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目的 评定氢化物原子荧光法测定大米中总砷含量的不确定度。方法 依据JJF 1059.1—2012《测量不确定度的评定与表示》和CNAS—GL006: 2019《化学分析中不确定度的评估指南》,样品经硝酸-高氯酸-硫酸消解,硫脲-抗坏血酸还原测定总砷含量。同时分析检测过程中的不确定度来源,计算相对标准合成不确定度,最终得到大米中总砷的扩展不确定度。结果 当大米中总砷含量为0.144 mg/kg时,在95%的置信区间下,扩展不确定度为0.012 mg/kg(k=2)。结论 采用氢化物原子荧光法测定时,不确定度的主要来源为样品消解、标准溶液的配制及测量重复性所产生的不确定度。 相似文献
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高氯酸湿消化-原子荧光光度法测定饲料中总砷的不确定度评定 总被引:2,自引:1,他引:1
对高氯酸湿消化法处理饲料样品后用原子荧光光度法测定总砷含量的测量不确定度进行了评定。通过建立测量过程中各分量的数学模型,分析、识别了不确定度来源,其测量不确定度来源于样品测试液总体积、样品称量、样品重复测定、回收率、标准物质、标准曲线等因素,估算出各不确定度分量对测量不确定度的影响,在对各不确定度分量进行量化的基础上,合成得到了测量结果的相对标准不确定度。结果表明,样品重复测定和回收率,是影响该方法不确定度的主要因素,从而为采用该方法测定饲料中总砷含量的质量控制提供了理论依据。 相似文献
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目的:为提高电感耦合等离子质谱法(ICP-MS)测定茶多酚片中痕量重金属铅和总砷含量的准确性,通过建立数学模型,对不确定度来源进行分析。方法:样品经过微波消解前处理,采用ICP-MS法分别测定茶多酚片中铅和总砷的含量,根据JJF1059.1-2012《测量不确定度评定与表示》分析不确定度来源,计算合成不确定度和扩展不确定度。结果:经过分析计算,茶多酚片中铅和总砷的扩展不确定度分别为0.029、0.010mg/kg。结论:影响茶多酚片中铅和总砷ICP-MS法测定的不确定度主要来源为样品前处理和标准溶液。 相似文献
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目的 评定微波消解-原子荧光法测定大米粉中总砷含量的不确定度。方法 依据JJF 1059.1-2012《测量不确定度评定与表示》及CNAS-GL 006-2019《化学分析中不确定度的评估指南》, 采用微波消解-原子荧光法测定大米粉质控样品中总砷含量, 建立数学模型, 并对整个分析过程中产生的不确定度分量进行评定。结果 当大米粉质控样品中砷测定结果为0.156 mg/kg时, 其扩展不确定度为0.0067 mg/kg(k=2)。结论 量化后测定过程中各影响因素所产生的不确定度表明实验过程的不确定度主要来源于标准曲线拟合, 其次是加标回收率及测量重复性。 相似文献
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为更科学合理的表示微波消解-石墨炉法测定食品中铅含量的测量结果,根据JJF1059-1999《测量不确定度评定与表示》技术规范要求,以测定雪菜中铅为例对测量不确定度进行评定,分析其主要来源并定量,计算相对合成标准不确定度,评定扩展不确定度。结果表明,影响测量结果的主要因素依次为样品的消化、试剂空白以及仪器测量时标准曲线的拟合;样品的称重、消解液的定容以及标准物质引入的不确定度相对来说较小;用该法测得雪菜铅含量为0.22mg/kg,扩展不确定度为0.026mg/kg(95%,k=2);该评价方法及结果对实际工作中提高测量结果的准确性有一定的指导意义。 相似文献
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为了准确测定烟草中总植物碱,降低检测过程中的安全风险,采用硫氰化钾和二水合二氯异氰尿酸钠(DCIC)为在线反应试剂,利用连续流动分析仪,建立了一种测定烟草中总植物碱的方法。通过优化反应条件,确定了硫氰化钾和DCIC的最佳反应浓度分别为0.124和0.04 mol/L。运用此方法检测烤烟、白肋烟和香料烟等9种烟草样品,并将测定结果与现行行业标准方法的结果进行比较。结果表明:总植物碱的检出限为0.0018 mg/mL,定量限为0.0062 mg/mL,回收率为94.4%~105.4%。该方法避免使用剧毒的氰化钾试剂,降低了安全风险,适用于烟草中总植物碱的测定。 相似文献
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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 studies3,4 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. 相似文献15.
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。 相似文献
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南通市2003年食品污染状况监测与分析 总被引:1,自引:0,他引:1
为系统准确地了解南通市食品污染物的污染状况和污染水平,从而提出相应的预防方法及改进措施。2003年在严格的质量控制下,按照统一的方法对南通市6县2区共8类食品进行了有关食品污染物的污染状况监测。监测指标为铅、镉、甲胺磷。178份样品中有2份铅超标,均为乳类,合格率为98.88%;动物肾脏、鱼、虾中的镉含量高于CAC标准,合格率分别为27.27%、62.5%、71.4%;蔬菜中甲胺磷的平均检出率为15%,检出率最高的为小白菜(30%)。监测结果提示动物肾脏镉污染严重,应寻找污染源,进一步研究干预措施,从根本上阻断镉在食物链中的迁移。 相似文献