高效液相色谱法测定食用植物油中5种抗氧化剂的含量

提出了高效液相色谱法测定食用植物油中没食子酸丙酯、特丁基对苯二酚、叔丁基羟基茴香醚、没食子酸辛酯和2,6-二叔丁基对羟基甲酚等5种抗氧化剂的方法。样品(1.000g)用甲醇5mL)提取2次,涡旋振荡10min,取上清液在4℃冷藏,使残留脂肪析出。取其上清液浓缩后用甲醇定容为10 mL,取5μL进样用高效液相色谱法进行测定。ZORBAX SB-C_(18)色谱柱及不同比例混合的甲醇(A)和乙酸-水(1+99)(B)的混合液作为流动相进行梯度淋洗分离,柱温为30℃,流量为1.0mL·min~(-1),检测波长为280 nm。结果表明:5种抗氧化剂的检出限(3S/N)依次为0.10,0.34,0.32,0.14,0.57mg·kg~(-1)。在3个浓度水平上(200,500,1000mg·kg~(-1))对方法做回收试验,测得回收率在90.5%～102.0%之间,相对标准偏差(n=6)在0.02%～1.35%之间。     

离子液体双水相萃取-高效液相色谱法测定香精香料中的抗氧化剂

建立了香精香料中没食子酸丙酯(PG)、特丁基对苯二酚(TBHQ)、叔丁基对羟基茴香醚(BHA)和2,6-二叔丁基对甲酚(BHT)四种抗氧化剂的高效液相色谱检测方法。香精香料样品经离子液体双水相前处理,用高效液相色谱-二极管阵列检测法(HPLC-DAD)测定。结果表明,在0.5～100μg/mL浓度范围内,四种抗氧化剂的色谱峰面积均与其浓度呈线性关系,相关系数r≥0.9990,检出限分别为3.0、7.1、5.1和9.7ng/mL,回收率为85%～97%,相对标准偏差为1.2%～6.7%。     

高效液相色谱测定食品中的7种抗氧化剂

建立了高效液相色谱同时定量测定食品中叔丁基对羟基茴香醚、2,6-二叔丁基对甲酚、特丁基对苯二酚、没食子酸丙酯、没食子酸辛酯、没食子酸异戊酯和没食子酸月桂酯7种抗氧化剂的分析方法.液态油脂样品经甲醇反复提取后氮气吹干,5 mL甲醇定容;固体样品使用正己烷提取,再用乙腈反萃取多次,氮气吹干,5 mL甲醇定容.提取液经Eclipse XDB-C18色谱柱(250 mm x4.6 mm,5μm)分离,以1.5％乙酸-甲醇为流动相,梯度洗脱.用二极管阵列检测器(PDA)进行检测,结合保留时间和紫外光谱进行定性分析,定量检测波长280 nm.7种抗氧化剂在1～100 mg/L范围内具有较好的线性关系,相关系数r2＞0.999,定量下限(LOQ,S/N=10)为1.0～1.5 mg/kg;空白样品的加标回收率为79％～ 101％,相对标准偏差均低于7％.将该方法应用于食品中抗氧化剂的检测,从成品植物油、坚果等食品中检出抗氧化剂的残留.该方法准确快速、灵敏度高,满足食品中添加剂的检测要求.     

聚乙烯塑料包装材料中4种抗氧化剂向脂肪食品模拟物迁移的研究

本文基于超高效液相色谱建立了一种脂肪食品模拟物异辛烷中抗氧化剂叔丁基对羟基茴香醚(BHA)、2,6-二叔丁基对甲酚(BHT)、四[甲基-β-(3,5-二叔丁基-4-羟基苯基)丙酸酯]季戊四醇酯(Irganox1010)以及β-(4-羟基-3,5-二叔丁基苯基)丙酸正十八酯(Irganox1076)的提取检测方法,加标回收率在78.0%～108.7%之间,相对标准偏差(RSD)在4.0%～13.7%之间。研究了聚乙烯(PE)膜中抗氧化剂向异辛烷的迁移,讨论了温度及时间对迁移的影响,并根据迁移数据进行了初步的数学模型的建立,对实验值与数值模拟结果计算值作了对比分析。     

高效液相色谱法测定食用植物油中6种合成抗氧化剂

建立高效液相色谱法测定食用植物油中没食子酸丙酯、叔丁基对苯二酚、叔丁基对羟基茴香醚、二丁基羟基甲苯、没食子酸、山梨酸6种合成类抗氧化剂的含量。样品经正己烷溶解,再用饱和正己烷的乙腈萃取,振荡,超声25 min,离心后取乙腈层,定容,过0.45μm滤膜。以0.4%乙酸水溶液–乙腈为流动相,流量为0.8 mL/min,梯度洗脱,检测波长为280 nm,采用高效液相色谱法进行检测。6种合成抗氧化剂的质量浓度在0.1～10μg/mL范围内与色谱峰面积呈良好的线性关系,相关系数均大于0.999,方法检出限均为1.0～2.5 mg/kg。样品的加标回收率为79.6%～108.9%,测定结果的相对标准偏差为2.03%～5.77%(n=6)。该方法操作简单,能同时检测6种合成抗氧化剂,适用于多种食用植物油中合成抗氧化剂的测定。     

