倒数示波计时电位法在合金样品测定中的应用

应用倒数示波计时电位法，在含有吸附络合物的溶液中，采用桂汞电极作为极化电极，测定了Ｃｕ＾２＋、Ｎｉ＾２＋、Ｃｄ＾２＋、Ｐｂ＾２＋等几种金属离子的检测下限，并通过沿（ｄＥ／ｄｔ）－１￣Ｅ曲线上的峰高对合金样品进行定量分析，得到满意结果。实现了示波分析由常量到微量的飞跃。     

微波辐照增强原煤磁分离脱硫机理探讨

采用~(57)Fe穆斯堡尔谱学方法,研究微波-磁分离法脱硫机理及微波辐照深度对脱硫率的影响。结果表明,微波选择性介质加热,可以激励煤中顺磁性黄铁矿FeS_2热解,使其转化为非化学计量的磁黄铁矿Fe_(1-x)S(0相似文献   

Substoichiometric isotope dilution determination of manganese in biological smples using 2-thenoyltrifluoroacetone in isobutyl methyl ketone

A substoichiometric isotope dilution method was developed for the determination of microgram amounts of manganese. The method involves the use of carrier-free ⁵⁴Mn with Mn(II) carrier and its complexation with 2-thenoyltrifluoroacetone (TTA) at pH 8.5, the complex then being extracted into isobutyl methyl ketone. A minimum of 50 ng of manganese can be determined. The method was applied to the determination of manganese in several standard reference materials and biological samples such as tea leaves, spices and condiments. The method is simple and fast and yields results with high accuracy and precision.     

不同水煤浆分散剂与煤之间的相互作用规律研究Ⅹ分散剂在煤粒表面上的吸附作用特征

研究了6种水煤浆分散剂在14种不同变质程度煤上的吸附作用特征。结果表明,多数分散剂在煤粒表面达到单层饱和吸附后,又形成多层吸附,单层饱和吸附量与煤的变质程度、比表面积以及分散剂的性质有关。在相同粒度分布下,煤的变质程度越低,表面含氧亲水官能团的比例越高,孔隙率越高,比表面积越大,这对增大吸附量有利。煤的变质程度越高,其表面疏水区面积的比例越高,分散剂通过疏水基团紧密吸附在煤表面的比例越大,这对增加高阶煤的吸附量有利。对不同煤,是变质程度还是比表面积为吸附分散剂的主控因素,主要依赖于分散剂的结构与性质。对同种煤,疏水与亲水基团呈线型分立分布的分散剂,吸附量明显高;而疏水与亲水基团呈线型间隔分布的分散剂,吸附量明显小。     

Investigation of the luminescent properties of terbium-anthranilate complexes and application to the determination of anthranilic acid derivatives in aqueous solutions

The luminescent properties of terbium complexes with furosemide (FR), flufenamic (FF) acid, tolfenamic (TF) acid and mefenamic (MF) acid have been investigated in aqueous solutions. For all four compounds, complexation occurs when the carboxylic acid of the aminobenzoic group is dissociated and is greatly favoured in the presence of trioctylphosphine oxide as co-ligand and Triton X-100 as surfactant. Under optimum conditions, luminescence of the lanthanide ion is efficiently sensitised and the lifetime of the resonance level of terbium in the complex is ranging between 1 and 1.9 ms, against 0.4 ms for the aqua ion. The sensitivity of the method for the determination of anthranilic acid derivatives is improved by one to two orders of magnitude with respect to that achieved using native fluorescence or terbium-sensitised luminescence in methanol. The limits of detection are 2×10⁻¹⁰, 5×10⁻¹⁰ and 2×10⁻⁹ mol l⁻¹ for flufenamic acid, furosemide and tolfenamic acid, and mefenamic acid, respectively, with within-run RSD values of less than 1%. The method has been applied to the determination of flufenamic acid in spiked calf sera with and without sample pretreatment. Depending on the method and the analyte concentration, the recovery was ranging between 83 and 113% and the lowest concentration attainable in serum samples was close to 1×10⁻⁷ mol l⁻¹.     

Determination of organochlorine pesticides by gas chromatography with solid-phase microextraction

Summary A study of different extraction techniques for the determination of a selected group of organochlorine compounds in surface waters is presented. Comparison of liquid-liquid extraction (LLE) with solid-phase extraction (SPE) and solid-phase microextraction (SPME) with fibers of different polarity shows that SPME with a recently commercialised fiber of polydimethylsiloxane divinylbenzene allows these compounds to be determined in surface waters with good extraction efficiencies. Extraction time, effect of temperature, ionic strength and pH were optimised, allowing quantification in agricultural effluents in the range 1.0–60 ng·L⁻¹.     

The identification of tricyclic neuroleptics and sulphonamides by high-performance thin-layer chromatography

Circular high-performance thin-layer chromatography (HPTLC) has been used to differentiate a series of twelve tricyclic neuroleptics, using both normal phase and reverse phase procedures. The use of normal phase systems also allows the resolution of geometric isomers of chlorprothixene, clopenthixol and flupenthixol. Thirteen sulphonamides and Trirnethoprim may also be distinguished using HPTLC.     

煤的超临界醇萃取脱硫：Ⅲ.形态硫的变化

本文分别应用Ｍｏｓｓｂａｕｅｒ谱和ＸＰＳ（Ｘ射线光电子能谱）技术考察不同反应 条件下固体产物中的无机硫和有机硫的形态变化，结果表明；在超临界醇萃取脱硫过程中，黄铁矿硫的转化反应如下：ＦｅＳ２－ＦｅＳ＋Ｆｅ１－ｘＳ，，转化的数量和深度主要取决于反应温度。２７５℃时磁黄铁矿（Ｆｅ１－ｘＳ）形式为ＦｅＳ１．１０１，４５０℃时为ＦｅＳ１．０８５；有机硫基团中ＰｈＳＨ ，Ｐｈ２Ｓ和四氢噻吩较易脱除，Ｐｈ２Ｓ     

HPLC of antibiotics. 1. Streptolydigin and related compounds

Two new acyltetramic acids related to streptolydigin have been isolated from fermentations of Streptomyces lydicus. The principal members of this complex were resolved by TLC on silica gel. However, the methods of detection, permanganate spray or bioautography, were not suitable for both crude fermentation broths and purified extracts. Gas chromatography is unsuitable for the detection of either underivatized or silylated streptolydigins. High performance liquid chromatography (HPLC) particularly on triethylaminoethyl cellulose is rapid and sensitive and is the method of choice for the analysis of both crude and purified samples. Using high performance liquid chromatography, two components were detected in the complex, which are not observed using any of the other chromatographic procedures.     

在Ar气流中热处理KOH-煤焦制大比表面积活性炭

本文将煤焦与ＫＯＨ混合，在Ａｒ气流中进行低温、高温二次热处理，制得了比表面积为２９１８ｍ２／ｇ的活性炭。考查了操作条件对产品性能的影响，同时用Ｘ射线衍射分析研究了煤焦制活性炭过程中的结构变化特征