石墨炉原子吸收分光光度法测定茶叶中的铅

采用石墨炉原子吸收分光光度法测定了产自福建等地茶叶中的铅含量。方法的线性范围为0—80μg/L，回收率达91．7％-101．5％，相对标准偏差1．47％-3．88％。茶样检测结果表明，铅合格率为92．0％；不同茶类铅含量前3位由高到低依次为绿茶，乌龙茶，红茶；各类茶铅含量平均值为1．069mg／kg。     

茶叶的铅污染问题及铅污染的来源

介绍了我国茶叶中铅污染的大致情况,指出我国茶叶中的铅超标问题是一个不争的事实。土壤母质中铅含量较高本底值,土壤特有的理化性质,汽车运行的影响,有机肥料的影响,土壤微生物的影响,茶叶的加工过程,以及茶树本身的生理特征都可能是导致茶叶中铅含量超标的原因。当前,急需解决的问题是各个地区根据本地的实际情况,摸清茶叶铅污染的来源,并通过切实有效的途径来控制或缓解当地茶叶中铅污染问题。     

饮茶与人体健康

茶叶是世界三大饮料(茶叶、咖啡、可可)之一,是我国传统的出口商品。茶叶所以能成为今天人们普遍爱好的饮料,是与它对人们健康有良好作用分不开的。早在公元前二千七百三十七年以前我国劳动人民就发现了茶叶的解毒作用。《神农本草》中有:“神农尝百草,日遇七十二毒,得荼(“荼”即是现在的“茶”)而解之”的记载。到公元二百年左右东汉时代,名医华陀     

石墨炉原子吸收光谱法测量茶叶中铅的不确定度评定

介绍了石墨炉法测定茶叶中铅的测量不确定度的评价.依据GB/T5009.12-2003分析了1 g茶叶中的铅含量.对影响铅含量不确定度的每一个分量进行分析评估,计算得到其扩展不确定度为0.016 mg/L.     

茚三酮比色法测定茶叶中游离氨基酸总量方法存在问题的探讨

氨基酸是茶叶中的主要成分,茶叶中氨基酸与茶叶嫩度有密切关系,它对茶汤的滋味、色泽也有较明显的影响,是形成茶叶香气和鲜爽度的重要成分.茶叶中有20多种游离氨基酸,其中茶氨酸占氨基酸总量的50%以上.     

茶叶中的铅污染问题

介绍了研究茶叶中铅污染的意义以及污染现状,从地域上和时间上阐述了茶叶铅污染现象的一般规律,从土壤母质、环境空气、农药化肥三个方面介绍可能导致茶叶铅含量超标的原因。     

湖北宜昌两种能源加工方式下绿茶铅含量研究

湖北宜昌绿茶的加工能源主要有煤、电。研究采用了原子吸收法对湖北宜昌绿茶的含铅量进行分析,结果表明,在茶叶鲜叶铅含量无明显差异的情况下,以煤作为能源加工的绿茶铅质量分数为(1.67±0.05)mg·kg-1;以电作为能源加工的绿茶铅质量分数为(1.08±0.04)mg·kg-1。通过以电代煤的方式,可以控制茶叶含铅量。     

红茶、绿茶和乌龙茶多糖及多酚对DNA的保护作用研究

用溴化乙锭(EB)作为荧光探针研究了各种茶叶多糖、多酚类化合物对DNA的保护作用.测定了龙井、普耳茶、乌龙茶等8种茶叶中多糖和多酚类提取物存在下DNA与EB混合液的荧光积分强度,并把不同茶叶与DNA相互作用的常数定义为结合常数D,根据D的大小讨论了多糖及多酚类化合物的存在DNA保护作用的影响.结果表明,8种茶叶与DNA...     

浅论绿茶与乌龙茶氟含量对人体健康的影响

分别用重蒸水和自来水，通过蒸煮法和浸泡法制出不同浓度的绿茶液和乌龙茶液，对比测定研究茶液中氟含量，结果表明，茶液中的氟含量随茶叶浓度增加而增加，且乌龙茶高于绿茶，当茶叶浓度超过１０．０ｇ／Ｌ时，茶液中的氟含量即超过国家饮水卫生标准，提示人们饮用水茶液浓度在５．０ｇ／Ｌ左右为宜。     

茶叶和蔬菜中铅的同位素稀释电感耦合等离子体质谱的测定

采用同位素稀释电感耦合等离子体质谱(ID-ICP-MS)法测定了铅的含量,通过对茶叶标准物质(GBW-07605)中铅的测定,考察了方法的准确度和精密度,比较了同位素稀释法与普通外标定量法的测定结果。在5mLHNO3～0.5mLHF～1mLH2O2的消解体系中,ID-ICP-MS法测量茶叶中铅的回收率可达97.7%,相对标准偏差(RSD)小于1.2%。实验对市售的12种茶叶和10种蔬菜中Pb进行测定,铅含量符合相应国家标准的样品分别占总样品数的83%和90%。该法适合于植物样品中微量铅的测定。     

茶叶铅污染来源的研究进展

根据近年来国内外对茶叶铅污染研究的相关报道,综述了茶叶中铅污染的主要来源。这些来源主要包括:茶园土壤酸化和较高的有机质含量,大气沉降物中的铅和茶叶的加工过程。还根据各种茶叶铅污染来源的特征,有针对性地提出了一些防治措施。     

