金银花茶中8种微量元素溶出特性研究

目的 探究金银花茶样品中8种微量元素的溶出特性。方法 基于电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS),测定样品中Na、Ca、Mg、Mn、Fe、Zn、Cu、Se 8种微量元素含量,并分别研究了浸泡时间、浸泡次数及浸泡温度与元素溶出特性之间的关系。结果 结果表明,金银花茶中微量元素含量丰富,8种元素含量由高到低的顺序为：Ca>Mg> Fe>Na>Mn> Zn>Cu>Se。各元素溶出量随浸泡时间延长而升高,其中Fe溶出率最低,表明Fe最难溶出。除Na和Se以外,各元素溶出量随浸泡次数增加而降低,随浸泡温度升高而升高;Na的溶出量随浸泡次数增加呈先降低后升高的趋势,而Se的溶出量随浸泡次数增加而降低;Na和Se的溶出量均随浸泡温度升高呈先升高再降低的趋势。各元素溶出量与浸泡时间、浸泡次数及浸泡温度之间的关系均可通过建立不同类型的数学模型进行描述。结论 从保健茶饮的功能性和风味角度考虑,金银花茶冲泡应选用100℃的水温,且冲泡次数应不超过4次。     

ICP–OES法测定绿茶中7种重金属元素的溶出量

建立了以电感耦合等离子体原子发射光谱(ICP–OES)法同时测定绿茶中铁、铜、锰、镍、锌、镉、铅等7种重金属元素溶出量的方法。以3种绿茶为研究对象,通过模拟实际生活中的泡茶方式,用100℃的水浸泡茶叶,过滤后用ICP–OES法进行测定。结果表明,随着浸泡时间的延长,重金属元素的溶出量逐渐增加;随着茶叶被浸泡的次数增加,重金属元素的溶出量逐渐降低。7种重金属的添加水平为0.003~4μg/m L时,加标回收率为100.00%~109.55%。测定结果的相对标准偏差为2.17%~7.13%(n=7)。检出限为0.012~0.622 mg/kg。该方法快速简单,具有良好的精密度与准确度,可用于茶叶中重金属的测定。     

大承气颗粒剂中微量元素的溶出量分析

采用原子吸收光谱法测定了大承气颗粒剂中铅、砷、镉、 铬、铜和锌的含量及其在人工胃液和人工肠液中的溶出量。结果表明，大承气颗粒剂中微量重金属元素在人工胃液中的溶出量明显高于人工肠液中，其中铜、 锌的溶出百分率较其它元素高。     

麦饭石中微量元素的溶出及其动力学特征

通过改变颗粒尺寸、温度、时间、溶出次数及活化处理等条件 ,分析了麦饭石溶出液中微量元素的溶出情况 ;通过ICP AES检测了不同时间及温度条件下微量元素Sr的溶出量 ,并进行了元素溶出的动力学特征的研究。结果显示 ,麦饭石颗粒尺寸减小 ,溶出温度增加 ,溶出时间延长 ,溶出次数减少以及对麦饭石进行活化处理都将提高麦饭石微量元素的溶出能力 ;微量元素Sr的溶出过程受控于扩散传质过程 ,其活化能为 4 5 3 6kJ/mol,速率常数与温度的关系为kΣ=0 1 46×е- 4536 /RT,动力学模型的计算结果与实测值吻合较好。通过考察不同溶出条件下麦饭石中微量元素溶出情况以及溶出动力学特征 ,获得微量元素溶出的控制性环节 ,为提高微量元素溶出量提供条件。     

ICP-MS法测定新会柑普茶元素溶出特性

为研究新会柑普茶浸泡过程中元素溶出特性,采用电感耦合等离子体质谱法分别对柑普茶中元素含量及浸泡茶水中相应元素进行测定。通过模拟实际生活中的泡茶方式,用100℃的水浸泡茶叶,过滤后进行测定。结果表明,柑普茶中含有丰富的Mg,Mn,Fe,Zn等多种有益元素,以及一些重金属元素,如Pb,As,Cr,Cd,Hg。元素的溶出率与浸泡次数成指数关系,第1次浸泡的溶出率最高,随着茶叶被浸泡次数的增加,元素的溶出量逐渐降低。各元素的加标回收率为86.5%～98.5%,测定结果的相对标准偏差为0.74%～6.2%(n=6)。该方法具有良好的精密度和准确度,可用于柑普茶中多元素的分析测定。     

