火焰原子吸收分光光度法测定洗发液、护发液中的铅

建立了一种准确测定洗发、护发用品中铅含量的火焰原子吸收分光光度检测方法,样品用硝酸-高氯酸-硫酸于高温下消解后,在优化的仪器操作条件下进行含量测定,在0~10.00μg/mL内,线性方程为A=0.017 9c 0.001 4,相关系数为0.999 5。4种样品3个不同添加水平试验铅的回收率为86.4%~100.7%,测量结果的相对标准偏差为1.3%~2.2%,铅的检出限为0.017μg/g。     

微量直接进样-二元泵联用ICP-MS分析大米蛋白中痕量铅

建立了微量直接进样—二元泵联用ICP-MS分析大米蛋白样品中痕量铅的方法。将酶解后的大米蛋白液离心,取上清液过0.45μm膜直接进样。优化分析条件:流动相为体积分数2%HNO3/甲醇(99:1,V/V),流速0.5 m L/min,进样量50μL。在0~50μg/L范围内线性相关系数为0.9998,方法检出限为5.37 ng/L,加标样品的回收率在93.2%~97.4%之间,RSD为0.96%~4.1%(n=9)。方法可作为大米蛋白中痕量铅的批量分析方法。     

氢化物发生-原子荧光光谱法测定金属镁中痕量铅

样品以盐酸、过氧化氢进行溶解,以铁氰化钾作氧化剂,用氢化物发生-原子荧光光谱法测定金属镁中痕量铅。研究了氢化物发生的介质和酸度、硼氢化钾溶液的浓度、氢氧化钠的浓度、铁氰化钾的浓度对测定结果的影响,确定了最佳的测定条件。同时对仪器的操作参数进行了最佳选择。在最佳条件下,铅浓度在0~20μg/L范围内与荧光强度呈良好的线性关系,相关系数大于0.9995,方法的检出限为0.37μg/L。样品中铅的加标回收率在91%~102.7%之间,相对标准偏差为4.2%。     

布洛芬注射液包材相容性研究中铅、镉、砷、锑的测定

建立中性硼硅玻璃包材加速试验后布洛芬注射液中铅、镉、砷、锑含量的检测方法。采用微波消解仪以硝酸分解样品,用石墨炉原子吸收光谱仪测定铅、镉含量,测定波长铅为283.3 nm,镉为228.8 nm,铅、镉分别在5.0~50.0,0.5~5.0μg/L范围内有良好的线性,相关系数分别为0.999 7,0.996 2,检出限分别为0.26,0.01μg/L,测定结果的相对标准偏差分别为1.06%,2.40%(n=6),加标回收率分别为100.2%~101.9%,97.1%~105.1%。用原子荧光光谱仪测定砷、锑含量,测定波长砷为193.7 nm,锑为217.6 nm,砷、锑在1~10μg/L范围内均有良好的线性,相关系数分别为0.999 9,0.999 5,检出限分别为0.03,0.01μg/L,测定结果的相对标准偏差分别为1.04%,2.65%(n=6),加标回收率分别为94.2%~96.5%,92.6%~96.5%。该测定方法快速,灵敏度高,适用于内包装材料加速试验后药品中重金属元素含量变化的研究。     

固相萃取-电感耦合等离子体原子发射光谱（ICP-AES）法测定地下水中三种重金属

为拓宽固相萃取技术在生态环境监测领域应用范围,建立了树脂固相萃取前处理ICP-AES法测定地下水中铅、铬、镉含量的方法。经前处理条件优化,硝酸洗脱液浓度5%、缓冲溶液pH 7、洗脱速率10 mL/min及进样体积为500mL条件下,铅、铬、镉等三种重金属回收率均可以达到95%以上。该方法中各目标元素在0.02~20 μg/L范围内线性关系良好,相关系数均大于0.999;铅、铬、镉方法测定下限分别0.56μg/L,0.04μg/L,0.24μg/L满足评价要求;方法精密度RSD值在0.44%~5.49%;加标回收率范围分别在98.55%~101.84%、98.5%~104%、95.5%~105%。经监测井实样测试,铅、铬、镉结果处于《地下水质量标准》（GB/T14848-2017）I类限值范围内。该方法干扰小,易操作,为相关国家标准修订提供参考。     

