Low-Pressure Chromium Speciation in P2O5 using the Spectro ARCOS MV ICP and the ESI SC-DX chromfast System Dion Tsourides AAFPCO Meeting Albuquerque, NM (Acknowledgements ESI)
Introduction Chromium exists in fertilizers in several forms which differ in their effects upon plants and organisms. Chromium enters the air, water and soil as Cr(III) and Cr(VI) through natural processes and human activities. At certain levels, Cr(III) is an essential nutrient for humans. On the other hand, Cr(VI) is detrimental to human health and is considered carcinogenic. For this reason, there is an interest in knowing the level of Cr(VI) in various materials. Normally an HPLC is used to separate the Cr (III) from the Cr (VI), while the ICP us used as the detector system. However, there is a more cost effective method. Elemental Scientific s chromfast chromium speciation kit is an economical, robust, and easy-touse system that uses a peristaltic pump and a low-pressure anion exchange column to separate, detect, and quantify Cr(III) and Cr(VI) species in aqeous samples.
Species Detection Limit (ppb) Cr (III) 1.9 Cr (VI) 1.1
Separation Schematic
Instrumentation, Sample Introduction, and ICPMS Parameters ESI chromfast speciation kit (CF-KIT-Cr36) with the Cr anion exchange column (CF-Cr-01) ESI MP2 micro peripump (MP2-4-52) Smart Chroma software (Spectro SAV Module) Arcos MV ICP OES in Radial Mode Procedure Samples and standards were automatically loaded into the sample loop and injected onto the Cr column. The Cr species were separated on the column and nebulized using a pneumatic nebulizer. The peaks for Cr(III) and Cr(VI) were measured using the time-resolved software built into the Arcos Software and were exported for data analysis. Data Analysis The collected data were analyzed with the SAV Chroma software package. This software utilizes an intensity based spreadsheet to integrate the chromatographic peak areas. The resulting data can then be used for calibration and determination of Cr species.
Obtaining accurate measures of trace amounts of Cr species can be costly and time consuming. ICP OES with the chromfast low-pressure anion exchange chromium speciation kit (CF-KIT-Cr36) and the SC-DX FAST is an economical alternative to HPLC-ICPMS systems. The fully-automated and easy-to-use system can switch between multi-element ICP sample analysis to elemental speciation detection modes in minutes. The robust anion exchange column can be used for multiple samples and efficiently separates Cr species providing a cost-effective solution for speciation needs.
Spectrometer Hardware SPECTRO ARCOS MV 2 ICP-OES systems in 1
Major Points of Development Development of a MultiView plasma interfaces True axial- and radial plasma observation with one instrument Development of a solid state generator Small, high power, robust, energy and cost efficient, future proof Integration of the SPECTROBLUE concept Modern, ergonomic design and sample introduction system OPI-Air Interface Optic window slider Improved accessibility for service and maintenance
Optical System - Design
Axial Plasma Observation Challenges Axial plasma observation improves the sensitivity by sampling the emitted light from the entire excitation channel However, it also suffers from stronger influences, since all phenomena present in the excitation are viewed Pros and Cons: High sensitivity Stronger matrix effects Less suitable for high TDS and applications with organic solutions Viewing volume 10
Radial Plasma Observation The choice for high stability, high matrix loads and organic solutions Radial plasma observation provides lower sensitivity since the central channel is only partially view However, it provides high stability and freedom from matrix effects since the affected zones in the plasma are blanked out Pros and Cons: High stability High matrix tolerance High linear dynamic range Freedom from matrix effects Lower sensitivity Viewing volume
Dual View really the best of both worlds? Dual View appears to solve the dilemma having to make a choice between axial and radial plasma observation But! Only one view uses the direct light path, the other is compromised Sensitivity loss due to additional optical components Coupling mirror Optic window Torch Sensitivity loss in the UV since the light path cannot be purged effectively Entrance slit optic Mirror, plain Mirror, concave 12
Dual View really the best of both worlds? For highest sensitivity, instrument using a Dual View technique typically have a horizontal torch orientation Disadvantages with higher matrix loads and organic solutions Compared to a dedicated radial interface the sampling volume using a periscope is smaller Ultra high stability and precision as compared to a dedicated radial systems cannot be achieved The dual view technique serves a purpose, but does not provide the highest possible performance 13
What to do, if ultimate performance is required? Turn the plasma! Using MultiView, the plasma orientation can be changed The instrument can be used as a dedicated radial as well as a dedicated axial instrument 14
MultiView - Radial/Axial Plasma in one Instrument Analytical performance without compromise Highest sensitivity Highest stability and precision Highest dynamic range Highest matrix compatibility Freedom from matrix interferences Other techniques or instruments are not anymore required 15
MultiView Easy to change Interface 16
Cost savings using OPI Air Does not require an external cooling system No investment costs No maintenance costs Uses the available torch box extraction
Smart Chrom Pro Separate, optional module for advanced transient data acquisition and evaluation Automatic acquisition and evaluation of transient signals with ICP- OES Suitable for the coupling of chromatographs, laser ablation, ETV and more Innovative work flow operation Start /Stop synchronization with external equipment Sampling frequency up to 10 Hz Shortest integration time 10 ms Package calculation mode Simultaneous measurement of up to 40 channels Off peak background correction Base line correction Internal standardization Auto regression with linear, quadric and rational models
Smart Chrom Pro Concentration based standardization Calibration and accuracy verification using control samples Recalculation of results XML and Copy to Clipboard result export Batch list automation Sample Result Manager Comprehensive search and filter options Configurable result output Printing, XML, XPS, Excel Optional SPC module
Smart Chrom Pro Start /Stop synchronization with external equipment Sampling frequency up to 10 Hz Shortest integration time 10 ms Package calculation mode
Smart Chrom Pro Simultaneous measurement of up to 40 channels Off peak background correction Base line correction Internal standardization Auto regression with linear, quadric and rational models
Data for P2O5 sample spikes (20/20 spike) P2O5 spiked with 40ppb total Cr 20 ppb Cr 6 20 ppb Cr 3 Analysis by ICP (total Cr) Analysis by ESI-ICP (speciation) 22
Speciated Results Cr 205 used for Speciation Cr 267 SIM used for Total Cr P2O5 Blank & 40ppb Cr Spike Spike = 20ppb Cr 3 + 20ppb Cr 6 23
Thank you for your attention!