数字图像比色法测定水样中的六价铬

在125mL分液漏斗中,加入水样50mL、50%(体积分数)硫酸溶液0.5mL、50%(体积分数)磷酸溶液0.5mL、2.0g·L~(-1)二苯碳酰二肼(DPCI)显色剂溶液2.0mL,摇匀,静置5min,加入5.0g·L~(-1)十二烷基硫酸钠溶液2 mL、正丁醇2 mL,摇匀,加入5 mL三氯甲烷,剧烈振摇2min,形成微乳液,静置分层,使DPCI和六价铬在酸性条件下生成的紫红色络合物可以被萃取到三氯甲烷中。将底层的三氯甲烷相转移到样品比色皿中,利用自搭数字图像比色装置进行数字图像比色分析。该装置采用智能手机采集检测区域照片,通过Color Grab软件获取待测物照片R(红色)、G(绿色)、B(蓝色)值中的G值来对水样中的六价铬进行定量。结果显示:六价铬质量浓度在0.010～0.160 mg·L~(-1)范围内与三氯甲烷层G值呈线性关系,方法检出限(3s/k)为0.008mg·L~(-1)。将该方法用于水样中六价铬的测定,测定值的相对标准偏差(n=10)为1.0%～4.2%,加标回收试验结果为95.0%～97.5%。按此方法分析了加标水样,本方法与国家标准方法得到的结果一致。     

碱消解-电感耦合等离子体发射光谱法(ICP-OES)测定土壤中六价铬的研究

采用碱消解—电感耦合等离子体发射光谱(ICP-OES)检测方法对土壤中六价铬含量进行分析。土壤样品以碳酸钠-氢氧化钠为消解液,加入氯化镁和磷酸氢二钾-磷酸二氢钾缓冲溶液,经90-95℃消解溶出六价铬,用电感耦合等离子体发射光谱仪测定消解液中六价铬含量。在选定的测定条件下,方法的检出限为0.24 mg/kg,测定下限为0.96 mg/kg,加标回收率在99.6 %～104.1%之间,相对标准偏差2.53%-7.48%。该方法简便快速,稳定性好,结果准确可靠,适用于土壤中六价铬含量的分析。     

快速溶剂萃取-离子色谱法同时测定塑料中的三价铬和六价铬

建立了采用快速溶剂萃取-离子色谱同时测定塑料中三价铬和六价铬的方法。三价铬和六价铬分别以吡啶-2,6-二羧酸(PDCA)和1,5-二苯卡巴肼(DPC)作为络合剂在柱前和柱后进行衍生化,分别在紫外和可见波长下采用紫外检测器进行检测,灵敏度高,基体干扰小。本方法对三价铬和六价铬的检出限分别为5.0 μg/L和0.5 μg/L;分别在50～1000 μg/L和5.0～100 μg/L范围内呈现良好的线性关系,线性相关系数分别为0.9994和0.9998;三价铬和六价铬的回收率范围为90.7%～101.1%,相对标准偏差(RSD)为1.7%～4.4%。该方法分析速度快、灵敏度高、重现性好,可用于塑料中三价铬和六价铬的同时测定。     

柱后衍生-液相色谱法测定食品接触纸制品中六价铬

建立柱后衍生-液相色谱法测定食品接触纸制品中六价铬残留量的方法。试样用磷酸盐缓冲液萃取后进行过滤,以硝酸铵为流动相,经过AS 7阴离子交换柱进行分离,分离后的六价铬与衍生试剂(1,5-二苯碳酰二肼)在酸性条件下进行衍生化反应,采用紫外检测器在540 nm处进行检测。六价铬质量浓度在5～500μg/L的范围内与色谱峰面积线性关系良好,相关系数大于0.999,方法检出限为0.91μg/L。样品加标回收率为87.3%～96.1%,测定结果的相对标准偏差为4.14%～8.48%(n=7)。该方法选择性高,重复性好,设备简单,能满足食品接触纸制品中六价铬含量的测试要求。     

空气辅助溶剂去乳化-分散液液微萃取-数字成像比色法测定水样中的六价铬

建立了基于空气辅助溶剂去乳化-分散液液微萃取(AA-SD-DLLME)-数字成像比色法(DIC)快速测定水环境中六价铬的新方法。自制的一次性塑料滴管中加入样品，在硫酸介质中六价铬与二苯碳酰二肼、十二烷基硫酸钠反应生成紫红色的三元络合物。以轻质溶剂正己醇作为萃取剂，采用空气辅助-分散液液微萃取方法对该络合物进行萃取获得乳化体系，然后加入去乳化剂甲醇破坏乳化体系，无需离心步骤即可使两相分离；取出滴管窄端上层富集的萃取层到离心管中，可通过数字成像比色装置对六价铬进行比色测定。优化了显色剂浓度、十二烷基硫酸钠浓度、pH、萃取剂种类及用量、萃取混匀次数、去乳化剂种类及用量等条件。在优化实验条件下，方法的线性范围为10～150μg/L,相关系数(R²)为0.9989,检出限为2μg/L,加标回收率为92.3%～110.3%,相对标准偏差(RSD)为1.3%～2.0%(n=10)。该方法具有较高的灵敏度、较好的准确性，能现场快速测定环境水样中六价铬。     

