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4 T H A N N U A L I C P C O N F E R E N C E
SEPTEMBER 25 –26, 2018 CHRI ST IANSBURG, VA
2018 ICP Conference Meeting Agenda
T U E S DAY , S E P T E M B E R 2 5
8:00–8:30 Check In — Coffee 8:30–8:45 Welcome and Introduction
Thomas Kozikowski Chemist, R&D
Basic Needs and Considerations for an ICP Analysis
8:45–9:30
Mike Booth Quality Control Manager
ICP Instrument Maintenance and Tuning
9:30–10:15
10:15–10:30 Break
Paul Gaines, Ph.D. CEO, Senior Technical Director
Reliable Measurements Part I: Planning a Trace Analysis
10:30–11:30
11:30–1:00
Lunch
Brian Alexander, PhD. VP Technical Operations
ICP-MS: Limits and Reliable Measurements
1:00–2:00
2:00–2:15
Break
Lesley Owens, Ph.D. Senior Research Chemist
Application of Basic Statistics in Measurement Uncertainty
2:15–3:00
James King Chemist, Technical Manager
ICP Calibration Standards: Design, Handling and Troubleshooting
3:00–3:45
3:45–4:00 Break 4:00–6:00 Tour of Inorganic Ventures and Catered Cocktail Reception
W E D N E S DAY , S E P T E M B E R 2 6
8:00–8:30 Check In — Coffee 8:30–8:45 Morning Remarks
Trace Metals Analysis of Multi-Element Standards by ICP-OES
8:45–9:30
Thomas Kozikowski
ICP-MS: Planning for Tough Samples and Problem Elements
9:30–10:15
Brian Alexander, Ph.D.
10:15–10:30 Break 10:30–11:30
Reliable Measurements Part II: Sample Preparation
Paul Gaines, Ph.D.
11:30–1:00
Lunch
Fundamentals of Method Validation
1:00–1:45
Lesley Owens, Ph.D.
1:45–2:00 Break
Paul Gaines Ph.D. Brian Alexander Ph.D. Lesley Owens Ph.D. Thomas Kozikowski
Roundtable Discussion
2:00–4:00
Mike Booth James King
2018 ICP CONFERENCE SPEAKERS Reliable Measurements: Part I: Planning a Trace Analysis Reliable Measurements: Part II: Sample Preparation Paul Gaines, Ph.D. / CEO, Senior Technical Director
Dr. Paul R. Gaines has four decades of spectroscopic experience. After earning his Ph.D. in chemistry at Iowa State University, Dr. Gaines worked in the laboratories of Exxon Research and Engineering and Union Carbide. Dr. Gaines is also an accomplished web author of many popular guides and papers for fellow spectroscopists.
ICP-MS: Limits and Reliable Measurements ICP-MS: Planning for Tough Samples and Problem Elements Brian Alexander, Ph.D. / Vice President, Technical Operations
Dr. Brian Alexander is an earth scientist specializing in geochemistry. His research has focused on radiogenic isotope and rare earth element studies of natural waters and chemical sediments, as well as trace metal analyses using ICP techniques. A native of southwest Virginia, Brian received his B.Sc. in geology from Virginia Tech, and a M.Sc. and Ph.D. in geochemistry from Penn State and Jacobs University Bremen, respectively.
Application of Basic Statistics in Measurement Uncertainty Fundamentals of Method Validation Lesley Owens, Ph.D. / Senior Research Chemist
Dr. Lesley Owens is an analytical chemist with research specialties including chromium speciation, environmental sample design, elemental spectroscopy, and metal contamination in food products. Dr. Owens graduated from Emory & Henry with a B.S. in Chemistry, and a minor in Mathematics. Owens, a Cunningham Fellow, received her Ph.D. in Analytical Chemistry from Virginia Tech.
ICP Calibration Standards: Design, Handling and Troubleshooting James King, M.Sc. / Chemist, Technical Manager
James King is an inorganic chemist with experience in synthesis and purification. His research has focused on the synthesis and characterization of organometallic compounds to be used as molecular magnets. A native of Hampton, Virginia, James received his undergraduate and graduate degrees from North Carolina A&T State University and Virginia Tech, respectively.
Basic Needs and Considerations for an ICP Analysis Trace Metals Analysis of Multi-Element Standards by ICP-OES Thomas Kozikowski / Chemist, R&D
Thomas Kozikowski is a chemist with expertise in the manufacturing, quality control, technical support, stability, and homogeneity of inorganic metals standards. His experience covers many areas including reagent synthesis and purification, trace metals analysis using ICP techniques, transpiration studies, and container cleanliness. Thomas has a B.S. degree in Chemistry and a B.S. degree in Forensic Science from Virginia Commonwealth University.
ICP Instrument Maintenance and Tuning Michael Booth / Quality Control Manager
Mike Booth is a chemist with expertise in quality control and instrumentation. His experience covers areas including ICP-OES, ICP-MS, Ion Chromatography and various titration techniques. Today Mr. Booth is a Quality Control Supervisor at Inorganic Ventures.
4 T H A N N U A L I C P C O N F E R E N C E
BAS IC NE EDS AND CONS I DERAT IONS FOR AN ICP ANALYS I S
inorganicventures.com
Basic Needs & Considerations for an ICP Analysis
Thomas Kozikowski
Key Topics • Tips for preventing environmental contamination • Strategies for different types of samples • Instrument-driven concerns • Defining detection limits • What methods does IV use?
