气相色谱-质谱法检测塑料食品包装材料中的五种挥发性有机物

建立了使用气相色谱-质谱仪检测塑料食品包装材料中常见的5种挥发性有机物(苯、甲苯、乙酸乙酯、乙酸丁酯、丁酮)的分析方法.实验中以欧盟标准EU 10/2011限定的4种模拟液为提取介质,二氯甲烷为有机萃取溶剂,对样品的前处理、色谱分离条件和质谱检测条件进行了优化.在最优化的实验条件下,这5种有机物能够完全分离,且在0.5~20.0mg/L浓度范围内线性较好,相关系数大于0.999 7,仪器精密度的相对标准偏差为1.08%~2.52%之间,样品在不同模拟液中的加标回收率介于81%~118%之间,最低检出限可达0.02 mg/m2.使用该方法测定了5种不同用途的塑料包装材料中的溶剂残留量,方法简便、快速、重现性好,完全能满足塑料包装材料中溶剂残留量的分析.     

固相萃取-高效液相色谱-荧光法测定方便面和烤肠中的苯并[a]芘

建立了固相萃取-高效液相色谱-荧光法检测方便面和烤肠中苯并[a]芘的方法。采用正己烷作为提取溶剂,经苯并[a]芘专用固相萃取柱HiCapt Benzo富集净化,高效液相色谱-荧光法对样品中苯并[a]芘进行分离分析。苯并[a]芘的质量浓度在0.5~20.0μg/kg范围内与色谱峰面积呈良好的线性关系,相关系数R2为0.9997。方便面和烤肠中苯并[a]芘的加标回收率分别为92.2%~98.3%和95.9%~97.9%,日内和日间相对标准偏差分别为3.34%~5.01%和2.11%~4.07%。与传统方法相比,该方法快速简单、有机溶剂消耗少,在油炸烟熏食品的苯并[a]芘分析中具有较大应用前景。     

高效液相色谱法测定煤沥青中16种多环芳烃

建立了煤沥青中苯并[a]蒽、苯并[a]芘等16种多环芳烃(PAHs)的高效液相色谱分离检测方法。以甲苯为溶剂对煤沥青进行萃取,萃取液处理后经柱层析分离,层析洗脱液分组回收,然后进行液相色谱分析。采用ZORBAX Eclipse PAH柱分离,以乙腈-水为流动相进行梯度洗脱,紫外检测器进行测定。结果表明,16种PAHs的线性范围为0.5~20 mg/L,相关系数(r)均大于0.999,检出限为0.0031~0.035μg/L,方法的回收率为97.2%~108.3%,相对标准偏差(RSD)为0.18%~3.5%。方法用于两种不同煤沥青中16种PAHs含量的测定,两种煤沥青中16种PAHs的含量分别为107.86 g/kg和103.71 g/kg,其中苯并[a]芘的含量分别为11.86 g/kg和13.82 g/kg。     

高效液相色谱法测定化妆品中11种二苯酮类紫外线吸收剂

建立了化妆品中11种二苯酮类紫外线吸收剂的高效液相色谱分析方法。采用四氢呋喃-甲醇-水或二氯甲烷-水体系提取化妆品中二苯酮类紫外线吸收剂,经离心(5000 r/min),上清液过0.22 μm滤膜后,进入高效液相色谱分析。采用C18色谱柱进行分离,以0.1% (体积分数)甲酸水溶液(含10 mmol/L乙酸铵)为流动相A,以0.1% (体积分数)甲酸甲醇为流动相B,梯度洗脱。方法加标回收率(n=7)为93.4%~103.8%,相对标准偏差为0.1%~4.2%,方法的检出限为4.0~30 μg/g,方法的定量限为15~100 μg/g。采用该方法对42种市售化妆品检测分析发现,有5种二苯酮类紫外线吸收剂被检出,其中防晒隔离液中二苯酮-3和香水中二苯酮-2的检出量分别为2785 μg/g和2106 μg/g。研究结果表明,所建立的方法具有良好的回收率、重现性和较高的灵敏度,可用于化妆品中多种二苯酮类紫外线吸收剂的分析。     

涡旋混合辅助超声提取-高效液相色谱法同时测定水基胶中的苯系物和邻苯二甲酸酯类增塑剂

采用涡旋混合辅助超声提取样品的前处理方式,应用高效液相色谱法同时测定水基胶中的苯系物和5种邻苯二甲酸酯类增塑剂.基于样品基质的属性,采用漩涡混合器混合样品,使样品均匀分散于萃取溶剂中,再使用超声萃取的方式提取目标物.研究了不同萃取溶剂、提取方式及其条件对目标物检测结果的影响.优选了色谱分析所用的流动相、检测波长、流量和进样量等条件.在优化条件下,5种苯系物和5种邻苯二甲酸酯类增塑剂的峰面积与其质量浓度呈线性关系,相关系数(R2)都大于0.997,回收率分别在91.9%~111.4%和88.3%~121.4%之间,相对标准偏差RSD分别在1.41%~2.80%和1.24%~2.94%之之间.检出限分别在0.3~0.6 mg/kg和0.2~0.3 mg/kg之间.研究表明方法简便、耗溶剂量少、准确,与现行标准方法具有较好的吻合性,适合于同时测定水基胶中的苯系物和5种邻苯二甲酸酯类增塑剂.     

