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当前位置:首页  >  技术文章  >  购买X射线荧光光谱仪XRF分析仪器的技巧,注意事项和要领

购买X射线荧光光谱仪XRF分析仪器的技巧,注意事项和要领

更新时间:2021-08-09      点击次数:1957

选购、购买X射线荧光光谱仪XRF分析仪器的技巧,注意事项和要领

不积跬步,无以至千里;不积小流,无以成江海

XRF 是一种原子发射光谱仪。在XRF中,来自X射线管主X射线束的辐射会使荧光X射线辐射表现出样品中存在的元素能量分散的特性

其原理是 X 射线管通过产生入射 X 射线(初级 X 射线)来激发被测样品。被激发样品中的每种元素都会发出二次X射线(也称为X射线荧光),不同元素所发出的二次X射线具有特定的能量特性或波长特性。检测系统测量这些发射的二次 X 射线的能量和数量或波长。然后,仪器软件将检测系统采集到的信息转化为样品中各种元素的种类和含量。元素的原子被高能辐射激发,引起内部电子跃迁,同时发出具有一定特定波长的X射线。因此,只要测量荧光X射线的波长或能量,就可以知道元素的类型。这是荧光 X 射线定性分析的基础。此外,荧光X射线的强度与相应元素的含量也有一定的关系。在此基础上,可以进行元素的定量分析。当样品用 X 射线照射时,样品可以被激发以发出各种波长的 X 射线荧光。需要将混合后的X射线按波长(或能量)分离,分别测量不同波长(或能量)的X射线强度。对于定性和定量分析,为此使用的仪器称为 X 荧光光谱仪。

国产与进口X射线荧光光谱仪技术对比与选购

进口品牌主要有以下几家公司

Thermo Fisher 旗下的 Niton 手持设备和便携式桌面设备

德国斯派克光谱

日本岛津

英国牛津

还有日本的奥林巴斯。

国产品牌主要有

SKYRAY、ESI英飞思科学、HTEK、Cfan等

在技术上,经过近20年的深入积累和研发,国产XRF光谱仪与进口仪器的性能已经非常接近。这也是造成国外设备*逐步下降、终端价格大幅下降的主要原因。

2000年之前,进口XRF设备的价格通常在40万到50万之间。随着国产XRF的逐步推进,进口设备的技术优势也逐渐赶超。它必须进行大幅度的价格调整以适应中国市场。目前,进口设备的价格普遍定在20万至40万的水平。

具体到购买仪器和技术对比,客户应注意以下几点:

1.探测器的类型。不同类型的探测器,如比例计数盒、Si-pin、SDD和FSDD,其性能有很大差异,价格也有很大差异。

2、光管的选择(功率、目标、端窗或侧窗、玻璃或铍窗、稳定性)

3、设备的测试重复性和稳定性非常重要。 X射线荧光光谱仪是基于X射线的元素定性定量分析技术。每个制造商根据不同的校准曲线对样品进行量化。如果每次测试的偏差很大,无论声称多么精确的仪器,它都不起作用。这方面也是研究XRF仪器的重要依据。很多销售人员会说XRF本身有不稳定性,这是事实,但如果偏差过大,也说明技术不够好,测试起不到检测的作用。测量稳定性和重复性是测量设备性能的关键指标。

通常我们可以对同一个标准样品连续测量50次,通过检测各元素RSD的相对标准偏差来验证一个设备的性能。

如果光谱仪的硬件技术不够好,仪器的稳定性是无法保证的。

4.设备的灵敏度是检测下限。通常,很多厂家都吹嘘仪器的检测限可以达到1ppm,这其实是销售人员的吹嘘。客户可根据手中的实际样品进行跟踪,测试设备检测低含量样品的性能。例如,它可以测试塑料中50ppm的Cl氯;铜合金中0.01%镉Cd,0.005%铅Pb,0.03%铝Al;贵金属金中0.01%镉Cd;锡合金中0.005%铬Cr;矿物质等中镁、铝、硅含量低。

5、为了仪器的长期稳定性,客户可以每周对厂家提供的校准样品进行测试。对于仪器长期稳定性优良的设备,同一校准样品在长期跨度内的结果波动很小。

6. 软件算法。由于X荧光光谱仪的主要干扰是基体效应和元素间增强吸收的作用,为了减少或消除这种干扰。软件算法(包括光谱处理技术、强度拟合法、FP基本参数法、α理论系数法、经验系数法等)尤为重要。

7. 售后和技术支持。这通常是国产仪器的优势所在,而良好而持续的售后服务也是国产仪器*不断提升的重要原因之一。

ESI拥有一整套自主研发的X荧光光谱仪技术,与市场上大多数设备相比具有明显的技术优势。该仪器在测试稳定性和灵敏度方面可以达到进口仪器的水平。

近年来,随着XRF国产化的不断深入,市场上的品牌良莠不齐。很多厂商只是在打价格战,降低了研发投入和售后质量

如果客户在采购XRF仪器时遇到困难,建议直接寄样品给厂家进行检测。或请厂家到现场PK,一目了然地见证产品的测试性能。不要被销售人员片面的言论所迷惑。

如果您有任何测试需求,ESI提供免费元素测试服务

Technical comparison and purchase of domestic and imported X-ray fluorescence spectrometers

If a worker wants to do his job well, he must first sharpen his tools.

