什么是XRF土壤重金屬分析光譜儀？X射線熒光光譜儀---Compass200系列
背景介紹
隨著工業化和城市化的快速發展，土壤環境問題越來越受到重視。土壤重金屬污染，特別是工業區土壤金屬污染，已逐漸成為環境科學研究的熱點。土壤污染中的重金屬主要是指汞、鎘、鉛、鉻等重金屬和砷等具有明顯毒性的各種金屬。它們也指具有一定毒性的一般重金屬，如鋅、銅、鈷、鎳和錫。重金屬對土壤的污染是一個短期的不可逆過程。在土壤-植物系統中，重金屬污染通過食物鏈進入農產品，影響農產品質量安全，危害人類健康。因此，有必要對土壤中的重金屬污染進行監測。
調查數據顯示，中國10%以上的耕地已受到重金屬污染。他們大多集中在經濟發達地區。中國環境與發展合作委員會宣布，環保部對我國30萬公頃基本農田土壤中有害重金屬進行了抽樣調查。研究發現，3.6萬公頃土壤重金屬超標，超標12.1%。
近年來，重金屬污染事故頻發。這些重金屬污染事件不僅給社會帶來了巨大的經濟損失，也威脅著人們的健康生活。它們也引起了國家環保部門的關注。同時，深化重金屬防控、深化重金屬監測顯得尤為緊迫和重要。
同時，2015年12月14日，環境部發布了《土壤和沉積物環境標準HJ 780-2015》，《波長色散X射線熒光光譜法測定土壤和沉積物中無機元素》。本標準自2016年2月1日起實施。該標準規定了25種無機氧化物和7種氧化物的質量分數范圍。針對這一標準，ESI推出了EDX9000B熒光光譜儀，可以快速準確地分析土壤中的金屬元素。鉛、砷的檢出限略高于標準要求； Fe、Co、Ni、Cu、Zn、Ga、Rb、Y、Ba、Sr、Br、Th和K、Ca、Ti、V、Cr、Mn Zr元素的檢出限和定量限*HJ要求780-2015環保標準。
XRF光譜儀的基本原理：
X 射線具有電離或“激發”材料中存在的元素的*能力。當電離元素恢復到松弛或穩定狀態時，它們會發出熒光 X 射線，其能級是發出這些 X 射線的特定元素的“特征”。
ESI XRF 分析儀利用這種現象，將電離 X 射線發送到樣品中，測量返回的熒光 X 射線的能級(元素的“特征”)，并對這些 X 射線進行計數以確定相對每個人的濃度。
潤滑油中的磨損金屬 xrf 分析儀
能量色散X射線光譜儀：Compass200；電子天平(精度0.0001g)；自動貼合機一臺(壓力不小于40T)；鼓風干燥爐；振動磨機；一個非金屬樣品篩(200 項)
試劑：硼酸粉(分析純)；土壤國標材料；土壤樣品
1.2 樣品采集、儲存和預處理
土壤樣品的采集和維護按照HJ/T166進行。風干或樣品干燥應按HJ/T166的有關規定進行。樣品研磨后過200目篩，105℃烘干備用。
用電子天平稱取 5.00 g 過篩(200 目)土壤標準或樣品和 12.00 g 硼酸粉(條狀材料)，稱量誤差為 ±0.05 g。然后放入壓片機成片，壓力30T(壓力范圍20~30T)，保壓時間30s。
1.3 校準建立和樣品分析
設置合適的測量條件，使用Compass200掃描國標材料(簡稱標準品)GSS-1~GSS-15，建立土壤標準中元素含量和強度的線性工作曲線。然后，測量未知樣品。
2. 測量和數據分析
2.1 土壤中金屬的檢出限
Compass200配備三組濾波器，可根據感興趣的元素特性設定測試條件
測試結果如下
| 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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