The image part with relationship ID rid4 was not found in the file. Welcome

The image part with relationship ID rid4 was not found in the file. Welcome

Trace Metals Analysis: Impurity Determinations By Thomas Kozikowski Chemist, R&D at Inorganic Ventures

Key Considerations What types of samples do I need to test? What kinds of impurities do I care about? Do I need to certify their levels? What instrumentation do I have available for use?

The image part with relationship ID rid4 was not found in the file. Goals ü Measuring what s not supposed to be in the solution ü Ignoring what is expected to be in the solution ü Defining instrument detection limits ü Defining real-world detection limits of the sample ü Determining interferences and method contamination ü Confirming observations by second methods If possible

Types of Samples Pure Samples Metals or Pure Salts High Purity Acids High Matrix Solutions Drinking Water/Wastewater/Seawater Food Products High Matrix Solids Those that require acid digestion, fusion, or ashing

Impurities of Interest Only the majors (Ca, Mg, K, Na, Al, Fe, etc.) Transition metals (Cr, Co, Cu, Ni, Ti, etc.) EPA (Method 200.8 or others) USP 232 (As, Cd, Pb, Hg, etc.) Hg

The image part with relationship ID rid4 was not found in the file. Table of EPA and USP Elements Method 200.8 USP 232 Al Co Se Cd Pt Cu Sb Cu Ag Pb Rh As Pb Tl As Ru Ba Mn Th Hg Cr Be Hg U Ir Mo Cd Mo V Os Ni Cr Ni Zn Pd V

Do I need to certify trace levels? Validated method Calibration Curve Internal Standard Ionization Buffer Standard Additions Uncertainty determination What is a reasonable uncertainty for trace levels?

Instrumentation Available ICP-OES (Axial or Radial) ICP-MS (Quad or Hi-Res) Analytical Balances For precision measurements Calibrated Pipets For delivering liquids Volumetric Glassware/Plasticware Not required if using a balance

Sources for Common Issues Sample Prep Containers Tips/Weigh Boats Chemical Stability Reagent Purity Introduction System Spectroscopic Interferences

Sample Prep Issues Containers LDPE, HDPE, PTFE, PFA, PP, Borosilicate Glass Plastic made from virgin polyethylene is critical Sample tubes vs. bottles Leaching containers with dilute HNO 3 (1-5% v/v) https://www.inorganicventures.com/container-material-properties PP? PP HDPE PTFE

Sample Prep Issues Pipet Tips Same contamination concerns as with sample tubes Leaching tips if effective Sterilized tips are for biologicals, not inorganic metals Weigh Boats Notorious for dust contamination Colored boats will have metallic contamination Virgin or natural material is critical May have surface calcium contamination

Sample Prep Issues Chemical Stability Most elements okay in HNO 3 Some need HCl Ir, Ru, Au, etc. Some need HF W, Ta, Hf, Nb, etc. Hg Can be stabilized in LDPE with HCl Can be stabilized in LDPE with HNO3 / 1ppm Au Can be stabilized in Borosilicate glass with HNO3 https://www.inorganicventures.com/part-billion-stability-study https://www.inorganicventures.com/periodic-table

The image part with relationship ID rid4 was not found in the file. Periodic Table of TMI Standards This standard scheme is used for ICP-OES using 2 calibration curves.

The image part with relationship ID rid4 was not found in the file. Periodic Table of TMI Standards This standard scheme is used for ICP-MS using 2 standard addition spike sets.

Reagent Purity Clean Acids (HNO3, HCl, etc.) Clean Bases (TEA, NH4OH, etc.) Clean DI Water (ASTM Type 1) Particle Filtration (0.3µm or smaller) Use of reagent blanks Critical for blank subtraction to determine true real-world sample impurity levels and detection limits

Introduction Systems Classical Quartz Systems If HF is used, problems testing B and Si HF Resistant Systems If high levels are run, B, Si, and Hg can stick Peristaltic Pump Many elements stick to the PVC tubing Syringe Drive Peristaltic pump tubing eliminated much faster washout More specialized maintenance required

Spectroscopic Interferences ICP-OES High levels of transition metals or rare earth elements can create some very challenging spectra Works very well for Group 1 & 2 elements Ca, Mg, K, Na, Li, Be, Sr, Ba Some detection limits not very low compared to MS, but OES analysis usually doesn t require solution to be diluted Signal intensity suffers when high salt is run through May need internal standard or standard addition approach Examining actual spectra is crucial to verifying results Checking multiple lines when possible is also very important

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Spectroscopic Interferences ICP-MS Chloride can cause issues for certain elements (As, Se, V) Rare earth elements can be very challenging due to Oxides Very low detection limits, but requires high dilution factors This results in a much higher than expected real-world detection limit Collision Cell Technology opens up interference resolution Newer technology that will need thorough validation

The image part with relationship ID rid4 was not found in the file. Case Study 1 Concentrated Fluoroboric Acid Customer wanted a cleaner source of HBF4 Also thought current source contained Re Testing Parameters Preferred HF resistant intro system on OES Run Undiluted Allowed for Silicon contamination verification Observed a peak on Re 227.525nm but appeared to be an interference from the HBF4 Used a Quartz system on ICP-MS Didn t need to check B, can t see Si by ICP-MS anyway Confirmed the absence of Re

The image part with relationship ID rid4 was not found in the file. Re 227.525nm Undiluted HBF4 1ppm Re Sample 185 Re (cps) 187 Re (cps) Blank 1 1 1:200 HBF 4 4 48 + 4ppb Re Spike 194,475 325,305 Strong evidence of signal noise, not analyte signal. According to ICP-MS data, Re is not detected with a detection limit of 0.001ppb in the diluted solution. After applying the dilution factor of 1:200, the detection limit of Re in the undiluted solution of HBF 4 is actually 0.2ppb

The image part with relationship ID rid4 was not found in the file. Case Study 2 Tantalum-free niobium For years, IV has used Nb powder for Nb products. TMI always reported interference for Tantalum impurity ICP-OES appeared to have a direct interference ICP-MS appeared to have a major interference Obtained a tantalum-free Niobium pentoxide powder Spectral data looked quite different for Ta

The image part with relationship ID rid4 was not found in the file. Is this peak an interference or is it Ta? ICP-MS data is so high, normal standard addition method is giving unusable data. This really is 30ppm Ta in a 20,000ppm Nb. Real-world level: 1,400ppm in the Nb powder L Using a different source of starting material, the peak is gone! ICP-MS is claiming that this no-peak really contains 0.3ppm Ta in a 20,000ppm Nb. Real-world level: 10ppm Ta in the Niobium oxide powder. The elevated background is hiding the true signal.

The image part with relationship ID rid4 was not found in the file. Final Thoughts Always use clean containers and materials Examine actual spectra and evaluate blanks Ensure the use of stable calibration standards Evaluate multiple methods to verify observations

The image part with relationship ID rid4 was not found in the file. Technical Support Available to Everyone Online Resources at inorganicventures.com Customers can visit our website s Tech Center, which includes: Interactive Periodic Table Sample Preparation Guide Trace Analysis Guide ICP Operations Guide Expert Advice And much, much more.