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 Identifying interferences and method contamination ü Confirming observations by second methods • If possible Overall Goals for TMI Determination
Environmental Contamination
• Container Selection • Pipet Tips • Weigh Boats • Clean Air • Reagent Purity
Container Selection • LDPE , HDPE, PTFE, PFA, PP, Borosilicate Glass • Plastic made from virgin polyethylene is critical • Sample tubes vs. bottles • Leach containers with dilute HNO 3 (1-5% v/v) • High temperature leaching is more effective (50°C)
PP
PP?
Boro Glass
PTFE
HDPE
Containers: More in-depth
Element LDPE HDPE PP PTFE Boro Al 2 * 87 8750 Ba 5000 B 9400 Ca 28 * 25 2800 Fe 150 95 125 Mg 6 11 575 15 125 K 16 3600 Na 42 63 42 90 27500 Zn 125
Values are the ng of impurity per 125mL bottle. * We’ve seen it on occasion.
LDPE
High Temperature Leaching
Element LDPE 20C
LDPE 50C Stationary
LDPE 50C Tumbling
LDPE Chemical Dishwasher 1X
LDPE Chemical Dishwasher 2X
Unleached
Al Cr
2.00 0.03 0.08 1.90
2.20 0.02 0.06 1.50
0.53 0.02 0.06
5
14 30
10
Mn
1 4 1 1
2 8 2
Ni Ag Zn
3.00 2 Values are the ng of impurity per 30mL bottle. The HNO 3 used contains some Al, Cr, and Zn. 2.70
Leaching Observations • Un-leached bottles do contain some metallic impurities • After high temperature leaching, impurities are significantly reduced. • Allowing hot solution to mix within the bottles significantly reduced the amount of impurity left behind • Chemical dishwashers deposited significant amounts of metallic impurities onto the bottle walls. • We believe that the dishwasher contained stainless steel parts.
Other sources of contamination
• 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
How do we leach containers, pipet tips?
5 min Live Demo
Clean Air
• Classed clean rooms help prevent particle contamination • Several criteria to consider to class a clean room • Air changes per minute
• Filter efficiency (ULPAs or HEPAs) • Ceiling type / ceiling panel material • Light fixture type • Wall and floor material • Air return location • Assessed by counting # of particles of specified size
Classed Clean Room Summary
Class 10 ISO4
Class 100 ISO5
Class 1,000 ISO6
Class 10,000 ISO7
Class 100,000 ISO8
Criteria
Air changes/min Filter Coverage Filter Efficiency
8-10
5-8
3
1
0.33 4-5%
90-100%
60-70%
20-30%
7-15%
99.9997% 99.997% 99.997% 99.997%
99.97%
Conventional T- bar grid
Ceiling Type
Al T-bar grid Al T-bar grid Al T-bar grid Conventional T- bar grid
Tear Drop or 2’x4’ cleanroom fixture Low wall on long axis
2’x4’ cleanroom fixture Low wall on perimeter
2’x4’ cleanroom fixture
2’x4’ standard fixture
Light Fixture Type Tear Drop or flow thru
Raised Floor or center
Low wall or ceiling
Air Returns
Low wall
Classed Clean Room Standards
Particle Size
Class 10 ISO4
Class 100 ISO5
Class 1,000 ISO6
Class 10,000 ISO7
Class 100,000 ISO8
≥ 0.1µm 10,000 100,000 1,000,000 ≥ 0.2µm 2,370 237,000 237,000 ≥ 0.3µm 1,020 102,000 102,000 ≥ 0.5µm 352 3,520 35,200
352,000 83,200
3,520,000
≥ 1.0µm ≥ 5.0µm
83
8,320
8,320 2,930
832,000 29,300
293
2,930
• Specifications listed are (Number of Particles / m 3 ). • ISO Class according to ISO 14644-1 cleanroom standards • Class 10, Class 100, etc. are the FED STD 209E equivalent
Reagent Purity
• Clean Acids (HNO 3 • Clean Bases (TEA, NH 4 OH, etc.) • Clean DI Water (ASTM Type 1, 18MΩ) • Particle Filtration (0.3µm or smaller) • Use of reagent blanks , HCl, etc.)
• Critical for blank subtraction to determine true real- world sample impurity levels and detection limits
Key Topics • Tips for preventing environmental contamination • Strategies for different types of samples • Instrument-driven concerns • Defining detection limits • What methods does IV use?
• Pure Samples • Metals or Pure Salts • High Purity Acids and Bases • High Matrix Solutions • Wastewater/Seawater • Food Products • High Matrix Solids • Those that require acid digestion, fusion, or ashing Types of Samples
Pure Samples
• Only one major source of interferences • Depending on concentration level… • May cause signal depression for trace elements • Consider using internal standard • Consider using standard additions method
• Calibration curves that don’t contain the major element at the same concentration will yield a low bias in the trace element results unless corrected.
High Matrix Solutions
• Contains multiple major sources of interferences • Depending on concentration level… • The same concerns for pure samples apply • Interference identification is much more important • Close examination of spectra required • Confirm peak centering and background positions • Background shifting will need to be evaluated • Confirm results on multiple emission lines
High Matrix Solids
• Contains multiple major sources of interferences • The type of digestion will dictate your path • Acid method blanks will be critical • Consider the acid content and the effect that will have on the introduction system parts • High HF needs to be neutralized for quartz systems • HF resistant systems still have certain limitations • Dilution of the sample will increase sample detection limit values
Key Topics • Tips for preventing environmental contamination • Strategies for different types of samples • Instrument-driven concerns • Defining detection limits • What methods does IV use?
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
How do we assess memory interferences?