茶叶中的铅

采用原子吸收汾光光度法对我国一些常用茶中Ｐｂ进行了测定，结果表明茶叶中的Ｐｂ通过一般食品，应引起重视。     

陕南茶叶及其产地土壤中微量元素含量的测定

采用微波消解一火焰原子吸收光谱法测定了陕南茶叶及其栽培土壤中Zn、Fe、Cu、Cr、Pb5种微量元素的含量,以指导茶农合理施肥,提高陕南地区茶叶品质。结果表明,茶叶与土壤中矿质元素的含量呈一定的正相关性,不同产地的茶叶和土壤中微量元素的含量有一定的差异;茶叶和土壤中Zn、Fe元素的含量较高,而对人体健康有影响的Pb元素含量低于国家允许标准。     

Evaluation of soil to tea plant elemental correlation using instrumental neutron activation analysis

Instrumental neutron activation analysis using relative and k ₀-based internal monostandard methods were employed for determination of concentrations of 12 elements in soil and tea plants collected from three different tea producing regions in India namely Assam, Darjeeling and Kangra. A total of 17 tea leaf samples along with corresponding soil samples were analyzed for elemental content. The obtained concentration data was used for the soil–plant elemental correlation studies. Positive correlation was observed between elemental concentrations of tea plants and the associated soil with Pearson correlation coefficient values in the range 0.6–0.9 for ten elements. Variations in transfer factor values were also observed according to the geo-chemical variation.     

茶叶中稀土元素的萃取分离-ICP-AES法测定

采用1-苯基-3-甲基-4-苯甲酰基-5-吡唑酮(PMBP)苯溶液萃取分离-ICP-AES法同时测定茶叶中15种稀土元素,消除了基体的干扰,并对样品前处理方法、萃取分离条件进行了考查.方法回收率为: 92.3%～112%,相对标准偏差＜2.5%.在最佳工作条件下,测定了茶叶标准物质(GBW07605)中稀土元素,结果与标准值吻合.     

The impact of lead pollution on the environment of Rabat-Sale' (Morocco)

There are numerous possible vectors of industrial lead poisoning in unprotected work environments and the areas surrounding industrial sites. In the Rabat-Salé region, ceramics is the industry which uses most lead. Galena (PbS) is used in the fabrication of some types of pottery, and other lead-based compounds are used as glaze. A second source of lead pollution is the production of some fuels, in which lead is used as an anti detonator. In order to evaluate the impact of lead contamination on the environment, our investigation is focused on the lead concentration in the atmosphere, soil and vegetation at five stations in the Rabat-Salé region. We found concentrations of lead higher than those published for any other country in the atmosphere and vegetation near the ceramics factories of Rabat-Salé. These concentrations decreased significantly as we moved away from urban areas.     

Contamination with cadmium from micropipette tips

Contamination by cadmium from micropipette tips from two different manufacturers was tested. Tips were washed with two different acids and the washing solutions were analysed by atomic absorption (graphite furnace). The washed tips were controlled by analysing pure acids and were found decontaminated. Clear contamination was found in yellow Eppendorf pipettes, which varied according to the consignment. The decontamination of disposable micropipette tips is emphasized when trace metal contamination should be avoided.     

Profiling of In Vitro Bioaccessibility and Intestinal Uptake of Flavonoids after Consumption of Commonly Available Green Tea Types

The aim of this study was to profile the bioaccessibility and intestinal absorption of epicatechins and flavonols in different forms of green tea and its formulation: loose leaf tea, powdered tea, 35% catechins containing GTE, and GTE formulated with green tea-derived polysaccharide and flavonols (CATEPLUS™). The bioaccessibillity and intestinal absorption of epicatechins and flavonols was investigated by using an in vitro digestion model system with Caco-2 cells. The bioaccessibility of total epicatechins in loose leaf tea, powdered tea, GTE, and CATEPLUS™ was 1.27%, 2.30%, 22.05%, and 18.72%, respectively, showing that GTE and CATEPLUS™ had significantly higher bioaccessibility than powdered tea and loose leaf tea. None of the flavonols were detected in powdered tea and loose leaf tea, but the bioaccessibility of the total flavonols in GTE and CATEPLUS™ was 85.74% and 66.98%, respectively. The highest intestinal absorption of epicatechins was found in CATEPLUS™ (171.39 ± 5.39 ng/mg protein) followed by GTE (57.38 ± 9.31), powdered tea (3.60 ± 0.67), and loose leaf tea (2.94 ± 1.03). The results from the study suggest that formulating green tea extracts rich in catechins with second components obtained from green tea processing could enhance the bioavailability of epicatechins.     

How suitable are scalp hair and toenail as biomonitors?

This paper describes the assessment of exposure levels to metals and possible workers' contamination in three galvanizing factories applying the same processes. Concerning the elements determined in air filters, 92.3% of them were also determined in hair and toenail samples: Ag, Al, As, Au, Cl, Cr, Cu, Fe, Mn, Na, Sb and Zn. These result point out that hair and toenail reflect the influence of the polluted environment on workers' health and can be useful as bioindicators in epidemiological studies. Instrumental neutron activation analysis was applied to all matrices which confirms its status as one of the most versatile analytical techniques.