XRF is an atomic emission spectrometer. In XRF, the radiation from the main X-ray beam of the X-ray tube will cause the fluorescent X-ray radiation to show the characteristics of the dispersed energy of the elements present in the sample

The principle is that the X-ray tube excites the sample under test by generating incident X-rays (primary X-rays). Each element in the excited sample emits secondary X-rays (also called X-ray fluorescence), and the secondary X-rays emitted by different elements have specific energy characteristics or wavelength characteristics. The detection system measures the energy and quantity or wavelength of these secondary X-rays emitted. Then, the instrument software converts the information collected by the detection system into the types and contents of various elements in the sample. The atoms of the element are excited by high-energy radiation to cause the transition of the inner electrons, and at the same time emit X-rays with a certain specific wavelength. Therefore, as long as the wavelength or energy of the fluorescent X-rays is measured, the type of the element can be known. This is fluorescence The basis of X-ray qualitative analysis. In addition, the intensity of fluorescent X-rays has a certain relationship with the content of corresponding elements. Based on this, quantitative analysis of elements can be carried out. When the sample is irradiated with X-rays, the sample can be excited to fluoresce X-rays of various wavelengths. It is necessary to separate the mixed X-rays by wavelength (or energy) and measure the intensity of X-rays of different wavelengths (or energy) respectively. For qualitative and quantitative analysis, the instrument used for this is called X fluorescence spectrometer.

Technical comparison and purchase of domestic and imported X-ray fluorescence spectrometers

Imported brands mainly include the following companies

Niton handhelds and portable desktop devices under Thermo Fisher

Spectro Germany

Shimadzu

Oxford, UK

And Olympus of Japan.

Domestic brands mainly include

SKYRAY, ESI, HTEK, Cfan, etc.

Technically, with the in-depth accumulation and research and development in the last 20 years, the performance of domestic XRF spectrometers and imported instruments have been very close. This is also the main reason for the gradual decline in the market share of foreign equipment and the sharp decline in terminal prices.

Before 2000, imported high-end XRF equipment was usually at a price of 400,000 to 500,000. With the gradual progress of domestic XRF, the technical advantages of imported equipment have gradually caught up and surpassed. It has to make substantial price adjustments to adapt to the Chinese market. At present, the price of imported equipment has generally been set at the level of 200,000 to 400,000.

This is a convenient change in market pricing. From a purely technical perspective, the current advantages of imported XRF fluorescence spectrometers are mainly in software core algorithms and brand premiums. In terms of hardware technology, except for some sub-sectors, such as wavelength dispersive X fluorescence spectrometer, secondary target X fluorescence spectrometer, etc., imported equipment has no advantages at all.

Specific to the purchase of instruments and technical comparison, customers should pay attention to the following points:

1. The types of detectors. Different types of detectors, such as proportional counting box, Si-pin, SDD and FSDD, have very different performances, and their prices are also very different.

2. Selection of light pipe (power, target, end window or side window, glass or beryllium window, stability)

3. The test repeatability and stability of the equipment are very important. X-ray fluorescence spectrometer is based on the element qualitative and quantitative analysis technology of X-ray. Each manufacturer quantifies the samples according to different calibration curves. If the deviation of each test is large, No matter how precise an instrument is claimed, it will not work. This aspect is also an important basis for investigating XRF instruments. Many sales staff will say that XRF itself has instability, which is a fact, but if the deviation is too far, it also means that the technology is not good enough, and the test will not play the role of detection. Measurement stability and repeatability is a key indicator for measuring equipment performance.

Usually we can measure the same standard sample 50 times continuously, and examine the relative standard deviation of the RSD of each element to verify the performance of a device.

If the hardware technology of the spectrometer is not good enough, the stability of the instrument cannot be guaranteed.

4. The sensitivity of the equipment is the lower limit of detection. Usually, many manufacturers boast that the detection limit of the instrument can reach 1ppm, which is actually the boast of the salesperson. Customers can follow up the actual samples in their hands to test the performance of the equipment in detecting low-content samples. For example, it can test 50ppm Cl chlorine in plastic; 0.01% cadmium Cd in copper alloy, 0.005% lead Pb, 0.03% aluminum Al; 0.01% cadmium Cd in precious metal gold; 0.005% chromium Cr in tin alloy ; Low content of magnesium, aluminum and silicon in minerals, etc.

5. For the long-term stability of the instrument, customers can test the calibration samples provided by the manufacturer every week. For equipment with excellent long-term stability of the instrument, the fluctuation of the result of the same calibration sample in the long-term span is very small.

6. Software algorithm. Since the main interference of the X fluorescence spectrometer is the matrix effect and the effect of enhancing the absorption between elements, in order to reduce or eliminate this interference. Software algorithms (including spectrum processing technology, intensity fitting method, FP basic parameter method, alpha theoretical coefficient method, empirical coefficient method, etc.) are particularly important.

7. After-sales and technical support. This is usually the advantage of domestically-made instruments, and good and continuous after-sales service is also one of the important reasons for the increasing market share of domestically-made instruments.

ESI has a complete set of self-developed X fluorescence spectrometer technology, which has obvious technical advantages with most equipment on the market. The instrument can reach the level of imported instruments in terms of test stability and sensitivity.

In recent years, as the localization of XRF continues to deepen, brands on the market are mixed with good and bad. Many manufacturers are simply fighting price wars, which reduces R&D investment and after-sales quality.

If customers encounter difficulties in the procurement of XRF instruments, it is recommended to send samples directly to the manufacturer for testing. Or ask the manufacturer to go to the site to PK and witness the test performance of the product at a glance. Don't be fooled by the one-sided words of the salesperson.

If you have any testing requirements, ESI provides free element testing services, please consult for details


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