Comparing the Performance and Reliability of Waters Alliance HPLC Systems for Carbamate Analysis

Significance of the Topic

The analysis of carbamate pesticides at trace levels is essential for monitoring drinking water safety and ensuring compliance with environmental regulations. Sub-ppb detection capability supports public health protection, quality assurance in food and environmental testing, and adherence to US EPA Method 531.2.

Objectives and Study Overview

This work compares the performance of the legacy Waters Alliance HPLC system and the 2013 upgraded model for analysis of twelve carbamate compounds. The study focused on:

• Linearity across seven calibration levels (1 to 100 ppb)
• Precision and reproducibility for retention time and concentration
• Limit of detection (LOD) determination per EPA guidelines
• Evaluation using a blind QC sample

Methodology and Instrumentation

The experimental procedure employed a Waters Carbamate column (3.9 x 150 mm, 4 μm) at 30 °C with a ternary gradient of water, methanol, and acetonitrile. A flow rate of 1.5 mL/min and a 400 μL injection volume (1000 μL for ultra-trace levels) were used. Fluorescence detection (Ex 339 nm, Em 445 nm) and Empower 2 software were applied for data acquisition and processing.

Instrumentation

• Waters Alliance HPLC Systems (legacy and 2013 models)
• Waters Carbamate Column
• 2475 Fluorescence Detector
• Empower 2 Chromatography Software

Results and Discussion

Both platforms demonstrated excellent linearity (R2 > 0.999) for all analytes. Retention time reproducibility across 21 injections showed RSD values below 0.25% for both systems. Concentration precision for 75 ppb and 25 ppb levels yielded RSDs below 0.8% and 0.9%, respectively. At 10 ppb, most compounds remained below 1.5% RSD, with 1-naphthol exhibiting slightly higher variability as expected. LODs were generally below 0.1 ppb, except for 1-naphthol (up to 0.36 ppb). Blind evaluation with an ERA performance mix confirmed results within QC limits and agreement within 1 ppb between systems.

Benefits and Practical Applications

The demonstrated comparability validates the 2013 Alliance system as a direct upgrade, providing:

• Regulatory compliance with EPA Method 531.2
• Baseline separation of twelve carbamate analytes in a 25-minute run
• High precision and low detection limits
• A turnkey solution for environmental, food, and water testing laboratories

Future Trends and Potential Applications

Advancements may include integration with mass spectrometric detectors for further sensitivity and selectivity, miniaturized HPLC formats to reduce solvent use, automation of sample preparation, and application of machine learning algorithms for rapid data interpretation. Adoption of green solvents and on-line sampling techniques could enhance throughput and sustainability in routine analysis.

Conclusion

The legacy and 2013 Waters Alliance HPLC systems perform equivalently for carbamate pesticide analysis, delivering robust linearity, precision, and sub-ppb detection. The 2013 system offers modern hardware and software enhancements while maintaining method continuity, supporting regulatory requirements and operational efficiency.

References

1. Waters Corporation. Alliance System for Carbamate Analysis Method Guide p/n 71500017101 Rev D.
2. US EPA. 40 CFR Part 136 Appendix B MDL Procedures.
3. de Bertrand et al Photodegradation of the Carbamate Pesticides Aldicarb Carbaryl and Carbofuran in Water Analytica Chimica Acta 1991 254 235–244.