Analysis of High Purity Zinc by Glow Discharge Mass Spectrometry for Use in Thermometry T. Gusarova, B. Lange, H. Kipphardt, R. Matschat and U. Panne Federal Institute for Materials Research and Testing (BAM) Working Group “Primary Calibration Materials; Trace Analysis” Physikalisch-Technische Bundesanstalt Federal Institute for Materials Research and Testing

Content PTB + BAM co-operation work GD-MS: basic principles, advantages and limitations Calibration with pellets (sample preparation) Calibration with Zinc Certified Reference Materials Pure zinc samples, used in thermometry Conclusions Prospects

Trace element mass fraction Co-operation work Trace element mass fraction Temperature PTB and BAM: joint development of a basis for creation of fix points based on certified pure materials taking into account national and international regulations estimating corresponding uncertainty Solid state Ultra-high purity materials Multielement ultra-trace determination (μg/kg, ng/kg) Method traceable to SI –precondition for certification of RM

Glow Discharge Mass Spectrometry (GD-MS) Multielement Solid sampling No sample preparation No losses of analytes No chemical contamination of the sample Less time is needed Decreased non-spectral Interferences (compared to ICP-MS)

Main advantages of Finnigan ELEMENT GD (Thermo Fisher Scientific) (with Sample Holder) GD Ion Source Ion Transfer Optics ESA SEM Faraday Cup Detection System Magnet Grimm-type ion source High sputter rate, short analysis time High sample throughput (6 Samples per hour) More than 12 orders of magnitude automatic detection system Complete determination of matrix and trace elements (up to ng/kg) Extremely high SBR (Signal to Background Ratio) Double focussing mass spectrometer (Resolution up to 10000)

Calibration with doped pellets Quantification with Element GD Semiquantitative Quantitative Traceable to SI IBR Direct Indirect Standard RSF RSF Calibration with doped pellets Calibration with RM

Preparation of Zn Pellets by wet doping 52 elements 1% HNO3 Mixing shaking in 3 dimensions of space Pressing ~ 1 g of the powder in pellets into a sample steel ring under 90 kN/cm2 Sample diameter ≈ 12 mm Thickness ≈ 2 mm Analysing

Observation of intensity-time behaviour of different elements Doped with powders: grain size between 3 and 900 μm 123Sb 70 μm 10 ppm 58Ni 3-7 μm 1 ppm 56Fe > 840 μm 50 ppm Doped with liquids 24Mg 5 ppm 64Zn matrix 114Cd 5 ppm Pre-sputter time Measurement time Pre-sputter time Measurement time Pre-sputter time Measurement time

Mass fractions of trace elements in the pellets Analysing data Mass fractions of trace elements in the pellets 10 mg/kg; 5 mg/kg; 1 mg/kg; 500 µg/kg; 100 µg/kg; 50 µg/kg; 10 µg/kg; 5 µg/kg; blank Zn powder 99,999% pure <150 micron Parameters Voltage ~500 V Current 20 mA Ar Gas Flow 375 ml/min Peltier Cooling 20 °C Low Resolution (LR) ≈ 400 Medium Resolution (MR) ≈ 4000 High Resolution (HR) ≈ 10000

Calibration with doped pellets

Calibration with doped pellets

Trace element mass fraction in mg/kg Zn Certified Reference Materials Voltage ~500 V Current 20 mA Ar Gas Flow 375 ml/min Peltier Cooling 20 °C Trace element mass fraction in mg/kg ± uncertainty mg/kg

CRMs measurements

Procedure for samples analysis Scanning (6 – 239 u) ↓ elements of interest Pellet preparation 114Cd 112Cd 116Cd 111Cd 113Cd 38Ar40Ar40Ar Compiling of measurement method and parameter optimisation Calibration of Element GD with pellets Sample measurements

Comparison of materials for thermometric use PTB-Zn1 and PTB-Zn2a can be easily distinguished. That might also be visible in the temperature measurements Limits of detection (6s) for most of the elements are < 1 mg/kg (many of them go down to µg/kg level) These limits of detection could be in future improved with enhancement of the sensitivity of the method by special calibration of detection system and other measures.

Analysis of In In-Sample in sample holder Light optical microscope image

Enhancement of signal sensitivity of Glow Discharge Optical Emission Spectroscopy Titanium in pure copper Flat sample Sample with a hole a.u. a.u. mass fraction, mg/kg mass fraction, mg/kg

Conclusions Pellets doped with solutions can be successefully used for the calibration of GD-MS It is the most accurate calibration procedure to obtain small uncertainty (compared to factor 2 or even more uncertainty by use of RSF approach) In this way direct traceability of the measurement results to SI is achieved – this procedure is a precondition for the certification of reference materials (CRMs) with GD-MS CRMs of pure zinc were also measured. The measurement results were in good agreement with the calibration curves of Zn-pellets A procedure for the analysis of materials used for fix-point cells is being worked out Two samples of fix-point materials from different producers were compared First investigations with In samples were carried out Another analytical techniques such GD-OES will be improved and tried to be used for the analysis of the fix-point materials

Prospects Preparation of doped In-pellets and calibration for In matrix Analysis of the material for fix-points-cells Graphite analysis Comparison of analyses with ICP-MS, LA-ICP-MS, GD-OES and GD-MS Determination of non-metallic elements (O, S…) Expansion of GD-MS to analysis of other materials

Thank you for your attention Thank you for financial support … Dr. Fischer, J. Dr. Rudtsch, S. Fahr, M. Dr. Lange, B. Dr. Hodoroaba, V.-D. Dr. Kipphardt, H. Dr. Matschat, R. Prof. Dr. Panne, U. … and help during investigations! BAM Division I.1 Richard-Willstaetter-Strasse 11 12489 Berlin, Germany Contact: tamara.gusarova@bam.de or heinrich.kipphardt@bam.de