5-10 min Live Demo
100ppm Boron in 0.1% v/v HNO 3 Monitoring Washout on B 208.959nm Rinse w/ 5% HNO 3 Rinse w/ 5% NH 4 OH No obvious difference in washout at first glance.
Washout Example
Monitoring Washout on B 208.959nm Rinse w/ 5% HNO 3 Rinse w/ 5% NH 4 OH 5% HNO 3 doesn’t go to baseline even within 2
minutes. 5% NH 4
OH rinses it out
within 80 seconds.
Washout Considerations
• Boron took much longer to washout when rinsing with the normal 5% v/v HNO 3 . • Washout time was significantly reduced using NH 4 OH. • Time graph only tells part of the story. • A very small peak is still present when viewing in spectra mode. • Time graph can help determine estimated washout. • Verify absence of impurity by viewing the spectra.
Peri-Pump vs. Syringe Drive on MS Blank1 Blank2 Blank2 Sample +4ppb Spike Blank4 Blank5 Blank6 95Mo 6 6 12 1,229 28,443 297 116 77 Peri Pump 95Mo 17 11 13 756 28,443 56 15 15 Syringe Drive 121Sb 17 9 23 437 70,605 1,547 731 443 Peri Pump 121Sb 9 2 4 193 70,605 7 2 11 Syringe Drive 178Hf 36 18 26 5 134,673 134 87 64 Peri Pump 178Hf 0 0 0 4 134,673 11 2 4 Syringe Drive 181Ta 34 55 43 27 461,654 1,467 801 514 Peri Pump 181Ta 20 13 11 7 461,654 87 20 29 Syringe Drive 184W 85 58 58 394 127,417 2,876 1,097 669 Peri Pump 184W 35 26 44 150 127,417 420 226 141 Syringe Drive 209Bi 78 75 50 131 271,275 7,664 2,590 1,323 Peri Pump 209Bi 18 18 31 51 271,275 38 22 24 Syringe Drive 232Th 5 35 12 1,467 349,163 478 173 163 Peri Pump 232Th 15 7 6 15 349,163 26 30 15 Syringe Drive The sample run in this example is 100µg/g Mn.
• Washout of select “sticky” elements after a 4ppb spike containing over 60 elements. • Bi is by far the worst. • PVC tubing is used for peri- pump introduction systems. • Faster washout of elements using syringe drive systems allows us to run more samples free of “memory” interferences. • This results in less maintenance when running TMI samples.
Key Topics • Tips for preventing environmental contamination • Strategies for different types of samples • Instrument-driven concerns • Defining detection limits • What methods does IV use?
Defining Detection Limits
• Limit of Detection (LOD) • Defined as 3 times the standard deviation of the blank • Can be calculated using • peak to peak noise or extrapolation to zero on a calibration curve • Calibration curve should have 3 concentration zones
(low,mid,high) approximately 10x difference in concentration, (ex. 0.1ppm, 1ppm, 10ppm)
Defining Detection Limits
• Limit of Quantification (LOQ) • Defined as 10 times the standard deviation of the blank • Calculated using the same values used for LODs • LOQs will have an uncertainty of approximately 30% at the 95% confidence level • Most impurities found in clean standards are below LOQ, which is one reason why we don’t “certify” trace levels of impurity
Defining Detection Limits
• Detection limit values are run-specific on an ICP • Defined by the background signal noise of a blank
• Depend on the standards used • Depend on instrument conditions • As an instrument ages, the detection limit values will raise over time • You will never have the same levels attainable at the time of instrument setup with a brand new ICP
• Must use dilution factors to translate back to starting material • Most samples must be diluted in order to run at levels that will keep the ICP running • High Na, K, Cs can shut the plasma off • High total dissolved solids (TDS) can clog the nebulizer • Greater than 2000ppm TDS on MS will make internal lenses dirty (requires a service call to clean) Real World Detection Limits
Real World Detection Limits 99.93µg/g Sn Found 452pg/g Pb DL 1pg/g 17,738µg/g Sn Found 80.23ng/g Pb DL 0.18ng/g
1,000,000µg/g Sn Found 4,523ng/g Pb DL 10ng/g Pb
Dilution of sample acceptable for ICP-MS Testing
Sn dissolved in HCl and H 2 O OK on ICP-OES
Sn Shot Starting Material
Key Topics • Tips for preventing environmental contamination • Strategies for different types of samples • Instrument-driven concerns • Defining detection limits • What methods does IV use?
• Calibration curve uses 0ppm, 0.1ppm, & 1.0ppm STDs • 2 x peak-to-peak noise for LOD • We’d rather report more impurity information than to say an element is not detected just to make the purity look better • Quicker calculation: Easy to visually inspect spectra and quickly enter actual count data. Don’t have time to center peaks and correct background point for each element. • Easier when evaluating complex spectra • No internal standards used yet • Would have to allow for different IS elements What IV does on the OES
Our LOD Calculation on OES
1.0ppmMg
1,727,150 cps 0.1ppmMg
Max
Max: 56,523 cps Min: 55,460 cps
Min
56,011 cps BKG
DL Calculation: !.#$$% (#,()(,#*!+*,,!##) (56,523-55,460)(2) = 0.000064ppmMg
Periodic Table of TMI-OES Standards This standard scheme is used for ICP-OES using 2 calibration curves.
