石墨炉原子吸收光谱法测定茶叶中铅含量的方法学研究

目的:建立石墨炉原子吸收光谱法测定茶叶中铅含量的方法。方法:研究几种常用的基体改进剂对茶叶中铅原子吸收信号的影响;以磷酸二氢铵为基体改进剂,应用响应面分析法获得测定茶叶中铅含量的最佳灰化温度和原子化温度,编辑石墨炉升温程序,建立石墨炉原子吸收光谱法测定茶叶中铅含量的方法。结果:磷酸二氢铵是石墨炉原子吸收光谱法测定茶叶中铅含量的理想的基体改进剂,最佳灰化温度和原子化温度分别为730℃和2 166℃。铅标准曲线的回归方程为ABS=0.00514C,相关系数0.9999,线性范围1.7～30μg/L,特征质量浓度为0.86μg/L,检出限为0.34μg/L。茶叶成分分析标准物质的测量值为(1.41±0.04)mg/kg,与标称值(1.5±0.2)mg/kg吻合,相对标准偏差为3.06%,加标回收率为95.79%。3种茶叶样品的铅含量分别为0.71±0.03、0.82±0.04和(0.52±0.01)mg/kg。结论:以磷酸二氢铵为基体改进剂,石墨炉原子吸收光谱法能够准确、可靠地测定茶叶中的铅含量。     

石墨炉原子吸收光谱法测定皂树皮提取物中铅的不确定度评定

目的:探讨石墨炉原子吸收光谱法测定皂树皮提取物中铅不确定度的评定方法。方法:用原子吸收光谱仪测定皂树皮提取物样品中铅含量,根据该分析过程的测量数学模型从样品称量、样品定容、标准溶液配制、标准曲线测定、样品和空白测定等方面进行测量不确定度的计算。结果:样品X_1铅含量为1.28 mg/kg,扩展不确定度为0.090 mg/kg(k=2);样品X_2铅含量为3.90 mg/kg,扩展不确定度为0.250 mg/kg(k=2)。结论:测量过程中的不确定度主要来源于方法的回收率、样品空白变动性、消化液中铅浓度和重复性。通过建立测量数学模型,可对石墨炉原子吸收光谱法测定固体样品中铅测量的不确定度进行合理的评定。     

石墨炉原子吸收光谱法测定红葡萄酒中的微量铅

研究了石墨炉原子吸收法测定葡萄酒中微量铅的适宜条件,采用标准加入法和塞曼效应校正背景,铅的线性范围为10μg／L-50μg／L,回收率为90％-110％。并用此法对5种市售红葡萄酒样品进行测定,结果发现铅含量范围为43．50μg／L-91．77μg／L。     

溶剂稀释植物油直接进样石墨炉原子吸收测定铅含量

建立了溶剂稀释植物油直接进样石墨炉原子吸收测定铅含量的方法。以磷酸二氢铵和硝酸镁混合溶液为基体改进剂,正丁醇溶解植物油,形成均匀透明的溶液,利用石墨炉原子吸收光谱仪测定植物油中的铅含量。优化了石墨炉原子吸收光谱法测定参数。结果表明:在优化条件下,该方法在铅质量浓度0~80μg/L范围内具有良好的线性关系(r=0.996),精密度实验RSD为3.4%~5.8%,检出限为3.2μg/L,回收率为96.0%~104.0%,RSD为3.6%~4.2%。该方法简单快速,灵敏度高,回收率好,适用于植物油中的铅含量测定。     

固相萃取柱脱盐-石墨炉原子吸收法测定酱油中铅

目的 建立固相萃取柱脱盐—石墨炉原子吸收法测定酱油中铅的方法.方法 酱油经微波消解后,消解液用乙酸铵调节至pH≈5.5,过经用5 ml 1 mol/L乙酸铵活化后的DigiSEP-Blue柱,将被测元素铅吸附与基体中高盐分离,再分别用8 ml 2 mol/L硝酸、2 ml纯水洗脱,应用石墨炉原子吸收法测定洗脱液中铅含量.结果 用固相萃取柱可将酱油中98％以上的钠盐与被测元素铅分离,消除了石墨炉原子吸收分光光度计测定铅时的基体干扰.低、高两个铅浓度(10和30 ng/ml)的加标平均回收率(n=7)分别为91.3％ ～95.1％,97.9％～98.6％,相对标准偏差为2.1％ ～7.0％,检出限为1.33 ng/g.结论方法准确、灵敏度高,适于高盐样品酱油中铅含量的测定.     

