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Determination of Elemental Concentrations in Lichens Using ICP-AES/MS
ICP-AES/MS法测定地衣中元素的浓度   

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Abstract

Lichens are good biomonitors for air pollution because of their high enrichment capability of atmospheric chemical elements. To monitor atmospheric element deposition using lichens, it is important to obtain information on the multi-element concentrations in lichen thalli. Because of serious air pollution, elemental concentrations in thalli of lichens from North China (especially Inner Mongolia, Hebei, Shanxi and Henan province) are often higher than those from other regions, therefore highlighting the necessity to optimize ICP-AES/MS (Inductively coupled plasma-atomic emission spectroscopy/mass spectrometry) for analyzing lichen element content. Based on the high elemental concentrations in the lichen samples, and the differences in the sensitivity and detection limits between ICP-MS and ICP-AES, we propose a protocol for analyzing 31 elements in lichens using ICP-AES/MS. Twenty-two elements (Cd, Ce, Co, Cr, Cs, Cu, K, La, Mo, Na, Ni, Pb, Rb, Sb, Sc, Sm, Sr, Tb, Th, Tl, V and Zn) can be identified by using microwave digestion- ICP-MS, and 9 elements (Al, Ba, Ca, Fe, Mg, Mn, P, S and Ti) by using ashing-alkali fusion digestion- ICP-AES.

Keywords: Element content(元素含量), Heavy metal(重金属), ICP-AES(ICP-AES), ICP-MS(ICP-MS), Lichens(地衣), Microwave digestion(微波消化), Ashing-alkali fusion(灰化-碱熔)

Background

Lichens have been widely used in biomonitoring of air pollution in many regions of the world, including China that experiences heavy-metal atmospheric pollution in some areas. Recent studies found that the element concentrations in lichens from North China are higher than or at the upper range of the literature values from other regions (Liu et al., 2016a; 2016b and 2016c), due to the severe air pollution in this region.

Compared with other techniques (for example spectrophotometric methods, atomic absorption spectrometry and atomic fluorescence spectrometry), ICP-AES/MS is a multi-element analysis method involving simple procedure with relatively low detection limits. This method is widely used in the quantitative analysis of lichen elements outside China. However, to date, there have been no reports on the application of ICP-AES/MS to analyze elements in lichens of North China. Specific procedures for the sample preparation of the lichens are required due to the high loadings of elements with great variation in concentration. Therefore, to facilitate the biomonitoring of atmospheric elemental deposition with lichens in China, we propose a protocol for lichen elemental concentration analyses using ICP-AES/MS.

Materials and Reagents

  1. Paper bags
  2. 10 mesh nylon standard inspection sieve (pore size 2 mm) (Shangyu Huafeng Hardware Instrument)
  3. 50 ml plastic centrifuge tube (SARSTEDT, catalog number: 62.559.001 )
  4. National certified reference materials: GBW10010 (rice), GBW10014 (cabbage) and GBW10015 (spinach; All materials mentioned above were provided by the Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences). Lichen material IAEA-336 (International Atomic Energy Agency)
  5. Lichens: Xanthoria mandschurica and Xanthoparmelia mexicana, collected from Taihang Mountains, Hebei Province, China
  6. H2O2, > 30% (w/v) (Beijing Institute of Chemical Reagents, catalog number: 160215 )
  7. 103Rh: 1.00 mg/ml (GSB-G62037-90, National Analysis Center for Iron & Steel, Beijing, China)
  8. HCl, 35-37% (w/v) (Beijing Institute of Chemical Reagents, catalog number: 160718 )
  9. Standard stocking solutions: 1.00 mg/ml Al (GBW[E]086219), Ba (GBW[E]080243), Ca (GBW[E]080261), Cd (GBW08612), Ce (GSB04-1775), Co (GBW08613), Cr (G130008614), Cs (GSB04-1724), Cu (GSB04-1725), Fe (GBW08616), K (GBW[E]080125), La (GBW08651), Mg (GBW[E]080126), Mn (GSB04-1736), Mo (GBW[E]080218), Na (GBW[E]080127), Ni (GBW08618), P (GBW[E]080186), Pb (GBW08619), Rb (GSB04-2836), S (GBW[E]080266), Sb (GBW[E]080545), Sc (GBW[E]3141), Sm (GSB64-1778), Sr (GSB04-1754), Tb (GSB04-1781), Th (GBW[E]080174), Ti (GBW3041), Tl (GSBG62070-90), V (GBW[E]080243), and Zn (GBW[E]080607) (National Research Center for standard materials, Beijing, China)
  10. Standard intermediate solutions (see Recipes; Table 8)
  11. Standard working solutions (see Recipes; Table 8)

