双波长分光光度法同时测定溶液中的硝酸根和碘离子

食品和环境样品中往往同时含有硝酸根和碘离子,用紫外分光光度法直接测定硝酸根或碘离子时,二者相互干扰。为此建立了主、次波长分别为220.0、231.5 nm的等吸收点双波长紫外分光光度法测定溶液中的硝酸根和共存的碘离子。当溶液中硝酸根的浓度在0~0.12 mmol/L的范围内,碘离子的浓度在0~0.10 mmol/L的范围内时,主、次波长下的吸光度差值A220-231.5与溶液中硝酸根的浓度 呈良好线性关系,线性方程为A220-231.5 = 2.9958 0.0016（R2 = 0.99994）;其中A220 (NO3-) = 3.6099 0.0084（R2 = 0.99994）,利用吸光度的加和性：A220 (I-) = A220 - A220 (NO3-) = 10.7394 0.0029（R2 = 0.99994）,间接得到碘离子含量 。硝酸根和碘离子的平均相对标准偏差分别为0.6%、0.2%,回收率分别为99.5~102%、99.9~100%。方法简便快捷,可用于溶液中微量硝酸根和碘离子的同时测定。     

酸性深蓝5R的极谱分析方法及其与环糊精的超分子体系研究

建立并研究了酸性深蓝 5R(AC5R)的极谱分析法.结果表明,在pH=7. 0的Na2HPO4 KH2PO4底液中,AC5R产生一峰形好、稳定、灵敏的还原峰,其峰电位EP约 -0. 60V(vs.SCE),峰电流及二阶导数极谱峰高随AC5R浓度变化的线性范围在 3. 0×10-8 ~6. 0×10-5 mol/L(r=0. 992 6 ~0. 999 1 ),检测限为 6. 0×10-9mol/L.RSD为 1. 16% (n=10),标准回收率在 95. 85% ~103. 3%之间,可望用于AC5R的定量分析.此外,还应用极谱伏安法研究了各种环糊精对AC5R电化学行为的影响和超分子体系;利用电流法测定了AC5R与α CD、β CD、γ CD、DM β CD、TM β CD、HP γ CD的包结常数和包结比,比较AC5R与不同类型环糊精的包结能力,并初步研究影响包结能力大小的可能因素.     

分光光度法测定马来酰肼中痕量肼

采用碱溶中和法提高马来酰肼(MH)溶液试样中肼的浓度，分别采用对二甲氨基苯甲醛(DAB)和茚三酮测定MH中的痕量肼。结果表明，DAB的乙醇溶液和二甲基亚砜(DMSO)溶液作为显色剂时，在痕量肼浓度范围内具有良好线性关系，前者在0～0.1mg/L肼浓度范围内，线性方程为y=0.9733x-0.0018，线性相关系数(R²)为0.9987；后者在0～0.05 mg/L肼浓度范围内，线性方程为y=1.4672x-0.0016, R²为0.9982；茚三酮作显色剂时仅在较高肼浓度范围2.4～12 mg/L时呈线性关系，线性方程为y=0.0067x-0.003, R²=0.9899。加入乙醇有利于相关试剂和生成物溶解，而且比加入DMSO耐光照。     

紫外吸光光度法同时测定乙醛酸和乙二醛

利用醛基与羟胺在酸性条件下的加成反应产物乙醛酸肟和乙二醛二肟的不同紫外吸收峰,用双波长法同时测定溶液中的乙醛酸和乙二醛。结果表明,乙醛酸在 0.03~0.156 g·L-1范围内符合比耳定律,其回归方程为 y=0.109 4x-0.003 7,r=0.999 9(n=5),乙二醛在 0.1~0.5 g·L-1范围内符合比耳定律,其回归方程为y=0.223 11x-0.023 5,r=1.000 0(n=5)。乙醛酸和乙二醛质量比大于1,乙醛酸的回收率为 96.2%~101.5%,乙二醛的回收率为 101.6%~106 8%。方法操作简便、经济、精密度较好。     

