Lead in Hair of Children Exposed to Gross Environmental Pollution

Abstract

In the context of a cross-sectional study, concentrations of lead in hair (PbH) were determined by atomic absorption analysis among 263 children aged 1 to 9 years, living less than 900m from a lead smelter in Santo Amaro City, Bahia, Brazil. PbH levels ranged from 20 to 4933 ppm; the median was 349 and the geometric mean was 313 ppm. The mean PbH level was increased among individuals with the following characteristics: female; younger age; shorter distance between residence and smelter; longer residence time in the area; racial group Dark; curly hair; being a child of a lead worker; high lead content in peridomiciliar area. The mean PbH level did not vary markedly according to the child's nutritional status, iron status and the habit of pica. The marked variations in pbH levels point out the feasibility of its use as an epidemiological index in situations of heavy environment pollution.     

流动注射在线液-液萃取火焰原子吸收法测定水中痕量铅

提出了一种流动注射在线液－液萃取火焰原子吸收直接测定水中痕量铅的分析方法。实验以APDC为螯合剂,用MIBK为萃取剂,研究了在线萃取中各种实验参数、酸度条件的影响,考察了共存元素的干扰。方法的RSD（n=12)为2．7％,测定检出限为3．1μg/L,回收率为96％－106％。     

Thermal characterization of tetrabasic lead sulfate used in the lead acid battery technology

The thermal production of 4PbO·PbSO₄ was comprehensively studied and characterized for two syntheses routes, i.e. either heating 3PbO·PbSO₄·H₂O, or a mixture of 4PbO:PbSO₄, in air to about 700 °C. In the 3PbO·PbSO₄·H₂O approach, the formation of an intermediate amorphous phase occurred at around 210 °C with the loss of H₂O from the hydrated structure. Formation of 4PbO·PbSO₄ initiated at around 270 °C with predominantly 4PbO·PbSO₄ and 13% residual PbO·PbSO₄ existing at 700 °C. With the synthesis route of mixing a stoichiometric ratio of 4PbO with PbSO₄, an intermediate phase of PbO·PbSO₄ formed at around 300 °C, before the 4PbO·PbSO₄ phase started to form at around 500 °C. Upon further heating, 4PbO·PbSO₄ was the predominant phase with 8% of PbO·PbSO₄ remaining. Both samples decomposed upon further heating to 850 °C. Powder neutron diffraction studies of the final 4PbO·PbSO₄ products from the two different synthesis routes showed similar crystallographic unit cell lattice parameters with slight differences in the PbO:PbSO₄ contents. This could possibly be linked to differences observed in the microscopic crystallite shapes from the two synthesis routes.     

Coprecipitation for the Determination of Copper(II), Zinc(II), and Lead(II) in Seawater by Flame Atomic Absorption Spectrometry

A TiO(OH)₂ precipitate was used for the preconcentration of copper(II), zinc(II), and lead(II) in seawater prior to determination by flame atomic absorption spectrometry. The influence of pH, sample volume, amount of precipitate, and centrifugation time were optimized for quantitative recoveries of the analytes. Under the optimum conditions, the detection limits of copper(II), lead(II), and zinc(II) were 4.3, 9.7, and 9.6 micrograms per liter, respectively. The recoveries of analytes were between 95.00 and 103.00 percent with the relative standard deviation below 6 percent. The procedure was validated by the analysis of NASS-5 and SPS-WW1 Batch 109 standard reference materials and the procedure was successfully applied to seawater.     

纳米硅羟基磷灰石分离富集-火焰原子吸收法测定水样中痕量铅

提出了纳米硅羟基磷灰石(Si-HAP)分离富集,火焰原子吸收光谱法(FAAS)测定水样中痕量铅的新方法。考察了铅在纳米Si-HAP上的吸附动力学、最佳酸度和吸附容量。实验结果表明:在最佳实验条件下,纳米Si-HAP能定量、快速地吸附水中的痕量Pb2+,其静态吸附容量24.33 mg/g;吸附在纳米Si-HAP上的Pb2+可用0.01mol/L EDTA-Ca完全洗脱。本法对Pb2+的检出限为1.33 ng/mL,相对标准偏差为4.0%(n=11,c=1μg/mL),加标回收率在94.9%~102.0%之间。方法用于实际水样中铅的测定,结果满意。     

