Purity Analysis of N-Methyl Pyrrolidone (NMP) Using an Agilent 8850 GC

Importance of the Topic

High-purity analysis of N-methylpyrrolidone (NMP) is critical across multiple industries, including semiconductors, coatings, adhesives and pharmaceuticals. In lithium-ion battery (LiB) manufacturing, NMP dissolves polymer binders for electrode slurry preparation and must be closely monitored for residual levels after drying. Robust GC methods that detect trace impurities help ensure product consistency, process control and performance reliability.

Objectives and Study Overview

This work aimed to develop and validate a gas chromatography (GC) method on the compact Agilent 8850 GC for rapid, precise purity analysis of NMP. Commercial and customer-sourced NMP samples were analyzed using an Agilent J&W DB-23 capillary column to resolve major and minor impurities, quantify their abundance and compare results with existing solvent certifications.

Methodology and Instrumentation

A flame ionization detector (FID) method with a split/splitless inlet and a 1 µL injection volume was implemented. Key GC parameters included split ratio 100:1, helium carrier at 2.5 mL/min, oven ramp from 45 °C to 230 °C and a 30 m×320 µm, 0.5 µm DB-23 column. An Agilent 7650A automatic liquid sampler (ALS) performed sample introduction and multi-step wash cycles to minimize carryover. Agilent OpenLab CDS 2.7 software handled data acquisition, peak evaluation and sample overlap scheduling to optimize throughput.

Key Results and Discussion

• Column Screening: DB-23 was selected over wax, cyanopropyl and apolar phases for superior separation of NMP, N-methylsuccinimide (NMS), 2-pyrrolidinone (2PYR) and an unidentified late-eluting impurity.
• Sample Comparison: Chromatograms of fresh (2024) vs aged (2019) commercial NMP revealed elevated NMS in older solvents, highlighting degradation pathways and the value of impurity profiling.
• Precision: Ten-replicate injections of each sample yielded area RSDs of 0.5–4% for NMP and impurity peaks, with calculated purities within ±0.22% of certification values.
• Unknown Marker: A consistent impurity eluting at 18 minutes served as a run-end marker and underscored the need for baseline stability over extended temperature holds.

Benefits and Practical Applications

This GC approach delivers high resolution of both major and trace impurities in NMP, enabling granular quality control in solvent production, storage and end-use processes. The combination of precise autosampler washing, sample overlap scheduling and onboard peak evaluation reduces downtime and ensures consistent data quality in high-throughput laboratories.

Future Trends and Potential Applications

Emerging capabilities such as automated maintenance feedback and advanced impurity tracking will further enhance method robustness. The approach can be extended to residual NMP quantitation on battery electrodes, integrated with laboratory information management systems (LIMS) and adapted for purity assessment of other high-boiling, polar solvents.

Conclusion

The Agilent 8850 GC with 7650 ALS and DB-23 column offers a compact, reliable solution for comprehensive purity analysis of NMP. Its high precision, enhanced impurity separation and intelligent features support stringent quality requirements and efficient workflow management in industrial and research settings.

References

1. Liu, Y.; Zhang, R.; Wang, J.; Wang, Y. Current and Future Lithium-Ion Battery Manufacturing, iScience 2021, 24(4), 102332.
2. Shang, H.; Zhang, J.; Jiang, F. Analysis of N-Methyl-2-Pyrrolidone in Battery Electrodes, Agilent Technologies application note, pub. 5994-7715EN, 2024.
3. Zhang, J.; Shang, H. Analysis of Residual N-Methyl-2-pyrrolidone in Li-Ion Battery Electrodes, Agilent application note, pub. 5994-7677EN, 2024.
4. Agilent 7560A Automatic Liquid Sampler (ALS) data sheet, Agilent Technologies, pub. 5991-0150EN, 2019.
5. Agilent Peak Evaluation Videos, Agilent Technologies, 2025.