氯化钯作基体改进剂GFAAS法测定中药材中微量铅的研究

建立了氯化钯作基体改进剂,石墨炉原子吸收测定中药材中微量铅的方法.对氯化钯用量、介质酸度、共存离子干扰及方法回收率、精密度、检出限进行了考查.氯化钯作基体改进剂对铅的改进效果优于磷酸二氢铵.方法回收率为90%～104%,精密度(RSD)＜5.0%,特征质量为8.5 pg,检出限为0.066 mg·kg-1.方法简单、灵敏、准确、可靠,值得推广.     

Study on a New Method of Extraction of Metal Ions from Solid Matrices by Supercritical Fluid

TOdate.mostofthepublishedSFEworkshavefocusedonorganiccompound',andsomereportshaverelatedtoSFEofmetalions2.DirectextractionofmetalionsbysupercriticalCO,ishighlyinefficient.OneapproachofextractingmetalionsbysupercriticalCO=issuggestedtoconvertthechargedmetalionsintoneutralmetalcomplexesbyusingchelatingagentinthesupercriticalCO,.Avarietyoforganicchelatingagentssuchasthiocarbamate,D-diketones,andcrownetherhavebeenusedinSFEofmetalions3.8Hydroxyquinolinecontainsdoublecoordinationatoms(N,O-),…     

毛细管区带电泳法快速分离硝基酚和除草剂

 运用毛细管区带电泳法 ,通过在缓冲溶液中添加多阳离子化合物改变电渗流方向的方法 ,快速分离了 11种一取代、二取代和三取代硝基酚及 4种在德国常用的除草剂Bromoxynil,DNOC ,Dinoterb和Ioxynil。使用UV检测 ,这些化合物的检测限在 0 5mg/L～ 1 1mg/L。为满足环境样品分析的要求 ,使用固相萃取方法对样品进行了预处理 ,使硝基酚的检测限达到 1μg/L以下 ,并对实际样品进行了分析。     

Study of some palladium-containing chemical modifiers in graphite furnace atomic absorption spectrometry

Several chemical modifiers based on palladium have been evaluated: the individual Pd(II) and the mixed modifiers Pd + Zr, Pd + W, Pd + Zr + citric acid, Pd + W + citric acid. The mechanisms by which these chemical modifiers stabilize analytes and control atomization have been suggested. Factors that might have an influence on the characteristic mass and non-spectral interferences are discussed. The advantages and limitations of the palladium-tungsten modifiers are shown.     

分子烙印聚合物作超临界流体萃取后处理用固体吸附剂

利用离线超临界流体萃取与高效毛细管电泳相结合，分析了标准添加样品中的除草剂（2，4－二氯苯氧乙酸（2，4－D）），探讨了温度、压力和改性剂对萃取的影响，考察了在不同条件下合成的2，4－D为烙印分子的子烙印聚合物对2，4－D在不同极性溶剂中的吸附能力，并将分子烙印聚合物作为超临界流流体萃取后处理用固体吸附剂，结果表明，在甲醇和水的混合极性溶剂中制备的分子烙印聚合物对提高分析选择性的效果最佳。     

Electrothermal vaporization inductively coupled plasma atomic emission spectrometry determination of gold, palladium, and platinum using chelating resin YPA(4) as both extractant and chemical modifier

