Artifacts in the Determination of Trace Metal Binding Forms in Anoxic Sediments by Sequential Extraction

Abstract

The binding forms of Co, Cd, Cu, Pb, and Zn in an anoxic, sulfide-bearing sediment were investigated by performing both thermodynamic equilibrium calculations and sequential extractions. Care was taken to maintain oxygen-free conditions during the whole experiment. The calculations suggested that trace metals were bound to sulfidic minerals. Sequential extraction results, however, showed increased importance of exchangeable and reducible fractions in the order Cu < Cd < Pb < Zn < Co. Thermodynamic equilibrium calculations of the chemical reactions during extraction showed that Cd, Co, Pb, and Zn sulfides are to a significant extent soluble in the acetate-exchangeable (step 1 + 2) and oxalate-reducible (step 3) fractions. Neglecting the dissolution of sulfide minerals would lead to a misinterpretation of the experimental results.     

产母及新生儿血铅水平及影响因素的研究

为了解佛山市产母、新生儿血铅水平及其相关影响因素 ,采用电感耦合高频等离子体发射光谱法 ,于 2 0 0 2年 5～ 9月 ,取本院产科产母静脉血及其新生儿脐血 1 5 2例 ,进行血铅、钙、锌、铁、铜和锰水平测定 ,按妇幼保健管理卡内容 ,进行相关记录。结果表明 ,产母血铅水平90 1± 3 4 8μg/L ,BPb≥ 1 0 0 μg/L者占 2 0 3 9% ;新生儿脐血铅水平 89 2± 3 1 6μg/L ,铅中毒率为2 2 3 7% ;母子血铅值呈显著正相关 (r=0 85 7,P <0 0 1 ) ,产母血铅值与其血钙、铁值显著负相关 (r=0 2 66,-0 3 0 1 ,P <0 0 5 ) ;城郊产母及新生儿血铅水平显著高于城区。揭示市郊孕妇、新生儿血铅较高 ,血钙、锌、铁含量影响血铅水平     

Amperometric determination of 6-mercaptopurine on functionalized multi-wall carbon nanotubes modified electrode by liquid chromatography coupled with microdialysis and its application to pharmacokinetics in rabbit

In this paper, multi-wall carbon nanotubes fuctionalized with carboxylic groups modified electrode (MWNT-COOH CME) was fabricated. This chemically modified electrode (CME) can be used as the working electrode in the liquid chromatography for the determination of 6-mercaptopurine (6-MP). The results indicate that the CME exhibits efficiently electrocatalytic oxidation for 6-MP with relatively high sensitivity, stability and long-life. The peak currents of 6-MP are linear to its concentrations ranging from 4.0×10⁻⁷ to 1.0×10⁻⁴ mol l⁻¹ with the calculated detection limit (S/N=3) of 2.0×10⁻⁷ mol l⁻¹. Coupled with microdialysis, the method has been successfully applied to the pharmacokinetic study of 6-MP in rabbit blood. This method provides a fast, sensible and simple technique for the pharmacokinetic study of 6-MP in vivo.     

Parallel iterative solution-phase synthesis of 5-amino-1-aryl-[1,2,4]triazolo[1,5-a]pyridine-7-carboxylic acid amide derivatives

The parallel iterative solution-phase synthesis of 5-amino-1-aryl-[1,2,4]triazolo[1,5-a]pyridine-7-carboxylic acid amide derivatives is described. The key intermediate 2,6-bis-aminopyridine-4-carboxylic acid methyl ester was synthesised in a two step procedure in 64% overall yield and elaborated to a variety of triazolopyridine-5-carboxylic acid methyl ester by selective pyridine-N-amination, condensation of the adduct with a wide selection of aldehydes and subsequent cyclisation and oxidation. The desired esters were obtained in yields up to 70%. The final transformation to the amide derivatives was accomplished by application of carefully optimised reaction conditions thus giving access to a library of total 500 triazolopyridine amide derivatives. Iterative synthetic cycles (12-48 library members each) allowing for maximal flexibility in chemistry and maximal efficiency in in vitro biological activity optimisation guided by molecular modelling efforts constitute a synergistic procedure for rapid lead optimisation.     

