Amplifying ICPMS Productivity Using Discrete Sampling Technology

Transcription

1 Amplifying ICPMS Productivity Using Discrete Sampling Technology Continuing the discussion on high throughput ICP-MS Steve Wilbur Agilent Technologies March 26, 2009

2 Previously, in Tripling the Productivity of ICP-MS * We discussed various options to reduce the run time in conventional ICP-MS by systematically optimizing each component of the analysis. We were able to reduce a typical 30 element analysis from around 7 minutes to less than 3 minutes with little or no compromises in performance. We touched on Discrete Sampling as the final way to further improve throughput and showed some preliminary data. Today, we will expand on the mechanisms of discrete sampling and explore significant benefits in addition to high throughput. *Recorded version available on SpectroscopyNOW.com Link from Go to ICP-MS then click on e-seminars

3 Hardware Overview All discrete sampling systems use the same general hardware configuration. The hardware consists of: sample uptake pump carrier (nebulizer) pump 6 port valve with sample loop control hardware and software

4 Hardware basic configuration valve in load position (valve flow path indicated in red) sample loop 6-port valve sample uptake pump to nebulizer carrier pump carrier waste sample Sample uptake pump draws sample through valve, filling loop. Excess goes to waste, rinsing the loop in the process Simultaneously, carrier pump is pumping clean carrier (dilute acid blank) through the valve to the nebulizer During the load operation, no sample reaches the nebulizer, only clean carrier

5 Hardware basic configuration valve in inject position (valve flow path indicated in blue) 6-port valve sample uptake pump to nebulizer carrier pump carrier waste sample Valve rotates (switches), changing flow path. Loop is now in the carrier flow path. Sample uptake pump switches off. Carrier pump pushes sample through the loop to the nebulizer Sample never contacts carrier pump directly

6 Hardware basic configuration addition of online internal standards 6-port valve sample uptake pump to nebulizer carrier pump ISTD mixing tee carrier waste sample ISTD Online internal standard addition is achieved in the normal way. 2 nd channel of carrier pump pumps internal standard solution which is mixed with sample just prior to nebulization

7 Two types of discrete sampling 1. Time resolved mode (left) 2. Spectrum (steady state) mode (right) log y scale In time resolved mode, a small sample loop creates a peak which is integrated over its entire width, concentration ti is proportional to the area under the peak In Spectrum mode, a larger loop is used to create a period of steady state signal, which is analyzed in the same way as conventional ICP-MS

8 Time Resolved Discrete Sampling Time resolved discrete sampling is very fast and lends itself to analyses where a single replicate is sufficient (EPA methods require 3 replicates), and/or only a few elements need to be measured. Quantification is based on the total area under the extracted ion peak for each ion of interest, exactly in the way that a chromatographic peak would be quantified

9 Steady State, Spectrum Mode Discrete Sampling Spectrum mode discrete sampling has the advantage of a constant signal during sample measurement. Integration times, number of isotopes and number of replicates are only limited by the size of the loop. This seminar will discuss the throughput and performance advantages of spectrum mode discrete sampling

10 Process of Spectrum Mode Discrete Sampling -load loop, inject, wait, acquire data, rinse, load next sample Rep 1 Rep 2 Rep ISTD Signal Analyte Signal Signal Intensity [CPS] Delay Acquire data Rinse Go to Next Co59 In Load Inject Load Time [sec]

11 Process is Fast Because High speed uptake fills the loop in ~ 10 seconds (load). carrier waste to nebulizer sample Rep 1 Rep 2 Rep 3 ISTD Signal Signal Intensity [CPS] Delay Acquire data Analyte Signal Rinse Go to Next Co59 In Load Inject Load Time [sec] Agilent Restricted

12 Process is Fast Because High speed uptake fills the loop in ~ 10 seconds (load). Acquisition delay is ~ 15 seconds from inject to reaching steady state signal. Acquisition can be optimized to ~ seconds or less sample Rep 1 Rep 2 carrier Rep 3 waste ISTD Signal to nebulizer Signal Intensity [CPS] Delay Acquire data Analyte Signal Rinse Go to Next Co59 In Inject Load Time [sec] Agilent Restricted