What IV does on the MS
• Standard Additions Method • Dilute sample to 100ppm of the major element • Spike half of that sample with 4ppb of standard • 3 Blanks → Sample → Sample+Spike → 3 Blanks • We use 3 times the standard deviation for LOD • Not utilizing spectra but do evaluate washout • Easier to automate the process
Our LOD Calculation on MS Mass Blank1 Blank2 Blank3 Sample +Spike Blank4 Blank5 Blank6 24Mg 237 196 222 352 67,562 222 174 252
LOD Using Blanks 1,2,3 3(21) &.()**+ ,-,/&/ =0.0039ppb LOD Using Blanks 4,5,6 3(39) &.()**+ ,-,/&/ =0.0073ppb
Average Blanks 1,2,3 Blank Corrected +Spike 219 21 219 39 133 67,343 STDEV Blanks 1,2,3 Average Blanks 4,5,6 STDEV Blanks 4,5,6 Blank Corrected Sample
Detected Value for Mg 4.18334 (// ,-,/&/5(// = 0.0083ppb
Periodic Table of TMI Standards This standard scheme is used for ICP-MS using 2 standard addition spike sets.
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.
4 T H A N N U A L I C P C O N F E R E N C E
ICP INS TRUMENT MAINTENANCE AND TUNING
inorganicventures.com
ICP Instrument Maintenance and Tuning
Mike Booth
Introduction Maintenance • Normal maintenance is essential for your ICP instrument to perform as expected day to day. • Most maintenance is done on the parts of the sample introduction system. • Some instrument maintenance may have to be done by trained field engineers. Tuning • Instrument tuning is performed after your instrument has equilibrated. • There should be a set performance goal that you instrument should reach by tuning. • The inability to complete a performance check my indicate that maintenance is needed.
Introduction Maintenance • Normal maintenance is essential for your ICP instrument to perform as expected day to day. • Most maintenance is done on the parts of the sample introduction system. • Some instrument maintenance may have to be done by trained field engineers. Tuning • Instrument tuning is performed after your instrument has equilibrated. • There should be a set performance goal that you instrument should reach by tuning. • The inability to complete a performance check my indicate that maintenance is needed.
6 Components of Sample Introduction Systems
• Peristaltic Pump or Syringe Drive
• Nebulizer
• Spray Chamber
• Torch
• Cones / Interface
• Tubing
6 Components of Sample Introduction Systems
• Peristaltic Pump or Syringe Drive
• Nebulizer
• Spray Chamber
• Torch
• Cones / Interface
• Tubing
Peristaltic Pumps / Syringe Drives • The method timings for uptake delay, stabilization delay, and rinse will depend on peristaltic pump and/or syringe drive performance
• Peristaltic Pumps
• More common, usually variable speed • Require Peristaltic Pump Tubing • Peristaltic Pumps can cause the sample flow rate to pulsate • Syringe Drives • Usually used with a peristaltic pump and switching valve • Push the sample at a more constant flow rate
Maintenance – Peristaltic Pumps and Syringe Drives • These devices require very little maintenance • Contact the manufacturer if you suspect a malfunctioning peristaltic pump or syringe drive
• Inspect and change peristaltic pump tubing and syringes as needed
6 Components of Sample Introduction Systems
• Peristaltic Pump or Syringe Drive
• Nebulizer
• Spray Chamber
• Torch
• Cones / Interface
• Tubing
Nebulizers • Two widely used types of nebulizers
Concentric • Produces very consistently sized droplets • Some models can easily clog • Newer models are better at handling samples with high total dissolved solids (TDS)
Cross Flow • Generally better at handling high TDS • Argon and sample ports can be fixed or adjustable • Droplets produced are not as consistent
Nebulizers
• Other types of nebulizers • V-Groove • Parallel Path • Direct Injection
• All nebulizers produce an aerosol by mixing your sample with a nebulizer gas
• Nebulizers are usually designed for specific flow rates
• Some nebulizers types can come in glass and plastic • Glass nebulizers have a better nebulization efficiency • Plastic nebulizers are used for samples with HF
Maintenance – Nebulizers (Concentric) • Nebulizers are very delicate – Handle with extreme care • Do not sonicate • The Nebulizer tip is very narrow and may clog from time to time • Never insert anything into the nebulizer • Use an in line filter when running samples with particulate matter
• Clogs can be cleared by forcing water through the nebulizer or back flushing the nebulizer with a special tool • Stubborn clogs may require that the nebulizer be soaked in dilute acid or 25% solution of RBS-25
6 Components of Sample Introduction Systems
• Peristaltic Pump or Syringe Drive
• Nebulizer
• Spray Chamber
• Torch
• Cones / Interface
• Tubing
Spray Chambers • Designed to allow consistently sized droplets to the torch (<8 µm) • Large droplets could overload the plasma causing inconsistent results or cause the plasma to extinguish
• Temperature Control
• Spray chambers are cooled to control water vapor and help prevent oxide interferences • Volatile organics are easier to analyze at lower temperatures
Spray Chambers • Two Styles have remained popular over the years Scott double pass style
• First commercially available spray chamber • Very popular • More nebulizer options
Cyclonic style
• More efficient • Gaining in popularity • Baffled cyclonic spray chambers are often used for organics
Maintenance – Spray Chambers • Flush with DI water frequently
• If instrument performance worsens try soaking in 25% RBS-25 then rinsing with DI water
• Some HF resistant spray chambers may need to be resurfaced after extended use
6 Components of Sample Introduction Systems
• Peristaltic Pump or Syringe Drive
• Nebulizer
• Spray Chamber
• Torch
• Cones / Interface
• Tubing
Torches • It’s important to choose the right torch for your application Full Torch • Easy to use
• Outer tube length, injector length, and injector diameter are fixed
Demountable Torch • Ability to easily change outer tube and injector • Requires more maintenance • More cost effective in most cases