测定心灵丸中痕量铅的喷涂石英管原子吸收光谱法

采用火焰原子吸收光谱法测定中成药心灵丸中的铅。以混合酸消化待分析物，以氘灯扣除背景吸收，采用经钒酸盐溶液喷涂的石英缝管进行测定，考察了样品的预处理方法及提高测定灵敏度和高温下喷涂石英管的抗腐蚀性的机理。结果表明该消化方法可获得澄明的样品溶液而铅没有损失。灵敏度提高了近３倍，检出限为８３７μｇ／Ｌ（σ＝３），ＲＳＤ为０９％～１２％，其回收率为９７９％～１０２３％。     

降铅冲剂对低水平铅暴露仔鼠血铅及脑铅的影响

目的:研究降铅冲剂对低水平铅暴露仔鼠血铅及脑铅的影响,为评价降铅冲剂的作用提供依据。方法:选用Wister大鼠仔鼠60只,体质量80~100 g,随机分成6组,每组10只,分别为空白组、模型对照组、EDTA对照组、降铅冲剂低剂量组、降铅冲剂中剂量组、降铅冲剂高剂量组;造模后开始给药,EDTA对照组给CaNa2EDTA注射液10(mg/kg)/d腹腔注射,降铅冲剂低、中、高剂量组分别予降铅冲剂5(g/kg)/d、10(g/kg)/d、20(g/kg)/d的剂量灌胃,空白组和模型对照组予等量蒸馏水灌胃,给药共30 d。用石墨炉原子吸收光谱仪测定仔鼠血铅、脑铅。结果:(1)染铅后,各染铅组的血铅水平与空白组比较都显著升高(P<0.001),经过30 d的治疗后,各治疗组的治疗后血铅水平均有不同程度下降,与模型对照组比较均有统计学意义。(2)染铅后,各染铅组的脑铅水平与空白组比较都显著升高(P<0.05),治疗后,各组脑铅与治疗前比较均显著升高,降铅冲剂低、中剂量组的脑铅与模型对照组比较显著下降。结论:降铅冲剂能显著降低低水平铅暴露仔鼠的血铅和脑铅含量,其综合疗效优于CaNa2EDTA。     

Voltammetry as Virtual Potentiometric Sensor in Modelling of a Metal/Ligand System and Refinement of Stability Constants. Part 5

The concept of virtual potential (employed here in modelling operations), a unique experimental setup designed and built in our laboratories, and new regression equations derived for nonlinear fitting of quasi‐reversible direct‐current polarograms were combined with the existing rigorous treatment and refinement of polarographic data to establish reliable metal/ligand models and accurate stability constants for the lead(II)/glycine/OH^? and lead(II)/sarcosine/OH^? systems (sarcosine = N‐methylglycine). In the case of glycine, the complexes [M(HL)], [ML], [ML₂], and [ML₃] were identified, and their stability constants (as log β) were established to be 10.51 ± 0.06, 4.58 ± 0.02, 7.19 ± 0.10, and 9.27 ± 0.02, respectively, the complex [ML₃] being reported here for the first time (Table 2). The system with sarcosine involving [M(HL)], [ML], [ML₂], [ML₃], and [ML₂(OH)₂], with the stability constants (as log β) 11.01 ± 0.04, 4.18 ± 0.03, 7.23 ± 0.03, 9.1 ± 0.3, and 15.97 ± 0.07, respectively, is reported for the first time (Table 3). The log K₁ value for Pb^II with sarcosine is a fraction of a log unit smaller when compared with the Pb^II complex with glycine, in agreement with the literature data for Cu^II, Ni^II, and Zn^II showing the same trend for these two ligands. The proposed nonlinear curve‐fitting operations expand the applicability of polarography to study reliably and conveniently quasi‐reversible, on the polarographic time scale, metal/ligand systems (systems with involved heterogeneous kinetics).     