13 Process is Fast Because High speed uptake fills the loop in ~ 10 seconds (load). Acquisition delay is ~ 15 seconds from inject to reaching steady state signal. Acquisition can be optimized to ~ seconds or less After inject, ALS probe can be moved to rinse position to begin rinsing during acquisition. Loop is rinsed by next sample or optional post-acquisition rinse can be added. Total run time: min depending on element list and sample type 2-3x faster than normal (continuous) sample introduction Signal Intensity [CPS] rinse port Inject Delay sample Rep 1 Rep 2 Acquire data carrier Rep 3 Analyte Signal Rinse waste ISTD Signal normal (continuous) sample Go to Next Time [sec] Load to nebulizer Co59 In Agilent Restricted

14 Integrated Sample Introduction System (ISIS) configured for spectrum mode discrete sampling ISIS-DS Uptake pump 6-port valve Second ISIS pump and optional second valve are not used Sample loop Nebulizer pump Carrier reservoir ISTD reservoir

15 Significantly Reduced Matrix Loading Conventional sample introduction system (Entire sample consumption goes to the nebulizer ~2.5 ml) Sample Uptake (~0.5 ml) Stabilization (~0.5 ml) Analysis (~0.5 ml) Rinseout (~1 ml) Discrete sampling introduction system (Sample is nebulized only during analysis ~ ml depending on acquisition method which determines the necessary loop size) Sample uptake (0 ml) Analysis (~ ml) Rinseout (0 ml) Discrete sampling achieves the same actual measurement time with Only 10-20% of the matrix load on the interface* *actual sample consumption is higher, closer to ml, but most of the sample does not reach the p p g,, p nebulizer and is used to rinse the sample uptake system including the loop.

16 Performance Advantages of Discrete Sampling (in addition to much faster run times) Significantly reduced exposure of ICP-MS to high TDS samples Constant nebulization speed Reduced signal drift Reduced cleaning and maintenance Ability to run much higher matrix samples routinely Longer peripump tube life Improved precision Elimination of peristaltic pump tubing from sample path Absolutely l constant t internal standard addition Reduced contamination Better rinseout Improved internal standard correction

17 Internal Standard Stability During Sample Uptake and Washout - monitored in tune screen Analytes, Be, Co and U Sc and In internal standards <2% RSD

18 Example Internal Standard Stability Over Calibration Range (7 level calibration shown) Ge Rh Lu These are 7 overlaid points Level CPS RSD Level CPS RSD Level CPS RSD

19 Analytical Conditions for 75 second analysis Plasma Robust mode 1550 Watts Nebulizer Glass concentric (standard) Number of elements (including internal 31 standards) d ORS Mode He - 4 ml/min (single mode) Integration time per point 0.1 seconds (all elements) Points per peak 1 Replicates 3 Total acquisition time (3 reps) 26 seconds Loop volume 300µL Loop rinse and fill time 8-10 seconds Acquisition delay (after valve rotation to inject) 15 seconds Steady state signal time (before valve rotation 30 seconds to fill again)

20 Sample Sequence Using ISIS-DS 1. Initial Calibration (0.1, 1, 10 and 100 ppb all elements) 2. Sample block repeated 26 times 50 ppb calibration check (CCV) NIST 1643e water CCB (blank) USEPA Interference Check Solution A (ICS-A) USEPA ICS-AB (spiked with all analytes at 100 ppb to monitor carryover) 216 Samples analyzed in 4 hours 29 minutes (He only mode) 75.6 seconds per sample, run to run Sample consumed - 22mlpersample 2.2

21 Stability: Internal Standard Recoveries (n = 216) 6Li Sc Ge 115 In Tb Lu Lowest values are EPA ICS-A and ICS-AB samples (still ~90% recovery) 1ppb 50ppb CCV ICS-A NIST1643e ICS- 50ppb CCV ICS-A NIST1643e ICS- 50ppb CCV ICS-A NIST1643e ICS- 50ppb CCV ICS-A NIST1643e ICS- 50ppb CCV ICS-A NIST1643e ICS- 50ppb CCV ICS-A NIST1643e ICS- 50ppb CCV ICS-A NIST1643e ICS- 50ppb CCV ICS-A NIST1643e ICS- 50ppb CCV ICS-A NIST1643e Typical suppression is ~40% with conventional systems

