高效液相色谱法测定食用菌中10种荧光增白剂

采用高效液相色谱法同时测定食用菌中10种双三嗪氨基二苯乙烯型荧光增白剂的含量。色谱分离中,以Athena C18-WP色谱柱(4.6 mm×200 mm,5μm)为固定相,用乙腈和0.02mol·L-1乙酸铵溶液以不同比例混合的溶液为流动相进行梯度洗脱,用荧光检测器测定,激发波长为350nm,发射波长为430nm。10种荧光增白剂的质量浓度均在2.0~100μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.002~0.005mg·kg-1之间。以空白样品为基体进行加标回收试验,所得回收率在73.0%~121%之间,测定值的相对标准偏差(n=6)在0.90%~7.8%之间。     

超声萃取-高效液相色谱法测定棉织物中5种荧光增白剂

应用超声萃取-高效液相色谱法测定棉织物中5种荧光增白剂的含量。棉织物样品在40℃温度下用二甲基甲酰胺-水(70+30)混合液超声提取20min。提取液按仪器工作条件进行色谱测定。分离中用Agilent Eclipse XDB-C18色谱柱为固定相,用乙腈和10mmol·L-1乙酸铵溶液以不同比例混合后作为流动相进行梯度洗脱。用二极管阵列检测器测定。5种荧光增白剂的质量浓度均在0.5~200.0mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.05~0.10mg·L-1之间,测定下限(10S/N)在1.2~2.1mg·kg-1之间。以空白样品为基体进行加标回收试验,所得回收率在76.5%~103%之间,相对标准偏差(n=6)在2.6%~7.1%之间。     

液相色谱-串联质谱法测定发泡聚苯乙烯餐具中8种荧光增白剂的含量

采用液相色谱-串联质谱法测定发泡聚苯乙烯餐具中FWA135、FWA184、FWA185、FWA199、FWA367、FWA368、FWA378、FWA393等8种荧光增白剂的含量。样品以三氯甲烷提取,加入甲醇使聚合物沉淀。在液相分离中,所得经过滤后的提取液,以Eclipse Plus C18色谱柱为分离柱,以不同体积比的0.1%(体积分数)甲酸-水溶液和0.1%(体积分数)甲酸甲醇溶液的混合液为流动相进行梯度洗脱。质谱测定中,采用电喷雾正离子源多反应监测模式检测。8种荧光增白剂的线性范围均为1.00~250μg·L~(-1),检出限(3S/N)在0.5~2.0μg·L~(-1)之间。以空白样品为基体进行加标回收试验,所得回收率在85.2%~98.4%之间,测定值的相对标准偏差(n=6)在4.1%~8.3%之间。     

液相色谱-高分辨质谱法测定壮阳类保健品中非法添加物

采用液相色谱-高分辨质谱法检测壮阳类保健品中的5种非法添加物。样品经甲醇超声提取后,以C18色谱柱为分离柱,以0.1%(体积分数)乙酸溶液与乙腈组成的混合溶液为流动相进行梯度洗脱,采用电喷雾正离子源及全扫描/二级质谱目标离子扫描模式进行测定。5种非法添加物的线性范围为1.0~50μg·L-1,方法测定下限(10S/N)在0.3~0.4μg·L-1之间。对样品进行加标回收试验,回收率在78.0%~102%之间,测定值的相对标准偏差(n=6)在0.62%~2.3%之间。     

洗涤用品中5种荧光增白剂的高效液相色谱法检测及质谱确证

建立了同时测定洗涤用品中5种荧光增白剂类化合物(荧光增白剂393、荧光增白剂KCB、荧光增白剂CBS-127、荧光增白剂KSN和荧光增白剂OB)的高效液相色谱分析方法及质谱确证方法。洗涤样品以四氢呋喃为提取溶剂进行超声提取,提取液离心处理后,取上清液经微孔滤膜过滤后测定。采用Agilent Eclipse XDB-C18色谱柱(250 mm×4.6 mm,5μm)分离,以甲醇-水二元流动相梯度洗脱,流速1.0 mL/min,柱温25℃,荧光增白剂KCB和荧光增白剂CBS-127的检测波长为359 nm,荧光增白剂393、荧光增白剂KSN和荧光增白剂OB的检测波长为372 nm。荧光增白剂393的定量限为0.25 mg/kg,荧光增白剂KCB、荧光增白剂CBS-127、荧光增白剂KSN和荧光增白剂OB的定量限为0.5 mg/kg。在低、中、高3种加标水平下的平均回收率为87.8%~103.7%,相对标准偏差为1.5%~4.4%。方法的日内RSD均小于1%,日间RSD均小于2%。适用于洗涤用品中5种荧光增白剂类化合物的测定。     