邻苯二甲酸二(2-乙基)己酯和偏苯三酸三辛酯在临床不同药液中溶出量的比较

聚氯乙烯(PVC)材质的医疗器械产品中需要加入增塑剂以改善柔韧性,目前最常用的增塑剂是邻苯二甲酸二(2-乙基)己酯(DEHP)和偏苯三酸三辛酯(TOTM)。本文考察了PVC一次性使用输液器产品在脂溶性药液(紫杉醇注射液)、肠外营养液(脂肪乳)、酸性药液(左氧氟沙星,pH 3.0~5.0)和碱性药液(呋塞米,pH 8.0~9.0)中的DEHP和TOTM溶出量,并进行对比分析。先建立了一种高效液相色谱-紫外检测(HPLC-UV)方法测定增塑剂的溶出量,并利用该方法对增塑剂的溶出量进行了分析。实验结果表明,增塑剂在不同药液中均有一定的溶出情况,其中紫杉醇注射液对增塑剂的溶出量要高于脂肪乳,并远高于左氧氟沙星和呋塞米注射液。通过对比DEHP和TOTM的溶出量可以看出,在相同的浸提条件下,TOTM的溶出量远低于DEHP的溶出量。利用紫杉醇注射液浸提24 h,PVC输液器产品DEHP的溶出量为21.14 mg,而TOTM的溶出量仅为0.078 mg。DEHP的溶出量为TOTM溶出量的270倍。因此,TOTM具有的较好耐迁移性,是一种潜在的DEHP替代增塑剂。     

差分脉冲溶出伏安法测定陶瓷器皿中铅和镉的溶出率

采用4%的乙酸浸泡陶瓷样品24 h,应用同位镀汞差分脉冲溶出伏安法测定了陶瓷样品中微量重金属铅、镉的溶出量。以0.1 mol/L的硝酸溶液做底液,0.1 mol/L的KCl溶液做支持电解质,2 g/L的Hg2+溶液做镀汞液,测得铅的溶出峰电位为-0.5 V(vsSCE),镉的溶出峰电位为-0.7 V(vsSCE),两者含量在5×10-4～1 mg/L和5×10-4～0.5 mg/L范围内峰电流和其含量呈良好的线性关系,检出限分别为2×10-4和4.3×10-3mg/L。     

土壤环境生态对重金属元素迁移影响分析

作物中重金属元素主要来自土壤，其含量与作物种类和土壤环境有关。土壤中重金属元素含量、土壤pH值、Eh值、土壤化学组成、土壤质地等环境因素都影响作物中重金属元素含量。土壤pH值和Eh值影响重金属元素的活动性。重金属元素的水溶态容易被作物吸收，而难溶态和被土壤胶体固定的重金属元素，不能被作物吸收。同种作物重金属元素含量的差异主要取决于土壤环境。     

萃取液浓度对火焰原子吸收光谱法测定日用陶瓷铅、镉溶出量的影响研究

采用火焰原子吸收光谱法测定日用陶瓷的铅、镉溶出量和标准曲线,通过对不同浓度的萃取液及其稀释液在各自相应的标准曲线条件下进行重金属溶出量检测,运用单因素多水平方差分析法(F检验)验证结果数据的显著性差异水平,并依据Lambert-Beer定律研究差异形成原因.推导在置信度为95%的条件下,当样品中铅的质量浓度低于80.00 mg/L、镉的质量浓度低于1.000 mg/L时,原始样液与其稀释液的测定结果间无显著性差异.当样液中铅的质量浓度高于100.00 mg/L、镉的质量浓度高于1.000 mg/L时,原始样液与其稀释液测定结果之间的显著性差异程度将随重金属元素浓度升高而加大.     

不同产地磁石炮制前后元素的溶出量分析

利用吸收光度法测定三种不同产地磁石的生品和炮制品的水煎液中铁的含量,用电感耦合等离子体发射光谱法测定其余十四种元素的含量。结果表明,三种磁石中铁及微量元素的溶出量有明显差别;经煅淬后主成分铁及大部分微量元素的溶出量都有明显增加,而砷、铅的溶出量显著降低。磁 石中各种元素的溶出量与其产地和炮制有关。     

Copper release kinetics from a long-term contaminated acid soil using a stirred flow chamber: effect of ionic strength and pH

The effect of pH and ionic strength on copper release in a long-term Cu-polluted soil was studied using a stirred flow chamber. The presence of Ca(2+) and Na(+) was also evaluated. More copper was released as the ionic strength increased, and it was significantly higher in the presence of Ca(2+) than in the presence of Na(+). The maximum amount of Cu that could be released under experimental conditions increased logarithmically as the ionic strength increased, and the release rate parameters were not significantly correlated with ionic strength values. The maximum amount of Cu that could be released was similar for solutions with pH values between 5.5 and 8.5. For solutions with a pH value below 4.5, the amount of Cu released increased exponentially as the pH decreased. The release rate parameters and Cu release pattern were affected by pH, especially for more acidic solutions (pH values of 2.5 and 3.5).     

