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什么是XRF土壤重金属分析光谱仪?Compass200

更新时间:2021-08-06      点击次数:2662

什么是XRF土壤重金属分析光谱仪?X射线荧光光谱仪---Compass200系列

背景介绍

   随着工业化和城市化的快速发展,土壤环境问题越来越受到重视。土壤重金属污染,特别是工业区土壤金属污染,已逐渐成为环境科学研究的热点。土壤污染中的重金属主要是指汞、镉、铅、铬等重金属和砷等具有明显毒性的各种金属。它们也指具有一定毒性的一般重金属,如锌、铜、钴、镍和锡。重金属对土壤的污染是一个短期的不可逆过程。在土壤-植物系统中,重金属污染通过食物链进入农产品,影响农产品质量安全,危害人类健康。因此,有必要对土壤中的重金属污染进行监测。

 

调查数据显示,中国10%以上的耕地已受到重金属污染。他们大多集中在经济发达地区。中国环境与发展合作委员会宣布,环保部对我国30万公顷基本农田土壤中有害重金属进行了抽样调查。研究发现,3.6万公顷土壤重金属超标,超标12.1%。

 

近年来,重金属污染事故频发。这些重金属污染事件不仅给社会带来了巨大的经济损失,也威胁着人们的健康生活。它们也引起了国家环保部门的关注。同时,深化重金属防控、深化重金属监测显得尤为紧迫和重要。

 

同时,2015年12月14日,环境部发布了《土壤和沉积物环境标准HJ 780-2015》,《波长色散X射线荧光光谱法测定土壤和沉积物中无机元素》。本标准自2016年2月1日起实施。该标准规定了25种无机氧化物和7种氧化物的质量分数范围。针对这一标准,ESI推出了EDX9000B荧光光谱仪,可以快速准确地分析土壤中的金属元素。铅、砷的检出限略高于标准要求; Fe、Co、Ni、Cu、Zn、Ga、Rb、Y、Ba、Sr、Br、Th和K、Ca、Ti、V、Cr、Mn Zr元素的检出限和定量限*HJ要求780-2015环保标准。

 

Compass 200 xrf soil analyzer.jpg

 

XRF光谱仪的基本原理:

 

X 射线具有电离或“激发”材料中存在的元素的*能力。当电离元素恢复到松弛或稳定状态时,它们会发出荧光 X 射线,其能级是发出这些 X 射线的特定元素的“特征”。

 

ESI XRF 分析仪利用这种现象,将电离 X 射线发送到样品中,测量返回的荧光 X 射线的能级(元素的“特征”),并对这些 X 射线进行计数以确定相对每个人的浓度。


润滑油中的磨损金属 xrf 分析仪


能量色散X射线光谱仪:Compass200;电子天平(精度0.0001g);自动贴合机一台(压力不小于40T);鼓风干燥炉;振动磨机;一个非金属样品筛(200 项)




试剂:硼酸粉(分析纯);土壤国标材料;土壤样品




1.2 样品采集、储存和预处理




土壤样品的采集和维护按照HJ/T166进行。风干或样品干燥应按HJ/T166的有关规定进行。样品研磨后过200目筛,105℃烘干备用。




用电子天平称取 5.00 g 过筛(200 目)土壤标准或样品和 12.00 g 硼酸粉(条状材料),称量误差为 ±0.05 g。然后放入压片机成片,压力30T(压力范围20~30T),保压时间30s。




1.3 校准建立和样品分析




 设置合适的测量条件,使用Compass200扫描国标材料(简称标准品)GSS-1~GSS-15,建立土壤标准中元素含量和强度的线性工作曲线。然后,测量未知样品。




2. 测量和数据分析




2.1 土壤中金属的检出限

 

Compass200配备三组滤波器,可根据感兴趣的元素特性设定测试条件

测试结果如下

 

 

 

Name

K2O

CaO

Ti

V

Cr

Mn

Fe2O3

Co

Ni

Cu

Soil

3.34

1.33

3976

35.8

32.1

276

2.16

12.4

8.6

6.4

Name

Zn

Ga

As

Rb

Sr

Y

Zr

Pb

Th

Ba

Soil

41.3

24.3

12.5

101

286

17.6

296

12.2

12.1

685

 

Introduction

 

With the rapid development of industrialization and urbanization, soil environmental issues have attracted more and more attention. Soil heavy metal pollution, especially soil metal pollution in industrial areas, has gradually become a hot spot in environmental scientific research. The heavy metals in soil pollution mainly refer to heavy metals such as mercury, cadmium, lead, chromium and various metals with obvious toxicity, such as arsenic. They also refer to general heavy metals with certain toxicity, such as zinc, copper, cobalt, nickel and tin. The pollution of soil by heavy metals is a short-term irreversible process. In the soil-plant system, heavy metal pollution enters agricultural products through the food chain, affecting the quality and safety of agricultural products and endangering human health. Therefore, it is necessary to monitor heavy metal pollution in the soil.