Equipment

  1. Inductively coupled plasma mass spectrometer (ICP-MS) (Agilent Technologies, model: Agilent 7700X ICP-MS )
  2. Inductively coupled plasma optical emission spectrometer (ICP-AES) (Varian, model: Varian Vista MPX )
  3. Microwave digestion system (equipped with Teflon digestion vessels) (CEM Corporation, Matthews, model: MARS X-press )
  4. Grinding mill equipped with Tungsten Carbide jars (Retsch, model: Retsch MM400 )
  5. Stereo microscope (Motic, model: Motic SMZ-140 )
  6. Muffle furnace (Yiheng, model: SX2-4-10TP )
  7. Oven (50-120 °C)
  8. Tweezers
  9. 50 ml volumetric flask
  10. 30 ml nickel crucible (Jiangsu Plaza Premium Electric Instrument, catalog number: 30 ml crucible )
  11. Deionized water: resistivity ≥ 18.0 MΩ cm (Aquapro International, model: Aquaplore3 )

Procedure

  1. Sample preparation
    1. Sample preparation for microwave digestion – ICP-MS
      1. The lichen samples (> 200 g per sample, fresh weight) are air-dried at room temperature in paper bags for at least 5 days. Carefully remove soil particles and other debris on lichen thalli under a stereo microscope using clean tweezers.
      2. The cleaned samples are oven-dried at 70 °C for 72 h to constant weight (determined by weighting each sample at an interval of 8-12 h). Cool down the samples to room temperature and ground each sample to powder in a grinding mill, then pass each sample through a 10 mesh nylon sieve.
      3. Transfer an accurately weighted portion of each sample (0.3000 g) to a Teflon digestion vessel. Add 4.0 ml HNO3 to the vessel and incubate for 4 h at room temperature. Then add 2.0 ml H2O2, and transfer the digestion vessel to a microwave digestion system (MARS-X), applying the following temperature control procedure (Table 1).

        Table 1. Temperature control procedure for microwave digestion


      4. After digestion, when the pressure inside the vessel lowered to normal pressure and the vessel is cooled down to room temperature, open the vessel and wash the sample into a 50 ml volumetric flask by using deionized water (20-40 ml). Dilute the sample to 50 ml with deionized water for ICP-MS testing.
      5. Prepare blank samples and certified reference material samples (IAEA-336, GBW10010, GBW10014 and GBW10015) according to the above mentioned procedures.
    2. Sample preparation for microwave digestion – ICP-MS
      1. Transfer an accurately weighted portion of each sample (1.0000 g) of the lichen (obtained in step A1b) to a nickel crucible and then all samples are heated to 500 °C until they turn grayish white (and therefore are fully ashed).
      2. Add 1.5 g of NaOH to decompose each sample at 700 °C for 10 min. Cool down all samples to room temperature and wash each sample into a 50 ml plastic centrifuge tube using hot deionized water (70-80 °C, 20-30 ml). To ensure complete transfer of each sample, also wash the nickel crucible according to the method mentioned above. Dilute the solution in the tube to 50 ml and shake it well before ICP-AES testing.
      3. Prepare blank samples and certified reference material samples (IAEA-336, GBW10010, GBW10014 and GBW10015) according to the procedures mentioned above.

  2. Measurement of element concentrations in lichens
    1. ICP-MS analysis
      1. Set the optimal operating conditions for ICP-MS (Table 2).

        Table 2. Optimal operating conditions of ICP-MS


      2. Measure twenty-two elements (Cd, Ce, Co, Cr, Cs, Cu, K, La, Mo, Na, Ni, Pb, Rb, Sb, Sc, Sm, Sr, Tb, Th, Tl, V and Zn) in samples obtained in step A1d using ICP-MS. Select the isotopes of the 22 elements for analysis to remove isotopic interference (Table 3).

        Table 3. Isotope of 22 elements for ICP-MS analysis


      3. Add 5 μg/L of the internal standard 103Rh into each sample to remove physical interference in the ICP-MS analysis.
      4. The linear regression equation and correlation coefficient are determined using standard working solution series (see Recipes; Table 8), and are given by the machine (Table 4). The concentration (μg/ml) for each element is also given by the machine.

