示波极谱—铜试剂法测定磺酰胺类药物的含量

报道以ＣｕＳＯ４作沉淀剂,ＤＤＴＣ（二乙基二硫代氨基甲酸钠,铜试剂）为滴定剂,ＮａＡｃ为极谱底液,采用交流示波极谱滴定法测定呋喃苯胺酸,乙酰唑胺二种磺酰胺类药物制剂的含量,该法快速,简便,终点直观回收率实验获得满意结果。     

采用电位滴定法在DMSO/H2O混合溶剂体系中测定磺酰脲(胺)类除草剂的酸离解常数

采用电位滴定法在DMSO/H₂O(质量比80:20)混合体系中测定了磺酰脲和三唑并嘧啶磺酰胺类除草剂的酸离解常数,进而采用回归分析方法探讨了测得的pK_a值与化合物的前沿轨道能级以及取代基效应之间的相关性,结果较为满意,从而证明从该体系测得的pK_a值用于构效关系分析是完全可行的.     

超高效液相色谱-串联质谱法同时测定牛奶中38种抗生素残留

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定牛奶中5类(磺胺类、喹诺酮类、四环素类、氯霉素类和大环内酯类)38种抗生素的分析方法。牛奶样品以0.5%(体积分数)甲酸乙腈提取,利用Oasis PRiME HLB固相萃取小柱进行净化,经Acquity UPLC HSS T3柱(100 mm×2.1 mm i.d.,1.8μm)分离,采用电喷雾离子源,多反应监测模式(MRM)进行定性定量分析。结果表明,38种抗生素在各自线性范围内呈良好的线性关系,相关系数(r~2)均大于0.99,定量下限为0.10～1.0μg/kg;在1.0、5.0、10.0μg/kg加标水平下,平均回收率为70.7%～94.9%,相对标准偏差(RSD,n=6)为4.0%～9.4%。该方法操作简单、灵敏度高、重现性好,适用于牛奶中多种抗生素残留的监测要求。     

固相萃取-高效液相色谱法测定动物肉组织中磺胺类药物的残留

建立了一种快速、灵敏、环保的固相萃取-反相高效液相色谱同时分析动物肉组织中5种磺胺类药物残留的方法。将样品加入到盛有无水硫酸钠的离心管中,再用乙酸乙酯提取;提取液经氨基固相萃取柱净化后,用1.5%（体积分数）乙酸乙醇溶液洗脱。洗脱液用高效液相色谱分离,二极管阵列检测器检测,外标法定量。5种磺胺类药物的线性关系良好,磺胺二甲基嘧啶(SM2)、磺胺间甲氧嘧啶(SMM)、磺胺甲唑(SMZ)的线性范围均为30～5000 μg/L,磺胺二甲氧嘧啶(SDM)、磺胺喹啉(SQ)的线性范围均为60～5000 μg/L。2种动物肉组织(鸡肉、猪肉)中5种磺胺类药物的加标回收率在73.2%至97.3%范围内,当添加水平为50 μg/kg时,加标回收率的相对标准偏差在2.5%至11.6%范围内;SM2,SMM和SMZ的检测限（S/N=3）和定量限（S/N=10）分别为3 μg/kg和10 μg/kg,SDM和SQ的检测限和定量限分别为7 μg/kg和25 μg/kg。     

高效液相色谱-串联质谱法同时测定鳗鱼和虾中残留的33种喹诺酮和磺胺类药物

建立了鳗鱼和虾中33种喹诺酮类(QNs)和磺胺类(SAs)药物残留量的高效液相色谱-串联质谱(HPLC-MS/MS)测定方法。以氘代试剂为内标,样品经酸性乙腈萃取后,用正己烷脱脂,旋转蒸发浓缩,采用LC-MS/MS选择反应监测(SRM)正离子模式测定,同时对鳗鱼和虾中的33种QNs和SAs进行定性和定量。33种QNs和SAs的检出限(S/N=3)为1.0 μg/kg,定量限(S/N=10)为2.0 μg/kg;在10.0～200.0 μg/L时目标物的峰强度与质量浓度的线性关系良好(r>0.99);平均回收率为66%～123%。该法简便快捷,降低了分析成本,也在一定程度上实现了药物残留的快速检测。     

Dramatic catalyst evolution in the asymmetric addition of diethylzinc to benzaldehyde

We have observed product ee's that begin at 20% at low reaction conversion and rise to 79% ee at the completion of the reaction in the asymmetric addition of alkyl groups to benzaldehyde. This rare behavior is attributed to autoinduction, in which the catalyst evolves by incorporation of the product. Based on this, we have been able to optimize the catalyst by variation of achiral, rather than enantiopure ligands.     

Aqueous Oxidation of Sulfonamide Antibiotics: Aromatic Nucleophilic Substitution of an Aniline Radical Cation

Sulfonamide antibiotics are an important class of organic micropollutants in the aquatic environment. For several, sulfur dioxide extrusion products have been previously reported upon photochemical or dark oxidation. Using quantum chemical modeling calculations and transient absorption spectroscopy, it is shown that single‐electron oxidation from sulfadiazine produces the corresponding aniline radical cation. Density functional theory calculations indicate that this intermediate can exist in four protonation states. One species exhibits a low barrier for an intramolecular nucleophilic attack at the para position of the oxidized aniline ring, in which a pyrimidine nitrogen acts as a nucleophile. This attack can lead to a rearranged structure, which exhibits the same connectivity as the SO₂‐extruded oxidation product that was previously observed in the aquatic environment and characterized by NMR spectroscopy. We report a detailed reaction mechanism for this intramolecular aromatic nucleophilic substitution, and we discuss the possibility of this reaction pathway for other sulfonamide drugs.     

Synthesis of 5,6-Dihydrophenanthridine (DHPA) Sulfonamides and Subsequent Acid-Catalyzed Rearrangement to Diaryl Sulfones

Selective method of reduction of the ortho-nitro groups in 2,4,6-trinitrotoluene by hydrazine hydrate in the presence of FeCl₃ and charcoal has been elaborated. This method allows obtaining either 2-amino-4,6-dinitrotoluene or 2,6-diamino-4-nitrotoluene as well as 2,4,6-triaminotoluene from TNT.     

Fluoroalkanosulfonyl fluorides-mediated cyclodehydration of β-hydroxy sulfonamides and β-hydroxy thioamides to the corresponding aziridines and thiazolines

An efficient method for the fluoroalkanosulfonyl fluoride-induced cyclodehydration of β-hydroxy sulfonamides and β-hydroxy thioamides to the corresponding aziridines and thiazolines is reported. Mild reaction conditions, operational simplicity, and high yields are the major advantages of this method.