Is trace metal release in wetland soils controlled by organic matter mobility or Fe-oxyhydroxides reduction?

Aerobic and anaerobic incubation experiments on a wetland soil samples were used to assess the respective roles of organic matter (OM) release, Fe-oxyhydroxides reduction and redox/speciation changes on trace metal mobility during soil reduction. Significant amounts of Cu, Cr, Co, Ni, Pb, U, Th and Rare Earth Elements (REE) were released during anaerobic incubation, and were accompanied by strong Fe(II) and dissolved organic matter (DOM) release. Aerobic incubation at pH 7 also resulted in significant trace metal and DOM release, suggesting that Fe-oxyhydroxide reduction is not the sole mechanism controlling trace metal mobility during soil reduction. Using these results and redox/speciation modeling, four types of trace metal behavior were identified: (i) metals bound to organic matter (OM) and released by DOM release (REE); (ii) metals bound to both OM and Fe-oxyhydroxides, and released by the combined effect of DOM release and Fe(III) reduction (Pb and Ni); (iii) metals bound solely to soil Fe-oxyhydroxides and released by its reductive dissolution (Co); and (iv) metals for which release mechanisms are unclear because their behavior upon reduction is affected by changes in redox state and/or solution speciation (Cu, Cr, U and Th). Even though the process of soil Fe-oxyhydroxide reduction is important in controlling metal mobility in wetland soils, the present study showed that the dominant mechanism for this process is OM release. Thus, OM should be systematically monitored in experimental studies dedicated to understand trace metal mobility in wetland soils. Due to the fact that the process of OM release is mainly controlled by pH variations, the pH is a more crucial parameter than Eh for metal mobility in wetland soils.     

Nickel and chromium release from stents into isotonic NaCl solution investigated with the aid of neutron activation analysis

Stent placement has become an effective treatment for abrupt or threatened vessel closure in recent years. As a preliminary investigation on the allergy problem towards to Ni and Cr metals from implanted stent, the release of the two elements from stents into isotonic NaCl solution was investigated. Trace amounts of Ni and Cr metals released from stents are successfully determined by neutron activation analysis (NAA). An extreme experimental condition is applied in the NAA procedure to reach a low detection limit of 1 ng Ni. A conclusion is given about the influence on the Ni and Cr release from gold coating, from the expansion, and from the different incubation periods.     

Effect of moisture on copolymer fibers based on 5-amino-2-(p-aminophenyl)-benzimidazole

In recent years, there has been concern in the soft body armor community that copolymer fibers based on 5-amino-2-(p-aminophenyl)-benzimidazole can release hydrochloric acid, which is present in these fibers as a by-product of the manufacturing process. The presence of acids could potentially be detrimental to other fibers that might come in contact with these materials. In an effort to examine this issue, a study was designed to investigate the release of acid in different environments from these fibers. During the first phase of the study, fibers were exposed to water and pH decreases were observed. While immersed in deionized water, two of the fiber samples studied released a sufficient amount of acid to drop the pH of the solution from approximately pH 6.0 to approximately pH 3.0 in less than 10 d at room temperature. Further ion-selective electrode studies of chloride ion released from these fibers indicated that hydrochloric acid may not be the species responsible for this pH reduction. In a second phase of the investigation, fibers were exposed to water vapor in an elevated temperature environment (conditions were 65 °C, 80% RH). While the pH reduction released by the water vapor exposure was substantially less than observed in the submersion phase, a reduction in the yarn tensile strength of some of the fibers was observed during this phase of the study. In a third phase, fibers were exposed in a dry oven (less than 5% RH) at 65 °C. Almost no pH reduction or strength reduction was observed. Molecular spectroscopy was also performed to better understand the effect of elevated temperature and moisture environments on these fibers.     

Release of copper from commercial solid-state copper ion-selective electrodes

The release of copper from two commercial solid-state cupric ion-selective electrodes [Orion 94-29 Cupric Electrode (I) and Radiometer F1112 Selectrode (II)] was measured by immersion in the following media: 0.1M potassium nitrate (pH = 4.7), 0.5M sodium chloride (pH = 4.7) and 0.1M nitric acid. In the 0.1M potassium nitrate medium, the amount of copper released from both electrodes causes interference when they are used for the determination of cupric ion at the 10⁻⁷M level. In comparison with the 0.1M potassium nitrate medium, the copper release in the 0.5M sodium chloride and 0.1M nitric acid media was increased for electrode II but not for electrode I. The release of copper was not affected by removal of oxygen from the media but can be substantially lowered by coating the electrodes with a thin cation-exchange membrane (Nafion). The mechanism of copper dissolution is investigated.     

