氢化物－无色散原子荧光法测定人发中的铅

本文研究了氢化物－无色散原子荧光法测定人发中的铅。仔细检测了各种共存离子引起的干扰。仅铜（６０μｇ／ｍＬ）引起负误差。增加铁氰化钾的用量，克服了铜的干扰。方法的检出限为０．００１５μｇ／ｍＬ，相对标准偏差４．６６％，回收率在９５％－９８％范围。本法快速、灵敏。已用于人发样品的测定，得到满意结果。     

水浴浸提-氢化物发生-原子荧光光谱法检测土壤中痕量砷和汞

采用盐酸-硝酸混合酸水浴浸提土壤样品,以氢化物发生-原子荧光光谱法(HG-AFS)测定土壤中砷和汞,同时对前处理酸的用量和样品介质(盐酸)进行了试验,筛选出检测土壤中砷和汞的浸提最佳实验条件为6mL HCI、0.5mL HNO3、样品介质(盐酸)3mL HCl,并对国家级土壤标准物质GBW07402、GBW07404和土壤样品进行验证,测定结果与标准值相吻合.方法的检出限为As:0.096 μg·L-1,Hg:0.031 μg·L-1;加标回收率为As:90.41%,Hg:82.22%.相对标准偏差As:3.3%,Hg:5.19%.     

Ruthenium hydride complexes of chiral and achiral diphosphazane ligands and asymmetric transfer hydrogenation reactions

The half-sandwhich ruthenium chloro complexes bearing chelated diphosphazane ligands, [(η⁵-Cp)RuCl{κ²-P,P-(RO)₂PN(Me)P(OR)₂}] [R = C₆H₃Me₂-2,6] (1) and [(η⁵-Cp^∗)RuCl{κ²-P,P-X₂PN(R)PYY′}] [R = Me, X = Y = Y′ = OC₆H₅ (2); R = CHMe₂, X₂ = C₂₀H₁₂O₂, Y = Y′ = OC₆H₅ (3) or OC₆H₄^tBu-4 (4)] have been prepared by the reaction of CpRu(PPh₃)₂Cl with (RO)₂PN(Me)P(OR)₂ [R = C₆H₃Me₂-2,6 (L¹)] or by the reaction of [Cp^∗RuCl₂]_n with X₂PN(R)PYY′ in the presence of zinc dust. Among the four diastereomers (two enantiomeric pairs) possible for the “chiral at metal” complexes 3 and 4, only two diastereomers (one enantiomeric pair) are formed in these reactions. The complexes 1, 2, 4 and [(η⁵-Cp)RuCl{κ²-P,P-Ph₂PN((S)-^∗CHMePh)PPhY}] [Y = Ph (5) or N₂C₃HMe₂-3,5 (S_CS_PR_Ru)-(6)] react with NaOMe to give the corresponding hydride complexes [(η⁵-Cp)RuH{κ²-P,P-(RO)₂PN(Me)P(OR)₂}] (7), [(η⁵-Cp^∗)RuH{κ²-P,P′-X₂PN(R)PY₂}] [R = Me, X = Y = OC₆H₅ (8); R = CHMe₂, X₂ = C₂₀H₁₂O₂, Y = OC₆H₄^tBu-4 (9)] and [(η⁵-Cp)RuH{κ²-P,P-Ph₂PN((S)-^∗CHMePh)PPhY}][Y = Ph (10) or N₂C₃HMe₂-3,5 (S_CS_PR_Ru)-(11a) and (S_CS_PS_Ru)-(11b)]. Only one enantiomeric pair of the hydride 9 is obtained from the chloro precursor 4 that bears sterically bulky substituents at the phosphorus centers. On the other hand, the optically pure trichiral complex 6 that bears sterically less bulky substituents at the phosphorus gives a mixture of two diastereomers (11a and 11b). Protonation of complex 7 using different acids (HX) gives a mixture of [(η⁵-Cp)Ru(η²-H₂){κ²-P,P-(RO)₂PN(Me)P(OR)₂}]X (12a) and [(η⁵-Cp)Ru(H)₂{κ²-P,P-(RO)₂PN(Me)P(OR)₂}]X (12b) of which 12a is the major product independent of the acid used; the dihydrogen nature of 12a is established by T₁ measurements and also by synthesizing the deuteride analogue 7-D followed by protonation to obtain the D-H isotopomer. Preliminary investigations on asymmetric transfer hydrogenation of 2-acetonaphthone in the presence of a series of chiral diphosphazane ligands show that diphosphazanes in which the phosphorus centers are strong π-acceptor in character and bear sterically bulky substituents impart moderate levels of enantioselectivity. Attempts to identify the hydride intermediate involved in the asymmetric transfer hydrogenation by a model reaction suggests that a complex of the type, [Ru(H)(Cl){κ²-P,P-X₂PN(R)PY₂}(solvent)₂] could be the active species in this transformation.     