平衡移动法测定配合物组成和稳定常数的研究进展

平衡移动法是测定配合物组成和稳定常数的一种重要方法，本文综述了该法的研究进展，引用参考文献３０篇。     

铅染毒家兔脂质过氧化水平和神经传导速度的变化及关系研究

为观察铅对脂质过氧化水平和神经传导速度(NCV)的影响,并探讨两者关系,1 6只家兔随机分为2组,每组8只,染铅组饮用0 1 %醋酸铅水,对照组予以去离子水,持续8周,测定了两组家兔股神经NCV及血浆和脑组织丙二醛(MDA)、总超氧化物歧化酶(T -SOD)水平,分析了MDA、T -SOD与NCV之间的关系。结果表明,染铅组NCV显著低于对照组(P <0 0 1 ) ,NCV与脑组织MDA之间存在相关关系(r=-0 5 2 1 ,P <0 0 5 ) ,但染铅组MDA、T -SOD与对照组比较未达到显著性差别(P >0 0 5 )。提示铅中毒能引起NCV减慢,这与脂质过氧化水平有关,脂质过氧化损伤可能是铅致中毒性周围神经病的机制之一。     

BaO∙4B2O3∙5H2O纳米材料的制备及其对聚丙烯阻燃性能的热分解动力学方法评价

Borate is considered one of the most important additives for improving the fire-resistance of combustible polymers because of its smoke suppression, low toxicity, and good thermal stability. However, the size of prepared borate is usually in the micrometer range, which makes it difficult to disperse in a polymer matrix, thus hindering its use as fire-retardant material. The preparation and application of borate nanomaterial as flame retardant is considered an effective method. However, the preparation of barium borate nanomaterials as flame retardant has not been reported. In this paper, nanosheets and nanoribbons with different sizes for a new barium borate BaO·4B₂O₃·5H₂O are prepared by hydrothermal method, and characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), thermogravimetric analysis-differential scanning calorimetry (TG-DSC), and scanning electron microscope (SEM). The flame-retardant properties of polypropylene (PP)/BaO·4B₂O₃·5H₂O composites are investigated by thermogravimetric analysis (TG), differential scanning calorimetry (DSC) thermal analysis methods and limited oxygen index (LOI) method. Considering the near TG mass losses and the near LOI values for PP with 10% prepared BaO·4B₂O₃·5H₂O nanosheet and nanoribbon, their flame-retardant properties need to be further evaluated by non-isothermal decomposition kinetic method. The apparent activation energy for this decomposition reaction was obtained from the slope by plotting ln(β/T_p²) against 1/T_p according to Kissinger's model. With the reduction of TG mass loss, increased heat absorption in DSC under N₂ atmosphere, increased apparent activation energy E_a for the thermal decomposition of PP/BaO·4B₂O₃·5H₂O composite as well as increased LOI value, the flame-retardant performance of prepared BaO·4B₂O₃·5H₂O samples with PP gradually improved from bulk to nanoribbon to nanosheet. This can be attributed to the decrease in the size of BaO·4B₂O₃·5H₂O samples because the smaller sample size leads to improved dispersion and increased contact area with the polymer. The flame-retardant mechanism is discussed by analyzing the after-flame chars of the PP/BaO·4B₂O₃·5H₂O composite in SEM images, which show that the char layer is more compact and continuous for the PP/BaO·4B₂O₃·5H₂O nanosheet composite. The influence of loading BaO·4B₂O₃·5H₂O nanomaterials on the mechanical properties of PP is also tested using a universal material testing machine, in which the PP/BaO·4B₂O₃·5H₂O nanosheet composite has higher tensile strength. The PP/BaO·4B₂O₃·5H₂O nanosheet composite has the best flame-retardant and mechanical properties, which is promising to be developed for the application as flame-retardant material.     

