Maximizing Productivity in High Matrix Samples using the Agilent 7700x ICP-MS with ISIS Discrete Sampling

Significance of the Topic

In contract environmental laboratories growing sample loads and stringent quality requirements drive the need for faster high matrix analysis without compromising accuracy or precision. Integrating discrete sampling with helium collision cell and advanced aerosol dilution addresses these challenges.

Objectives and Overview

This work evaluates a workflow combining ISIS Discrete Sampling with the Agilent 7700x ICP MS in helium collision mode and High Matrix Introduction to achieve EPA 6020A compliant analysis in under two minutes per sample. Performance was assessed over an eight hour sequence of 275 diverse environmental samples including soils sludges and seawater spikes.

Methodology and Instrumentation

An Agilent 7700x ICP MS was configured with nickel cones a concentric nebulizer helium collision cell HMI and ISIS DS discrete sampling. Key settings included 1550 W RF power 0.5 L min carrier gas 2.3 mL min cell gas 600 μL loop volume 10 s uptake 25 s delay and preemptive rinsing. Calibration spanned 0.1 to 100 ppb for trace and 10 to 10000 ppb for mineral elements without matrix matching or mid run recalibration.

Main Results and Discussion

Throughput and Stability

• 275 analyses in 8 h 8 min corresponding to 1.99 min per sample a 30 percent gain by maintaining single helium cell mode

Detection Limits

• Three sigma MDLs met EPA reporting limits across all isotopes from U down to sub ppb

QA QC Compliance

• Low level initial calibration verification recoveries fell within 30 percent of nominal
• Continuing calibration checks remained within 10 percent except for minimal sodium drift
• Internal standard recoveries were stable confirming absence of matrix buildup

Accuracy and Precision

• Seawater matrix spikes and duplicates yielded recoveries of 61 to 114 percent RPD below 20 percent
• Certified reference materials returned 92 to 114 percent recoveries and percent relative standard deviations under 8 percent

Benefits and Practical Applications

The combined use of HMI helium collision mode and ISIS DS provides rapid run to run times HMI enabled suppression of matrix effects and ISIS DS minimized sample exposure and maintenance. A single cell mode for all analytes simplifies method setup and supports EPA 6020A compliance in high throughput laboratories.

Future Trends and Applications

Potential developments include automation of QA QC workflows real time data analytics expanded applications to clinical and industrial matrices and improved blank strategies for further lowering detection limits.

Conclusion

This optimized configuration of the Agilent 7700x ICP MS demonstrates robust accurate and high throughput analysis of challenging high matrix samples fully meeting EPA 6020A requirements while maintaining ease of use and reduced maintenance burden.

References

1. Wilbur S Jones C Simple Reliable Analysis of High Matrix Samples According to US EPA Method 6020A using the Agilent 7700x ICP MS Agilent Technologies publication 5990 5514EN
2. Wilbur S Kuwabara T Sakai T High Speed Environmental Analysis Using the Agilent 7500cx with Integrated Sample Introduction System Discrete Sampling ISIS DS Agilent Technologies publication 5990 3678EN