Determination of lead in sediments and sewage sludge by on-line hydride-generation axial-view inductively-coupled plasma optical-emission spectrometry using slurry sampling

Among the “traditional” hydride-forming elements, lead is probably the most difficult, and its determination in this form has rarely been reported in the literature. In this paper a simple and rapid method, axial-view inductively-coupled plasma optical-emission spectrometry using on-line hydride generation (HG–ICP–OES) from samples prepared as slurry, is proposed for determination of lead in environmental samples. The samples (20–50 mg, particle size ≤120 μm) were treated with 1 mL aqua regia in a 40-kHz ultrasonic bath for 60 min. The slurry was diluted to a final volume of 50 mL with a 10% m/v solution of (NH₄)₂S₂O₈. The concentrations of NaBH₄, tartaric acid, and (NH₄)₂S₂O₈, used for on-line plumbane generation were optimized by means of a complete factorial analysis applied to an aqueous standard solution and to the slurry of a sediment certified reference material (CRM). External calibration against aqueous standards in the concentration range 10–100 μg L⁻¹ was used for analysis of six CRM—three marine sediments, one river sediment, and two sewage sludges. Analysis of the filtered slurry showed that Pb was only partially extracted into the liquid phase. Several major concomitants tested did not affect the Pb signal. The detection limit (3s, n = 10) for 20 mg sample in a final volume of 50 mL was 5.0 μg g⁻¹. Tin was the only other hydride-forming analyte that could be determined satisfactorily with Pb; for tin the detection limit was 1.0 μg g⁻¹. The values obtained for Pb and Sn were not significantly different from the certified concentrations, according to the t-test at the 95% confidence level. Nine river sediments collected locally were also analyzed and the concentrations were in agreement with results obtained after total digestion.     

Determination of lead in wine by hydride generation atomic fluorescence spectrometry in the presence of hexacyanoferrate(III)

A rapid, accurate, and precise method is described for the determination of Pb in wine using continuous-flow hydride generation atomic fluorescence spectrometry (CF-HGAFS). Sample pretreatment consists of ten-fold dilution of wine followed by direct plumbane generation in the presence of 0.1 mol L⁻¹ HCl and 1% m/v K₃[Fe(CN)₆] with 1% m/v NaBH₄ as reducing agent. An aqueous standard calibration curve is recommended for Pb quantification in wine sample. The method provides a limit of detection and a limit of quantification of 0.3 μg L⁻¹ and 1 μg L⁻¹, respectively. The relative standard deviation varies between 2–6% (within-run) and 4–11% (between-run) at 3–30 μg L⁻¹ Pb levels in wine. Good agreement has been demonstrated between results obtained by CF-HGAFS and direct electrothermal atomic absorption spectrometry in analyses of red and white wines within the concentration range of 9.2–25.8 μg L⁻¹ Pb.     

Reactivity of the unsaturated manganese dihydrides [Mn2(μ-H)2(CO)6(μ-L2)] [L2 = (EtO)2POP(OEt)2, Ph2PCH2PPh2, Me2PCH2PMe2] toward silicon and tin hydrides

