Hiroshi Sawai TKG Laboratory Center International Standardisation Office

Transcription

1 Achieving ISO17025 Accreditation For Au Assay by ICP-OES Using Au-Reference Materials Hiroshi Sawai TKG Laboratory Center International Standardisation Office TANAKA KIKINZOKU KOGYO K.K. 7-8 March

2 Overview 1. Tanaka s Role in LBMA RM Project 2. Assay Procedure 3. Points for the Procedure 4. What is ISO/IEC 17025? 5. Benefits of Achieving ISO17025 Accreditation 6. Role of LBMA RMs in TKKs Achievement of Obtaining ISO17025 Accreditation 7. Evaluation for Assay 8.Uncertainty 9. Conclusion TANAKA KIKINZOKU KOGYO K.K. 1.Tanaka s Role in LBMA RM Project 1. Member of the Steering Committee (with RCM, Metalor SA, Great Wall,Rand Refinery and Umicore) 2. Au-RM Project *Manufacturer *Assayer for derivation of certificated value 3. Ag-RM Project *Assayer for derivation of certificated value 7-8 March

3 2. Assay Procedure for Gold Sample Weighing Adding Acid Liquefaction Make up Measurements (HCl & HNO3) By Volume to Level By Heat Block Required ICP-OES Make up Standard Solution + Preparation of the Au mother solution Preparation of mixed metal standard solution Make up standard solution for ICP measurement March

4 3. Points for the Procedure Concerning the procedure, the main points are as follows: 1. The concentration of gold and acid in the sample solution must be the same as in the standard solution. 2. In order to avoid evaporation of acid during dissolution, samples are heated in sealed vessels. 3. To prevent errors due to the contamination of the standard solution with other metals, the impurities in the commercial standard solutions should be carefully analysed. 4.What is ISO/IEC 17025? ISO/IEC is the main standard used by testing and calibration laboratories. Oii Originally it was started tdi in order to provide assurance about the accuracy of assaying or analysis carried out by accredited laboratories, and thus avoiding the need for additional assays. The two main sections in ISO/IEC are Management Requirements and Technical Requirements. Technical requirements include factors which determine the correctness and reliability of the tests and calibrations performed in the laboratory. 7-8 March

5 5. Benefits of Achieving ISO17025 Accreditation In the accredited Assay range 1. The reliability of your assaying will be recognised internationally. 2. Applying for ISO17025 accreditation will improve your assaying ability. 3. Your customer will have increased confidence in your assaying results. 6. Role of LBMA RMs in TKKs Achievement of Obtaining ISO17025 Accreditation? 1. To achieve ISO17025, you must prove that your assay results match the international standards. 2. However, before the LBMA-RM, there were no reliable international standards for gold and silver. 3. LBMA-RMs are the first standards to have been produced by means of a collaborative international effort. 4. Comparing with LBMA RM, your assay ability can be judged using appropriate statistical methods. 5. For achieving ISO17025 Accreditation, use of the LBMA RMs is the most effective means of producing a trustworthy assay. 7-8 March

6 7. Evaluation for Assay Ability En =(LAB-REF)/(U LAB2 +U REF2 ) 0.5 LAB:Assay by Laboratory(TKK Assay result) REF:Basis by Reference (LBMA Certified ) U LAB :Uncertainty at Laboratory(TKK s value) U REF : Uncertainty at Reference (LBMA s value) -1 < En < 1 Good assay ability En < -1, En >1 Bad assay ability 8. Uncertainty Calculation of the uncertainty is most important item to get the accreditation of ISO Assay results are given from many process. So at first, we must calculate uncertainty at each process. Then final uncertainty is calculate by of each uncertainty 7-8 March

7 Certificate of LBMA Au-RMs Element Concentrations, mg/kg AuRM1 AuRM2 Ag 20.0 ± ± 5.6 Al 9.6 ± ± 1.8 As 14.5 ± ± 2.8 Bi 30.4 ± ± 0.8 Ca 9.6 ± ± 2.6 Cr 9.4 ± ± 2.2 Cu 13.5 ± ± 2.4 Fe 10.6 ± ± 2.2 Mg 30.1 ± ± 0.9 Mn 9.7 ± ± 1.5 Ni 9.8 ± ± 2.6 Pb 9.8 ± ± 2.4 Pd 9.7 ± ± 1.3 Pt 10.3 ± ± 2.1 Rh ± ± Sb 35.7 ± ± 1.6 Se 11.8 ± ± 2.8 Si 9.4 ± ± 3.8 Sn 9.7 ± ± 1.8 Te 40.7 ± ± 3.2 Ti 10.5 ± ± 1.3 Zn 10.3 ± ± 2.3 AgRM1 AgRM2 Al 7.9 ± ± 8.1 As 19.0 ± ± 1.0 Au 6.1 ± ± 1.5 Bi 7.3 ± ± 3.0 Cd 8.0 ± ± 1.2 Cr 62.9 ± ± 1.2 Cu 30.2 ± ± 2.6 Fe 22.4 ± ± 2.2 Mg 13.9 ± ± 4.6 Mn 8.9 ± ± 0.9 Ni 66.1 ± ± 2.5 Pb 37.5 ± ± 1.0 Pd 5.2 ± ± 1.7 Pt 5.5 ± ± 4.2 Rh 13.4 ± ± 1.3 Sb 4.5 ± ± 2.4 Se 23.0 ± ± 0.6 Si 10.0 ± ± 8.2 Sn 49.2 ± ± 0.6 Te 4.7 ± ± 3.5 Zn 26.9 ± ± 0.5 LBM A RM -1 Elem ents C oncentration mg/kg U ncertainty(k=2) mg/kg En LBM A Basis TKK Assay Dif LBMA TKK A g Al A s B i Ca Cr C u Fe M g Mn Ni Pb Pd Pt Rh Sb Se Si Sn Te Ti Zn March

8 Conclusion 1. TKK achieved ISO17025 Accreditation for Au Assay by ICP OES. 2. To obtain this accreditation, the reliability of your assay will be evaluated from an international viewpoint. 3. Using of LBMA RM is the most effective method of achieving accreditation. Thank you for your kind attention Lt Let s join ji world 7-8 March