离子色谱法测定啤酒中6种无机阴离子的含量

取啤酒样品(10.0mL)超声脱气30min,用经活化的固相萃取小柱净化。收集净化液2.0mL,用水稀释至20.0mL。所得样品溶液经0.22μm滤膜过滤后,直接进样进行离子色谱分析。采用阴离子交换柱IonPac AS11作为分离柱,用氢氧化钾淋洗液发生器产生的不同浓度的氢氧化钾溶液作梯度淋洗,流量为1.0 mL·min~(-1),柱温为35℃。6种无机阴离子(Cl~-、NO_2~-、Br~-、NO_3~-、SO_4~(2-)、PO_4~(3-))在一定质量浓度范围内呈线性,检出限(3S/N)在0.005~0.028mg·L~(-1)之间。对同一个啤酒样品进行精密度试验,测定值的相对标准偏差(n=6)在2.1%~3.0%之间。按标准加入法进行回收试验,回收率在89.0%~105%之间。     

高效液相色谱法测定食品包装材料中双酚A的含量

样品(2.000 0 g)经甲醇50 mL超声提取60 min,提取液用水稀释至100 mL,经0.22μm滤膜过滤后进行色谱分离。以Agilent Eclipse plus C18柱为固定相,50 mmol·L-1柠檬酸缓冲液(p H6.0)-甲醇(45+55)混合液为流动相。电化学检测器的检测池电压为400 m V(ECD1)和575 m V(ECD2)。双酚A的质量浓度在0.2~20.0μg·L-1内与其峰面积呈线性关系,检出限(3S/N)为3.3μg·kg-1。按标准加入法在3个浓度水平上进行回收试验,回收率在95.6%~98.2%之间,测定值的相对标准偏差(n=5)在2.1%~5.3%之间。     

柱切换-液相色谱法测定婴儿配方奶粉中4种雌激素

婴儿配方奶粉样品用水超声溶解后,用乙腈超声提取30min,以15 000r·min^-1转速在5℃下离心10min,残渣用乙酸乙酯提取,合并两次提取液。上层有机相于40℃下用氮气吹至近干,加入50%(体积分数)甲醇溶液溶解,溶解液过0.22μm滤膜,采用柱切换-液相色谱法测定滤液中4种雌激素的含量。以Thermo BioBasic SEC-120色谱柱为净化柱,Waters XBridge BEH C18色谱柱为分析柱,用水和甲醇以不同比例混合的溶液为流动相进行梯度洗脱,用紫外检测器测定。4种雌激素的质量浓度均在1.0~20μg·L^-1内与其对应的峰面积呈线性关系,测定下限(10S/N)为0.1~0.3μg·kg^-1。以空白样品为基体进行加标回收试验,所得回收率为90.0%~105%,测定值的日内相对标准偏差(n=6)为1.6%~5.4%,日间相对标准偏差(n=11)为3.5%~6.2%。     

高效液相色谱-串联质谱法测定食品中的乙二胺四乙酸二钠

应用高效液相色谱-串联质谱法(HPLC-MS/MS)测定了食品中EDTA二钠盐。液态食品(5g)直接加水40mL提取;固态或酱状食品(5g)加水15mL及三氯甲烷20mL匀质后离心,取其上清液,残渣重复提取2次。合并上清液,在提取液中加入三氯化铁溶液超声10min衍生化后,定容至50mL。取样品溶液5mL,经MAX阴离子交换柱净化,用甲酸-甲醇-水(10+50+40)混合液6mL洗脱,洗脱液经80℃吹氮蒸干,用水溶解后进行HPLC-MS/MS分析。EDTA二钠盐的质量浓度在1.0~50.0mg·L-1范围内呈线性。方法的检出限(3S/N)为5mg·kg-1。应用提出的方法分析了4种食品样品并进行加标回收试验,测得回收率在88.3%~96.0%之间,测定值的相对标准偏差(n=6)均小于10%。     

气相色谱-质谱法测定化妆品中10种防腐剂

采用气相色谱-质谱法(GC-MS)同时测定化妆品中10种防腐剂含量。样品经甲醇超声提取,无水硫酸钠脱水后过滤进样检测。采用Agilent HP-5MS毛细管色谱柱(30m×0.25mm,0.25μm)分离,程序升温,分流进样进行测定。结果表明:17min内即可完成10种防腐剂的测定,各防腐剂的质量浓度均在5.00~100mg·L-1范围内与峰面积呈线性关系,方法的检出限(3S/N)为0.30~0.70ng。方法用于化妆品测定,加标回收率在96.5%~105%之间,测定值的相对标准偏差(n=6)在0.66%~3.2%之间。     