Torches - Injectors • Torch injectors can be interchanged when using a demountable torch
• Quartz – General purpose, No HF • Sapphire/Ceramic – HF Resistant • Platinum – Trace Al Analysis
Torches - Devitrification • All quartz torches will devitrify
• Running samples with high concentrations of total dissolved solids or running at higher temperatures will speed up this process
• Torches with heavy devitrification will need to be replaced • Try a shorter or ceramic outer tube if you have a lot of trouble with devitrification
Maintenance - Torches • Be cautious when sonicating quartz torches
• Flush with DI water
• Soak in dilute acid and 25% RBS-25
• Make sure that the torch is dry before reinstallation
• Organic deposits can be burned off in a muffle furnace (500 C) or dissolved by soaking the torch in a mix of 3:1 concentrated H 2 SO 4 to 30% H 2 O 2 (Piranha solution)
• Broken quartz torches or torches with heavy devitrification may be repairable
6 Components of Sample Introduction Systems
• Peristaltic Pump or Syringe Drive
• Nebulizer
• Spray Chamber
• Torch
• Cones / Interface
• Tubing
Cones / Interface • ICP-MS cones are usually Nickel coated with a Copper core • Platinum tipped cones are also available • Pt cones operate at a higher temperature. This helps reduce buildup from samples with high concentrations of total dissolved solids
• ICP-OES instruments have an interface that needs to be maintained
Maintenance – Cones / Interface • ICP-OES interface should be cleaned daily with dilute acid and water or isopropyl alcohol • Inspect cones frequently • The orifice must retain its shape for the cones to properly function • Clean off buildup with DI water and sonication • The manufacturer’s instrument manual should have sonication instructions • Sonicating with DI water and dilute acid should be OK • Make sure to dry the cones before reinstallation
6 Components of Sample Introduction Systems
• Peristaltic Pump or Syringe Drive
• Nebulizer
• Spray Chamber
• Torch
• Cones / Interface
• Tubing
Tubing • Most connections between introduction system parts are made with tubing • Source the cleanest tubing possible • IV uses PVC and PTFE
• Peristaltic Pump tubing will stretch with use. • Inspect and change frequently
• Most other tubing needs to be inspected and changed when it looks dirty or damaged
Maintenance - Tubing • Periodically change all tubing on your instrument • One clogged piece of tubing could cause a torch to melt, the plasma to extinguish, or cause a large spill
• Make sure that all tubing fittings are tight. • Recommend daily check of fittings
• Pay close attention to the following: • Spray Chamber drain tubing • Torch and nebulizer gas lines • Waste tubing • Rinse station tubing
• Checking the tubing is vital but can be often overlooked - One forgotten connection can melt a torch instantly
Maintenance – General Tips • Make sure to keep a detailed instrument maintenance log • Always inspect all sample introduction parts and connections before turning the instrument on • Rinse the system with dilute acid and DI water before turning the instrument off • Keep an inventory of all your spare sample introduction parts • Make sure to record part numbers • Keep the instrument serial number, instrument manuals, and the phone number to technical support near the instrument • Backup all of your data and have a plan for what to do if your instrument goes down
The manufacturer’s instrument manual should have a recommended maintenance schedule
IV Recommended Maintenance Schedule
Daily
ICP-OES • Clean Interface
ICP-MS • Inspect Cones • Inspect Torch • Inspect Spray Chamber • Inspect Nebulizer • Inspect/Replace Peristaltic Pump Tubing • Inspect Tubing Connections • Acquire Performance Report • Inspect Other Intro System Parts
Necessary maintenance will vary based on instrument make, model, and sample matrix
• Clean/Replace Torch • Clean Spray Chamber • Clean Nebulizer • Replace Peristaltic Pump Tubing • Inspect Tubing Connections • Acquire Performance Report • Inspect Other Intro System Parts
Weekly
Monthly
ICP-OES • Perform Wavelength Calibration • Inspect All Tubing
ICP-MS • Clean Cones
ICP-MS • Replace All Tubing • Check Filters and Chiller • Check Vacuum Pump
ICP-OES • Replace All Tubing • Check Filters and Chiller
• Clean/Replace Torch • Clean Spray Chamber • Clean Nebulizer • Perform Mass Calibration • Inspect All Tubing
Introduction Maintenance • Normal maintenance is essential for your ICP instrument to perform as expected day to day. • Most maintenance is done on the parts of the sample introduction system. • Some instrument maintenance may have to be done by trained field engineers. Tuning • Instrument tuning is performed after your instrument has equilibrated. • There should be a set performance goal that you instrument should reach by tuning. • The inability to complete a performance check my indicate that maintenance is needed.
ICP Instrument Tuning – What are you looking for? ICP-OES • High Intensity • Low RSDs ICP-MS • High Intensity • Low RSDs • Low Oxides • Low Doubly Charged Species
ICP Instrument Tuning – What to adjust? ICP-OES • High Intensity • Torch Alignment • Confirm Gas Flows • Low RSDs • Confirm Method Timings • Check Intro System Connections • Confirm Gas Flows ICP-MS • High Intensity • Low RSDs • Low Oxides
• Low Doubly Charged Species
ICP Instrument Tuning – What to adjust? ICP-OES • High Intensity • Torch Alignment • Confirm Gas Flows • Low RSDs • Confirm Method Timings • Check Intro System Connections • Confirm Gas Flows ICP-MS • High Intensity • Torch Alignment • Confirm Gas Flows • Lens Tuning • Low RSDs • Confirm Method Timings • Check Intro System Connections • Confirm Gas Flows • Low Oxides • Nebulizer Gas Flow • Spray Chamber Temperature • Low Doubly Charged Species • Lens Tuning
ICP-MS Instrument Tuning Auto-Tuning
• The Auto-Tune will usually work best to tune the instrument for the entire mass range. • Depending on your instrument software this can be done as part of the start up routine.
