布鲁克Bruker-X射线荧光光谱分析备样技术

1、X射线荧光光谱分析技术之二：制样方法制样的目的：1、均匀2、重复性好3、颗粒效应小4、矿物效应小5、无限厚（薄膜法除外）分析层的厚度：无限厚X-ray tubeto soller slit(collimator)analysed layer(saturation depth)Sample 分析层的厚度：无限厚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分析层的厚度：无限厚

3、0,01 mm = 10 nm = 100 Aatom radius: 0,5 - 3 Atube分析层的厚度：对于轻基体（如液体）Light matrix颗粒效应: 不均匀的颗粒样品CaCO3SiO2压片样品松散样品颗粒效应:不均匀的颗粒样品分析层 !analysed layer颗粒效应:不均匀的颗粒样品颗粒效应: 产生90%荧光强度的样品厚度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射线荧光光谱可以分析的样品种类固体，块状样品金属块矿石块粉末状样品矿石粉，如铁矿、煤炭液体样品油品水样块状样品的制样方法对于金属样品研磨研磨+抛光（分析轻元素时需要）需要考虑样品加工时带来的污染，如SiO2、Al2O3基体效应教严重，不过采用新的软件，可以对基体效应进行校正块状样品的制样方法对于矿样考虑到样品的不均匀性，一般先制成粉末也可以直接进行定性或

5、半定量分析粉末样品的制样方法直接装入液体杯中测量，称为松散样品压片制样特点：简单、快速、节省 存在颗粒效应、矿物效应熔融制样制样精密度好均匀性好 可以人工配制标样消除了颗粒效应、矿物效应缺点：制样麻烦、成本高、影响检出限松散样品 Na to Uabsorption in foilHe flushing required ?for qualitative and semiquantitative analysis for quantitative analysis in special cases only（一般是压不成片的时候）压片制样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)压片制样的精密度熔融制样熔融设备 马弗炉 燃气炉inductively heated 熔剂lithiumtetraborate Li2B4O7lithiummetaborate LiBO2mixtures of Li2B4O7 and LiBO2 白金坩埚(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压片制样和熔融制样的分析结果的比较压片制样和熔融制样的分析结果的比较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液体样品 水,油, 溶液,泥浆, . 尽量不要分析对仪器有腐蚀或污染的样品，如酸溶液液体样品：用液体杯直接分析不同的样品要选择合适的膜光路为氦气光路，千万不要抽真空 液体样品可以分析的元素范围: Na - UWD-XRF Mg in Oil: 0 -

9、 900 ppmWD-XRF Mg in Oil: 0 - 900 ppm油品样品中各元素的检出限液体样品：滤纸片法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熔融制样方法：常用熔剂Li2B4O7（熔点：920o C ）LiBO2 （熔点：850o C ）Li2B4O7+LiBO2：混合熔剂如12：22常用的熔融比：1：5，1：10，1：20脱模剂（改变熔液的浸润特