离子色谱法同时测定那屈肝素钙中氯离子和硫酸根离子的含量

建立了一种抑制电导检测器离子色谱法同时测定那屈肝素钙中氯离子和硫酸根离子含量的方法。采用强阴离子交换柱,3 mmol/L碳酸钠溶液为流动相,流速2.0 mL/min,柱温30℃,进样量25μL,检测器为配有化学抑制器的电导检测器。结果表明,氯离子和硫酸根离子在1~20μg/mL浓度范围内线性关系良好,氯离子线性方程为y=0.1314x-0.0081,线性相关系数R²=0.9999;硫酸根线性方程为y=0.123x-0.0098,线性相关系数R²=0.9998。那屈肝素钙中氯离子和硫酸根离子的平均回收率均为101%,检出限为0.01μg/mL。方法具有操作简单、线性范围良好、检出限低等优点,可作为那屈肝素钙中氯离子和硫酸根离子的质量控制方法。     

超声波-微分脉冲伏安法测定超痕量铜

以循环伏安和微分脉冲伏安法研究了超声作用下铜在铂电极上的电沉积行为,建立了超痕量铜的超声波-微分脉冲伏安法。超声波增加了铜的阳极溶出峰电流近一个数量级,提高了方法的灵敏度。在优化实验条件下,铜的微分脉冲阳极溶出峰电流与铜离子浓度在两个范围内呈线性关系。在5.00~200nmol/L的浓度范围内,线性方程为I=0.0453 0.00101c(nmol/L,R=0.9963,SD=0.0078);检出限为0·20nmol/L(13ng/L);在0.200~8.00μmol/L浓度范围内,线性方程为i=0.243 0.0864c(μmol/L,R=0·9983,SD=0.0188)。常见金属离子一般不干扰。方法简便快速,直接用于自来水实际样品的测定,加标回收率为95.4%~104.6%;RSD为3.36%,结果令人满意。     

富勒烯C~6~0与二茂铁酮亚胺电荷转移相互作用的研究

C~6~0与三种二茂铁酮亚胺η^5-C~5H~5Fe[C~5H~4C(CH~3)=N-C~6H~4R-p]-η^5(1a R=H,1bR=CH~3,1c R=OCH~3)在甲苯和室温下可发生电荷转移相互作用形成三种电荷转移配合物η^5-C~5H~5Fe[C~5H~4C(CH~3)=N-C~6H~4R-p]-η^5/C~6~0 (2a R=H,2b R=CH~3,2c R=OCH~3)。通过紫外光谱证实了它们的存在,并用Benesi-Hildebrand方程求出了2a、2b和2c的电荷转移平衡常数分别为0.769、0.928和2.353mol^-^1·dm^3。鉴于它们远大于普通有机胺与C~6~0形成的电荷转移配合物的平衡常数,因此可认为在2a～2c中存在着由二茂铁核及亚胺基向C~6~0的双重电荷转移相互作用。     

稀土化合物晶格熵的估算

考虑到化合物的阳离子质量和摩尔体积对其晶格熵的影响,提出一个估算同构同阴离子稀土化合物晶格熵的公式:S_(298.15)~0=S_(ref)~0 (3/2)n_1R·lnM/M_(ref) (3/2)n_2R·lnV/V_(ref)计算结果能满意地与实验值相吻合.     

硝酸铀酰—硝酸—磷酸三丁酯体系的反萃取动力学研究

本文采用恒界面池法和上升单液滴法研究了UO_2(NO_3)_2/HNO_3/TBP-环己烷体系的反萃取动力学。得出扩散控制下的反萃速率方程为R=k_1[U]_(O)[TBP]_(O)~(-1.17)[HNO_3]~(-1.70;在恒定硝酸浓度下化学反应控制的反萃速率方程为R=k_2[U]_(O)[TBP]_(O)~0,并对二种速控类型下的反萃机制进行了讨论。     

原子荧光光谱法测定食品添加剂山梨酸钾中砷含量

采用微波消解法处理样品,建立了原子荧光光谱法测定食品添加剂山梨酸钾中砷含量的方法。实验结果表明,方法的检出限为3.1μg/kg,砷的质量浓度在5~50μg/L范围内,回归方程为:y=91.199x-20.113,r=0.999 9。平均回收率为84.4%~96.8%,相对标准偏差(RSD)为2.4%(n=6)。方法线性关系良好,检出限低,准确度高,精密度好,能够快速准确地检测出食品添加剂中砷的含量,满足食品添加剂山梨酸钾检测工作的要求。     

苯基脲与甲醇合成苯氨基甲酸甲酯的研究

采用苯基脲与甲醇反应合成了苯氨基甲酸甲酯,考察了不同催化剂、原料配比及反应工艺条件的影响,确定了适宜的合成条件,并根据产物分布对催化反应机理进行了初步探讨.结果表明,以PbO为催化剂,于140℃反应4h后,苯基脲转化率为95.2%,苯氨基甲酸甲酯收率为80.6%.     

