X—射线荧光光谱测定甜饮料中微量元素

本文提出了低温蒸干和炭化制样Ｘ－射线荧光分析甜饮料中１６种微量元素的方法，试样在电热板上经低温蒸干，于马旨炉中３００℃炭化３０ｍｉｎ，在液压样品成形机上压制成样片进行测定，所测元素不需用任何基体校正，由微机从校正曲线查得含量，榈分析结果与ＩＣＰ－ＡＥＳ和ＡＡＳ法相吻合。     

Ultrasonic-assisted leaching of trace metals from sediments as a function of pH

The effects of ultrasonication on the leaching of trace metals form sediments as a function of pH have been investigated using atomic absorption spectrometry. Cu, Pb, Ni, Zn and Mn were leached from sediments by ultrasonic effect using phthalate buffers at pH values of 2.2-6.0. Parameters influencing leaching, such as leaching time, solution matrix, wet or dry sample and final pH were evaluated. Results from ultrasonic leaching experiments were comparable to those of conventional procedure. In addition, this ultrasonic-assisted leaching method reduces the time required for conventional method approximately from 12 h to 25 min. Depending on the metal and sample type, metal removal increased linearly or exponentially with decreasing pH. The accuracy of the method was tested by comparing obtained results with this of conventional method. The average relative standard deviation (R.S.D.) of ultrasonic-assisted leaching method (ULM) varied between 1.71 and 3.00% for N = 36, depending on the analyte. This technique shows promise for studying chemical and biological availability and uptake/release processes for metals in sediment and soil as a function of pH.     

制备纳米氧化锌的新方法

以草酸和醋酸锌为原料，用室温固相化学反应首先制备前驱物二水合草酸锌，后者在微波场辐射分解得到产物纳米氧化锌。用XRD，TEM和IR等技术对产物的组成，大小及形貌进行了表征。结果表明：产物纳米氧化锌为粒度分布均匀的球形六角晶系结构，平均粒径约为8nm。     

稀土（Ⅲ）（4＇－溴－5＇－硝基苯并－15－冠－5）配合物的制备与表征

在乙腈和丙酮介质中合成了６种轻稀土硝酸盐与４＇－溴－５＇－硝基苯并－１５－冠－５（Ｌ）的固体配合物，经元素分析确定其组成为ＲＥ（ＮＯ＿３）＿３·Ｌ（ＲＥ＝－Ｌａ～Ｎｄ），Ｓｍ（ＮＯ＿３）＿３·Ｌ·Ｈ＿２Ｏ和Ｅｕ（ＮＯ＿３）＿３·Ｌ·ＣＨ＿３ＣＮ·４Ｈ＿２Ｏ，并进行了ＩＲ、ＵＶ、ＴＧ－ＤＴＡ、摩尔电导及Ｘ－射线粉末衍射物相分析等表征，探讨了冠醚苯基上引入双取代基（－Ｂｒ，－ＮＯ＿２）后对稀土离子配位作用的影响．     

Air sampling of aromatic hydrocarbons in the presence of ozone by solid-phase microextraction

Effects of ozone on air sampling of standard gas mixtures of aromatic hydrocarbons were tested using solid-phase microextraction (SPME). Standard concentrations of ozone ranging from 10 ppb (v/v) to 6400 ppm (v/v) were generated using an in-house built ozone generator based on corona discharge. Effects of temperature, discharge voltage, and oxygen flow on the ozone generation were tested. The working dc voltage had the greatest effect on generated ozone concentration and was proportional to the ozone concentration. Generation temperature and oxygen flow rate were inversely proportional to ozone concentrations. Produced ozone was mixed with standard benzene, toluene, ethylbenzene, and xylenes (BTEX) gas at less than 100 ppb (v/v). Air samples were collected with poly(dimethylsiloxane) (PDMS) 100 microm SPME fibers and analyzed by gas chromatography (GC)-flame ionization detection (FID) and GC-MS. Significant reductions of BTEX concentrations were observed. In addition, some products of BTEX-ozone-oxygen reactions were identified. SPME worked well as a rapid sampler for BTEX and BTEX-ozone-oxygen reaction products. No significant deterioration of the PDMS coating and no significant reduction of absorption capacity were observed after repeated exposure to ozone.     

用高效液相色谱法优化苯与对氯氯苄烷基化反应催化剂

用高效液相色谱法优化苯与对氯氯苄烷基化反应催化剂刘红霞张书胜袁倬斌＊（郑州大学分析测试中心郑州）（中国科学技术大学研究生院北京１０００３９）关键词氯－二苯甲烷，制备，三氯化铝，硝基苯，硝基乙烷，高效液相色谱法１９９７－０３－３１收稿，１９９７－０９－...     

具有谷胱甘肽过氧化物酶活性的催化抗体的研究Ⅰ．谷胱甘肽特征全抗原的合成、表征及性质

用２，４－二硝基氯苯保护谷胱甘肽的巯基制出半抗原，再通过戊二醛共价反应使其与牛血清白蛋白表面的氨基结合，经超胶ＡｃＡ５４凝胶层析纯化，制备出有较强免疫原性的谷胱甘肽全抗原。用元素分析、红外光谱及核磁共振表征了半抗原的结构。电泳分析得全抗原分子量平均为８７０００道尔顿。光谱分析及圆二色谱研究表明其有较强的可见、紫外及荧光特征吸收，且抗原结构的紧密性增强。     

X射线荧光分析中熔融制样条件的研究

本文研究了熔融制样时熔融温度、熔融时间和脱模剂的加入量对分析结果的影响。研究结果表明,随着熔融温度的升高和熔融时间的加长,分析结果的总值将随之增大。相反,脱模剂量的增加会使分析结果降低。通过对熔融样品时产生的升华物的研究,发现在熔触过程中,四硼酸锂比样品以更大的比例逸出熔融体,从而造成了样品在分析圆片中的相对浓缩。而且在高温熔融时,钾和钠比样品中的其他元素例如硅、铝、铁、钛、钙、镁等更易于逸失。制样条件的不同引起样品和熔剂逸失的比例会有变化,它直接影响测定的结果,这证明了在X射线荧光光谱分析中保持制样条件一致的重要性。     

白钨酸研究——Ⅶ.K3W2Cl9的制备及反应

用粉状白钨酸作原针,在一般条件下制备K₃W₂Cl₉,产率达53%,证明白钨酸是比黄钨酸优越的钨化学试剂。研究了K₃W₂Cl₉经离子又换转化为酸的形态后与Ndz₂(C0₃)₃的反应。得到了新的化合物NdW₂Cl₉,提出了一条新的制备溶解度大的各种金属离子与W₂Cl₉^3-的化合物的途径。 对K₃W₂Cl₉和NdW₂Cl₉进行了紫外可见尤谱和X针线粉末衍射的测定。