电热消解-石墨炉原子吸收法测定白酒中铅含量的研究

为了更加方便、快速地检测批量白酒中铅的含量,建立了一种蒸发浓缩-电热消解-石墨炉原子吸收法测定白酒中铅的方法。试验结果表明,该方法在0~80.0μg/L范围内呈线性相关,相关系数为0.999 9,检出限为0.41μg/L,样品的加标回收率在90%~110%之间。该方法准确度、精密度良好,能够简便、快速、有效的测定白酒中的铅含量。     

石墨炉原子吸收法测定高盐食品中的铅及其干扰消除的研究

目的通过研究高盐食品中石墨炉原子吸收法测定铅的基体干扰模式,探讨各种基体改进剂、升温程序和校正模式对减少或消除氯化钠干扰的效果与能力,建立了石墨炉原子吸收法测定高盐食品中铅的方法。方法采用微波消解、湿法消解、高压罐消解和直接稀释法4种前处理方式,硝酸钯-磷酸二氢铵为混合基体改进剂,标准加入法测定高盐食品中铅含量。结果选择283.3 nm为测定波长,磷酸二氢铵-硝酸钯作为基体改进剂,标准加入法为校正模式,在盐度2.2%以下可消除氯化钠的基体干扰。该方法的线性范围为1.8~40.0μg/L,当称样量为0.5 g,定容量为10 ml时,定量限为0.036 mg/kg。结论在较高的盐度中,该方法可消除石墨炉原子吸收测定食品中铅的基体干扰,提高了分析结果的准确性和可靠性。本研究为国标的修订与整合做好了技术储备。     

微波消解石墨炉原子吸收法测定烟草中的铅含量

采用硝酸一过氧化氢体系微波消解,而后以磷酸二氢铵作化学改进剂,利用塞曼自动扣除背景,采用石墨炉原子吸收法测定了部分烟草样品的铅含量.结果表明,铅的检出限为0.28μg/L,回收率在92.0%～102.0%之间,RSD＜3.0%.该法简便快速,适用于批量烟草样品中铅的测定.     

全自动石墨加热消解-石墨炉原子吸收法测定麦苗粉中铅含量的不确定度评定

目的评定全自动石墨加热消解-石墨炉原子吸收法测定麦苗粉中铅含量的不确定度。方法麦苗粉样品经全自动石墨加热消解后,石墨炉原子吸收法测定,外标法定量,根据建立的数据模型对每个不确定度分量进行评定,最终得出对合成不确定度的贡献度。结果置信概率为95%,取包含因子k=2,湿法消解-石墨炉原子吸收法测定麦苗粉中铅含量结果报告为X=(0.17±0.01)mg/kg。结论该方法测量铅不确定度的主要因素是曲线拟合的不确定度。     

石墨炉原子吸收测定大米中的铅不确定度评定

评定石墨炉原子吸收光谱法测定大米中铅含量的不确定度,找出影响不确定度的主要因素。按GB 5009.12—2010建立不确定度的数学模型,根据《化学分析中不确定度评估指南》对石墨炉原子吸收光谱法测定大米中铅含量的不确定度进行评定。结果表明:大米铅含量0.100㎎/kg时,其扩展不确定度为0.009 mg/kg(k=2)。石墨炉原子吸收光谱法测定大米铅含量时,样品消解过程和测定样品消解液中铅的质量浓度产生的不确定度对总不确定度影响最大。     

Changes in smoking prevalence in Ukraine in 2001-5

Objectives

To analyse trends in smoking prevalence in Ukraine from three surveys conducted in 2001–5, and to explore correlates of observed changes, in order to estimate the stage of tobacco epidemic in Ukraine.

Design

Repeated national interview surveys in Ukraine in 2001, 2002 and 2005.

Main outcome measure

Prevalence of current smoking among the population aged ⩾15 years.

Results

The age‐standardised prevalence of current smoking in Ukrainian men was 54.8% in 2001 and 66.8% in 2005. Among Ukrainian women, prevalence increased from 11.5% in 2001 to 20.0% in 2005. ORs for yearly increase in prevalence were estimated as 1.164 (95% CI 1.111 to 1.220) for men and 1.187 (1.124 to 1.253) for women, which implies that, on average, 3–4% of men and 1.5–2% of women living in Ukraine join the smoking population each year.

