選購、購買X射線熒光光譜儀XRF分析儀器的技巧，注意事項(xiàng)和要領(lǐng)

不積跬步，無以至千里；不積小流，無以成江海

XRF 是一種原子發(fā)射光譜儀。在XRF中，來自X射線管主X射線束的輻射會(huì)使熒光X射線輻射表現(xiàn)出樣品中存在的元素能量分散的特性

其原理是 X 射線管通過產(chǎn)生入射 X 射線（初級(jí) X 射線）來激發(fā)被測(cè)樣品。被激發(fā)樣品中的每種元素都會(huì)發(fā)出二次X射線（也稱為X射線熒光），不同元素所發(fā)出的二次X射線具有特定的能量特性或波長(zhǎng)特性。檢測(cè)系統(tǒng)測(cè)量這些發(fā)射的二次 X 射線的能量和數(shù)量或波長(zhǎng)。然后，儀器軟件將檢測(cè)系統(tǒng)采集到的信息轉(zhuǎn)化為樣品中各種元素的種類和含量。元素的原子被高能輻射激發(fā)，引起內(nèi)部電子躍遷，同時(shí)發(fā)出具有一定特定波長(zhǎng)的X射線。因此，只要測(cè)量熒光X射線的波長(zhǎng)或能量，就可以知道元素的類型。這是熒光 X 射線定性分析的基礎(chǔ)。此外，熒光X射線的強(qiáng)度與相應(yīng)元素的含量也有一定的關(guān)系。在此基礎(chǔ)上，可以進(jìn)行元素的定量分析。當(dāng)樣品用 X 射線照射時(shí)，樣品可以被激發(fā)以發(fā)出各種波長(zhǎng)的 X 射線熒光。需要將混合后的X射線按波長(zhǎng)（或能量）分離，分別測(cè)量不同波長(zhǎng)（或能量）的X射線強(qiáng)度。對(duì)于定性和定量分析，為此使用的儀器稱為 X 熒光光譜儀。

國(guó)產(chǎn)與進(jìn)口X射線熒光光譜儀技術(shù)對(duì)比與選購

進(jìn)口品牌主要有以下幾家公司

Thermo Fisher 旗下的 Niton 手持設(shè)備和便攜式桌面設(shè)備

德國(guó)斯派克光譜

日本島津

英國(guó)牛津

還有日本的奧林巴斯。

國(guó)產(chǎn)品牌主要有

SKYRAY、ESI英飛思科學(xué)、HTEK、Cfan等

在技術(shù)上，經(jīng)過近20年的深入積累和研發(fā)，國(guó)產(chǎn)XRF光譜儀與進(jìn)口儀器的性能已經(jīng)非常接近。這也是造成國(guó)外設(shè)備*逐步下降、終端價(jià)格大幅下降的主要原因。

2000年之前，進(jìn)口XRF設(shè)備的價(jià)格通常在40萬到50萬之間。隨著國(guó)產(chǎn)XRF的逐步推進(jìn)，進(jìn)口設(shè)備的技術(shù)優(yōu)勢(shì)也逐漸趕超。它必須進(jìn)行大幅度的價(jià)格調(diào)整以適應(yīng)中國(guó)市場(chǎng)。目前，進(jìn)口設(shè)備的價(jià)格普遍定在20萬至40萬的水平。

具體到購買儀器和技術(shù)對(duì)比，客戶應(yīng)注意以下幾點(diǎn)：

1.探測(cè)器的類型。不同類型的探測(cè)器，如比例計(jì)數(shù)盒、Si-pin、SDD和FSDD，其性能有很大差異，價(jià)格也有很大差異。

2、光管的選擇（功率、目標(biāo)、端窗或側(cè)窗、玻璃或鈹窗、穩(wěn)定性）

3、設(shè)備的測(cè)試重復(fù)性和穩(wěn)定性非常重要。 X射線熒光光譜儀是基于X射線的元素定性定量分析技術(shù)。每個(gè)制造商根據(jù)不同的校準(zhǔn)曲線對(duì)樣品進(jìn)行量化。如果每次測(cè)試的偏差很大，無論聲稱多么精確的儀器，它都不起作用。這方面也是研究XRF儀器的重要依據(jù)。很多銷售人員會(huì)說XRF本身有不穩(wěn)定性，這是事實(shí)，但如果偏差過大，也說明技術(shù)不夠好，測(cè)試起不到檢測(cè)的作用。測(cè)量穩(wěn)定性和重復(fù)性是測(cè)量設(shè)備性能的關(guān)鍵指標(biāo)。

通常我們可以對(duì)同一個(gè)標(biāo)準(zhǔn)樣品連續(xù)測(cè)量50次，通過檢測(cè)各元素RSD的相對(duì)標(biāo)準(zhǔn)偏差來驗(yàn)證一個(gè)設(shè)備的性能。

如果光譜儀的硬件技術(shù)不夠好，儀器的穩(wěn)定性是無法保證的。

4.設(shè)備的靈敏度是檢測(cè)下限。通常，很多廠家都吹噓儀器的檢測(cè)限可以達(dá)到1ppm，這其實(shí)是銷售人員的吹噓?？蛻艨筛鶕?jù)手中的實(shí)際樣品進(jìn)行跟蹤，測(cè)試設(shè)備檢測(cè)低含量樣品的性能。例如，它可以測(cè)試塑料中50ppm的Cl氯；銅合金中0.01%鎘Cd，0.005%鉛Pb，0.03%鋁Al；貴金屬金中0.01%鎘Cd；錫合金中0.005%鉻Cr；礦物質(zhì)等中鎂、鋁、硅含量低。

5、為了儀器的長(zhǎng)期穩(wěn)定性，客戶可以每周對(duì)廠家提供的校準(zhǔn)樣品進(jìn)行測(cè)試。對(duì)于儀器長(zhǎng)期穩(wěn)定性優(yōu)良的設(shè)備，同一校準(zhǔn)樣品在長(zhǎng)期跨度內(nèi)的結(jié)果波動(dòng)很小。

6. 軟件算法。由于X熒光光譜儀的主要干擾是基體效應(yīng)和元素間增強(qiáng)吸收的作用，為了減少或消除這種干擾。軟件算法（包括光譜處理技術(shù)、強(qiáng)度擬合法、FP基本參數(shù)法、α理論系數(shù)法、經(jīng)驗(yàn)系數(shù)法等）尤為重要。

7. 售后和技術(shù)支持。這通常是國(guó)產(chǎn)儀器的優(yōu)勢(shì)所在，而良好而持續(xù)的售后服務(wù)也是國(guó)產(chǎn)儀器*不斷提升的重要原因之一。

ESI擁有一整套自主研發(fā)的X熒光光譜儀技術(shù)，與市場(chǎng)上大多數(shù)設(shè)備相比具有明顯的技術(shù)優(yōu)勢(shì)。該儀器在測(cè)試穩(wěn)定性和靈敏度方面可以達(dá)到進(jìn)口儀器的水平。

近年來，隨著XRF國(guó)產(chǎn)化的不斷深入，市場(chǎng)上的品牌良莠不齊。很多廠商只是在打價(jià)格戰(zhàn)，降低了研發(fā)投入和售后質(zhì)量

如果客戶在采購XRF儀器時(shí)遇到困難，建議直接寄樣品給廠家進(jìn)行檢測(cè)?；蛘?qǐng)廠家到現(xiàn)場(chǎng)PK，一目了然地見證產(chǎn)品的測(cè)試性能。不要被銷售人員片面的言論所迷惑。

如果您有任何測(cè)試需求，ESI提供免費(fèi)元素測(cè)試服務(wù)

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