        Table 4. Parameters of the standard curves and detection limits for elements measured by ICP-MS


    2. ICP-AES analysis
      1. Set the optimal operating conditions for ICP-AES (Table 5).
      2. Measure nine elements (Al, Ba, Ca, Fe, Mg, Mn, P, S and Ti) in the samples obtained in step A2c using ICP-AES. The analytical spectral lines for these elements are listed in Table 6.
      3. The linear regression equation and correlation coefficient are determined using standard working solution series (see Recipes; Table 8), and are given by the machine (Table 7). The concentration (μg/ml) for each element is also given by the machine.

        Table 5. Optimal operating conditions of ICP-AES


        Table 6. Analytical spectral lines of the elements


        Table 7. Parameters of the standard curves and detection limits for elements measured by ICP-AES


  3. Evaluation of the optimized methods
    1. Linear range and detection limit of the optimized methods
      Dilute the standard working solution for each element by 8% HNO3 using serial dilution (see Recipes). Detection limits were determined by 8 technical replicates of blank solutions.
      The linear regression equation, linear correlation coefficient, linear range and detection limit of 22 elements (Cd [linear ranges, 0-0.1μg/ml; detection limits, 0.00007 μg/ml], Ce [0-1; 0.00002], Co [0-0.1; 0.0001], Cr [0-1; 0.00017], Cs [0-0.1; 0.00006], Cu [0-1; 0.00038], K [0-100; 0.0052], La [0-0.1; 0.00003], Mo [0-0.1; 0.00093], Na [0-30; 0.0051], Ni [0-1; 0.00007], Pb [0-1; 0.00031], Rb [0-30; 0.00003], Sb [0-0.1; 0.00008], Sc [0-0.1; 0.00009], Sm [0-0.1; 0.00004], Sr [0-30; 0.00011], Tb [0-0.1; 0.00004], Th [0-0.1; 0.00004], Tl [0-0.1; 0.00008], V [0-1; 0.000052], and Zn [0-5; 0.00095]) analyzed by ICP-MS can be seen in Table 4, of 9 elements (Al [Linear ranges, 0-100; detection limits, 0.0054], Ba [0-5; 0.0004], Ca [0-100; 0.0053], Fe [0-100; 0.004], Mg [0-30; 0.0049], Mn [0-5; 0.00014], P [0-30; 0.013], S [0-30; 0.0053], and Ti [0-30; 0.0006]) analyzed by ICP-AES can be seen in Table 7. The results show that both methods had low detection limits and wide linear ranges.
    2. Accuracy and precision of the methods
      Prepare and decompose the certified reference materials (IAEA-336, GBW10014 and GBW10015) followed steps A1 and A2. The sample is analyzed with 8 technical replicates using ICP-AES/MS under optimal operating conditions (Tables 2 and 5). A comparison of the measured values with certified values is shown in Tables S1 and S2 for ICP-MS and ICP-AES analysis, respectively. The results show that both methods have a good accuracy (relative error < 10%) and precision (relative standard deviation ranging from 1.56% to 9.55%).

Data analysis

Accuracy and precision of the protocol for each element are obtained using Equation 1 and 2 (based on 8 technical replicates), respectively.


In both equations, Cj denotes the mean of certified reference material values based on n technical replicates; Cs denotes certified values of the certified reference material; Ci denotes the measured value of the certified reference material.

