如何测定家电产品中的Cd,Cr,Hg等元素

JORDANVALLEYApp Note #2173 JORDANVALLEYApp Note #2173Analysis of Cd， Pb， and Hg in Polyethylene CAnalysis of Cd， Pb，and Hg in PolyethyleneSI) APPLICATION NOTE OBJECTIVES 1) Calibrate the instrument using the polyethylene standards for Cd，Pb and Hg. 2) Demonstrate instrument precision and accuracy. BACKGROUND Most countries have regulations requiring that plastics contain less than 100 ppm cadmium. Recentlythe European Union has legislated that plastics used in electronic goods must be free (likely <5ppm) ofcadmium by July 2006. A number of handheld and benchtop devices are marginally useful for a fewmore years. These devices are a poor investment when compared to analytical instruments that meetfuture requirements. The goal of this application study was to develop an EDXRF method to certify thata plastic part contains less than 5 ppm cadmium， lead， and mercury. Energy Dispersive X-ray Fluorescence (EDXRF) provides an attractive alternative to the traditionalapproaches. The capabilities of Jordan Valley's EDXRF instruments offer the following benefits： 1.)Minimal sample preparation， as no sample digestion is required， 2.) Automated sample analysis withoutoperator intervention， 3.) The method is non-destructive， so that the sample can be tested by othermeans， and 4.) The technique is suitable for use by non-technical personnel. ANALYTICAL CONFIGURATION -EX-Calibur Table 1. Analytical Configuration Instrument EX-Calibur EDXRF Analyzer Excitation Rh-Anode X-ray Tube with X-ray Tube Filters Detector High resolution-LN free PIN Diode Analysis Time 1000 seconds per acquisition Calibration Method Regression Modifications None Environment Air Sample Preparation Plastic pellets were placed directly on sample tray APPLICATION NOTE Table 2.Correlation Plot for Cd in Polyethylene Element：Cd RMS Deviation： 0.5 Unit： ppm R2 Correlation： 0.999 Sample Given Measured Blank 0.0 0.2 Std 2 28.0 26.9 Std 3 86.0 86.3 Correlation Fit for Cd Correlation APPLICATION NOTE Table 3. Correlation Plot for Pb in Polyethylene Element： Pb RMS Deviation： 2.0 Unit： ppm R2Correlation： 0.999 Sample Given Measured Blank 0.0 1.1 Std 2 15.0 14.8 Std 3 38.0 33.7 Std 4 116.0 117.2 Correlation Fit for Pb Correlation Given(ppm) Table 4. Correlation Plot for Hg in Polyethylene Element： Hg RMS Deviation： 0.8 Unit： ppm R2Correlation： 0.999 Sample Given Measured Blank 0.0 0.0 Std 2 18.0 17.6 Std 3 44.0 45.4 Std 4 131.0 130.6 Correlation Fit for Hg Correlation Given (ppm) APPLICATION NOTE OBSERVED STATIC PRECISION (10 repeat analysis at 1000 seconds per analysis) Table 5： Precision for Cd Sample Sample Actual Concentration(ppm) Mean Concentration(ppm) StandardDeviation %RSD Std 3 86.0 86.2 1.1 1.25 Table 6： Precision for Pb Sample Sample Actual Concentration Mean Concentration StandardDeviation %RSD (ppm) (ppm) Std 4 116.0 115.9 1.5 1.26 Table 7： Precision for Hg Sample Sample Actual Concentration Mean Concentration StandardDeviation %RSD (ppm) (ppm) Std 4 131.0 130.3 2.3 1.77 Table 8： Detection Limits for the EX-Calibur Element Minimum Detection Limit(ppm) Cd 0.6 Pb 2.2 Hg 1.8 MDL are at 2o confidence interval DISCUSSION The Jordan Valley EX-Calibur is a state of the art benchtop liquid nitrogen free Energy Dispersive X-Ray Fluorescence Spectrometer. The EX-Calibur eliminates the cost and inconvience associated withliquid nitrogen and still retains the power that is achieved by a LN2 cooled Si(Li) detector. Thepowerful 50 kV， 50 watt spectrometer is contained within a single cabinet and features an integratedcomputer， for benchtop operation. APPLICATION NOTE This study successfully demonstrates that the Jordan Valley EX-Calibur can detect cadmium and otherelements below 5 ppm. The minimum detection limits for Cd， Pb， and Hg are 0.6， 2.2， and 1.8respectively. The calibration curves constructed for the analysis can be found in tables 2-4. Precisionruns were also performed to demonstrate the instrument repeatability and can be found in tables 5 -7.The superior performance is achieved with the EX-Calibur’s 50kV， 50 watt x-ray tube and carefulselection of an optimal filter. Because of this high performance， it is possible to make measurements at100 ppm with nearly 1% RSD. The EX-Calibur’s high precision allows the QA department to certify that products are below 100 ppmlevel when the measure 95 ppm or less.While a less precise 35 kV EDXRF analyzers， will only beuseful for certifying materials that are <100 ppm cadmium， when they measure less than 70 ppmcadmium.The EX-Calibur can minimize unnecessary waste now and easily meet the regulatoryrequirements of the future. All data was acquired with the latest version of Jordan Valley’s nEXt software. nEXt allows the operatorcomplete control ofthe EX-Calibur from every aspect of applied voltage， current， and tube filters. nEXtis powerful enough for research and development applications with numerous methodologies foranalysis such as Standardless Fundamental Parameters and several regression calibration algorithms.Alpha corrections used in the regression algorithms are automatically calculated by the nEXt software，and compensate for variations in x-ray absorption and enhancement within the matrix. The operator willalso find nEXt easy to use with helpful qualitative features， like auto peak ID， digital filter， KLMmarkers and a periodic table showing the K， L and M energy lines for all elements. Although powerfulenough for an advanced XRF user， the nEXt software is simple and logically intuitive enough to be usedby non-technical personnel. CONCLUSION The resultsof this study shows nearly 1% RSD is achieved at 100 ppm， and excellent precision andsuperior performance can be expected from the Jordan Valley EX-Calibur. Given sufficient independentstandards， precise calibrations can be built. The versatility， ease of use， and powerful software of theJordan Valley EX-Calibur makes this an ideal instrument for this application. The data presented herein is hereby warranted to be generated from standard Jordan Valley production instruments.Under qualifiedoperation - which includes sample preparation， instrument set up， and other variable parameters affecting performance - any asAnalysis of Cd， Pb， and Hg in Polyethylene APPLICATION NOTE instrument manufactured by Jordan Valley as specified by model type， including options， is expected to meet the performance statedabove. Figure 1： Spectra of 86 ppm Cd in polyethylene (overlap) with a polyethylene blank (main). YREVOC )ISC APPLICATION NOTE APPLICATION NOTE Jordan Valley AR， Inc.Ed VillarrealApplications Specialist of Denton Drive， Austin， TX USATEL ( FAX(