22 Precision: 50 ppb CCV recoveries (n=26) EPA limits (+/- 10%) shown in red % % % % % 95.00% 90.00% 85.00% 80.00% 9Be 51 V 53 Cr 55 Mn 59 Co 60 Ni 63 Cu 66 Zn 75 As 78 Se 95 Mo 107 Ag 111 Cd 121 Sb 205 Tl 208 Pb CCV #2 CCV #3 CCV #4 CCV #5 CCV #6 CCV #7 CCV #8 CCV #9 CCV #10 CCV #11 CCV #12 CCV #13 CCV #14 CCV #15 CCV #16 CCV #17 CCV #18 CCV #19 CCV #20 CCV #21 CCV #22 CCV #23 CCV #24 CCV #25 CCV #26

23 Accuracy and Precision: NIST 1643e (trace metals in water) Mass/Element Mean (n = 26) RSD Certified Recovery measured value (µg/l) (%) value (µg/l) (%) 9 Be % 23 Na % 24 Mg % 27 Al % 39 K % 43 Ca % 51 V % 53 Cr % 55 Mn % 56 Fe % 59 Co % 60 Ni % 9% 63 Cu % 66 Zn % 75 As % 78 Se % 95 Mo % 107 Ag % 111 Cd % 121 Sb % 205 Tl % 0% 208 Pb % %RSD for 26 separate analyses over 216 samples

24 Washout 3-4 orders of magnitude or better reduction Element ICS-AB spike % reduction mean mean mean 9 Be % 23 Na % 24 Mg % 27 Al % 984% 39 K % 43 Ca % 51 V % 53 Cr % 55 Mn % 56 Fe % 57 Fe % 59 Co % 60 Ni % 016% 63 Cu % 66 Zn % 75 As % 78 Se % 95 Mo % 107 Ag % 111 Cd % 121 Sb % 205 Tl % 208 Pb % Washout is equivalent to or better than traditional peristaltic pumped p sample introduction systems in a fraction of the run time. Intelligent sequencing can automatically add additional blanks after high samples to prevent possible carryover if necessary.

25 Ultimate Speed Plus Ultimate Matrix Tolerance ISIS-DS plus HMI* Seamless Integration of High Speed Discrete Sampling with Online Aerosol Dilution Fully compliant EPA 6020 analysis for ultra high matrix samples in under 3 minutes per sample No sample dilution No matrix matching of standards or blanks ICP-MS sensitivity and data quality ICP-OES speed and matrix tolerance *HMI Agilent s Unique High Matrix Introduction Accessory - allows direct analysis of % level TDS samples without prior sample dilution by using a combination of very robust plasma conditions and online aerosol dilution

26 ISIS-DS plus HMI - Simple, Seamless & Compatible with Intelligent Sequencing Sample uptake pump 6-port valve and loop HMI Makeup Gas Port Nebulizer and Internal Standard Pump Combination of ISIS-DS and HMI is easy - simply connect HMI makeup gas port. HMI optimization software works seamlessly with ISIS-DS

27 Performance Evaluation Sample Analysis 4 Sample types (75 samples each + QC = 114 runs each) -waters -soil digests (undiluted) -TCLPs (undiluted) d) -sea waters (undiluted) 47 elements including ISTDS 2 cell modes - He for all elements except Se and Si (H 2 ) Total run time 2.97 minutes, sample to sample (3 reps) A single HNO 3 /HCl calibration was used for 4 sample types Elements No matrix Cal 1 matching, Cal 2 Cal no 3 optimized Cal 4 tuning Cal 5 or Cal calibration 6 Cal 7 CCV Trace 0.2ppb 1 ppb 2 ppb 20 ppb 100 ppb 200 ppb 100 ppb elements Na, K, Ca, 20 ppb 100ppb 200 ppb 2000 ppb 10,000 ppb 20,000 ppb 10,000 ppb Mg, Fe, Si B, P 1 ppb 5 ppb 10 ppb 100 ppb 500 ppb 1000 ppb 500 ppb