Notes

  1. Lichen samples should be carefully cleaned to remove the attached particles on the surface of the lichen thalli to avoid inaccuracy in the determination of the element concentration.
  2. Sample preparation is essential in this protocol. The classic preparation methods for plant samples are dry ashing, wet digestion, and microwave digestion. The wet digestion method is less suitable for our samples, because of the cumbersome, time-consuming operations, high risk of contamination, and high blank values leading to low precision. Although all elements can be analyzed by using both microwave digestion- ICP-MS and dry ashing-alkali fusion digestion- ICP-AES, we propose that it is better to analyze 22 elements (Cd, Ce, Co, Cr, Cs, Cu, K, La, Mo, Na, Ni, Pb, Rb, Sb, Sc, Sm, Sr, Tb, Th, Tl, V and Zn) using ICP-MS and 9 elements (Al, Ba, Ca, Fe, Mg, Mn, P, S and Ti) using ICP-AES. Microwave digestion with the HNO3-H2O2 system is effective for most refractory elements, and the closed vessel helps in preventing losses of the volatile elements. Although the dry ashing method can lead to a lower result due to the loss of some volatile elements at high temperature, it can be used to prepare samples for analyzing 9 elements (Al, Ba, Ca, Fe, Mg, Mn, P, S and Ti) using ICP-AES analysis.
  3. Because of the high content of metals in lichens, the lichen samples should be soaked in HNO3 for 4 h, and then be digested by adding H2O2. If the sample is difficult to be completely digested, the sample size should be reduced and the soaking duration should be prolonged to overnight.
  4. This protocol is suitable for lichens collected from North China, particularly Inner Mongolia, Shanxi, Hebei and Henan Provinces which are characterized by heavy air pollution.

Recipes

  1. The standard intermediate solutions and standard working solutions for the measured elements are listed in Table 8.

    Table 8. The standard intermediate solutions and standard working solutions for the measured elements

Acknowledgments

This work was supported by the National Natural Science Foundation of China under grant No. 31000239 and the Natural Science Foundation of Hebei Province under grant Nos. C2014201032 and C2010000268. The procedure was previously employed in Liu et al. (2016a; 2016b and 2016c) and Zhao et al. (2016).

References

  1. Liu, H. J., Fang, S. B., Liu, S. W., Zhao, L. C., Guo, X. P., Jiang, Y. J., Hu, J. S., Liu, X. D., Xia, Y., Wang, Y. D. and Wu, Q. F. (2016a). Lichen elemental composition distinguishes anthropogenic emissions from dust storm input and differs among species: evidence from Xilinhot, Inner Mongolia, China. Sci Rep 6: 34694.
  2. Liu, H. J., Liu, S. W., Wang, L., Liu, X. D., Zhao, L. C. and Wu, Q. F. (2016b). Effects of species and substrate preference on element concentration of six lichens in Taihang Mountains, Hebei, China. Mycosystema 35(10): 1258-1267.
  3. Liu, H. J., Zhao, L. C., Fang, S. B., Liu, S. W., Hu, J. S., Wang, L., Liu, X. D. and Wu, Q. F. (2016c). Use of the lichen Xanthoria mandschurica in monitoring atmospheric elemental deposition in the Taihang Mountains, Hebei, China. Sci Rep 6: 23456.
  4. Zhao, L. C., Jiang, Y. J., Guo, X. P., Li, X., Wang, Y. D., Guo, X. B., Lu, F. and Liu, H. J. (2016). Optimization of ICP-AES and ICP-MS techniques for the determination of major, minor and micro elements in lichens. Spectrosc Spect Anal 36(10): 3320-3325.

简介

由于大气化学元素富集能力强,地衣是空气污染的良好生物监测器。使用地衣来监测大气元素沉积,重要的是要获取有关地衣中多元素浓度的信息。由于严重的空气污染,华北地区(特别是内蒙古,河北,山西,河南等地区)的地衣单质浓度通常高于其他地区,因此强调了优化ICP-AES / MS(电感耦合等离子体原子发射光谱/质谱)用于分析地衣元素含量。基于地衣样品中高元素浓度以及ICP-MS和ICP-AES敏感性和检测限的差异,我们提出了一种使用ICP-AES / MS分析地衣31种元素的方案。二十二个元素(Cd,Ce,Co,Cr,Cs,Cu,K,La,Mo,Na,Ni,Pb,Rb,Sb,Sc,Sm,Sr,Tb,Th,Tl,V和Zn)通过使用微波消解 - ICP-MS和9种元素(Al,Ba,Ca,Fe,Mg,Mn,P,S和Ti)通过使用灰化 - 碱熔融 - ICP-AES鉴定。

背景 地衣已被广泛应用于世界许多地区的空气污染生物监测,包括在一些地区遇到重金属大气污染的中国。最近的研究发现,华北地衣的元素浓度高于其他地区(Liu等人,2016a; 2016b和2016c)的文献价值的上限,这个地区严重的空气污染。
&nbsp;与其他技术(例如分光光度法,原子吸收光谱法和原子荧光光谱法)相比,ICP-AES / MS是一种多元素分析方法,涉及检测限较低的简单方法。该方法广泛应用于中国以外地衣单元的定量分析。然而,到目前为止,还没有关于ICP-AES / MS在华北地衣分析中的应用的报道。要求地衣样品制备的具体程序是由于浓度变化大的元素的高负载量。因此,为了促进中国大陆元素沉积与地衣的生物监测,我们提出了使用ICP-AES / MS进行地衣浓缩分析的方案。

