Submicro Determination of Copper and Zinc in Needle Biopsy-Sized Cardiac and Skeletal Muscles by Atomic Absorption Spectroscopy Using Stoichiometric Air-Acetylene Flame

Abstract

A highly sensitive and rapid procedure is described for submicro quantitation of copper and zinc contents from the nitric acid extract of fat free-dry-tissue (FFDT) by a double beam atomic absorption spectrophotometer using stoichiometric air-acetylene flame. Simultaneous background correction was afforded with a deuterium lamp for Zn analysis to eliminate interferences from non-atomic absorption at 213.9 nm. Cu and Zn standards, as well as the muscle extracts, were prepared in an aqueous medium containing 0.75 M Ultrex quality HNO₃ for spectral analysis which did not quench or enhance the relevant absorbance signals. Inherent mineral constituents of muscle such as Ca, Mg, Na, K, and P, when added upto ～10-60 fold greater than the physiological concentration, did not cause either analytical or chemical interferences. Muscle specimens weighing between 0.8-12.0 mg FFDT were extracted in 5 ml of 0.75 M HNO₃ and directly aspirated into the flame. Muscle Cu and Zn contents were expressed in mg/kg FFDT. The smallest sample size confidently analyzed using this technique was ～0.4 mg FFDT which corresponds to 2.0 mg of fresh tissue and can be safely obtained from a patient by muscle needle biopsy. Recovery studies from the inherent muscle matrix revealed 100.01 ± 0.399 and 99.64 ± 0.13% precisions for Cu and Zn respectively.     

Bi2223/Ag和YBCO高温超导带材在交流过电流冲击下的失超及恢复特性研究

采用交流冲击实验装置测量了在不同交流过电流、持续交流工作电流及冲击时间情况下,不同散热条件下Bi2223/Ag和YBCO高温超导带材的电压、电流和温度随时间变化曲线,分析了冲击期间和冲击后带材各参数变化及失超恢复时间与散热条件和冲击参数的关系。研究结果表明:带材在交流过电流冲击下的失超和恢复过程主要取决于冲击能量和冲击过后带材内发热与散热的竞争效应。     

GMPLS网络中基于优先级的M : N保护

给出了一个GMPLS网络中关于广义标签交换通道(G.LSPs)的具有严格优先级M : N保护的排队模型,并通过仿真验证了本模型的正确性.该模型可用于基于优先级的M : N保护设计,通过适当选择保护通道数,可以确保一定的可靠性要求,同时避免过度配置而造成资源浪费.     

Recovery and pre-concentration of gold onto poly((N-(Hydroxymethyl)methacrylamide)–1-allyl-2-thiourea) hydrogels synthesized by gamma radiation

Poly((N-(Hydroxymethyl)methacrylamide)–1-allyl-2-thiourea) hydrogels, Poly(NHMMA–ATU), were synthesized by gamma radiation using ⁶⁰Co γ source at different irradiation doses and different ATU content in the irradiated monomer mixture. The swellability of the synthesized hydrogels was changed by irradiation doses and by the content of ATU in the irradiated mixture. These hydrogels were used for the specific gold recovery and pre-concentration from single gold ion solutions and from different natural samples. It has been observed that gold adsorption capacity onto the hydrogels was high at low pHs and reached maximum value at pH = 0.5. Adsorption capacity of the hydrogels for gold at pH = 0.5 was found to be about 698 mg g^− 1 dry hydrogels. Adsorption equilibrium time of gold ions onto the hydrogels was found to be very short and also these hydrogels were showed extremely high selectivity to the gold ions in acidic media when the concentration of the other metal ions were extremely higher than gold. Because of the high specificity of these hydrogels to gold beside the other metal ions at low pHs, all matrix effects were easily eliminated adsorbing gold onto the hydrogels and desorbing into 3 M HCl solution containing 0.8 M thiourea. These hydrogels were found to be highly open pore size. This property of the hydrogels make them attractive due to high adsorption capacity of gold ions on/in the hydrogels penetrating inside and react to all functional groups in the interior surface of the hydrogels.     

