气相色谱-串联质谱法测定土壤中的有机氯农药

建立了气相色谱-串联质谱测定土壤中有机氯农药的方法,同时测定了上海郊区的20个农业土壤。样品前处理包括加速溶剂萃取(弗罗里硅土池内净化)和凝胶渗透色谱净化在线浓缩。采用多反应监测模式的气相色谱-串联质谱分析有机氯农药,降低了背景干扰,提高了分析的灵敏度。在0.001～2 mg/L的质量浓度范围内,各种农药标准溶液的线性相关系数均大于0.995。分别向3种实际土壤样品中添加农药的混合标准溶液,所测定的有机氯农药的平均回收率为65.9%～140.0%,相对标准偏差为1.5%～20.3%(n=5)。有机氯农药的检出限（S/N=3）为0.1～3.0 μg/kg,定量限（S/N=10）为0.3～8.0 μg/kg。实际土壤样品的测定结果表明：六六六(1.82～3.70 μg/kg)和六氯苯(0.94～9.8 μg/kg)有少量检出,滴滴涕的检出率高达100%,其含量范围较宽(1.08～308.76 μg/kg),平均值为53.28 μg/kg,其中85%的样品中滴滴涕含量/(滴滴伊+滴滴滴)含量的比值小于1,表明滴滴涕主要来自于早期的使用     

液相色谱-串联质谱法测定小型家用电器塑料部件中全氟辛酸

建立了高效液相色谱-串联质谱(HPLC-MS/MS)结合加速溶剂萃取测定小型家用电器塑料部件中全氟辛酸(PFOA)的分析方法。样品冷冻粉碎后采用甲醇作溶剂进行快速溶剂萃取,萃取液经C18固相萃取柱富集净化后,以C18柱为分离柱,以甲醇-水为流动相,梯度洗脱,电喷雾负离子模式下多反应监测(MRM))模式检测。PFOA在0.5～100.0μg/L范围内线性关系良好(r2=0.998 9),回收率为93%～107%,相对标准偏差为2.9%～7.6%,检出限(S/N=3)为0.5μg/kg。该方法操作简便、灵敏度高,适用于小型家用电器塑料部件中全氟辛酸残留分析。     

皮革和纺织品中重叠峰偶氮染料的气相色谱-串联质谱检测技术

建立了气相色谱-串联质谱一次进样同时检测重叠峰偶氮染料的分析方法.皮革和纺织品中的偶氮染料用柠檬酸盐缓冲液提取,再用连二亚硫酸钠将其还原裂解为胺类物质,经液-液萃取、浓缩处理,所得残渣用甲醇溶解,通过VF-5ms色谱柱分离,采用串联质谱的多反应监测模式开设多通道存储子离子信息,进行定性、定量分析.实验结果表明:优化质谱分析条件后,气相色谱一串联质谱可进一步消除杂质干扰,分离共流出组分.大部分芳香胺3种浓度水平的加标回收率(n=6)保持在71%～94%之间,检测限为0.008～0.672μg/mL(S/N=3),相对标准偏差(n=6)小于11%,2～50μg/mL浓度范围内线性相关系数大于0.9917,满足禁用偶氮染料的分析要求.     

固相萃取结合气相色谱-串联质谱测定卷烟中3种禁用香料

利用固相萃取结合气相色谱-串联质谱(SPE/GC-MS/MS)检测技术,建立了烟草制品中3种禁用香料(侧柏酮、樟脑及黄樟素)的高灵敏度分析方法。对前处理条件及质谱条件进行优化,在最佳实验条件下,3种香料在10.0~500.0μg/L质量浓度范围内的线性关系良好(r~2≥0.998 6),方法检出限(LOD,S/N=3)及定量下限(LOQ,S/N=10)分别为2.3~5.8μg/kg及7.7~19.3μg/kg。在LOQ,1.5LOQ及2LOQ加标水平下,3种禁用香料的平均回收率为74.9%~90.9%,相对标准偏差(RSD)均不大于2.6%。该方法准确可靠,灵敏度高,可满足国内对于这3种禁用香料的检测要求。     

加速溶剂萃取-气相色谱-串联质谱法测定党参中69种农药残留量

采用加速溶剂萃取-气相色谱-串联质谱法测定党参中69种农药残留量。样品以乙腈为溶剂经加速溶剂提取,提取液用Carb/NH2固相萃取小柱净化。在气相色谱分离中用VF-5MS柱为固定相,在质谱分析中采用多反应监测模式。69种农药在一定的质量浓度范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在0.03~21.2μg·kg-1之间。在20,100,200μg·kg-1等3个浓度水平进行加标回收试验,回收率在63.8%~110%之间,测定值的相对标准偏差(n=6)在1.9%~13%之间。     