关键字:元素含量, 重金属, ICP-AES, ICP-MS, 地衣, 微波消化, 灰化-碱熔

材料和试剂

  1. 纸袋
  2. 10目尼龙标准检验筛(孔径2 mm)(上虞华丰五金仪器)
  3. 50ml塑料离心管(SARSTEDT,目录号:62.559.001)
  4. 国家认证参考资料:GBW10010(水稻),GBW10014(卷心菜)和GBW10015(菠菜;上述所有材料均由中国地质科学院地球物理与化学勘探研究所提供)。地衣材料IAEA-336(国际原子能机构)
  5. 地衣:从中国河北省太行山收集的Xanthoria mandschurica 和xanthoparmelia mexicana
  6. H 2 O 2 O 2,> 30%(w/v)(北京化学试剂研究所,目录号:160215)
  7. 103 Rh:1.00mg/ml(GSB-G62037-90,National Analysis Center for Iron& Steel,Beijing,China)
  8. HCl,35-37%(w/v)(北京化学试剂研究所,目录号:160718)
  9. 标准储备溶液:GB(GBW [E] 086219),Ba(GBW [E] 080243),Ca(GBW [E] 080261),Cd(GBW08612),Ce(GSB04-1775),Co(GBW08613 ),Cr(G130008614),Cs(GSB04-1724),Cu(GSB04-1725),Fe(GBW08616),K(GBW [E] 080125),La(GBW08651),Mg(GBW [E] 080126) (GBB04-1736),Mo(GBW [E] 080218),Na(GBW [E] 080127),Ni(GBW08618),P(GBW [E] 080186),Pb(GBW08619),Rb(GSB04-2836) S(GBW [E] 080266),Sb(GBW [E] 080545),Sc(GBW [E] 3141),Sm(GSB64-1778),Sr(GSB04-1754),Tb(GSB04-1781) GBW [E] 080174),Ti(GBW3041),T1(GSBG62070-90),V(GBW [E] 080243)和Zn(GBW [E] 080607)(国家标准材料研究中心, br />
  10. 标准中间溶液(见配方;表8)
  11. 标准工作解决方案(见配方;表8)

设备

  1. 电感耦合等离子体质谱仪(ICP-MS)(Agilent Technologies,型号:Agilent 7700X ICP-MS)
  2. 电感耦合等离子体发射光谱仪(ICP-AES)(Varian,型号:Varian Vista MPX)
  3. 微波消解系统(配备特氟龙消化器皿)(CEM公司,马修斯,型号:MARS X-press)
  4. 研磨机配有碳化钨罐(Retsch,型号:Retsch MM400)
  5. 立体显微镜(Motic,型号:Motic SMZ-140)
  6. 马弗炉(义恒,型号:SX2-4-10TP)
  7. 烤箱(50-120°C)
  8. 镊子
  9. 50ml容量瓶
  10. 30毫升镍坩埚(江苏高级电器仪器,目录号:30毫升坩埚)
  11. 去离子水:电阻率≥18.0MΩ厘米(Aquapro International,型号:Aquaplore3)

程序

  1. 样品制备
    1. 微波消解样品制备 - ICP-MS
      1. 将地衣样品(> 200g,每个样品,鲜重)在室温下在纸袋中空气干燥至少5天。使用干净的镊子在立体显微镜下小心地清除苔藓上的土壤颗粒和其他碎屑
      2. 将清洁的样品在70℃烘箱干燥72小时以保持恒重(通过以8-12小时的间隔加权每个样品来确定)。将样品冷却至室温,并将每个样品在研磨机中粉碎,然后将每个样品通过10目尼龙筛。
      3. 将每个样品(0.3000g)的精确加权部分转移到特氟龙消化器皿中。向容器中加入4.0ml HNO 3,并在室温下孵育4小时。然后加入2.0ml H 2 O 2 O 2,并将消化容器转移到微波消解系统(MARS-X),应用以下温度控制程序(表1)。