高效液相色谱法测定降血压类健康产品中的6种二氢吡啶类成分

采用高效液相色谱法同时测定降血压类健康产品中非法添加的6种二氢吡啶类化学成分。样品经甲醇超声提取,提取液用ACE C_(18)色谱柱(250 mm×4.6 mm,5μm)分离,柱温35℃,流动相为0.2%(ψ)磷酸溶液-乙腈混合液,梯度洗脱,流量1.0mL·min~(-1),采用二极管阵列检测器,检测波长为235 nm,以外标法定量。6种化合物的质量浓度在一定范围内与峰面积呈线性关系,检出限(3S/N)为56 mg·kg~(-1),测定下限(10S/N)为167 mg·kg~(-1)。加标回收率在96.0%~101%之间。测定值的相对标准偏差(n=6)在1.0%~1.2%之间。对阳性样品采用液相色谱-质谱法进行验证。     

液相色谱-串联质谱法测定水产加工品中的甜蜜素

建立了液相色谱-串联质谱法测定水产加工品中甜蜜素的测定方法。样品用水提取,正己烷净化后,以0.1%甲酸-甲醇为流动相,C18色谱柱分离,在负离子模式下用配有电喷雾离子源的液相色谱-串联质谱测定。甜蜜素含量1~200 ng/m L范围内,线性关系良好(r~2=0.9999);方法定量限5μg/kg(S/N≥10)。甜蜜素在5μg/kg和50μg/kg添加水平下,平均回收率为81.0%~88.4%,相对标准偏差为4.0%~6.4%。方法适合水产加工品中甜蜜素的测定。本文根据甜蜜素的性质,选取水为提取剂,并对净化方法进行了研究,通过正已烷液-液萃取和冷冻方式去除了提取液中的油类物质和水溶性蛋白,确保了分析结果的稳定性和准确性。该技术的建立为水产加工品中甜蜜素监管提供技术支撑。     

固相膜萃取-气相色谱法测定养殖用水中痕量有机磷农药

采用固相膜萃取-气相色谱法测定养殖用水中乐果、甲基对硫磷和马拉硫磷等3种有机磷农药的含量。水样经C18固相萃取膜萃取后,用丙酮和二氯甲烷洗脱。用SPB-608毛细管色谱柱分离,氮磷检测器检测。3种有机磷农药的质量浓度均在0.02~1.0μg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.0025~0.004μg·L-1之间。以空白样品为基体进行加标回收试验,回收率在93.0%~111%之间,测定值的相对标准偏差(n=5)在0.13%~5.2%之间。     

气相色谱法测定修正类产品中10种苯类溶剂残留量

采用气相色谱法测定修正类产品中10种苯类溶剂的残留量。修正类产品样品用乙酸乙酯超声提取30min,用DB-WAX毛细管色谱柱(30m×0.32mm,0.25μm)分离,火焰离子化检测器检测。10种化合物的质量浓度均在0.20~100.0mg·L-1范围内与其信号强度呈线性关系,方法的测定下限(10S/N)在1.8~2.1mg·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90.3%~113%之间,测定值的相对标准偏差(n=6)在1.8%~6.1%之间。     

固相萃取-气相色谱法测定腌肉中5种生物胺北大核心CSCD

采用固相萃取-气相色谱法测定腌肉中酪胺、组胺、精胺、亚精胺和β-苯乙胺等5种生物胺的含量。腌肉样品用50g·L^(-1)三氯乙酸溶液提取,强阳离子交换固相萃取柱净化。用Agilent DB-1701色谱柱(30m×0.25mm,0.25μm)分离,氮磷检测器检测。5种生物胺的质量浓度均在1.0~50.0mg·L^(-1)内与其对应的峰面积呈线性关系,方法的检出限(3S/N)为0.12~0.32 mg·kg^(-1)。以空白样品为基体进行加标回收试验,所得回收率为78.0%~96.8%,测定值的相对标准偏差(n=6)为2.2%~7.1%。     

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%).     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.