾三级四极杆质谱测定鸡肉组织中氯霉素残留的研究

建立了鸡肉组织中氯霉素残留的液相色谱-电喷雾质谱联用(LC—ESI—MS—MS)测定法。采用微量化前处理方法,省去固相萃取步骤,以m／z321．0为母离子,m／z152．1、257．0和194．1为子离子,采用多反应监测(MRM)负离子模式对鸡肉组织中的氯霉素残留进行检测、方法的检出限为0．010μg／kg(S／N≥3),定量下限为0．10μg／kg,线性范围为0．100～1．00μg／L,加标回收率为74．3％～84．0％,相对标准偏差(n=6)为7．9％～12．7％。该法具有操作简便、有机试剂消耗量少、测定周期短等优点。     

高效液相色谱-线性离子阱质谱法测定畜禽肌肉中β2-受体激动剂及β-阻断剂类药物残留

利用高效液相色谱-线性离子阱质谱（HPLC-ITMS）以同位素稀释技术测定了肌肉组织中23种β2-受体激动剂及5种β-阻断剂．肌肉样品经5％的三氯乙酸溶液酸解提取,以弱阳离子固相萃取柱进行净化．以甲醇和含0．1％甲酸的水溶液为流动相在液相色谱柱上梯度洗脱分离,采用ESI源正离子模式在选择离子监测（SRM）模式下进行扫描．以9种经氘代同位素标记的β2-受体激动剂为内标进行定量．猪肉中23种β2-受体激动剂及5种β-阻断剂的线性范围为5-200μg／L,相关系数（力大于0．995,各化合物在肌肉中的检出限均能达到0．2gg／kg．以空白猪肉样品进行的加标水平为5、10、20μg／kg的加标回收试验,各化合物的回收率在47．3％-123．7％之间,相对标准偏差在3．2％～25．7％之间．对猪肉样品和鸡肉样品进行了测定,得到了满意的结果．该方法灵敏度高,定性准确,可以用于畜禽肌肉中β2-受体激动剂和β-阻断剂类药物残留的确证检测．     

高效液相色谱法同时测定调味料中的8种合成着色剂

建立一种同时测定调味料中8种合成着色剂的高效液相色谱分析方法。样品经30％甲醇水溶液提取,采用Diamonsil—C18柱（250mm×4．6mm）,以甲醇-1．55g／L乙酸铵为流动相,在最佳梯度洗脱条件下对8种合成着色剂进行分离,二极管阵列检测器检测,外标法定量。8种合成着色剂的线性范围为0．5～10．0μg／mL,回收率为95．0％～101％。对样品进行6次重复测定,峰面积测定结果的相对标准偏差为0．84％-3．51％（n=6）。     

鳗鱼、饲料中恩诺沙星残留的测定及真假阳性辨别

采用反相高效液相色谱法(RP-HPLC),测定鳗鱼、饲料中的恩诺沙星药物残留．在Waters Nova-Pak C18柱上,用荧光检测器,激发波长280nm;发射波长450nm．流动相为5mmol／L NaH2PO4溶液-乙腈溶液(体积比为70：30),磷酸调pH值为2．7,流速1．2mL／min,柱温40℃．在鳗鱼、饲料中的最低检测限分别达到1μg／kg和2μg／kg,标准曲线在30—500ng／mL线性范围内相关系数达0．9997．在3种浓度水平对鳗鱼组织和饲料中的3种浓度进行回收率测定,其回收率在76％～98％之间;变异系数RSD小于8％,符合痕量测定要求．还对如何辨别真假阳性进行特别介绍．     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.