超高效液相色谱-串联质谱法快速测定蔬菜中7种氨基甲酸酯类农药残留

采用超高效液相色谱-串联质谱联用(UPLC-MS/MS)技术建立了同时检测蔬菜中7种氨基甲酸酯类农药多残留量的快速检测方法。样品经乙腈提取,氨基固相萃取柱净化,WatersC18超高效液相色谱柱分离,进入电喷雾串联四极杆质谱进行检测,采用多反应监测(MRM)分析,对液质分离条件和样品前处理条件进行了优化。结果表明7种氨基甲酸酯类农药在2～500μg/L范围内线性良好(r≥0.9986)。在0.005～0.01mg/kg范围内,平均加标回收率在72.4%～112.1%之间;相对标准偏差小于13%。该方法检出限范围为1.31～3.72μg/L,测定结果满足多残留农残的检测要求。     

Determination of Perfluorooctanoic Acid (PFOA) in Plastic Component of the Household Appliances by High Performance Liquid Chromatography Tandem Mass Spectrometry

建立了高效液相色谱-串联质谱( HPLC - MS/MS)结合加速溶剂萃取测定小型家用电器塑料部件中全氟辛酸(PFOA)的分析方法.样品冷冻粉碎后采用甲醇作溶剂进行快速溶剂萃取,萃取液经C18固相萃取柱富集净化后,以C18柱为分离柱,以甲醇-水为流动相,梯度洗脱,电喷雾负离子模式下多反应监测(MRM))模式检测.PFOA在0.5～100.0 μg/L范围内线性关系良好(r2=0.998 9),回收率为93％～ 107％,相对标准偏差为2.9％～7.6％,检出限(S/N =3)为0.5μg/kg.该方法操作简便、灵敏度高,适用于小型家用电器塑料部件中全氟辛酸残留分析.     

加速溶剂萃取-在线凝胶渗透色谱-气相色谱-质谱联用法快速测定蔬菜和水果中多农药残留

建立了加速溶剂萃取-在线凝胶渗透色谱-气相色谱-质谱联用(GPC-GC-MS)快速测定蔬菜、水果中代表性农药残留的检测方法。样品经二氯甲烷-丙酮(1:1, v/v)加速溶剂提取,活性炭柱-氨基柱串联净化,氮吹至干,残留物用环己烷-丙酮(7:3, v/v)溶解后经GPC-GC-MS系统以选择离子监测(SIM)模式测定。结果表明,22种农药在各自的线性范围内线性关系良好(相关系数不低于0.9981),检出限(以信噪比(S/N)为3计算)为0.3～1.8 μg/kg,定量限（S/N=10）为1~6 μg/kg。在2种基质(大白菜、苹果)中3个添加水平下的回收率为70.5%～107.5%,相对标准偏差为2.1%～8.7%。该方法提取效率高,定性定量准确、灵敏,可实现对蔬菜、水果中多农药残留的快速检测。     

快速溶剂萃取-液相色谱-串联质谱法同时测定纺织品中有机氮农药和苯氧羧酸农药的残留

建立了一种同时检测纺织品中8种有机氮农药和6种苯氧羧酸类农药残留的快速溶剂萃取-液相色谱-串联质谱方法。采用加速溶剂萃取仪进行提取,优化了萃取溶剂和萃取温度,采用液相色谱-串联质谱的多反应监测模式进行分析。结果表明,该方法的平均回收率为80.7%~102.1%,相对标准偏差小于15%,检出限为0.5~9.1μg/kg,测定低限为1.7~30.3μg/kg。本方法快速,简便,准确度高,重现性好,适用于纺织品中14种农药残留的同时检测。     

HPLC-MS/MS正负离子切换测定农田土壤中的2,4-二氯苯氧乙酸、敌稗和二嗪磷

利用串联质谱正负离子切换模式功能,建立了一种能快速同时检测农田土壤中2,4-二氯苯氧乙酸,敌稗和二嗪磷残留的液相色谱-串联质谱(HPLCM S/M S)分析方法。样品以加速溶剂萃取,Supelclean ENVI-18固相萃取柱净化,多反应监测(MRM)正负离子切换电喷雾模式进行分析。色谱柱为Luna C18柱(150 mm×2.0 mm,3μm),流动相为梯度变化的5 mmol/L甲酸铵甲醇溶液和5 mmol/L甲酸铵水溶液。方法检出限(S/N≥3)介于0.94~8.35 ng/L,相关系数≥0.999;在1.0~10.0μg/kg添加水平内,平均加标回收率介于73.8%~106.9%之间,RSD介于5.8%~11%。利用该方法对某地区农田表土的筛查发现该地区存在二嗪磷使用历史,但污染程度较轻。     

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.     

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.     

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.     

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).     

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.