Flow injection determination of lead and cadmium in hair samples from workers exposed to welding fumes

A flow injection procedure involving continuous acid leaching for lead and cadmium determination in hair samples of persons in permanent contact with a polluted workplace environment by flame atomic absorption spectrometry is proposed. Variables such as sonication time, nature and concentration of the acid solution used as leaching solution, leaching temperature, flow-rate of the continuous manifold, leaching solution volume and hair particle size were simultaneously studied by applying a Plackett–Burman design approach. Results showed that nitric acid concentration (leaching solution), leaching temperature and sonication time were statistically significant variables (confidence interval of 95%). These last two variables were finally optimised by using a central composite design. The proposed procedure allowed the determination of cadmium and lead with limits of detection 0.1 and 1.0 μg g⁻¹, respectively. The accuracy of the developed procedure was evaluated by the analysis of a certified reference material (CRM 397, human hair, from the BCR). The proposed method was applied with satisfactory results to the determination of Cd and Pb in human hair samples of workers exposed to welding fumes.     

Effects of Halogen Bonding in Chemical Activity of Lead(II) Electron Pair: Sonochemical Synthesis,Structural Studies,and Thermal Analysis of Novel Lead(II) Nano Coordination Polymer

The nanoflower lead(II) coordination compound {[Pb(phen)(μ‐CH₃COO)][PF₆]}_n ( 1 ) (phen = 1,10‐phenanthroline) was synthesized by a sonochemical method. The nanostructure was characterized by using scanning electron microscopy (SEM), X‐ray powder diffraction, elemental analysis, and thermal analysis. The single‐crystal X‐ray structure shows that the overall structure of 1 is a 1D coordination polymer. Complex 1 has a bridging acetate pathway. Three halogen bonds observed in the structure and the strong halogen bonding of F–Pb causes chemical activity of the lead electron pair. This is further extended into a 3D supramolecular structure by weak π–π intermolecular interactions. The coordination number of the lead(II) ions is six, resulting in PbN₂O₄. PbO nanoparticles were obtained by the thermolysis of 1 at 180 °C with oleic acid as a surfactant. The morphology and size of the prepared PbO nanoparticles were further observed using scanning electron (SEM) and transmission electron microscopy (TEM), and were analyzed by X‐ray photoelectron spectroscopy (XPS).     

Rapid Determination of Cadmium and Lead in Maca (Lepidium meyenii) by Magnetic Solid-Phase Extraction and Flame Atomic Absorption Spectrometry

Multiwalled carbon nanotubes were modified by Fe₃O₄ nanoparticles with application for the preconcentration of metals. The modified materials were characterized by infrared spectroscopy, transmission electron microscopy, and X-ray diffraction. The Fe₃O₄ nanoparticle modified multiwalled carbon nanotubes were used as sorbents for the extraction of cadmium and lead from maca prior to analysis by flame atomic absorption spectrometry. The amount of nanoparticles, pH, adsorption time, coexisting ions, eluent solution, and reuse of the material were characterized to optimize the recoveries of the analytes. Under the optimum conditions, the calibration curves were linear from 0.05 to 20 milligrams per liter for cadmium and from 0.05 to 25 milligrams per liter for lead. The limits of detection were 0.32 and 0.57 micrograms per liter while the relative standard deviations were 2.1 and 1.9 percent, respectively. The method was employed for the determination of cadmium and lead in maca and recoveries between 94.8 and 105.6 percent were obtained.     

ZnO对Ag/SiO2催化剂银的分散作用及对吲哚合成稳定性的影响

将ZnO助剂加到由苯胺和乙二醇一步合成吲哚的Ag/SiO2催化剂中,发现ZnO助剂能大大提高催化剂的稳定性.XRD和TEM表征首次得到:ZnO是结构型助剂,它能使银很好地分散在SiO2表面上,并可有效地抑制反应过程中银粒子的烧结.     

具有优异热稳定性的磷修饰氧化钛及其对水中污染物的降解

通过水热法制得磷修饰氧化钛,它在亚甲基蓝和对氯苯酚的降解以及消除大肠杆菌的实验中都表现出高于纯氧化钛的优异活性,甚至优于商品化催化剂P25.在捕获剂中降解亚甲基蓝的实验证实羟基自由基是最主要的活性氧物种,并且磷修饰氧化钛在光照下拥有较强的产生羟基自由基的能力,同时,磷修饰氧化钛具有非常高的热稳定性,直到950℃才会发生...     