Manual Tuning • This can be done much more quickly than the auto-tune once you are familiar with your instrument. • You can tune for specific mass ranges.
Remember: You only have to tune to meet your performance checks
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.
4 T H A N N U A L I C P C O N F E R E N C E
RE L IABLE MEASUREMENT S
inorganicventures.com
Reliable Measurements A Guidebook for Trace Analysts
Paul Gaines, PhD
This society makes many decisions based upon chemical measurements. These decisions have legal, medical, environmental, and commercial impact upon each of us.
Trained Analysts
Reliable Results
Accurate CRMs
Accurate Procedures
Overview
1.1 - 1.14 Laying the Foundation (What is Trace Analysis?, Stages of a Trace Analysis, Training, Recommended References)
2.1 - 2.9 Planning the Project ( Defining The Problem, Detection Limits and Uncertainties, Constructing the Sampling Plan)
3.1 - 3.16 Sampling and Sub-sampling (Sampling Publications, Developing the Sampling Plan, Constructing a Sampling Program, Different Approaches to Sampling, Sub-sampling, Determination of Sampling and Sub-Sampling Errors, Contamination Issues During Sampling)
4.1 - 4.5 An Introduction to Sample Preparation (Preliminary Issues, Selecting a Sample Preparation Method)
Overview
5.1 - 5.13 Container Material Proper3es (Materials; Borosilicate, Glass, Porcelain, Quartz, Pla6num, Graphite, Plas6cs; The Purity and Cleaning of Plas6cs)
6.1 - 6.6 Container Transpira3on (Ini6al Transpira6on Study, Addi6onal Transpira6on Studies, Summary of Findings)
7.1 - 7.14 Stability of Elements at ppb Concentra3on Levels (Adsorp6on, ppb Stability Study, Summary of Findings)
8.1- 8.19 Environmental Contamina3on ( Reducing Environmental Contamina6on, Avoiding Environmental Contamina6on)
Overview
9.1- 9.18 Contamination From Reagents (High Purity Water, Storage of High Purity Water, High Purity Acids, Other Reagents)
10.1-10.12 Contamination From the Analyst and Apparatus (Contamination From the Analyst, Common Contaminants, Tips for the Analyst, Apparatus Contamination, A Closer Look at Quartz, Apparatus Tips)
11.1-11.7 Acid Digestions of Inorganic Samples ( Nitric Acid Digestions, Facts About Nitric Acid)
12.1-12.3 Acid Digestions of Organic Samples (Acid Digestions of Organic Samples)
Overview
13.1-13.8 Sample Prepara/on by Fusion (Useful Fusions for Trace Analysts, Lithium Carbonate Fusions, Sample Prepara=on Procedure)
14.1- 14.11 Ashing (Ashing Techniques, Advantages of Ashing, Disadvantages of Ashing, Examples of Ashing Procedures)
15.1-15.15 ICP-OES Measurement (Line Selec=on, Sensi=vity, Precision, Spectral Interferences, Example of a Method, Matrix Effects)
Overview
16.1 - 16.22 ICP-MS Measurement (ICP-MS References, Resolu4on, Interference, Isobaric Interference, Polyatomic Interferences, Doubly Charged Ion Interferences, Matrix Effects, Space Charge Effects, Salt Buildup, Quan4ta4ve Analysis Measurement Techniques, External Calibra4on using Calibra4on, Standard Addi4ons, Isotope Dilu4on) 17.1 - 17.30 Method Valida=on (Purpose of Method Valida4on, References, The Valida4on Process, Confirm Basic Performance Criteria, Robustness, Collabora4ve and Coopera4ve Tes4ng)
1:1 Laying the Foundation
What is Trace Analysis? Some analysts refer to trace analysis as a measurement below one ppm (μg/g) while others use the term to describe an analyte concentration low enough to cause difficulty. This difficulty may be caused by the sample size or the matrix (i.e. - the concentration of the analyte of interest relative to the matrix or the sample size causes difficulty for the analyst). Most trace analysts using ICP-OES / ICP-MS prefer the latter definition. Regardless of which definition you prefer, most analyses that require a measurement using ICP-OES or ICP-MS fall within the category of trace analysis.
1:2 Laying the Founda8on
Stages of a Trace Analysis
A. Planning - Prepare a plan that considers the objec3ve. Planning should begin with a discussion between the analyst and the ini3ator during which all possible problems are defined. The analyst is responsible for method selec3on or development.
B. Sample Collec8on and Storage - Ideally the analyst is involved in this stage, but if not, the analyst should be informed of the sampling procedure at the very least. Sample representa3on and contamina3on issues must be considered.
C. Sample Prepara8on - Contamina3on issues are a major concern during this stage, but not the only concern .
1:3 Laying the Foundation
D. Sample Measurement - The major concerns during this stage are:
• Availability of Cer/fied Reference Materials for method valida/on, plus stable and accurate calibra/on standards, interference standards, and quality control standards.
• Achieving the required precision. It serves no purpose in acquiring a precision that has been reduced to less than one-third of the sampling error. In situa/ons where the sampling error is small and the highest level of precision is required, the analyst faces a difficult task in acquiring precision equivalent to classical wet chemical techniques.
• Obtaining the required sensi/vity and determining the detec/on limit of the measurement.
