布魯克Bruker-X射線熒光光譜分析備樣技術(shù)

1、X射線熒光光譜分析技術(shù)之二：制樣方法制樣的目的：1、均勻2、重復(fù)性好3、顆粒效應(yīng)小4、礦物效應(yīng)小5、無(wú)限厚（薄膜法除外）分析層的厚度：無(wú)限厚X-ray tubeto soller slit(collimator)analysed layer(saturation depth)Sample 分析層的厚度：無(wú)限厚SampleB KA1 (0,18 keV)Sn LA1 (3,4 keV)Cr KA1 (5,4 keV)Sn KA1 (25,2 keV)tubeto soller slitIs your sample homogeneous ?Analysed layer on the sample

2、 surfaceno excitation within the inner (upper) part of the samplethe lower parts (layers) of the sample can be excited (by short wavelengths) but emmitted radiation will be absorbed within the samplefluorescence radiation to be measured comes from a layer near the sample (specimen) surface分析層的厚度：無(wú)限厚

3、0,01 mm = 10 nm = 100 Aatom radius: 0,5 - 3 Atube分析層的厚度：對(duì)于輕基體（如液體）Light matrix顆粒效應(yīng): 不均勻的顆粒樣品CaCO3SiO2壓片樣品松散樣品顆粒效應(yīng):不均勻的顆粒樣品分析層 !analysed layer顆粒效應(yīng):不均勻的顆粒樣品顆粒效應(yīng): 產(chǎn)生90%熒光強(qiáng)度的樣品厚度Thickness of the sample from which 90% of the measured intensity is derivedNBS 88b DolomitePressed Pellet without binderEspeci

4、ally for the lines of light elements average grain size layer thickness(typically grain sizes vary between : 20 - 200 mm)X射線熒光光譜可以分析的樣品種類固體，塊狀樣品金屬塊礦石塊粉末狀樣品礦石粉，如鐵礦、煤炭液體樣品油品水樣塊狀樣品的制樣方法對(duì)于金屬樣品研磨研磨+拋光（分析輕元素時(shí)需要）需要考慮樣品加工時(shí)帶來(lái)的污染，如SiO2、Al2O3基體效應(yīng)教嚴(yán)重，不過(guò)采用新的軟件，可以對(duì)基體效應(yīng)進(jìn)行校正塊狀樣品的制樣方法對(duì)于礦樣考慮到樣品的不均勻性，一般先制成粉末也可以直接進(jìn)行定性或

5、半定量分析粉末樣品的制樣方法直接裝入液體杯中測(cè)量，稱為松散樣品壓片制樣特點(diǎn)：簡(jiǎn)單、快速、節(jié)省 存在顆粒效應(yīng)、礦物效應(yīng)熔融制樣制樣精密度好均勻性好 可以人工配制標(biāo)樣消除了顆粒效應(yīng)、礦物效應(yīng)缺點(diǎn)：制樣麻煩、成本高、影響檢出限松散樣品 Na to Uabsorption in foilHe flushing required ?for qualitative and semiquantitative analysis for quantitative analysis in special cases only（一般是壓不成片的時(shí)候）壓片制樣pressas pure pelleton a suppo

6、rt of boric acidin steel rings in aluminium cupsadd binder if necessarywax ( C and H) boric acid ( B, H and O)壓片制樣的精密度熔融制樣熔融設(shè)備 馬弗爐 燃?xì)鉅tinductively heated 熔劑lithiumtetraborate Li2B4O7lithiummetaborate LiBO2mixtures of Li2B4O7 and LiBO2 白金坩堝(crucibles and moulds)Analysis of Raw Meal SamplesPressed pell

7、ets versus fused beadsSamplessix certified reference materials (Holderbank)Two different preparation methodsfused beads 0.9 g of material 8.1 g of fluxpressed pellets with 20% of wax Analysis of Raw Meal SamplesPressed pellets versus fused beads壓片制樣和熔融制樣的分析結(jié)果的比較壓片制樣和熔融制樣的分析結(jié)果的比較The comparison of the

8、 two different preparation methods clearly shows:sensitivities and LLDs are better for pressed pelletsthe accuracy is much better for fused beads up to a factor of 10 for SiO2液體樣品 水,油, 溶液,泥漿, . 盡量不要分析對(duì)儀器有腐蝕或污染的樣品，如酸溶液液體樣品：用液體杯直接分析不同的樣品要選擇合適的膜光路為氦氣光路，千萬(wàn)不要抽真空 液體樣品可以分析的元素范圍: Na - UWD-XRF Mg in Oil: 0 -

9、 900 ppmWD-XRF Mg in Oil: 0 - 900 ppm油品樣品中各元素的檢出限液體樣品：濾紙片法small quantities of sample (several 100l) dropped on a filter paper with an hydro-phobic ring to guarantee a constant area over which the sample is spreadunloaded filters necessary for blank measurement熔融制樣方法：常用熔劑Li2B4O7（熔點(diǎn)：920o C ）LiBO2 （熔點(diǎn)：850o C ）Li2B4O7+LiBO2：混合熔劑如12：22常用的熔融比：1：5，1：10，1：20脫模劑（改變?nèi)垡旱慕?rùn)特