A new method for determination of trace gold (Au), palladium (Pd), and platinum (Pt) in environmental and geological samples by electrothermal vaporization (ETV)-inductively coupled plasma atomic emission spectrometry (ICP-AES) with the use of chelating resin YPA₄ as both solid phase extractant and chemical modifier has been developed. The resin loaded with analytes was prepared to slurry and directly introduced into the graphite furnace without any pretreatment. The factors affecting the vaporization behaviors of Au, Pd, and Pt were investigated in detail. It was found that, in the presence of YPA₄, Au and Pd could be quantitatively vaporized at lower vaporization temperature of 1900 °C. Compared with the conventional electrothermal vaporization, the vaporization temperature was decreased by 700 °C, and the detection limits for Au and Pd was decreased by a three-fold. However, a little effect of YPA₄ on the ETV-ICP-AES determination of Pt was found. Under the optimized conditions, the detection limits (3σ) of Au, Pd, and Pt for this method are 75, 60, and 217 pg, respectively; and their relative standard deviations (R.S.D.) are 4.4, 5.6, and 3.7%, respectively (n=9, C=0.2 μg ml⁻¹). The proposed method has been applied to the determination of trace Pd and Pt in sewage sludge, and the results well agreed with the recommended values. In order to further verify the accuracy of the developed method, a GBW07293 certified geological reference material and an auto catalyst NIST SRM 2557 reference material were analyzed, and the determined values coincided with the certified values very well.     

Morphological and spectroscopic investigation of the behavior of permanent iridium modifier deposited on pyrolytic graphite coated and zirconium treated platforms in electrothermal atomic absorption spectrometry

In order to better characterise a permanent modifier based on iridium deposited on zirconium or tungsten treated platforms of transversely heated graphite atomizer, and to gain additional information about its chemical behavior directed to an eventual further optimization, a series of experiments were carried out, both by surface techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS or ESCA) and X-ray fluorescence (XRF) and by electrothermal atomic absorption spectrometry on the iridium release from unmodified and various other modified pyrolytic graphite platforms. Special attention was paid to the influence of the amount of iridium, zirconium carbide coating of the platform surface and the presence of citric acid on the iridium vaporization during pyrolysis and atomization. The processes of iridium losses during pyrolysis and atomization and peak maximum alignment depend on the amount of the iridium deposited on the pyrolytic graphite coated platforms in the presence of nitric acid. A fractional order of release which suggests an atom vaporization from the surface or edges of the iridium islands was estimated. In the presence of citric acid, mass independence and zero order of the atom release were found. The zirconium treatment of the platform results in change of the spatial distribution of iridium and hence its vaporization. Vaporization temperatures as high as 2100°C, and first order of the process of atom generation were obtained. While it was possible to study the iridium atomization from uncoated and zirconium coated surfaces, evidencing a different order for the release process, the same was not possible for the tungsten coated platforms due to an ‘overstabilization’ that brought the iridium atomization temperature out of the working range of the instrument used. The different chemical behavior of tungsten and zirconium was also confirmed by XPS investigations. With tungsten, evidence of both W---C and W---O bonding was found, while zirconium on the contrary shows only Zr---O bonding and no evidence of carbide bonding. The SEM revealed a highly dispersed distribution of spot-like features whose smallest average diameter was of the order of 0.1 μm. The XRF asserted the confinement of iridium in these features and a strict association with zirconium in the case of zirconium treated surfaces. It is worth mentioning that such structure was preserved also after 400 thermal cycles simulating an atomization step at 1900°C despite a quite evident deterioration of the graphite surface, thus confirming the excellent durability of this modifier.     

Chemical vapor generation—electrothermal atomic absorption spectrometry: new perspectives

Volatile species of Ag, Cu, Cd, and Zn were generated at room temperature by the addition of sodium tetrahydroborate (III) to an acidified solution of the analytes. The vapor-phase species were rapidly transported to a pre-heated graphite tube, the surface of which was previously treated with Ir as a permanent chemical modifier. The volatile species were trapped at the Ir treated tube surface, and the further heating of the furnace permits their determination by atomic absorption spectrometry. A univariate approach was used to achieve optimized conditions and derive the figures of merit. The limits of detection based on a 3σ_b criterion were 10 (1); 0.006 (6×10⁻⁴); 28 (2.8) and 1.1 (0.11) ng (μg ml⁻¹) for Ag, Cd, Cu and Zn, respectively. Precision of replicate measurements was typically approximately 10% R.S.D. Using a transfer line as short as possible should minimize losses of analyte during the transport to the graphite furnace. The overall efficiency of the volatile species generation and trapping process estimated for silver was 13%.