1:4 Laying the Founda2on
D. Sample Measurement - (CONT.)
• Overcoming interferences using ICP-OES that include matrix differences between standards and samples; spectral interferences (i.e. - direct spectral overlap, wing overlap, interference with background point); chemical enhancement of atom lines by high matrix element compositions (axial view); and drift due to nebulizer plugging, changes in sample argon, power supply instability, or room temperature changes. • Overcoming interferences using ICP-MS that include matrix differences between standards and samples; mass-discrimination effects; isobaric interferences; detector dead-time; and drift due to nebulizer plugging, changes in sample argon, power supply instability, or room temperature changes.
• Calculating and Reporting the Data - Working with error budgets and calculating the uncertainty is the trickiest part of this stage.
1:5 Laying the Foundation
Training Trace analysis is extremely difficult. All too o6en, samples submi:ed as "rou 1:6 Laying the Foundation Recommended References For some applications, a search of the literature is required. Larger companies typically have a library and often a staff of chemists trained to conduct literature searches. For smaller companies without these facilities, the Internet is of great value in finding technical information. A search of the scientific literature, complete with the ability to download or order specific papers, is available through the CAS Document Service at stneasy@cas.org. Visit our links section for additional links to EPA, AOAC, and other published methods. 1:7 Laying the Founda2on General References: CRC Handbook of Chemistry and Physics; Lide, D. R., Ed.; CRC Press: Boca Raton, FL. Encyclopedia of AnalyCcal Science; Townshend, A., Ed.; Academic Press: New York, 1995, Vols. 1-10. IV's AnalyCcal Periodic Table; InformaCon on elemental compaCbility, stability, sample preparaCon, preferred lines and spectral interferences for ICP-OES and ICP-MS; Inorganic Ventures / IV Labs: 2001-2002. 1:8 Laying the Foundation Sampling: Sampling and Sample Prepara/on; Stoeppler, M., Ed.; Springer Publishing: New York, 1994. Crosby, N. T.; Patel, I. General Principles of Good Sampling Prac/ce; The Royal Society of Chemistry: Cambridge, U.K., 1995. 1:9 Laying the Foundation Sample Preparation: Gorsuch, T.T. The Destruction of Organic Matter; Pergamon Press: Elmsford, NY, 1970. Introduction to Microwave Sample Preparation, Theory and Practice; Kingston, H. M., Jassie, L. B., Eds.; American Chemical Society: Washington D.C., 1988. A Handbook of Decomposition Methods in Analytical Chemistry; Bock, Rudolf, Ed.; Halsted Press, Div. Wiley & Sons: New York, 1979; translated by Ian L. Marr. Mizuike, A. Enrichment Techniques for Inorganic Trace Analysis; Springer-Verlag: New York - 1983. 1:10 Laying the Founda2on Trace Analysis: Trace Analysis: A Structured Approach to Obtaining Reliable Results; Prichard, E., MacKay, G. M., Points, J., Eds.; The Royal Society of Chemistry: Cambridge, U.K., 1996. Guidelines for Achieving Quality in Trace Analysis; Sargent, M., Mackay, G., Eds.; The Royal Society of Chemistry: Cambridge, U.K., 1995 1:11 Laying the Foundation Environmental Analysis: Smith, Roy-Keith Handbook of Environmental Analysis; Genium Publishing: U.S.A., 1994. Berger, W.; McCarty, H.; Smith, Roy-Keith Environmental Laboratory Data EvaluaMon; Genium Publishing: U.S.A., 1996. 1:12 Laying the Foundation Quality Assurance & Statistical Technique: Taylor, J. K., Quality Assurance of Chemical Measurements; Lewis Publishers: Chelsea, MI, 1987. Mark, H.; Workman, J. Statistics in Spectroscopy; Academia Press: San Diego, CA, 1991. Taylor, J. K. Statistical Techniques for Data Analysis; Lewis Publishers: Chelsea, MI, 1990. Swartz, M. E.; Krull, I. S. Analytical Method Development and Validation; Marcel Dekker: New York, 1997. Accreditation and Quality Assurance in Analytical Chemistry; Günzler, H., Ed.; Springer-Verlag: New York, 1994. Good Laboratory Practice Standards; Garner, W.Y., Barge, M. S., Ussary, J. P., Eds.; American Chemical Society: Washington D.C., 1992. 1:13 Laying the Founda2on ICP-MS References: Plasma Source Mass Spectrometry - Developments and Applica=ons; Holland, G., Tanner, S. D., Eds.; The Royal Society of Chemistry: Cambridge, U.K., 1997. Induc=vely Coupled Plasma Mass Spectrometry; Mantaser, A., Ed.; Wiley-VCH: New York, 1998. Taylor, H. E. Induc=vely Coupled Plasma Mass-Spectrometry, Prac=ces and Techniques; Academic Press: New York, 2001. 1:14 Laying the Foundation ICP-OES References: Induc3vely Coupled Plasmas in Analy3cal Atomic Spectrometry; Montaser, A., Golighty, D. W., Eds.; VCH Publishers: New York, 1992. Thompson, M.; Walsh, J. N. A Handbook of Induc3vely Coupled Plasma Spectrometry; Blackie: London, U.K., 1983. Developments in Atomic Plasma Spectrochemical Analysis; Barnes, R. M., Ed.; Heyden: London, U.K., 1981. 2:1 Planning the project Overview The first stage of a trace analysis is planning the project. This chapter discusses the process of planning, which involves defining the problem and assessing the technical requirements needed to solve the problem. Without careful planning, achieving reliable results becomes a game of chance. Analytical projects fall into categories of non-routine, semi-routine, and routine: • Non-routine - a project in which a validated method does not exist and little is known about the sample. • Semi-routine - a project in which something significant can be stated about the sample and the method of analysis. • Routine - a project in which the sample is chemically known and a validated method is available. 