28 Measured Minimum* Linear Dynamic Range Highest Calibration Linear Range Standard Measured Element (mg/l) Conc (mg/l) value (mg/l) Recovery % Aluminum % Antimony % Arsenic % Barium % Beryllium % Boron % Cadmium % Calcium % Chromium % Cobalt % Copper % Iron % Lead % Lithium % Magnesium % Manganese % Nickel % Phosphorus % Potassium % Selenium % Silicon % Silver % Sodium % Strontium % Thallium % Thorium % Tin % Titanium % Uranium % Vanadium % Zinc % Zirconium % *Most elements were limited by availability of high enough stock concentrations ti and solubilities of mixed standards Only silver was < 90% recovery at 10 ppm due to limited solubility in Cl containing standard mix

29 Internal Standard Recoveries High TDS Waters NIST 1643e contains Bi, here run undiluted Sc Sc Ge Ge Rh Rh Tb Tb Lu Pt Bi blank 1ppb 100ppb blank blank Water Water Water blank Water Water Water ppb Water Water Water NIST 11634e Water Water Water Water blank Water Water Water ppb Water Water Water NIST 11634e Water Water Water Water blank Water Water blank

30 Internal Standard Recoveries Undiluted Soil Digests 120.0% 100.0% 0% 80.0% 40.0% Bismuth Germanium 60.0% Germanium 20.0% 0.0% Standards and blanks samples Lutetium Rhodium Rhodium Scandium Scandium Terbium Terbium 0.2ppb 20ppb blank 100ppb Soils Soils Soils NIST 1643e Soils Soils Soils Soils blank Soils Soils Soils ppb Soils Soils Soils NIST 1643e Soils Soils Soils Soils blank Soils Soils Soils ppb Soils Soils Soils NIST 1643e Soils Soils NIST 1643e

31 Internal Standard Recoveries Undiluted, Undigested TCLP Extracts % % 80.00% 60.00% 00% TCLP EPA Method Toxicity Characteristic Leaching Procedure 40.00% 20.00% 0.00% ~25 g dry sample is added to 500 ml of water acidified with 5.7 ml glacial acetic acid and buffered with 64ml 1N NaOH (or not depends) and extracted with agitation for 18 hours (very simplified summary of method) Bismuth Germanium Germanium Lutetium Rhodium Rhodium Scandium Scandium Terbium Terbium TCLP TCLP NIST 1643e 0.2ppb 20ppb blank 100ppb TCLP TCLP TCLP NIST 1643e TCLP TCLP TCLP TCLP blank TCLP TCLP TCLP ppb TCLP TCLP TCLP NIST 1643e TCLP TCLP TCLP TCLP blank TCLP TCLP TCLP ppb TCLP TCLP TCLP NIST 1643e

32 Internal Standard Recoveries Undiluted* Sea Waters % % Note no downward drift due to cone clogging % 80.00% Bismuth Germanium 60.00% Germanium 40.00% 20.00% 00% 0.00% Lutetium Rhodium Rhodium Scandium Scandium Terbium Terbium 0.2ppb 20ppb CASS-4 Sea Water Sea Water Sea Water Sea Water blank Sea Water Sea Water Sea Water ppb Sea Water Sea Water Sea Water CASS-4 Sea Water Sea Water Sea Water Sea Water blank Sea Water Sea Water Sea Water ppb Sea Water Sea Water Sea Water CASS-4 Sea Water Sea Water Sea Water Sea Water blank Sea Water CASS-4 *No other ICP-MS can measure undiluted sea water All other instruments t are limited it to 10% seawater and then also require matrix matched standards to control suppression

33 Sample Cone after 75 undiluted sea water samples This is the reason there was no downward drift. No blockage of sampling orifice. Close up