聚苯硫醚反应淤浆的处理工艺

综述了聚苯硫醚反应淤浆的处理工艺，包括聚苯硫醚树脂的收集，溶剂的回收和反应助剂的回收两部分，并展望了聚苯硫醚反应淤浆处理工艺的发展趋势。     

Correction function on biased results due to matrix effects: Application to the routine analysis of pesticide residues

A new strategy to carry out the correction of analytical results affected by systematic errors due to the matrix effect is proposed. Two types of external calibrations must be established with the purpose to estimate the matrix effect: solvent calibration (SC) and matrix-matched calibration (MC). These calibration curves are statistically compared and a correction function (CF) is proposed with the aim to simplify the resolution to the problems associated with the incidence of matrix systematic error in the analytical results. Applying this correction function to the results obtained from the solvent calibration, it is possible to make a prediction of the values that would be obtained when the matrix-matched calibration is applied. On the other hand, a rigorous study of the associated uncertainty is developed and applied to the calculated correction function. Finally, this correction function is validated by means of obtained data of recovery studies carried out by a traditional methodology. The methodology has been satisfactorily applied to the quantification of the pesticide procymidone by HPLC for assessing dermal exposure.     

硝基苯的制备及废硫酸回收利用的研究

苯在四氯化碳溶剂中以硝酸和疏酸的混合酸为硝化剂在温和条件下进行硝化，硝基苯的产率高，硫酸可以回收再利用。例如，在带有搅拌器、滴液漏斗、温度计和冷凝器的四颈烧瓶中，加入４４．４毫升苯和４０毫升四氯化碳，将３９．５毫升浓硝酸和４１．５毫升浓硫酸混合后从滴液漏斗中滴加，维持温度在１５～５５℃之间，约４０分钟滴完后，在５５～６２℃继续反应３０分钟。有机层分别用水、１０％氢氧化钠溶液、水洗涤，干燥、蒸馏，先蒸出溶剂可再用。然后收集２０４～２１０．８℃的馏份，得硝基苯６０．６克，产率９８．５３％。废硫酸通过蒸馏浓缩后，可重新用于硝化反应。     

离子交换法从发酵液中提取L-异亮氨酸

采用天然高分子絮凝剂壳聚糖对L-异亮氨酸发酵液进行预处理，在发酵液pH=2，壳聚糖用量30mg／L的条件下可取得较好的絮凝效果．并通过静态吸附实验，考察了pH和L—异亮氨酸浓度对平衡吸附量的影响．最后确定了732″离子交换树脂提取L-异亮氨酸的最佳工艺条件：上柱发酵液pH=2，上样速度0．6BV／h，洗脱液为0.5mol／L的NH4Cl．流出液经脱色、浓缩结晶后得L-异亮氨酸成品，总提取率为55％．     

Recovery revisited

During the last decade, various IUPAC documents have presented concepts related to the important ability of a measurement procedure to provide correct quantity values for amount, concentration, or content of a component in a system. The measurement procedure often, but not necessarily, includes one or more separation steps prior to the final instrumental reading. The vocabularies present concepts with some definitions and terms that disagree or are ambiguous, mostly revolving around the term recovery and its derivatives. The present proposal consists in defining three concepts with the terms actual quantity, initially estimated quantity, and recovered quantity ratio, where quantity is used in the metrological sense of the international vocabulary of basic and general terms in metrology (BIPM, IEC, IFCC, ILAC, ISO, IUPAC, IUPAP, OIML International vocabulary of basic and general terms in metrology, draft, 3rd edn. BIPM, Sèvres, 2005), not as a synonym of amount.

Correlation of supercritical-fluid extraction recoveries with supercritical-fluid chromatographic retention data: A fundamental study

The possibility of using supercritical-fluid chromatographic retention data for examining the effects of operational parameters, such as pressure and flow rate, on the extraction characteristics in supercritical-fluid extraction (SFE) was investigated. A model was derived for calculating the extraction efficiency in SFE from retention data and peak shapes measured in supercritical-fluid chromatography (SFC). By performing the SFC experiments at the same pressure and temperature as the SFE extractions using the SFE extraction cell as the SFC column, an accurate prediction of extraction efficiencies could be made. Finally, the effects of matrix composition and analyte concentration on extraction efficiency were studied.