气相色谱-质谱法同时测定葡萄酒中13种防腐剂

采用气相色谱-质谱法同时测定了葡萄酒中的乙酸、丙酸、富马酸二甲酯(DMF)、2,6-二叔丁基对甲酚(BHT)、山梨酸、脱氢乙酸、苯甲酸、叔丁基羟基茴香醚(BHA)、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯、4-苯基苯酚共等13种防腐剂,建立了测定方法。样品以乙醚作为提取溶剂,饱和NaCl溶液作为释放剂,提取后乙醚层经无水Na2SO4脱水干燥过滤,旋转蒸发仪上浓缩至近干,定容后进行分析。采用程序升温,将13种防腐剂完全分离,平均回收率为84%～107%,检出限为0.10～1.46 mg/kg,RSD(n=7)为0.8%～5.4%。     

塑胶食品与药品包装材料中BHT的测定

采用索氏抽提法对食品与药品用塑料、橡胶包装材料样品进行前处理,正己烷提取其中的抗氧化剂2,6-二叔丁基-4-甲基苯酚(BHT).用毛细管柱气相色谱法、氢火焰离子化检测器、外标法测定样品中BHT的含量,用GC-MS对BHT定性分析.方法的检出限为0.1 mg/kg,回收率为90.0%～96.6%,测定结果的相对标准偏差为0.72%(n=5).     

中空纤维膜液相微萃取技术／气相色谱-质谱法对食品中防腐剂与抗氧化剂的测定

将中空纤维膜液相微萃取技术与气相色谱-离子阱质谱联用,测定食品中的4种防腐剂(对羟基苯甲酸甲酯(MP)、对羟基苯甲酸乙酯(EP)、对羟基苯甲酸丙酯(PP)及对羟基苯甲酸丁酯(BP))和3种抗氧化剂(叔丁基-4-羟基苯甲醚(BHA)、叔丁基苯二酸(TBHQ)、2,6-二叔丁基对甲酚(BHT)).优化的萃取条件:以15%(质量分数)Na2SO4的盐溶液为稀释溶剂,5 μL甲苯为萃取溶剂,搅拌速率为1 200 r/min,萃取时间为15 min.该方法的线性范围为0.4 ～80 mg/kg,检出限为0.002 ～8.0 μg/kg,加标回收率为94% ～115%,相对标准偏差为4.38% ～9.34%.     

固相萃取-高效液相色谱法测定炒货食品中抗氧化剂

提出了固相萃取-高效液相色谱法测定炒货食品中丁基羟基茴香醚(BHA)、二丁基羟基甲苯(BHT)、叔丁基对苯二酚(TBHQ)和没食子酸丙酯(PG)等人工合成的抗氧化剂和茶多酚、甘草抗氧化物、迷迭香提取物等天然抗氧化剂的方法。样品经甲醇-异丙醇-乙腈(2+1+2)混合溶剂提取后经C_(18)固相萃取柱富集,用甲醇从柱上洗脱抗氧化剂使其净化。洗脱液在50℃氮气吹干,定容至1.0 mL,取10μL试样溶液注入高效液相色谱仪测定。采用反相C_(18)色谱柱为分离柱,以乙腈和三氟乙酸-水(0.05+99.95)溶液为流动相作梯度淋洗,在280 nm作紫外检测(甘草酸在250 nm检测)。各抗氧化剂的质量浓度分别在一定的范围内呈线性关系,方法的测定下限(10S/N)在0.1～1.0 mg·kg~(-1)之间。以油炸花生空白试样为基体,加入标准溶液进行回收试验,测得试样中抗氧化剂的回收率在83.6%～106.0%之间,相对标准偏差(n=6)在1.3%～3.9%之间。     

UPLC研究塑料食品包装材料中的抗氧化剂及其迁移

对塑料食品包装材料中的抗氧化剂叔丁基对羟基茴香醚(BHA)、2,6-二叔丁基对甲酚(BHT)、β-(4-羟基-3,5-二叔丁基苯基)丙酸正十八酯(Irganox1076)3种抗氧化剂进行了研究,建立了一种快速、高效的检测方法。方法包括:以甲醇为萃取溶剂,快速溶剂萃取(ASE)塑料食品包装中的抗氧化剂;以异辛烷为脂肪食品模拟物,对迁移进入异辛烷中的抗氧化剂进行旋转蒸发浓缩;使用超高效液相色谱(UPLC)进行检测。本方法有较好的相关线性(R20.99)、平均回收率(分别为75.8%~108.7%)、精密度(RSD分别为2.8%~12.7%)及低于欧盟法规规定的特定迁移限量(SML)的检出限。本方法用于市售食品的包装检测,各抗氧化剂在包装材料中被检测出,迁移量均低于特定迁移限量。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.