高效液相色谱法测定美白面膜中7种荧光增白剂

建立了同时测定美白面膜中7种荧光增白剂的高效液相色谱-荧光检测(HPLC-FLD)法。样品经乙腈超声提取后,经Eclipse XDB-C18色谱柱分离,以甲醇-25mmol/L乙酸铵溶液为流动相,梯度洗脱,在激发波长365nm、发射波长430nm进行测定。结果表明,FWA 85和FWA 71以及其他5种荧光增白剂分别在5~35mg/L和0.025~4mg/L的浓度范围内呈良好的线性关系,线性相关系数大于0.991;方法的检出限(S/N=3)为0.00071~0.18mg/L,定量限(S/N=10)为0.12~12.24μg/g。3种不同添加水平下的样品加标平均回收率为93.62%~115.87%,相对标准偏差为0.43%~5.40%。该方法简便、灵敏、准确,可用于美白面膜中7种目标荧光增白剂的同时测定。     

高效液相色谱法测定化妆品中4种硝基咪唑类药物

采用高效液相色谱法测定化妆品中的甲硝唑、替硝唑、奥硝唑和塞克硝唑。样品经甲醇和0.1mol·L-1盐酸溶液以体积比1比1组成的混合溶液超声提取15min后,以C18色谱柱为分离柱,以甲醇-乙腈-水(7+1+2)混合液为流动相,在检测波长315nm处进行测定。4种硝基咪唑类药物在一定的质量浓度范围内与峰面积呈线性关系,方法检出限(3S/N)和测定下限(10S/N)分别低于10 mg·kg-1和30 mg·kg-1。以空白样品为基体进行加标回收试验,测得回收率在93.8%~104%之间,相对标准偏差(n=6)在0.2%~4.1%之间。     

高效液相色谱-荧光法同时测定食品接触纸制品中15种荧光增白剂

建立了高效液相色谱-荧光法同时测定食品接触纸制品中15种荧光增白剂的分析方法,测定对象包括离子型和非离子型荧光增白剂,其中包括部分同分异构体。样品经切碎后,采用一步溶剂提取法利用碱性提取液对样品中的荧光增白剂进行超声提取,提取液过膜后进行高效液相色谱分析。以乙腈、甲醇和四丁基溴化铵甲醇水溶液作为流动相,Agilent Pursuit 5 PFP(4.6 mm×250 mm×5.0 μm)为色谱柱进行梯度洗脱。结果表明,15种荧光增白剂在一定质量浓度范围内线性关系良好,相关系数(r)均不小于 0.998 9,检出限为0.030~0.60 mg/kg,定量下限为0.10~2.0 mg/kg。在3个加标水平下,15种荧光增白剂的回收率为90.0%~108%,相对标准偏差为0.70%~7.1%。所建立的方法成功应用于市售13种食品接触纸制品中荧光增白剂含量的测定,证明该方法实用性强,操作简便,灵敏度高。     

超声辅助分散液相微萃取-高效液相色谱法测定蜂蜜中的咖啡因

采用超声辅助分散液相微萃取技术结合高效液相色谱法测定蜂蜜中的咖啡因。将样品用水溶解配制成100g·L-1样品溶液,取7.5 mL样品溶液,加入三氯甲烷120μL和甲醇1.5mL,混匀后超声5min,离心后吸取5μL沉积相,在WondasilTM C18色谱柱上分离,以甲醇(1+1)溶液为流动相进行洗脱,紫外检测波长为274nm。咖啡因的线性范围为10.0~500μg·L-1,检出限(3S/N)为9μg·L-1。测定值的相对标准偏差为2.7%~4.1%,加标回收率在96.6%~104%之间。     

固相萃取-超高效液相色谱法测定水体中4种硝基呋喃类药物

采用固相萃取-超高效液相色谱法测定水体中呋喃西林、呋喃它酮、呋喃妥因、呋喃唑酮等4种硝基呋喃类药物的含量。样品经HLB固相萃取柱净化后,用氨水-甲醇(5+95)溶液洗脱。以BEH C18色谱柱为分离柱,以乙腈和含有0.1%(体积分数)甲酸的2mmol·L-1乙酸铵溶液以体积比23比77组成的混合液为流动相,在检测波长360nm处进行测定。4种硝基呋喃类药物的质量浓度均在5.0~200μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)为0.02μg·L-1。以空白样品为基体进行加标回收试验,所得回收率在84.5%~97.2%之间,测定值的相对标准偏差(n=6)在1.5%~4.5%之间。     

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%.     

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.     

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%).     

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.     

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.     

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.