Online Solid-Phase Extraction of Cd(II), Cu(II), and Co(II) Using Covalently Attached Bis(salicylaldimine) to Silica Gel for Determination in Food and Water by Flame Atomic Absorption Spectrometry

In this study, a novel sorbent material bearing a bis(aldimine) group was designed and successfully synthesized by covalently bonding a 2-[N,N′-bis(salicylaldimine)]aminoethyl amine ligand to the silica gel surface that was characterized by carbon, hydrogen, and nitrogen elemental analysis, thermogravimetric analysis, and the Fourier transform infrared spectroscopy technique. The sorbent was used for the online solid-phase extraction (SPE) of Cd(II), Cu(II), and Co(II) ions for their determination at trace concentration levels by flame atomic absorption spectrometry. The effective factors for the online SPE such as the pH and the flow rate of the sample solution, and type, volume, and flow rate of eluent were investigated. The concentration levels of Cd(II), Cu(II), and Co(II) were measured in certified reference materials including Virginia tobacco leaves (CTA-VTL-2) and water-trace elements (NWTM-15.2) to validate this method. The metal levels in environmental water were determined by this method, and the values were checked by spiking and recovery experiments and independent analysis by inductively coupled plasma-mass spectrometry. The adsorption capacities of the sorbent were found to be 41.2, 31.6, and 25.6?mg/g for Cd(II), Cu(II), and Co(II), respectively. This method was also successfully used for the determination of Cd(II), Cu(II), and Co(II) concentrations in rice and molasses.     

A Total Solution to Baseline Separation of 20 Brominated Flame Retardant Additives in Electronic Products with Automated Soxhlet Hot Extraction and Gas Chromatography‐Mass Spectrometry

An efficient and reliable separation technique based on automated Soxhlet hot extraction (AHSE) was developed and validated. It can be applied to rapid separations of 20 persistent organic pollutants, including two types of brominated flame retardants (BFRs), polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) contained in nonmetallic component parts of electronic products. The qualitative chromatographic analyses were carried out by using a gas chromatography coupled with a mass spectrometry detector (GC‐MS). The 20 persistent organic pollutants were simultaneously and completely separated by a 15 meter HP‐5MS short capillary column in 25 minutes. Through the tests of extraction performance, effects of solvent and extraction time on selected BFRs were investigated; toluene and 120 min extraction time were chose as the optimum conditions. Besides, this article examines the influence of temperature on the chromatographic analysis, the optimum temperature parameters were 280 °C and 320 °C for injector and column, respectively. The ASHE‐GCMS method was validated for the analysis of the certified reference material of CRM8110‐a and IRMM310. The limits of detection (LOD) for polymer sample was 0.55‐4.50 μg mL^?1; linearity range from 0.11 to 16 μg mL^?1. The proposed methodology can fully meet the requirement of relational directives.     

New Application of Chemically Modified Multiwalled Carbon Nanotubes with Thiosemicarbazide as a Sorbent for Separation and Preconcentration of Trace Amounts of Co(II), Cd(II), Cu(II), and Zn(II) in Environmental and Biological Samples Prior to Determination by Flame Atomic Absorption Spectrometry

The present article reports the application of Thiosemicarbazide‐modified multiwalled carbon nanotubes (MWCNTs‐TSC) as a new, easily prepared selective and stable solid sorbent for the preconcentration of trace Co(II), Cd(II), Cu(II) and Zn(II) ions in aqueous solution prior to the determination by flame atomic absorption spectrometry. The studied metal ions can be adsorbed quantitatively on MMWNTs at pH 5.0 and then eluted completely with HNO₃ (1.5 mol L^?1) prior to their determination by flame atomic absorption spectrometry. The separation/preconcentration conditions of analytes were investigated, including the pH, the sample flow rate and volume, the elution condition and the interfering ions. The maximum adsorption capacity of the adsorbent at optimum conditions were found to be 32.5, 27.3, 44.5 and 34.1 mg g^?1 for Co(II), Cd(II), Cu(II) and Zn(II), and the detection limits of the method were found to be 0.28, 0.13, 0.21 and 0.17 μg L^?1, respectively. The proposed method was successfully applied for extraction and determination of the analytes in well water, sea water, wastewater, soil, and blood samples.