2:2 Planning the project Overview (cont.) This sec(on assumes that the chemist will be analyzing samples that fall into one or more of the previous categories. Before the planning process can begin, the analyst must examine the following: • The need for sampling and sub-sampling • Reagent quality • Sample prepara(on • Measurement • QA/QC • Repor(ng requirements 2:3 Planning the project Defining the Problem A discussion between the ini6ator and the analyst must occur, where ques6ons are asked by both par6es. The intent is to define the exact nature of the problem, why analy6cal work is needed, and how the results will be used following the comple6on of the project. Method valida6on requirements should also be addressed. These requirements can include either the availability of a cer6fied reference material, or that of another validated technique -- one that is based largely on different principles. The problem's defini6on is further refined by asking other ques6ons: What is it that you want to accomplish? What is the purpose? What is the current situa6on or state of affairs? What is taking place that you need to understand, prevent, or improve? What decisions will be made based upon the data? When the answers to these ques6ons have been determined, the analyst is in a posi6on to begin planning the analy6cal process. 2:4 Planning the project Detection Limits and Uncertainty The analyst should know the detection limits for all analytes at several possible wavelengths. Typically, these measurements are obtained during the establishment of the analytical instrument's capabilities. Modern axial view ICP-OES and ICP-MS instruments are likely to have detection limits under normal sample introduction modes that will meet or exceed the requirements. It is best to not rely upon the limits published by the manufacturer. In addition, the detection limits will be a function of the sample matrix, in both a physical and spectral sense. A key point involves the analytical blank. Due to numerous contamination issues, the analytical blank often determines the detection limit capabilities. It is best for the analyst to be conservative when noting the detection limits, making sure not to quote capabilities calculated from published data or determinations made under "ideal" conditions. For the less common elements, an estimate of the "real" detection limit would be a factor several times higher than the limit determined under ideal conditions. Thus, elements like Na, Mg, Ca, Fe, Cr, Cu, Zn, Si, Al, Cl, and S may have a detection limit that is significantly larger than expected, due to the analytical blank. 2:5 Planning the project Detec%on Limits and Uncertainty (cont.) The uncertainty of an analy%cal measurement is not limited to the measurement precision of the instrument. Rather, it is a sta%s%cal sum of the random and systema%c errors that are encountered throughout the en%re analy%cal process. The uncertainty is a combina%on of errors from sampling, storage, weight and volume manipula%ons, prepara%on, calibra%on, and measurement, during which contamina%on issues play a major role in trace determina%ons. The sampling error can be a major source of uncertainty. In many cases, an es%mate of the sampling error can be impossible to judge. The ini%ator should be aware of this fact. In reality, the uncertainty of a trace measurement will not be known un%l the project is completed. The accuracy of this value will be only as good as the effort made to iden%fy and measure all of the errors encountered during the en%re analy%cal process. If measurements are being made between 3-5 %mes the detec%on limit for the less common elements, then an excellent uncertainty would be ± 30-70%. 2:6 Planning the project Construc)ng the Plan A2er the problem is defined, the planning process can begin. Analy)cal text books explain that you must consider the sample collec)on, sample storage, sample prepara)on, measurement, and repor)ng, along with any QA/QC requirements. With so many considera)ons, where should you start? Start by examining the following basic informa)on: • The analyte(s) of interest. • The required detec)on limit(s). • The uncertainty requirement(s). • The chemical composi)on (matrix) of the sample. • The quan)ty, availability, and history of the sample. 2:7 Planning the project Constructing the Plan (cont.) Much of the previous list can be determined based on information gathered while defining the problem. In most cases, analytical resources are available in-house to address the problem. For example: • The basic information listed previously is sufficient to determine whether publications or information is available in your reference library. Always start with a search of the literature. • The identity and detection limit requirement of each analyte indicates the analyte measurement technique(s) required and the amount of sample required. • The uncertainty requirement indicates the number of measurements, assuming there is sufficient sample available. • The chemical composition of the sample, together with the identity of the analyte(s), indicates possible sample preparation routes. 2:8 Planning the project Construc)ng the Plan (cont.) • The iden)ty of the analyte(s), together with the detec)on limit requirement(s), indicates the degree that contamina)on issues should be considered. This determines the need for analy)cal blanks and special apparatus or a clean area / room. • The sample composi)on indicates poten)al interference issues. • The sample composi)on or type indicates the uncertainty to be expected form the sample collec)on and/or the need to develop a sampling procedure and to determine sampling uncertainty. For example, the sample may be the only "world's supply", nega)ng the need for a sampling procedure. • The es)mated sampling uncertainty can be used to define the analy)cal measurement precision (i.e. -- reducing the analy)cal error to less than one third of the sampling error serves no purpose). 2:9 Planning the project Construc)ng the Plan (cont.) The basic informa)on can provide the analyst with poten)al analy)cal measurement technique(s), suspected interferences, contamina)on issues, and the number of sample measurements required per determina)on (measurement refers to a complete analysis including sampling, prepara)on, instrumental analysis and repor)ng the final result and uncertainty). At this stage of the planning process, the analyst can determine if a cer)fied reference material (CRM) should be obtained for method valida)on. In addi)on, the chemist can approximate the need for analy)cal reagents and apparatus and/or calibra)on standards. Lastly, es)mate the )me and cost of the project and base your ini)al approach on these es)mates. Remember, there is always the possibility that more than one itera)on may be required before an acceptable approach can be developed.
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