铜催化的苯并恶唑、五氟苯与O-苯甲酰羟胺的C-H键胺化反应

以四氢呋喃为溶剂，在碘化亚铜催化下，苯并恶唑和五氟苯等缺电子芳烃体系与O-苯甲酰羟胺发生C-H键亲电胺化反应，分别以42%~92%和20%~84%的收率合成了多种2-氨基苯并恶唑和五氟苯胺衍生物，其结构经¹H NMR和¹³C NMR表征。      

固相萃取/毛细管气相色谱法测定肉桂皮中六六六、滴滴涕农药残留量

研究了肉桂皮中六六六、滴滴涕农药残留量的测定方法。以丙酮-石油醚混合溶剂为提取剂,旋涡振荡提取,采用固相萃取技术对提取液净化,优化洗脱溶剂的比例和用量,用气相色谱/微电子捕获检测器(μECD)测定。在优化条件下,BHC及DDT农药在10~1 000μg/L质量浓度范围内线性关系良好,相关系数为0.995 8~0.998 1。2种农药在肉桂皮中的加标回收率为92.1%~112%,相对标准偏差(RSD)为2.8%~8.1%,方法的检出限(LODs)为5.0×10-3~2.4×10-2mg·kg-1,定量下限(LOQs)为1.3×10-2~6.0×10-2mg·kg-1。方法具有简单、灵敏、选择性高、重现性好等优点。     

溶解沉淀-气相色谱-质谱法测定食品接触用聚苯乙烯塑料中10种有机物

建立食品接触用聚苯乙烯塑料中10种有机物(苯、丙烯腈、甲苯、乙苯、对-二甲苯、间-二甲苯、异丙苯、邻-二甲苯、丙苯和苯乙烯)含量的溶解沉淀气相色谱–质谱检测方法。分别讨论了定量方式、溶解溶剂以及溶解溶剂与沉淀剂甲醇的体积比对10种有机物回收率的影响。样品用N,N-二甲基甲酰胺(DMF)超声溶解,甲醇沉淀,内标法定量可获得良好的定量结果。检测10种有机物的线性范围在0.2～100μg/mL内,相关系数均大于0.999,方法检出限为1.0～2.0 mg/kg,定量限为2.0～4.0 mg/kg;加标平均回收率为81.5%～101.9%,测定结果的相对标准偏差为0.9%～4.7%(n=6)。该方法快速、准确,适用于食品接触用聚苯乙烯塑料中10种有机物含量的检测。     

超高效合相色谱快速分析塑料制品中的18种多环芳烃

建立了一种超高效合相色谱-二极管阵列检测器快速分析塑料制品中萘、苊烯、苊、芴、菲、蒽、荧蒽、芘、苯并(a)蒽、(屈艹) 、苯并(b)荧蒽、苯并(k)荧蒽、苯并(j)荧蒽、苯并(e)芘、苯并(a)芘、茚并(1,2,3-cd)芘、二苯并(a,h)蒽、苯并(g,h,i)苝(二萘嵌苯)的方法。以甲苯为溶剂,超声萃取实际塑料制品中的多环芳烃,经超高效合相色谱分析。采用Daicel IB-3手性色谱柱,以CO₂为流动相,甲醇/乙腈(25:75, v/v)为流动相助溶剂,在柱温为40 ℃,背压为15.17 MPa的条件下,18种多环芳烃在8.5 min之内实现基线分离。18种多环芳烃的线性范围为0.05~50 mg/L(r≥0.9995),定量限(S/N> 10)为0.05 mg/L。加标回收率为78.3%~117.6%,相对标准偏差(RSD, n=5)小于5%。该方法具有分析速度快、分离效率高、节约有机溶剂的优点。     

高效液相色谱-串联质谱法测定茶叶、三七中胺苯磺隆和甲基胺苯磺隆的残留量北大核心CSCD

建立了测定茶叶、三七中胺苯磺隆和甲基胺苯磺隆残留量的高效液相色谱-串联质谱法。样品经超纯水浸泡,乙腈提取,QuEChERS净化,Phenomenex Kinetex C 18色谱柱(50×2.1 mm,2.6μm)分离,液相色谱-串联质谱法检测,基质匹配外标法定量。胺苯磺隆和甲基胺苯磺隆在1.0 ng/mL~100 ng/mL范围内线性关系良好,相关系数R均大于0.999,方法的检出限(S/N=3)为0.07μg/kg~0.20μg/kg,定量限(S/N=10)为0.21μg/kg~0.60μg/kg。在5μg/kg~100μg/kg范围的回收实验中,胺苯磺隆平均回收率为70.8%~108.1%,相对标准偏差(RSD,n=6)为3.3%~11.4%;甲基胺苯磺隆平均回收率为70.2%~105.5%,RSD(n=6)为2.9%~10.6%。本方法前处理简单、稳定、灵敏,适用于茶叶、三七中胺苯磺隆和甲基胺苯磺隆残留量的同时测定。     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

恶臭嗅辨实验室建设探讨

针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。     

Stages of thermal decomposition of sodium oxo-salts of sulphur

Thermal behaviour of sodium oxo-salts of sulphur: Na₂SO₄, Na₂S₂O₇, Na₂S₂O₆, Na₂SO₃, Na₂S₂O₅, Na₂S₂O₄, Na₂S₂O₃, Na₂S₃O₆ and of sulphides Na₂S and Na₂S₂ was studied on heating up to 1000°C. The experiments were performed with anhydrous compounds obtained from commercial products by recrystallisation and dehydration. The stage mechanisms of decomposition of anionic sub-lattices of the salts have been proposed basing on the Górski’s morphological classification of simple species. The thermal stability and the stage decomposition mechanisms were correlated with the structure and the potential chemical properties of the salt anions. The thermal decomposition processes were studied by means of thermal analysis, and the decomposition products were identified by means of X-ray phase analysis.