Synthesis of methyl N-phenyl carbamate from dimethyl carbonate and 1,3-diphenyl urea under mild conditions

Synthesis of methyl N-phenyl carbamate from dimethyl carbonate and 1,3-diphenyl urea was investigated under atmospheric pressure. The results showed that homogenous catalyst sodium methoxide had the excellent activity to efficiently catalyze the synthesis of methyl N-phenyl carbamate under atmospheric pressure.     

超高效液相色谱-电喷雾串联质谱法直接测定黄酒和葡萄酒中氨基甲酸乙酯

建立了超高效液相色谱-电喷雾串联质谱(UPLC-ESI-MS/MS)直接测定黄酒和葡萄酒中氨基甲酸乙酯含量的方法。黄酒和葡萄酒样品经蒸馏水简单稀释后,过0.22 μm微孔滤膜,直接进行UPLC-MS/MS分析检测。以Waters Acquity UPLCTMBEH C18色谱柱为分析柱,乙腈和0.1%(v/v)乙酸水溶液为流动相,采用电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测,以氨基甲酸丁酯(BC)作为内标进行定量。结果表明: 方法在2～500 μg/L的范围内线性关系良好(相关系数大于0.995),其对黄酒和葡萄酒的检出限为1.7 μg/L,定量限为5.0 μg/L,可达到黄酒和葡萄酒中氨基甲酸乙酯的检测要求。当添加水平为10、20和100 μg/L时,黄酒和葡萄酒中待测组分的回收率为90%～102%,日内精密度(n=6)为0.8%～4.5%,日间精密度(n=6)为1.4%～5.6%。该方法样品处理简单,前处理过程不使用有机溶剂,测定快速、准确,灵敏度高,非常适合黄酒和葡萄酒中氨基甲酸乙酯的快速检测和定量分析。     

Application of hollow fiber liquid phase microextraction for the determination of insecticides in water

In the present work, a novel sample pre-treatment technique for the determination of trace concentrations of some insecticide compounds in aqueous samples has been developed and applied to the determination of the selected analytes in environmental water samples. The extraction procedure is based on coupling polypropylene hollow fiber liquid phase microextraction (HF-LPME) with gas chromatography by flame thermionic detection (GC-FTD). For the development of the method, seven organophosphorous insecticides (dichlorvos, mevinphos-cis, ethoprophos, chlorpyrifos methyl, phenthoate, methidathion and carbofenothion) and one carbamate (carbofuran) were considered as target analytes. Several factors that influence the efficiency of HF-LPME were investigated and optimized including agitation, organic solvent, sample volume, exposure time, salt additives and pH. The optimized methodology exhibited good linearity with correlation coefficient = 0.990. The analytical precision for the target analytes ranged from 4.3 to 11.1 for within-day variation and 4.6 to 12.0% for between-day variation. The detection limits for all analytes were found in the range from 0.001 to 0.072 microg/L, well below the limits established by the EC Drinking Water Directive (EEC 80/778). Relative recoveries obtained by the proposed method from drinking and river water samples ranged from 80 to 104% with coefficient of variations ranging from 4.5 to 10.7%. The present methodology is easy, rapid, sensitive and requires small sample volumes to screen environmental water samples for insecticide residues.     