Conclusions

In Ukraine, smoking prevalence is increasing in most population groups. Among men, the medium deprivation group with secondary education has the highest smoking prevalence. Among women, while the most educated, young and those living in larger cities are the leading group for tobacco use, other groups are also increasing their tobacco use. Tobacco promotion efforts appear to have been significantly more effective in Ukraine than smoking control efforts. The decrease in real cigarette prices in Ukraine in 2001–5 could be the main factor explaining the recent growth in smoking prevalence.Ukraine is a large eastern European country with high smoking prevalence. Tobacco products are widely available at very low prices, and the transnational tobacco industry is extremely successful in promoting its products and lobbying for its interests in the legislative field. Advocacy of tobacco control has only recently achieved some success in the legislative field, with the first tobacco control law being adopted in late 2005. Ukraine ratified the Framework Convention on Tobacco Control in 2006, but there is still much cause for concern regarding the enforcement and effectiveness of the adopted legislative measures. Unfortunately, the government is not yet involved in nationwide surveillance of the tobacco problem, and the available data have mostly been gathered with funding from foreign donors. Several attempts have been made to measure the extent of the tobacco epidemic in the countries of the former Soviet Union (FSU).^{1,2,3,4,5,6,7} Most of these studies have shown rather high smoking prevalence among men (50–70%) and comparatively low prevalence among women (5–20%). Most countries in the FSU have similar smoking rates, while certain trends are shown to be related to the differences in how the transnational tobacco industry succeeds in every national tobacco market.⁶ Unfortunately, few studies have been published showing trends in smoking prevalence in the FSU.⁷ In Ukraine, two studies^3,4 provided point estimates of smoking prevalence.The aim of this study was to analyse trends in smoking prevalence in Ukraine, on the basis of three surveys conducted in 2001–5, and to explore correlates of observed changes in order to estimate the stage of the tobacco epidemic in Ukraine.     

2010年河南省部分食品中重金属污染状况分析

了解河南省部分食品中重金属污染的现状。方法 在河南省18个省辖市采集8大类3 657份食品样品,按照国家标准检测食品中铅、镉和汞的含量,检测结果按照GB 2762—2012《食品安全国家标准食品中污染物限量》进行评价。结果 河南省部分食品中铅含量的平均值为0.34 mg/kg,总体超标率为8.8%(320/3 656),其中粮食、肉类和蔬菜中超标率较高,分别为17.2%(95/552)、14.5%(85/587)和10.7%(57/534);部分食品中镉含量的平均值为0.054 mg/kg,总体超标率为3.9%(143/3 657),其中食用菌和蛋类中超标率较高,分别为9.6%(49/508)和8.1%(42/518);部分食品中汞含量的平均值为0.077 mg/kg,总体超标率为8.3%(303/3 657),其中蔬菜和粮食中超标率较高,分别为25.3%(135/534)和12.3%(68/551)。结论 河南省部分食品中铅、汞污染情况较为严重,其中粮食、蔬菜和肉类食品中污染情况尤为突出,需要加强监管。     

Moulds and mycotoxins in sorghum stored in traditional containers in India

Various traditional containers have been used in India for storage of sorghum grains. Sorghum is susceptible to fungal infestation and toxin elaboration. The present study relates to the mould and mycotoxin contamination (aflatoxin B₁ and T-2 toxin) in stored sorghum in different storage containers viz. “Kotlu” (Storage rooms), earthenware pots, gunny bags and reed baskets. Aspergillus sp. and Fusarium sp. were the prominent genera and the “Kotlu” form of storage was most susceptible to fungal attack. Storage treatment had little effect on fungal contamination, but despite the fungal infestation, the mycotoxin contamination was found to be very low.     

中国固态发酵白酒中功能细菌研究进展

细菌是白酒酿造3大类微生物之一,其在白酒生产中有着重要的作用,如:芽孢杆菌、乳酸菌、放线菌和梭菌等,它们能产生酯类、有机酸、吡嗪、萜烯等微量成分,从而影响白酒的风味与品质。基于细菌在白酒中的重要功能以及微生物分离培养技术和分析检测技术的进步,近年来相关研究越来越深入。该文综述了近年来白酒功能细菌的研究进展,介绍了酿酒各个环节中主要功能细菌及其在白酒中的作用,旨在为白酒功能细菌的研究提供参考。     

Heavy metals in vegetables sold in the local market in Jordan

Heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) in various vegetables (cabbage, green onion, lettuce, parsley, rocket, spinach, carrot, onion, potato and cauliflower) from the market in Jordan were measured using inductively coupled plasma-mass spectrometry. As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn ranged from 0.009–0.275 mg kg^?1 wet weight, 0.004–0.060 mg kg^?1, 0.003–0.401 mg kg^?1, 0.105–3.51 mg kg^?1, 0.15–1.15 mg kg^?1, 0.93–14.39 mg kg^?1, 0.044–0.702 mg kg^?1, 0.072–0.289 mg kg^?1 and 2.23–6.65 mg kg^?1, respectively. Parsley, followed by spinach, contained the highest concentration of heavy metals. Onion contained high levels of toxic heavy metals. The content of Cu in parsley and spinach and Pb in onion exceeded the Codex limits. However, the daily intake of heavy metals from the tested vegetables was lower than the maximum limits for allowable intake.