GC-MS Determination of 12 N-Nitrosamines in Rubber Teats

Importance of the Topic

N-Nitrosamines are a class of potent mutagenic and carcinogenic compounds that can migrate from rubber articles into food or beverages, posing health risks. Regulatory agencies such as the FDA and the EU have established strict limits for N-nitrosamine content in products intended for infants and children, highlighting the need for reliable analytical methods to monitor these contaminants.

Objectives and Study Overview

This study aimed to develop and validate a robust GC-MS method for simultaneous determination of 12 volatile N-nitrosamines released from rubber teats under simulated conditions. The approach focused on efficient extraction, clean-up, chromatographic separation, and sensitive detection in selected ion monitoring mode.

Methodology

• Sample Preparation: 5 g of ground rubber teats was subjected to microwave-assisted extraction with 30 mL methanol.
• Clean-Up: Extracts were filtered, concentrated, and purified using C18 solid-phase extraction cartridges (conditioned with methanol, loaded sample, eluted with methanol).
• Concentration: Eluates were reduced to 1 mL for GC-MS analysis.

Instrumental Setup

• Gas Chromatograph: Shimadzu GCMS-QP2010 Ultra with AOC-20i+s autosampler.
• Column: Stabilwax, 30 m × 0.25 mm i.d., 0.25 µm film thickness.
• Carrier Gas: Constant linear velocity (40 cm/s).
• Temperature Program: 50 °C (2 min) → 6 °C/min to 170 °C (6 min) → 30 °C/min to 245 °C (10 min).
• Injector: Splitless at 230 °C, injection volume 1 µL.
• MS Detection: Electron impact ionization, source 200 °C, interface 240 °C, SIM acquisition.

Main Results and Discussion

The method demonstrated excellent linearity (r > 0.999) over 50–1000 µg/L for all 12 N-nitrosamines. Limits of detection ranged from 0.15 to 0.61 µg/kg in spiked rubber samples. Recovery experiments at 50 µg/kg yielded 72–109% with relative standard deviations below 10%. These figures confirm the method’s precision, accuracy, and sensitivity for trace-level N-nitrosamine analysis.

Benefits and Practical Applications

This GC-MS approach enables quality control laboratories to monitor N-nitrosamine contamination in rubber products effectively, ensuring compliance with regulatory limits. The combination of microwave extraction, SPE clean-up, and SIM detection offers high throughput, minimal matrix interference, and low detection limits suitable for safety assessments of infant care articles.

Future Trends and Applications

• Integration of automated online SPE for higher sample throughput.
• Development of high-resolution mass spectrometry methods for non-targeted nitrosamine screening.
• Application to a broader range of polymeric materials and simulants.
• Exploration of greener extraction solvents and miniaturized sample preparation techniques.

Conclusion

A validated GC-MS protocol has been established for simultaneous quantification of twelve N-nitrosamines in rubber teats. The method achieves regulatory compliance criteria in terms of sensitivity, precision, and accuracy, supporting safeguarding of consumer health.

Reference

• Peng Gao, Jun Fan, XiaoLi Deng, TaoHong Huang. GC-MS Determination of 12 N-Nitrosamines in Rubber Teats. Shimadzu Analytical Application Note, IMSC 2012.