石墨炉原子吸收光谱法测定磷矿石中微量铅

研究了石墨炉原子吸收光谱法测定磷矿石中微量铅，探讨了熔样过程，基体效应，共存元素及载气流速等干扰，并进行了干扰抑制试验，提出了最优方式对磷矿石中微量铅进行测定，回收率为90．5％～107．0％。     

Hollow fiber supported liquid membrane extraction for ultrasensitive determination of trace lead by portable tungsten coil electrothermal atomic absorption spectrometry

Hollow fiber supported liquid membrane extraction (HF-SLME) was used to separate and enrich trace lead from a large volume of 250 mL water sample to a final tiny volume of 30 μL of 1-octanol, 5 μL of which was inject into a tungsten coil electrothermal atomic absorption spectrometer (W-coil ET-AAS) for determination of lead. Some important parameters that influenced the extraction and determination were investigated in detail, such as the concentration of ammonium pyrrolidine dithiocarbamate (APDC), pH of sample solution, stirring rate, extraction time, pyrolysis current, atomization current, carrier gas flow rate, as well as interferences. Under the optimized conditions, a practical enrichment factor of 499 and a limit of detection (3σ) of 0.2 ng mL^{− 1} were obtained. The calibration curve was linear in the range of 0.5–10 ng mL^{− 1}. The relative standard deviation (RSD) was 5.6% for five measurements of a 4 ng mL^{− 1} lead standard solution. The accuracy of this method was examined by the analysis of certified reference water samples (GBW(E)080398 and GSBZ(E) 50009-88) for lead. Finally, the proposed method was applied to the determination of lead in local tap water, pond water and river water, with recoveries in the range of 96–109% for spiked samples.     

HBF4溶液中全铅液流电池

报道了一种HBF₄水溶液中的全铅液流电池,正、负电极电解液均采用Pb（BF₄）₂的HBF₄水溶液.在酸性的四氟硼酸铅电解液中考察了石墨电极和玻碳电极作为工作电极的循环伏安性能,石墨电极较适于用作全铅液流电池的正、负电极.采用石墨电极作为电池的正、负电极并在四氟硼酸铅酸性电解液中进行充放电实验,其中Pb（BF₄）₂浓度分别为0.5、1.0和1.5 mol·L^-1,且保持游离的HBF₄浓度为1.0 mol·L^-1.该电池为单液流电池,不需要隔膜分隔正、负极的电解液,电流密度为10、20和40 mA.cm^-2,当限定充电容量为7.0 mAh.cm^-2,放电电压截止到1.0 V时,平均库仑效率大于87%,平均能量效率大于68%;当电解液采用1.0或1.5 mol·L^-1 Pb（BF₄）₂+1.0 mol·L^-1HBF₄水溶液时,在10及20 mA.cm^-2电流下的能量效率最高可超过74%.     

土壤中铅的含量及其化学形态分析

对广州市黄埔港区所取土壤中铅的化学形态分析进行了研究。采用含不同组分提取剂的连续提取程序对1 g土壤进行提取,使之分成8种形态的铅,并用火焰原子吸收光谱法(FAAS)对每种提取所得的形态中的铅进行了测定。另在一份试样中直接测定其总铅量,对提取剂的组成及其溶液的浓度及提取操作条件进行了研究和优化,对FAAS测定方法的仪器工作条件作了说明。试验结果表明,所取试样中大部分铅以稳定的结合形态存在,以可交换态和碳酸盐结合态存在的铅仅达6%,总铅量随土壤深度的增加而减少。FAAS测定方法的灵敏度和检出限依次为0.007 mg.L-1及0.01 mg.L-1,分析和测定了4个试样中8种形态的铅量,其加和量为147.9 mg.kg-1,与直接测得的总铅量(159.9 mg.kg-1)之间的偏差小于10%。     

微波消解-火焰原子吸收光谱法测定污泥中铅

研究了微波消解-火焰原子吸收光谱法测定污泥中铅。应用正交试验设计法确定了微波消解试样的最佳条件。该法与传统敞口消解法测定结果吻合。样品测定结果的相对标准偏差（n=6）为1.5％～4．7％,加标回收率为93．0%-106．2％。该方法省时省酸,减少环境污染,改善了工作环境。     

石墨炉原子吸收光谱法测定苦黄注射液及其中药材中的铅和镉

应用石墨炉原子吸收光谱（GF-AAS）法测定了苦黄注射液及其生中药材中铅及镉量。试样用浓硝酸及过氧化氢消解。对仪器的工作条件,包括波长、光谱带宽、灰化温度及原子化温度,作了试验和优化。选用柠檬酸作为基体改进剂,对大黄、茵陈、柴胡、苦参及“苦黄”注射液等试样中的铅及镉量作了测定,分析结果的相对标准偏差均小于4．4％。按标准加入法作了回收率试验,测得值在96%～110％之间。     

回流冷凝试样消解-电感耦合等离子体原子发射光谱法测定铝合金中铅、镉、铬和汞

采用回流冷凝技术,将电子电气产品中铝合金样品用稀盐酸加热溶解后,用电感耦合等离子体原子发射光谱法(ICP-AES)同时测定电子电气产品铝合金中铅、镉、铬和汞,方法的检出限为0.001 8~0.019 mg.L-1,方法的回收率和精密度分别为92.3%~96.1%和0.16%~3.71%。     

火焰原子吸收法测定氧化钼中铜、铅

本文介绍了用火焰原子吸收法测定氧化钼中铜、铅的方法,确定了两种元素最佳仪器工作条件,该方法快速、简便、准确,对试样的回收为９８．８－１０２％,样品测定的相对偏差小于１％,对实际样品了测定获得满意结果。     

The impact of stochastic lead time reduction on inventory cost under order crossover

We use exponential lead times to demonstrate that reducing mean lead time has a secondary reduction of the variance due to order crossover. The net effect is that of reducing the inventory cost, and if the reduction in inventory cost overrides the investment in lead time reduction, then the lead time reduction strategy would be tenable.We define lead time reduction as the process of decreasing lead time at an increased cost. To date, decreasing lead times has been confined to deterministic instances. We examine the case where lead times are exponential, for when lead times are stochastic, deliveries are subject to order crossover, so that we must consider effective lead times rather than the actual lead times. The result is that the variance of these lead times is less than the variance of the original replenishment lead times.Here we present a two-stage procedure for reducing the mean and variance for exponentially distributed lead times. We assume that the lead time is made of one or several components and is the time between when the need of a replenishment order is determined to the time of receipt.     

Quantification of Tin and Lead in Binary Alloys Using Voltammetry of Immobilized Microparticles

Voltammetry of immobilized microparticles (VMP) has been used in this work for the quantitative determination of tin and lead particles in their binary alloys. Carbon paste electrodes, which contained small amounts of tin and lead or their mixtures, were used as working electrodes and square wave voltammograms of each electrode were recorded. Quantification was performed using optimum experimental conditions, obtained by an experimental design technique. The calibration was made by measuring the percentage peak height of each metal taking the sum of peak currents of the both metals as 100 %. The results were compared with quantitative results of X‐ray fluorescence (XRF) technique to evaluate the capability of VMP method in its quantitative determination of solid samples.