高效液相色谱测定肉制食品中五种邻苯二甲酸酯

建立了肉制食品中5种邻苯二甲酸酯类增塑剂(PAEs)含量的检测方法.样品用正己烷提取,C18柱分离,柱温35.0℃,乙腈.水为流动相梯度洗脱,流速1.0 mL/min,紫外检测波长226 nm.5种PAEs分离特异性好,在0.02～10μg/mL之间均具有较好的线性关系,检出限在4.4～13.8 ng/mL之间,高、中、低3水平的回收率均在79.5%～102.0%之间,相对标准偏差均在1.1%～14%之间.方法适用于肉制食品中邻苯二甲酸酯类的检测.     

反相液相色谱法同时检测虾仁中合成色素的研究

建立了食品虾仁中合成色素(酸性大红GR、金黄粉、橙黄G、酸性红1号、酸性红26)的反相液相色谱同时检测方法。并且对提取剂、NH4Ac浓度和离子对种类等因素进行优化,使得5种色素完全分离,并且在色谱图上能与国标内的6种色素完全分离。金黄粉、酸性大红GR、橙黄G、酸性红1号、酸性红26的回收率均在80%以上,在0.05~10μg/mL范围内有良好的线性关系,相关系数大于0.9998。本法可用于食品虾仁中合成着色剂的快速检测。     

蚕丝蛋白固相萃取分离富集细胞色素c的研究

在特定实验条件下, 蚕丝蛋白对细胞色素c表现出选择性吸附. 以蚕丝蛋白微填充柱为载体, 在流动系统中建立了细胞色素c的分离富集方法, 以分光光度法在410 nm处检测分离富集过程. 在进样流速低于10 μL/s时, 2 mL样品溶液(pH=5.6的水溶液)中5 μg/mL的细胞色素c可被蚕丝蛋白微柱完全吸附, 而在洗脱流速低于15 μL/s时, 200 μL NaCl溶液(1.0 mol/L)可将吸附的细胞色素c完全洗脱, 分离富集系数为10. 用本方法测定细胞色素c的线性范围为1.0~10.0 μg/mL, 检出限为0.33 μg/mL, 精密度RSD为2.5%(5 μg/mL, n=9). 此外, 还采用本文方法对人全血中的蛋白质进行了分离富集, 并用SDS-聚丙烯酰胺凝胶电泳验证了分离后蛋白的纯度.     

超高效液相色谱法同时测定食品中7种合成色素

建立了超高效液相色谱法(UPLC)同时测定食品中柠檬黄、新红、苋菜红、胭脂红、日落黄、诱惑红和亮蓝7种人工合成色素。采用ACQUITY UPLBEHC18柱(50×2.1mm,1.7μm),以0.02mol/L的乙酸铵和甲醇为流动相,梯度洗脱,流速0.3mL/min,柱温30℃,检测波长为254nm和628nm,用外标法定量。7种合成色素在1~100μg/mL范围有良好的线性关系(r≥0.9994),平均回收率在83.5%~99.9%范围,相对标准偏差为0.57%~2.91%。该法简便、快速、灵敏,结果准确可靠,适用于食品中上述7种人工合成色素的分析。     

竹炭固相萃取-高效液相色谱法测定河水中多环芳烃

建立了竹炭固相萃取-反相高效液相色谱法检测水中16种多环芳烃的方法。通过实验综合分析,选定正己烷为洗脱溶剂,洗脱溶剂体积为15mL,上样速率为5mL/min,上样体积为750mL。此萃取条件下的萃取回收率在50.3%～143.2%之间。经萃取后,方法的最低检出限范围为0.011～0.069μg/L,精密度在3.3%～11%之间。用该法测定河水中多环芳烃的含量,水样的加标回收率在50.3%～138.4%范围内。     