超高效液相色谱串联质谱法测定银杏中氨基甲酸酯类农药残留

建立了银杏叶中15种氨基甲酸酯类农药残留量的超高效液相色谱一串联质谱测定方法。样品经乙腈提取,TPT固相萃取柱净化,通过XTerra MS Cl8色谱柱分离,供串联质谱测定。15种氨基甲酸酯类农药在0．02-0．5mg／L范围内线性良好,相关系数为0．9962-0．9999;在0．004,0．01,0．02,0．04mg／kg4个添加水平下,其平均回收率为65．22％-96．66％,相对标准偏差为1．43％-10．06％（n=5）。该方法净化效果好、灵敏度高、重现性好,可满足银杏叶中15种氨基甲酸酯类农药残留量的检验要求。     

高效液相色谱-串联质谱法测定食品中20种氨基甲酸酯类农药残留

建立了食品中20种氨基甲酸酯类农药残留量的高效液相色谱-串联质谱联用(HPLC-MS/MS)测定与确证方法。20种氨基甲酸酯类农药在0.005～0.1 mg/kg范围内线性良好,相关系数为0.991 7～0.999 6;在0.005～0.025 mg/kg范围内, 20种目标物的回收率为51.2%～125.0%,相对标准偏差为1.4%～19.8%。该方法准确、灵敏、快速,可满足国际上对食品中这20种氨基甲酸酯类农药残留量的检测需要。     

苯胺与氨基甲酸甲酯合成苯氨基甲酸甲酯反应研究

以无水氯化锌为催化剂,考察了温度、时间、催化剂含量及原料配比等条件对合成反应的影响,确定了最优化反应条件,并初步探讨了反应机理.最佳反应条件下MPC收率可达89.90%,选择性为99.76%.     

Thermal decomposition of poly(tert-butyl N-vinylcarbamate)

Pyrolysis of poly(tert-butyl N-vinylcarbamate) at 185–200°C in bulk yields a rigid foam containing cyclic urea units, primary amine units, and a small amount of urea crosslinks. The yield of primary amine units (ca. 13%) and the yields of carbon dioxide (ca. 57%), isobutylene (ca. 57%), and tert-butanol formed in this reaction indicate that it involves pairwise decomposition of adjacent carbamate units to form cyclic urea units, tert-butanol, carbon dioxide, and isobutylene. The vinyl amine units are formed from carbamate units that become flanked by urea units. The amounts of amine units and residual carbamate units were determined as a function of degree of pyrolysis by an ion-exchange technique and agreed with values expected for a random cyclization process. The pyrolyzed polymers are useful as ion-exchange resins and as rigid foams having good thermal stability.     

Equilibrium vs ground-state planarity of the CONH linkage

Planarity of the XC(=)NHY linkage has been investigated in unprecedented detail in a number of relatively simple compounds, including formamide (X = Y = H), acetamide (X = CH3, Y = H), urea (X = NH2, Y = H), carbamic acid (X = OH, Y = H), and methyl carbamate (X = OCH3, Y = H). Reliable estimates of the equilibrium structures of formamide, cyanamide, acetamide, urea, carbamic acid, methylamine, dimethyl ether, and methyl carbamate are derived, mostly for the first time. It is shown that formamide, considered prototypical for the amide linkage, is not typical as it has a planar equilibrium amide linkage corresponding to a single-minimum inversion potential around N. In contrast, several molecules containing the CONH linkage seem to have a pyramidalized nitrogen at equilibrium and a double-minimum inversion potential with a very small inversion barrier allowing for an effectively planar ground-state structure. Observables of rotational spectroscopy, including ground-state inertial defects, quadrupole coupling and centrifugal distortion constants, and dipole moment components, as well as equilibrium C=O and C-N bond lengths are reviewed in their ability to indicate the planarity of the effective and possibly the equilibrium structures.     

KF/Al2O3催化剂上苯脲醇解合成苯氨基甲酸甲酯的研究

采用浸渍法制备负载KF固体碱催化剂,应用于苯脲和甲醇制备苯氨基甲酸甲酯的反应,考察了氧化物载体、卤化钾种类对催化剂性能的影响,KF/Al₂O₃催化剂显示出良好的催化活性和苯氨基甲酸甲酯的选择性。通过对KF/Al₂O₃催化剂中KF的负载量和催化剂焙烧温度的研究发现,在500 ℃焙烧4 h、负载质量分数50%KF的催化剂能够更好地促进MPC生成,苯脲转化率和苯氨基甲酸甲酯选择性分别达到96.5%和86.3%。XRD分析表明,KF与Al₂O₃之间存在较强的相互作用,部分转化为K₃AlF₆。KF与K₃AlF₆分别对甲醇的活化和苯脲的选择性起促进作用,两者的协同效应共同促进了目标产物苯氨基甲酸甲酯的生成。