Sorption of copper by suspended particulate matter

The sorption of copper by suspended particulate matter from river water was investigated as a function of pH and solids concentration. Water was collected from the Delaware River and particulate matter was concentrated using Tangential-Flow Filtration (TFF). The adsorption of copper increased with increasing pH until pH 9.0. A decrease in copper adsorption was found for higher pH values. The adsorption of copper was greater for the samples with added copper than for the suspension for which no metal was added. An increase of copper adsorption proportional to particulate matter concentration was also observed. At both pH 6.0 and 7.0, there was a decrease in the adsorption of copper with increasing copper concentration.     

ICP-MS determination of toxic-metal release from pumping systems for food processing

The release of heavy metals from uncovered and nickel-covered brass pumps has been evaluated by ICP-MS analysis in both simple ultrapure water and 3% acetic acid solution (mimic of neutral and acid edible liquids, respectively), following a procedure similar to that recommended by the National Sanitation Foundation (NSF) International, Test Procedure P203. The results found highlight that the main release regards zinc, copper and lead, i.e. the three major metals present in brass alloys. The first contact of brass surfaces with the extraction solvent leads to an extensive Pb release which is comparable with that observed for Cu and Zn. Subsequent washings reduce markedly the Pb release, thus rising in evidence a progressive surface passivation. In particular, the Pb release found after four repeated washings turns out to approach the limit set by both Italian and USA governments for liquids used for food purposes when determined in neutral media, while it remains quite higher when evaluated in acid media. Release analyses conducted on nickel-covered brass pumps point out that the Niploy nickel coating process is very effective for brass surface protection, in that the Pb release is reduced of about three orders of magnitude, but a Ni release exceeding the relevant permitted level is in this case observed.     

Application d'un tétraasamacrocycle greffé sur polymère à l'extraction et au dosage du cuivre en eau de mer

(Application of a polymer-supported tetraazamacrocyle to the extraction of copper from sea water)Copper is extracted with 1,4,8,11-tetraazacyclotetradecane bound to poly(chloromethyl)vinylbenzene. The material has a very low affinity for alkaline and alkaline earth metals. The influence of salinity, pH and temperature on the complexation of copper is described. Results for waters agree well with those obtained with Chelex-100.     

"Acid extractable" metal concentrations in solid matrices: a comparison and evaluation of operationally defined extraction procedures and leaching tests

Different frequently used methods to determine the influence of acid conditions on heavy metal release from soils, sediments and waste materials, namely pH_stat leaching tests and acid extractions with acetic acid (HOAc) (0.11 M and 0.43 M) and sodium acetate (NaOAc) (1 M) were compared for 30 samples (soils, sediments and waste materials) with different physico-chemical properties and a different degree of contamination. However, no distinct relationship was found between physico-chemical sample characteristics, total element concentrations and acid-extractable metal concentrations in the presented dataset.

pH played an important role in explaining the release of metals from the contaminated soils, sediments and waste materials. The pH-shift after extraction with the different acetic acid solutions (0.11 M and 0.43 M) was both explained by the initial pH of the sample and its acid neutralizing capacity. The pH of the NaOAc extract was well buffered and the release of elements from solid matrices by NaOAc was both the result of the complexation with acetate and pH (pH 5). Generally, a linear correlation was found between the amount of Zn and Cd extracted by 0.11 M HOAc, 0.43 M HOAc and 1 M NaOAc. The amounts of Zn and Cd extracted with HOAc (0.11 M and 0.43 M) were comparable with amounts of respectively Zn and Cd released during pH_stat leaching at pH 4. However, for Cu, Pb and As, it was often not possible to relate the results of a pH_stat leaching test to the results of single extractions with acetic acid solutions.     

Different strategies to assess Cu and Pb mobilization in polluted river sediments

Summary For studying the mechanisms of trace metal mobilization in sediments several strategies have been employed, such as single extraction, sequential extractions, ion exchange, or progressive acidification. Several authors assert that sequential extraction is the best option. In this study two procedures are used in order to assess the mobility of copper and lead in heavily polluted river sediments: sequential extraction using a modified Tessier procedure, and progressive acidification, using an automated method. Six heavily polluted sediment samples are studied by applying the two procedures. The amount of metal released at different pH-values (pH 5 and pH 2) is compared with the resulting distribution when the sequential extraction procedure is applied. The information obtained from the two different approaches is discussed. For both metals a different behaviour is observed when applying each of the two procedures. Thus, copper is more easily released than lead when progressive acidification is followed, whereas an inverse situation is observed when sequential extraction is applied.