38 Environmental Analysis
Maximizing ICP-MS Productivity for High Matrix Samples Using the 7700x with ISIS Discrete Sampling
High Productivity Analysis of High Matrix Samples Maximum productivity requires more than just fast analysis times; it also requires the robustness and stability to maintain high speed analysis for an extended period. The typical ICP-MS interface is designed to tolerate samples containing up to 0.2% total dissolved solids (TDS). Above this level, the plasma may become overloaded, leading to:
• Signal drift caused by gradual deposition of undissociated material on the interface cones
• Higher levels of polyatomic interferences (such as strongly- bound matrix oxides)
• Increased suppression (signal loss), especially for poorly ionized analytes such as Be, B, Zn, As, Se, Cd and Hg
The Agilent 7700x ICP-MS was designed to alleviate these problems by increasing the matrix tolerance of the plasma, as well as enhancing the performance of the 3rd generation Octopole Reaction System (ORS3) cell operating in helium collision mode (He mode).
Agilent High Matrix Introduction (HMI) System The 7700x includes the unique HMI system which dilutes the aerosol stream from the spray chamber, thereby reducing the aerosol and matrix loading on the plasma. The result is a significant increase in the effective plasma temperature, which effectively eliminates matrix suppression, and also allows samples containing % levels of TDS to be analyzed routinely, without the need for time consuming dilutions of over-range samples.
Helium Collision Mode He mode on the ORS3 cell is widely acknowledged as the most effective and reliable method for removing the unknown and variable polyatomic interferences typically seen in complex natural samples. Since He mode works for any polyatomic interference, it provides significantly shorter run times compared to reaction cell methods, where multiple cell gases are typically required to address all the interferences that occur in complex samples.
Integrated Sample Introduction System (ISIS) Achieving the highest productivity in ICP-MS requires optimization of the sample uptake and washout steps, which account for more than half of the overall run time in a typical ICP-MS method. The ISIS option for the 7700 Series can be configured for maximum productivity using Discrete Sampling or DS which, while much faster than conventional sample introduction, still allows multiple replicates to be measured from each sample injection as required by USEPA methods.
The Result
A standard Agilent 7700x ICP-MS fitted with an optional ISIS-DS system was used for the measurement of a sequence of high matrix standard reference materials, 1/10 diluted seawaters, and all EPA 6020A required QA/QC samples. 275 analyses were performed in 8 hours 8 minutes, with an average run to run time of 1.99 minutes per sample. Excellent internal standard stability (Figure 1) is evidence of superior matrix tolerance and long term stability.
ISIS-DS He Collision Mode
High Matrix Introduction (HMI) System
Figure 2. The key components of high productivity
Combined ICP-MS Technologies for High Matrix Sample Analysis The unique combination of ISIS-DS, HMI and He mode for universal interference removal delivers much faster analysis, while also providing effective removal of polyatomic interferences, and the highest matrix tolerance of any ICP-MS – Figure 2.
For more information on the 7700x visit the Agilent Technologies web site at:
www.agilent.com/chem/icpms
High Speed Sample Uptake and Rinseout
Fast, Reliable Removal of all Interferences
Ultimate Matrix Tolerance
Figure 1. Minimal Internal Standard signal drift for sequence of 275 high matrix environmental samples (not all sample names are shown)
© Agilent Technologies, Inc., 2010 April 6, 2010 5990-5631EN
Reader Reply Card no 137 AET April/May 2010
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