        表1.微波消解的温度控制程序


      4. 消化后,当容器内的压力降至正常压力并将容器冷却至室温时,打开容器,并使用去离子水(20-40ml)将样品洗至50ml容量瓶中。用去离子水将样品稀释至50ml,进行ICP-MS测试
      5. 根据上述程序,准备空白样品和认证参考材料样品(IAEA-336,GBW10010,GBW10014和GBW10015)。
    2. 微波消解样品制备 - ICP-MS
      1. 将每个样品(1.0000g)的地衣(步骤A1b中获得)的精确加权部分转移到镍坩埚上,然后将所有样品加热至500℃直至变成灰白色(因此完全灰化)。 />
      2. 加入1.5g NaOH以在700℃下分解每个样品10分钟。将所有样品冷却至室温,并使用热去离子水(70-80℃,20-30ml)将每个样品洗至50ml塑料离心管中。为了确保每个样品的完全转印,也可以按照上述方法洗涤镍坩埚。将溶液稀释至50ml,并在ICP-AES测试前摇匀
      3. 根据上述程序准备空白样品和认证参考材料样品(IAEA-336,GBW10010,GBW10014和GBW10015)。

  2. 测量地衣中的元素浓度
    1. ICP-MS分析
      1. 设置ICP-MS的最佳工作条件(表2)
        表2. ICP-MS的最佳运行条件


      2. 测量二十二个元素(Cd,Ce,Co,Cr,Cs,Cu,K,La,Mo,Na,Ni,Pb,Rb,Sb,Sc,Sm,Sr,Tb,Th,Tl,V和Zn)在使用ICP-MS的步骤A1d中获得的样品中。选择22个元素的同位素进行分析以消除同位素干扰(表3)
        表3. ICP-MS分析的22个元素的同位素


      3. 在每个样品中加入5μg/L的内标物质,以消除ICP-MS分析中的物理干扰。
      4. 线性回归方程和相关系数使用标准工作液系列(见配方;表8)确定,由机器给出(表4)。每个元素的浓度(μg/ml)也由机器给出。

        表4.通过ICP-MS测量的元素的标准曲线和检测限的参数


    2. ICP-AES分析
      1. 设置ICP-AES的最佳工作条件(表5)
      2. 使用ICP-AES测量步骤A2c中获得的样品中的九种元素(Al,Ba,Ca,Fe,Mg,Mn,P,S和Ti)。这些元素的分析谱线列于表6.
      3. 线性回归方程和相关系数用标准工作液系列(见配方;表8)确定,由机器给出(表7)。每个元素的浓度(μg/ml)也由机器给出。

        表5. ICP-AES的最佳操作条件


        表6.元素的分析谱线


        表7.通过ICP-AES测量的元素的标准曲线和检测限制的参数


  3. 评估优化方法
    1. 优化方法的线性范围和检测限制
      使用连续稀释法稀释每种元素的标准工作溶液8%HNO 3 (见配方)。检测限由8个空白溶液的技术重复确定 线性回归方程,线性相关系数,线性范围和检测极限为22个元素(Cd [线性范围,0-0.1μg/ml;检测限,0.00007μg/ml],Ce [0-1; 0.00002] 0-0.1; 0.0001],Cr [0-1; 0.00017],Cs [0-0.1; 0.00006],Cu [0-1; 0.00038],K [0-100; 0.0052],La [0-0.1; 0.00003 ,Mo [0-0.1; 0.00093],Na [0-30; 0.0051],Ni [0-1; 0.00007],Pb [0-1; 0.00031],Rb [0-30; 0.00003],Sb [0 ,Sc [0-0.1; 0.00009],Sm [0-0.1; 0.00004],Sr [0-30; 0.00011],Tb [0-0.1; 0.00004],Th [0-0.1; 0.00004] ,通过ICP-MS分析的T [0-0.1; 0.00008],V [0-1; 0.000052]和Zn [0-5; 0.00095])可以在表4中看到9个元素(Al [线性范围, 0-100;检测限0.0054],Ba [0-5; 0.0004],Ca [0-100; 0.0053],Fe [0-100; 0.004],Mg [0-30; 0.0049],Mn [ 5; 0.00014],P [0-30; 0.013],S [0-30; 0.0053]和通过ICP-AES分析的Ti [0-30; 0.0006])可以在表7中看出。结果表明方法检测限低,线性范围宽。 >
    2. 方法的精度和精度
      按照A1和A2步骤准备和分解认证参考资料(IAEA-336,GBW10014和GBW10015)。在最佳操作条件下使用ICP-AES/MS进行8次技术重复分析样品(表2和5)。测量值与认证值的比较显示在表 S1 和< a class ="ke-insertfile"href ="http://en.bio-protocol.org/attached/file/20170207/20170207012415_8687.docx"target ="_ blank" > S2 分别用于ICP-MS和ICP-AES分析。结果表明,两种方法都具有良好的精度(相对误差<10%)和精度(相对标准偏差范围为1.56%〜9.55%)。

