| The paper topic selection comes from "863Project" resources and environment technology subject"High-Precision Spectrum Detection Instruments Development"(Project Number:2012AA061803). In recent years,air particles has become the main pollutants in many cities at Home and Abroad,they are not only related to human health,but also able to influence the photosynthesis of plants,and they can also change the genes of plants to some extent. Air particles can also harm animals in considerable degree,so it is very important to analyze the element of air particles.Currently many instruments can analyze the components and physico-chemical characteristics of air particles effectively,but these instruments are mainly indoor laboratory analysis,and they also need to have a higher annlysis environment,also there are many corresponding troubles for preservation and transportation of samples.Combined with relevant datas,the writer used hand-held EDXRF to analyze the air particles collected in real time.It is widely applied to the real-time analysis of the field geological samples and composition of construction materials and indoor nuclide analysis and so on because of its ability of quick,in situ and field measurement.PM2.5device is used to collect air particles,and the collection filter membrane material is PTFE,and the flow rate of sampling is100liters per minute.For a long time sampling and analysis of indoor,outdoor,we have gain the main results:1.Combination with relevant datas and through actual test,we chose the PTFE,which is less affectd to analysis of heavy metals.We used ICP-MS to analyze the content of Ti,Mn,Ni,Cu,Zn,As,Sr,Pb in the samples of PTFE filter membrane effectively,and the content is used to analyze as the standard content of membrane sample of EDXRF. 2.Through analysis content of PTFE filer membrane,we have evaluated the precision and accuracy of hand-held and multi-element EDXRF,and the results shew that the measurement pecision Ti was18.0%,Mn was7.9%, Ni was24.9%, Cu was6.1%,Zn was3.1%,As was20.9%, Pb was16.8%,Sr was10.0%,due to the less total mass of the test samples,the relative deviation of some elements is larger than others,but the precision of measurement results have reached the requirement of limit of25%in the specification.The logarithmic average deviation X of Ni was-0.19,logarithmic deviation λ was0.14;the logarithmic average deviation X of Cu was-0.06,logarithmic deviation λ was0.10;the logarithmic average deviation X of Pb was-0.03,logarithmic deviation λ was0.15;the logarithmic average deviation X of As was0.17,logarithmic deviation λ was0.20;the logarithmic average deviation X of Ti was0.05,logarithmic deviation λ was0.11;the logarithmic average deviation X of Mn was0.03,logarithmic deviation λ was0.05;the logarithmic average deviation X of Zn was0.05,logarithmic deviation λ was0.10;the logarithmic average deviation X of Sr was-0.09,logarithmic deviation λ was0.14,with reference to the monitoring limit requirements of standard samples2,the logarthmic average deviation of each is within the scope of monitoring limit of0.20,logarithmic deviation is within the limit of0.33.3.Due to the low concentrations of heavy metals of particles and less weight of samples,the environment background has great influence to analysis results,and we used the method of Fourier transform background subtraction to subtract the background of hand-held multi-element EDXRF,ignoring the absorption enhancement effects and through the net count rate,we calibrated the instrument.4. We analyzed the two sampling points for a long time,the results shew that the hand-held muli-element EDXRF can analyze the content of Ti,Mn,Ni,Cu,Zn,As,Sr,Pb effectively and determin the concentration of element in air particle,by analysis the abnormal of each element in the monitoring curves,we found the fog haze phenomenon in early march.the analysis results of indoor shew that the concentration of each element of the third floor is significantly lower than the first floor,especially each element had a very low concentration in the room of the large WDXRF.5. Through actual analysis,we found some problems and some respect to improve:(1),the analysis of ICP-MS needs more weight of sample,while the sample weight collected by sampling device within24hours is far short the standard analysis,when making standard sample by ICP-MS,we can try to extend the sampling time.(2),the program of XRF should try to separate the characteristic peak of As and Pb,avoiding the errors of analysis results.(3),we should choose the samples as far as possible that the count rate of each element has a larger gradient.(4),keeping ventilation as much as possible before and after work of each laboratory,it can avoid some unnecessary human flyash stranding in the air. |
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