Electrophilic addition of lead tetraacetate to 2-carene in an acidic medium

Oxidation of 2-carene by lead tetraacetate in acetic acid afforded p-menth-1(10),2-dien-7-ol, 2-acetyl-6,6-dimethylbicyclo[3.1.0]hexane, p-menth-2-ene-1,7-diol, p-menth-1-ene-3,7-diol, and 2-(m-tolyl)propanol-2.Deceased.A. M. Butlerov Scientific Research Chemical Institute, V. I. Ul'yanov-Lenin Kazan' State University, 420008 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 147–150, January, 1992.     

Oxidation of 1-methylcyclobutanol by Pb(IV) and Mn(III) compounds

The main product of the reaction of 1-methylcyclobutanol with Pb(OAc)₄ in benzene is 1-phenyl-4-pentanone; the use of Mn(OAc)₃ in acetic acid gives a mixture of 2,9-decanedione and methyl propyl ketone; 1-(chloro-, bromo-, thiocyano-, or cyano)-4-pentanone is formed in the presence of the systems Pb(OAc)₄-metal halide or Mn(OAc)₃-metal halide.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2760–2763, December, 1992.     

微分电位溶出法连续测定人发中锌、铜、铅、镉

本文报道了连续测定人发中痕量锌、铜、铅、镉的微分电位溶出法。实验确定最佳支持电解质组成为1M HAc-0.4M KCl-1.5×10~(-2)M Hg(Ⅱ)。在此体系中测定上述四种元素的分辨率好,峰形好,灵敏度高,重现性好。试验了共存离子的影响,方法干扰少,回收率为96.7～105%,测试范围从ppb到ppm级。     

1-苯基-3-甲基-4-苯甲酰基-5-吡唑酮与甲基膦酸二(1-甲基庚基)酯对Pb(Ⅱ)、Cd(Ⅱ)和Cu(Ⅱ)的萃取机理研究

本文用两相滴定法研究了1-苯基-3-甲基-4-苯甲酰基-5-吡唑酮(PMBP,简写为HA)与甲基膦酸二(1-甲基庚基)脂(P_(350),简写为B)对Pb~(2+)、Cd_(2+)和Cu~(2+)离子在不同的有机溶剂中的萃取机理.(?)定了萃合物的组成分别为:MA_2(M=Pb~(2+)、Ca~(2+)、Cu~(2+));MA_2·HA(M=Cd~(2+));MA_2·B(M=Pb~(2+)、Cd~(2+))和MA_2·2B(M=Cd~(2+)),同时求得了相应的萃合常数β值.     

1-苯基-3-甲基-4-苯甲酰基-5-吡唑酮与甲基膦酸二(1-甲基庚基)酯对Pb(Ⅱ)、Cd(Ⅱ)和Cu(Ⅱ)的萃取机理研究

本文用两相滴定法研究了1-苯基-3-甲基-4-苯甲酰基-5-吡唑酮(PMBP,简写为HA)与甲基膦酸二(1-甲基庚基)脂(P₃₅₀,简写为B)对Pb²⁺、Cd₂₊和Cu²⁺离子在不同的有机溶剂中的萃取机理.确定了萃合物的组成分别为:MA₂(M=Pb²⁺、Ca²⁺、Cu²⁺);MA₂·HA(M=Cd²⁺);MA₂·B(M=Pb²⁺、Cd²⁺)和MA₂·2B(M=Cd²⁺),同时求得了相应的萃合常数β值.     

低浓度含铅细颗粒物暴露大鼠体内生物转运研究

食品接触性塑料制品、可再生资源、汽车尾气中含有低浓度铅.铅等重金属体内蓄积严重影响机体健康,但机体长期暴露于铅环境的代谢依然未知.以低剂量含铅细颗粒物暴露为场景,探讨其在大鼠体内的生物转运及体内分布.通过比较每日吸入染毒(7.05±0.83)μg/m3及经口染毒0.42μg/d,连续染毒28 d.结果显示含铅细颗粒物入...