数据分析

使用等式1和2(基于8个技术重复)分别获得每个元素的协议的精度和精度。


在两个方程式中,表示基于技术重复的认证参考材料值的平均值; 表示认证参考资料的认证价值; 表示经认证的参考材料的测量值。

笔记

  1. 应仔细清洁地衣样品,以清除地衣表面上附着的颗粒,以避免元素浓度测定不准确。
  2. 样品制备在本协议中至关重要。植物样品的经典制备方法是干灰化,湿消化和微波消解。湿式消解法较不适合我们的样品,因为操作繁琐,耗时高,污染风险高,空白值高,导致精度低。尽管可以通过微波消解ICP-MS和干灰化碱融合消解ICP-AES分析所有元素,但我们建议分析22种元素(Cd,Ce,Co,Cr,Cs,Cu, K,La,Mo,Na,Ni,Pb,Rb,Sb,Sc,Sm,Sr,Tb,Th,Tl,V和Zn)和9种元素(Al,Ba,Ca,Fe, Mn,P,S和Ti)。使用HNO 3 H 2 O 2 O 2系统的微波消解对于大多数难熔元素是有效的,并且密闭容器有助于防止挥发性元素。虽然干法灰化方法可能导致由于高温下某些挥发性元素的损失导致的较低的结果,但可用于制备样品用于分析9种元素(Al,Ba,Ca,Fe,Mg,Mn,P,S和Ti),使用ICP-AES分析
  3. 由于地衣中金属含量高,地衣样品应在HNO 3中浸泡4 h,然后通过加入H 2 O 2 。如果样品难以完全消化,样品尺寸应减少,浸泡持续时间应延长至过夜。
  4. 该方案适用于从华北地区,特别是内蒙古,山西,河北,河南等地区收集的地衣,其特点是空气污染严重。

食谱

  1. 测量元素的标准中间解决方案和标准工作解决方案列于表8.

    表8.用于测量元素的标准中间解决方案和标准工作解决方案

致谢

这项工作得到中国国家自然科学基金资助,编号31000239和河北省自然科学基金资助,授予号为C2014201032和C2010000268。该程序以前在Liu等人使用。 (2016a; 2016b和2016c)和Zhao等人。 (2016)。

参考文献

  1. 刘晓J,方,SB,刘SW,赵,,,XP Jiang Jiang Hu Hu Hu Hu,and and and((((((((;;;;;;;;;;; 地衣元素组成区分了人为排放与沙尘暴输入和物种不同:来自内蒙古锡林浩特的证据。 6:34694。
  2. Liu,HJ,Liu,SW,Wang,L.,Liu,XD,Zhao,LC and Wu,QF(2016b)。  物种和底物偏好对中国河北太行山地区六种地衣的元素浓度的影响。 Mycosystema 35(10):1258 -1267。
  3. Liu,HJ,Zhao,LC,Fang,SB,Liu,SW,Hu,JS,Wang,L.,Liu,XD and Wu,QF(2016c)。  使用地衣Xanthoria mandschurica 在监测太行山大气元素沉积,河北,中国。 Sci Rep 6:23456.
  4. Zhao,LC,Jiang,YJ,Guo,XP,Li,X.,Wang,YD,Guo,XB,Lu,F. and Liu,HJ(2016)。  ICP-AES和ICP-MS技术的优化用于测定主要,次要和微量元素地衣。光谱分析 36(10):3320-3325。
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引用:Zhao, L., Wang, L., Jiang, Y., Hu, Y., Xu, C., Wang, L., Li, X., Wei, L., Guo, X., Liu, A. and Liu, H. (2017). Determination of Elemental Concentrations in Lichens Using ICP-AES/MS. Bio-protocol 7(5): e2165. DOI: 10.21769/BioProtoc.2165.
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