高效液相色谱法同时快速测定饮料中的12种食品添加剂

建立了高效液相色谱法同时测定12种食品添加剂(苯甲酸、山梨酸、安赛蜜、柠檬黄、日落黄、觅菜红、胭脂红、赤藓红、新红、酸性红、诱惑红、罗丹明B)的方法。样品经前处理后,以甲醇-0.02 mol/L乙酸铵溶液梯度洗脱,采用紫外检测器检测,检测波长为240 nm,流速为1.0 mL/min。12种食品添加剂在0.5~30 mg/L范围内线性关系良好,回归系数都在0.999以上,方法加标回收率为93.1%~106.9%,相对标准偏差为1.4%~8.2%,检出限为0.07~0.63 mg/kg。     

固相萃取-高效液相色谱法同时测定食品中4种合成色素

以可代替使用的水溶性合成色素-亮黑BN、固绿FCF、酸性红、酸性黄36为研究对象,建立了高效液相色谱同时测定食品中4种合成色素的方法。样品通过WAX固相萃取柱富集净化,10%氨化甲醇洗脱,采用C18色谱柱分离,以甲醇和10 mmol/L乙酸铵水溶液作为流动相梯度洗脱,外标法定量。通过固相萃取柱净化后,杂质对待测物的干扰明显降低,优化色谱条件下,4种色素在0.10~10.0 mg/L质量浓度范围内,线性良好,相关系数(r)≥0.9995。方法回收率为92.6%~101.8%,相对标准偏差(RSD)≤5.4%,方法检出限为0.01~0.04 mg/kg。该方法灵敏度高,准确可靠,适合食品中亮黑BN、固绿FCF、酸性红、酸性黄36的同时测定。     

高效液相色谱法检测食品中姜黄素类化合物

建立了食品中姜黄素类化合物的液相色谱分析方法。采用甲醇提取试样中姜黄素及其同系物去甲氧基姜黄素和双去甲氧基姜黄素,以YMCTMCarotenoid色谱柱(250 mm×4.6 mm,5μm)分离,甲醇水溶液(A)-甲基叔丁基醚(B)梯度洗脱。对所分析化合物的稳定性、前处理条件及色谱条件进行考察。3种分析物在0.5~100μg/mL范围内线性关系良好,相关系数为0.997 7~0.999 8。在10~100 mg/kg加标浓度范围内,平均回收率为72.2%~102%,相对标准偏差为3.4%~13.8%。对姜黄素、去甲氧基姜黄素和双去甲氧基姜黄素的检出限分别为6、5、5 mg/kg。方法稳定、可靠,已应用于实际样品的检测。     

固相萃取-液相色谱/质谱法同时测定食品中磺胺类人工合成甜味剂

采用超声波提取，阴离子交换固相萃取柱净化，液相色谱．质谱定量检测食品中3种磺胺类甜味剂。方法对固相萃取条件，包括提取溶剂、洗脱溶剂以及洗脱体积等条件进行了优化。方法对安赛蜜、糖精钠、甜蜜素的检出限低于10pg，平均回收率在88％以上。在0．01～50μg/mL范围内有良好的线性关系，相关系数大于0．9996。本方法可用于食品中磺胺类甜味剂的快速测定。     

聚偏氟乙烯微孔滤膜-聚多巴胺-氧化石墨烯固相萃取结合离子迁移谱快速检测尿液中的麻黄碱

建立了新型聚偏氟乙烯微孔滤膜-聚多巴胺-氧化石墨烯固相萃取结合便携式高分辨离子迁移谱对尿液中的麻黄碱进行快速检测的方法。通过对新型固相萃取膜的制备过程、吸附、洗脱过程进行优化,可对尿液中麻黄碱实现5 min吸附、10 min洗脱、30 ms进样的快速检测。结果显示,麻黄碱在0.124～6.129μg/mL质量浓度范围内的线性良好,检出限为9.60 ng/mL,方法的回收率为91.0%～113%。该方法能够快速地完成对尿液中麻黄碱的检测,为药驾在线检测和现场监察提供了有效手段。     

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.