34 CCV Recoveries, TCLPs and Seawaters TCLP Extracts Seawaters TCLP Extracts Seawaters Element undiluted undiluted Mean (n=9) %RSD Mean (n=9) %RSD Aluminum % 2.02% 94.70% 1.97% Antimony 98.84% 1.63% 98.67% 1.76% Arsenic 99.43% 2.28% 97.05% 1.55% Barium 99.46% 1.77% 97.81% 1.94% Beryllium % 0.92% 96.22% 3.12% Boron % 1.66% % 4.35% Cadmium 98.75% 1.42% 99.29% 1.79% Calcium 99.95% 1.42% % 1.56% Chromium 99.32% 1.49% % 15% 1.51% Cobalt 99.75% 1.50% % 1.71% Copper 98.85% 1.96% 95.78% 1.66% Iron % 0.96% 99.52% 1.80% Lead 99.54% 1.44% 98.85% 1.66% Lithium 99.76% 1.51% 95.22% 2.39% Magnesium % 1.52% % 1.76% Manganese 98.80% 1.33% % 1.62% Element Mean (n=9) %RSD Mean (n=9) %RSD Molybdenum 98.44% 1.39% 95.29% 1.48% Nickel % 1.26% 99.59% 2.24% Phosphorus 99.37% 1.78% 99.02% 1.44% Potassium % 1.49% % 3.08% Selenium % 1.23% % 1.99% Silicon % 1.25% % 2.30% Silver 98.64% 1.59% 96.63% 1.73% Sodium N/A N/A N/A N/A Strontium 98.24% 1.70% 96.28% 1.20% Thallium 99.25% 0.91% 98.31% 1.51% Thorium 99.66% 1.26% 92.19% 1.80% Tin 99.68% 1.77% 98.78% 1.77% Titanium 99.13% 1.44% 99.74% 1.68% Uranium 98.80% 1.06% 96.73% 1.73% Vanadium 99.10% 1.82% % 1.37% Zinc 99.52% 2.61% 95.54% 1.57% Zirconium 97.98% 1.64% 94.25% 1.26%

35 CCV Recoveries, Waters and Soil Digests Waters Soil Digests Waters Soil Digests undiluted Element Mean (n=9) %RSD Mean (n=9) %RSD Aluminum % 3.15% 99.74% 2.59% Antimony % 2.57% % 1.60% Arsenic 99.79% 2.15% % 1.79% Barium % 2.68% % 2.29% Beryllium % 2.73% % 5.04% Boron 99.24% 2.00% % 3.14% Cadmium % 2.15% % 2.19% Calcium % 3.26% % 2.11% Chromium % 1.93% % 2.76% Cobalt 99.85% 1.70% % 2.82% Copper 99.28% 2.62% % 2.41% Iron % 2.10% % 2.62% Lead % 2.23% % 3.15% Lithium % 2.55% % 4.33% Magnesium % 2.67% % 2.89% Manganese % 2.48% % 1.48% Element Mean (n=9) %RSD Mean (n=9) %RSD Molybdenum % 2.49% % 2.29% Nickel % 1.94% % 2.98% Phosphorus % 2.49% 97.34% 2.53% Potassium % 1.44% % 1.63% Selenium % 1.52% % 1.99% Silicon % 1.16% 94.07% 4.21% Silver % % 2.68% Sodium % 2.21% % 2.96% Strontium % 3.16% 98.37% 2.18% Thallium % 1.82% % 2.78% Thorium % 2.37% % 3.40% Tin % 2.73% % 2.28% Titanium % 2.13% % 1.87% Uranium % 2.75% % 3.36% Vanadium 99.90% 2.35% % 2.31% Zinc 99.99% 2.26% % 1.71% Zirconium % 2.19% 99.79% 2.11%

36 Conclusions ISIS-DS can significantly improve sample throughput with no compromise in analytical performance More samples per shift- up to 380 analyses in 8 hours Reduced interface exposure to sample matrix reduces signal drift and improves short and long term precision. Fewer recalibrations, fewer sample re-runs Less frequent need for cone cleaning and interface maintenance When coupled with Agilent s High Matrix Introduction Accessory y( (HMI), Analyze samples prepared for ICP-OES with ICP-MS Better DLs and freedom from interferences compared to ICP-OES, leading to superior data quality ISIS-DS can provide very rapid analysis of samples containing percent level TDS without special optimizations