 

According to the latest survey data from the Ministry of Land and Resources, more than 10% of China's arable land has been polluted by heavy metals. Most of them are concentrated in economically developed areas. The China International Environment and Development Cooperation Committee announced that the Ministry of Environmental Protection has conducted a sample survey of harmful heavy metals in the soil of 300,000 hectares of basic farmland in China. The study found that 36,000 hectares of soil exceeded the standard for heavy metals, exceeding the standard by 12.1%.

 

In recent years, heavy metal pollution accidents have occurred frequently. These heavy metal pollution incidents not only brought huge economic losses to the society, but also threatened people's healthy lives. They have also attracted the attention of relevant national environmental protection departments. At the same time, it is particularly urgent and important to deepen the prevention and control of heavy metals and deepen the monitoring of heavy metals.

 

At the same time, on December 14, 2015, the Ministry of Environmental Protection issued "Environmental Standards for Soils and Sediments HJ 780-2015", "Measurement of Inorganic Elements in Soils and Sediments by Wavelength Dispersive X-ray Fluorescence Spectrometry". This standard was implemented on February 1, 2016. The standard specifies the mass fraction range of 25 inorganic oxides and 7 oxides. In response to this standard, ESI launched the EDX9000B fluorescence spectrometer, which can quickly and accurately analyze the metal elements in the soil. The detection limits of lead and arsenic are slightly higher than the standard requirements; Fe, Co, Ni, Cu, Zn, Ga, Rb, Y, Ba, Sr, Br, Th and K, Ca, Ti, V, Cr, Mn The detection limit and quantification limit of Zr element fully meet the requirements of HJ 780-2015 environmental protection standard.

 

The basic principle of XRF spectrometer:

 

X-rays have the unique ability to ionize or "excite" the elements present in the material. When ionized elements return to a relaxed or stable state, they emit fluorescent X-rays whose energy level is a "characteristic" of the specific element that emits these X-rays.

 

The ESI XRF analyzer takes advantage of this phenomenon by sending ionized X-rays into the sample, measuring the energy level of the returned fluorescent X-rays (the "feature" of the element), and counting these X-rays to determine the relative concentration of each individual.

 

Energy dispersive X-ray spectrometer:Compass200; an electronic balance (precision 0.0001g); an automatic laminating machine (pressure not less than 40T); a blast drying furnace; a vibration mill; a non-metallic sample sieve (200 Item)

 

Reagents: boric acid powder (analytical grade); soil national standard materials; soil samples

 

1.2 Sample collection, storage and pretreatment

 

The collection and maintenance of soil samples are carried out in accordance with HJ/T166. Air drying or sample drying should be carried out in accordance with the relevant regulations of HJ/T166. After the sample was ground, it was passed through a 200-mesh sieve and dried at 105°C for use.

 

Use an electronic balance to weigh 5.00 g sieved (200 mesh) soil standard or sample and 12.00 g boric acid powder (strip material) with a weighing error of ±0.05 g. Then it is put into a tablet press to form a sheet, the pressure is 30T (pressure range is 20~30T), and the holding time is 30s.

 

1.3 Calibration establishment and sample analysis

 

Set appropriate measurement conditions, use Compass200 to scan national standard materials (referred to as standard products) GSS-1~GSS-15 to establish a linear working curve of the content and intensity of the elements in the soil standard. Then, the unknown sample is measured.

 

2. Measurement and data analysis

 

2.1 Detection limit of metals in soil

 

Compass 200 is equipped with three sets of filters, which can set the best test conditions according to the characteristics of the elements of interest in the soil. Use the national soil standard GSS-1-GSS-15 calibration instrument to establish an environmental soil working curve. Under the environmental soil working curve, high-purity SiO2 was used as the blank substrate and tested 11 times continuously. According to the detection limit formula: 3 times the standard deviation of the blank matrix divided by the sensitivity of the instrument.

 

1. Co is seriously interfered by Fe element Kb, and the extremely low detection limit is determined by the formula.

 

2. Since this model is not evacuated (or filled with helium), light elements such as Na2O, MgO, Al2O3 and SiO2 are not used. However, La, Ce and Hf are not affected by the scattering background. P, S and Cl are higher in the national soil standards. There is no suitable low standard. The main reason is that the background is greatly affected. Do not consider large, irregular spectrum.

 

3. The elements that meet the national standards are K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Y, Ba, Sr, Br, Th and Zr. Arsenic and lead

 

 

 

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