TRACE ANALYSIS OF 3-HYDROXY-1-NITROSOPYRROLIDINE, A NONVOLATILE N-NITROSAMINE, BY COMBINED GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC METHOD

The methylation technique used in this study is similar to that used by Lawrence and Iverson for alkylation of certain pesticides. Similar techniques were successfully used in the past for alkylation of amines, amides and alcoholic compounds. Ethyl acetate was used in this study as the reaction medium instead of benzene, toluene or dimethylsulfoxide as used by the above mentioned investigators. The reaction proceeded smoothly at room temperature and gave a yield of 90% or more after overnight standing. Low resolution and high resolution mass spectra confirmed the structure of the derivative. Examples of tracings obtained during GC-MS [gas chromatography-mass spectrometry] monitoring for the 2 specific ions were given. The minimum detection limit was 1 ng. Besides the procedure described above, 2 other methylation techniques were examined. Methylation by diazomethane, even with boron trifluoride etherate as a catalyst, gave only 30% yield. The other technique involved gradual addition of dimethylsulfate to an alkaline solution (1 N NaoH) of HNPY [3-hydroxy-1-nitrosopyrrolidine] over a period of 3 h which gave a yield of .apprx. 80%. This latter technique might be useful in methylating HNPY in samples containing excessive amounts of moisture or other interfering compounds. High resolution GC-MS techniques are considered to be the only reliable techniques available today for unequivocal confirmation of the presence of carcinogenic nitrosamines. This appears to be the 1st successful method reported for the analysis of HNPY. The methylated ether derivative is easy to prepare, and at the same time the product is stable and volatile enough to undergo vacuum distillation clean-up. It is hoped that the technique will be useful for trace analysis of HNPY and possibly other hydroxynitrosamines.