高效液相色谱法测定粮食中玉米赤霉烯酮及其代谢物

采用甲醇-水提取,C18小柱净化,反相HPLC荧光检测器测定了玉米、面粉、小麦样品中的玉米赤霉烯酮及其代谢物和黄曲霉B1。对样品预处理和高效液相色谱测定条件进行了优化,ZON,α-ZOL,β-ZOL和AFTB1的线性范围分别为5.0μg/L~146g/L,25.0μg/L~200g/L,25.0μg/L~160g/L和0.4μg/L~2.0g/L,检出限分别为0.5、2.5、2.5和0.04μg/kg;加标回收率在80.0%~110.0%范围内;日间相对标准偏差为4·5%~9.2%,日内精密度2.7%~7.4%。本方法灵敏准确,易于推广,适用于粮食中玉米赤霉烯酮及其代谢物的检测。     

微波消解-氢化物发生原子吸收光谱法测定大米中铅

采用微波消解方式处理样品,建立了氢化物发生-原子吸收光谱法测定大米中痕量铅的分析方法。对载气流速、硼氢化钠浓度、溶液酸度以及铅反应试剂加入量进行了研究。在选择了最佳实验条件下,方法的检出限为0.05μg/L,加标回收率在96.8%~103.8%。     

便携式钨丝电热原子吸收光谱仪测定天麻中的铅

采用微波消解-小型钨丝电热原子吸收光谱仪在优化条件下测定了天麻中的铅。进样10μL时,检出限为10.1μg/L。对600μg/L铅标准溶液进行5次连续测定,测定结果的相对标准偏差为5.2%。铅的线性范围为100~1500μg/L,回归方程为A=0.0002c-0.0103,线性相关系数r=0.995 8。该法测定结果与电感耦合等离子体发射光谱仪(ICP-OES)测定结果接近,该方法简便、快速,可用于天麻样品中痕量铅的测定。     

超高效液相色谱-串联质谱法分析鸡蛋中利巴韦林及其代谢物残留

建立了超高效液相色谱-串联质谱法同时快速测定鸡蛋中利巴韦林及其两种主要代谢物 TCONH2和RTCOOH 的分析检测方法。样品采用乙腈-水(9∶1, V/ V)提取,乙腈饱和正己烷除脂,C18结合 GCB 进行固相分散萃取除杂,Agilent ZORBAX SB-Aq 色谱柱(100 mm ×3.0 mm,1.8μm)分离,超高效液相色谱-串联质谱测定。结果表明：利巴韦林、TCONH2和 RTCOOH 分别在2.0~200μg/ L,0.5~200μg/ L,5.0~200μg/ L 浓度范围内,线性良好,相关系数 R2>0.99,检出限分别为0.54,0.09和1.54μg/ L,定量限分别为1.79,0.31和5.13μg/ L。在5.0,10.0和50.0μg/ L 加标水平下,利巴韦林和 RTCOOH 回收率分别为96.1%~99.6%和42.9%~58.3%;在0.5,2.0和5.0μg/ L 加标水平下,TCONH2的回收率为75.9%~106.7%,相对标准偏差均为4.2%~12.7%。实际样品测定结果表明,本方法操作简单、快速、准确,能够满足鸡蛋中利巴韦林及其两种主要代谢物的分析检测。     

氢化物发生–原子荧光光度法测定食品和食品添加剂中的砷、汞和铅

建立氢化物发生–原子荧光光度法测定食品和食品添加剂中砷、汞和铅元素的方法。对茶叶、方便面、精料与二氧化硅样品的前处理方法进行了研究,讨论了酸介质与酸度、还原剂浓度、铁氰化钾与草酸浓度等因素对样品测定的影响。当还原剂质量浓度为20 g/L、载流酸度为5%、铁氰化钾和草酸质量浓度分别为4 g/L和2 g/L时,砷、汞和铅的方法检出限分别为0.024,0.008,0.066μg/L,方法的回收率为85%~105%,测量结果的相对标准偏差分别为0.7%,0.7%,1.8%。该方法简便、快速、结果准确可靠,能满足食品和食品添加剂中砷、汞、铅的测定。     

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.     

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%).     

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.     

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.     

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.     

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.