超痕量六价铬分析仪快速测定水质中铬(Ⅵ)

利用超痕量六价铬分析仪快速测定环境水样中Cr(Ⅵ)的残留。环境水样经0.45μm滤膜过滤或离心去除杂质后,直接进行定量分析。Cr(Ⅵ)通过Prin-Cen Cr(Ⅵ) spec Fast column柱分离,以NH_4NO_3体系溶液为流动相进行洗脱,用长光程紫外可见检测器进行检测。结果表明,Cr(Ⅵ)质量浓度在0.50～1000μg/L范围内线性关系良好,相关系数均大于0.9999,方法检出限为80 ng/L。实际水样在不同加标浓度水平下,回收率为97%～111%,相对标准偏差为0.5%～4.0%。使用该方法对地表水、地下水、生活污水和工业废水进行测定,镀锡板工业废水和皮革工业废水均检出Cr(Ⅵ)。与传统的二苯碳酰二肼分光光度法(GB 7467-87)比较,本方法不受色度和氧化还原物质干扰,适用于分析环境水样中Cr(Ⅵ)的残留检测。     

流动注射分光光度法测定水中六价铬

建立全自动流动注射分光光度法测定水中六价铬。流动注射分析仪设置参数为：洗针时间10 s；峰宽50 s；到达阀时间50 s；样品周期90 s；出峰时间22 s；进载流时间20 s；积分时长50 s；进样时间50 s。选择安全低毒、低碳环保、经济实用的无水乙醇替代丙酮作为显色剂的溶剂测定水中六价铬。六价铬的质量浓度在0.001～0.5 mL/L范围内与吸光度（峰面积）具有良好的线性关系，线性相关系数为0.999 9，方法检出限为0.000 3 mg/L。利用该方法测定水质环境标准样品中的六价铬，测定结果相对误差为0.15%～2.77%，相对标准偏差为0.15%～1.54%(n=6)。不同浓度的样品加标平均回收率为98.7%～101%。该方法简便快捷，灵敏度高，适用于水中六价铬的测定。     

碱液提取-电感耦合等离子体质谱法快速准确测定土壤中的六价铬

建立碱液提取-电感耦合等离子体质谱法快速准确测定土壤中六价铬的方法。以碳酸钠-氢氧化钠溶液提取，经恒温水浴振荡后离心的方式提取土壤中的六价铬。对提取方式、提取时间、提取温度、振幅的选择等条件进行了优化，用电感耦合等离子体质谱仪测定土壤中的六价铬，使用内标元素Sc进行干扰校正。标准曲线线性系数为0.999 9，检出限为0.2 mg/kg。土壤六价铬标准物质测定结果的相对偏差为1.12%～5.56%(n=6)，回收率为97.81%～104.00%。与传统方法比较，该方法检测时间缩短了6 h，适合批量土壤样品中六价铬的分析，且检出限更低，重现性好，测量结果满足日常生产需要。     

离子色谱-柱后衍生可见光检测法测定海水中痕量六价铬

建立了银柱和钠柱串联净化-离子色谱-柱后衍生可见光检测法测定海水中痕量六价铬的分析方法。海水样品经稀释后通过银柱和钠柱串联净化，以Ion Pac^TM AS7柱(250 mm×2 mm)为分离柱，硫酸铵-氨水溶液为淋洗液，二苯羰酰二肼溶液为显色液，海水中六价铬经分离后与显色液在混合反应圈中进行衍生反应，衍生物经可见光检测器检测。六价铬的质量浓度在0.1～10.0μg/L范围内与色谱峰面积呈良好的线性关系，线性相关系数为0.999 9。当进样体积为200μL时，方法检出限为0.03μg/L。海水中六价铬的平均加标回收率为78.0%，测定结果的相对标准偏差为2.4%n=6)。该方法能够满足海水中痕量六价铬的测定要求。     

柱后衍生-离子色谱法测定土壤和沉积物中的六价铬

为了提高土壤和沉积物中六价铬测定的灵敏度、精密度和正确度,建立了柱后衍生-离子色谱法测定六价铬的分析方法。样品经过预处理后,使用仪器进行定量分析。样品中的六价铬经过Prin-Cen Cr（VI）Spec Column型阴离子分析柱分离出来,分别使用硝酸铵体系溶液和二苯碳酰二肼溶液作为流动相和柱后衍生液,并使用TLD检测器进行六价铬的定量分析。结果表明,六价铬质量浓度在5～100 μg/L范围内线性关系较好,相关系数为1.0000,检出限为0.02 mg/kg。该方法在实际土壤和沉积物样品中的加标回收率为84.0%～94.0%,相对标准偏差为2.34%～11%。本方法与火焰原子吸收分光光度法（HJ1082-2019）相比,六价铬的测定不受试样盐分、pH值及三价铬影响,而且该方法具有灵敏度高、精密度好、正确度高和稳定性强的优点,适用于测定土壤和沉积物中的六价铬。     

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.