The dimanganese hydride complexes [Mn₂(μ-H)₂(CO)₆(μ-L₂)] [L₂ = (EtO)₂POP(OEt)₂ (tedip), Ph₂PCH₂PPh₂ (dppm)] react with primary and secondary silanes H₂SiPhR (R = Ph, Me, H) to give the corresponding derivatives [Mn₂(μ-H₂SiPhR)(CO)₆(μ-L₂)] having a silane molecule displaying a relatively unusual μ-κ²:κ² coordination mode (averaged values are ca. Mn-H = 1.59 Å, H-Si = 1.69 Å and Mn-Si = 2.381 Å, when R = Ph and L₂ = tedip). These complexes display in solution cis and/or trans arrangement of the bridging silane relative to the diphosphorus ligands (and facial and/or meridional arrangements of the corresponding carbonyl ligands), depending on the bridging groups. The novel unsaturated dihydride [Mn₂(μ-H)₂(CO)₆(μ-dmpm)] (dmpm = Me₂PCH₂PMe₂) has been prepared through the reaction of [Mn₂(μ-Cl)₂(μ-dmpm)(CO)₆] and 5 equiv of Li[BH₂Me₂] in tetrahydrofuran followed by addition of water. The dihydride complexes [Mn₂(μ-H)₂(CO)₆(μ-L₂)] (L₂ = tedip, dppm, dmpm) react with HSnPh₃ to give different mixtures of products strongly dependent on the particular reaction conditions. We have thus been able to isolate and characterize five new types of dimanganese-tin derivatives: [Mn₂(μ-SnPh₂)₂(CO)₆(μ-L₂)], [Mn₂(μ-H)(μ-Ph₂SnO(H)SnPh₂)(CO)₆(μ-L₂)] (average values are Mn-Sn = 2.54 Å, Sn-O = 2.11 Å, when L₂ = tedip), [Mn₂(μ-H)(μ-κ¹:κ²-HSnPh₂)(CO)₆(μ-L₂)], [Mn₂(μ-H)(μ-κ¹:κ¹-O(H)SnPh₂)(CO)₆(μ-L₂)], and [Mn₂(μ-H)(SnPh₃)(CO)₇(μ-L₂)] (Mn-Mn = 3.237(1) Å, Mn-Sn = 2.642(1) Å, when L₂ = dppm).     

Method development and optimization for the determination of selenium in bean and soil samples using hydride generation electrothermal atomic absorption spectrometry

The present investigation is the first part of an initiative to prepare a regional map of the natural abundance of selenium in various areas of Brazil, based on the analysis of bean and soil samples. Continuous-flow hydride generation electrothermal atomic absorption spectrometry (HG-ET AAS) with in situ trapping on an iridium-coated graphite tube has been chosen because of the high sensitivity and relative simplicity. The microwave-assisted acid digestion for bean and soil samples was tested for complete recovery of inorganic and organic selenium compounds (selenomethionine). The reduction of Se(VI) to Se(IV) was optimized in order to guarantee that there is no back-oxidation, which is of importance when digested samples are not analyzed immediately after the reduction step. The limits of detection and quantification of the method were 30 ng L⁻¹ Se and 101 ng L⁻¹ Se, respectively, corresponding to about 3 ng g⁻¹ and 10 ng g⁻¹, respectively, in the solid samples, considering a typical dilution factor of 100 for the digestion process. The results obtained for two certified food reference materials (CRM), soybean and rice, and for a soil and sediment CRM confirmed the validity of the investigated method. The selenium content found in a number of selected bean samples varied between 5.5 ± 0.4 ng g⁻¹ and 1726 ± 55 ng g⁻¹, and that in soil samples varied between 113 ± 6.5 ng g⁻¹ and 1692 ± 21 ng g⁻¹.     

微液滴微流控芯片:微液滴的形成、操纵和应用

微流控芯片中形成的微液滴粒径均一、可控,与传统的连续流体系相比,具有能实现试剂的快速混合、通量更高等优点.本文介绍了微流控芯片中由微通道控制的微液滴的形成、分裂、合并、混合、分选和捕获等微液滴操纵技术,以及微液滴技术在纳米粒子、聚合物微粒的合成、纳米粒子自组装、蛋白质结晶研究和DNA、细胞分析等领域的研究进展.     

RP-HG-AFS联用研究长期汞暴露人群补硒前后血清中汞的形态

建立了反相色谱-氢化物发生原子荧光光谱联用测定血清中汞形态(无机汞和甲基汞)的方法,优化了载流液,还原剂以及2-巯基乙醇的浓度,以正辛醇作为消泡剂,成功地解决了测定血清样品时原子荧光仪器内气液分离器中产生大量泡沫的难题。采用反相色谱柱对无机汞和甲基汞形态进行了分离,回收率在95％～110％之间,无机汞和甲基汞的精密度R...     

A theoretical scheme for generation of Gazeau-Klauder coherent states via intensity-dependent degenerate Raman interaction

A theoretical scheme is presented for generating Gazeau-Klauder coherent states (GKCSs) via the generalization of degenerate Raman interaction with coupling constant to intensity dependent coupling. Firstly, we prove that in the intensity dependent degenerate Raman interaction, under particular conditions, the modified effective Hamiltonian can be used instead of Hamiltonian in the interaction picture, for describing the atom-field interaction. We suppose that the cavity field is initially prepared in a nonlinear CS, which is not temporally stable. As we will observe, after the occurrence of the interaction between atom and field, the generated state involves a superposition of GKCSs which are temporally stable and initial nonlinear CS. Under specific conditions which may be prepared, the generated state just includes GKCS. So, in this way we produced the GKCS, successfully.