Analytical Method of N-Nitrosamines in Side-Stream of Cigarette

Abstract

A new method was developed for the analysis of N-nitrosamines in a side-stream emitted by cigarette smoking. This method consists of the following procedures; collection of N-nitrosamines in a side-stream by a liquid-solid state sampling system, extraction of N-nitrosamines by dichloromethane, concentration of the extracted solution by the use of the K-D Condenser and gentle evaporation under a nitrogen stream, and determination of N-nitrosamines by gas chromatography with TEA analyzer.
In the sampling system, N-nitrosamines in a side-stream was collected by passing it through 1N KOH, 0.5M sulfamic acid, desiccant (Na₂CO₃) and ThermoSorb/N tube, successively. This system was proved to be free from artifactual formation of N-nitrosamines even when a side-stream contained NO₂ in a high concentration of 8 ppm, and also to give high collection efficiency of 99% or more for N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR).
In prior to the solvent extraction, a known amount of N-nitrosodi-n-buthylamine was added as an internal standard to the sampling solution in order to obtain a high repeatability for the analysis. GC-TEA used here was very useful for elimination of a clean-up treatment and was highly sensitive.
This method was applied to the analysis of NDMA and NPYR in a side-stream from a Japanese cigarette. Cigarette smoking was carried out by a constant volume smoking machine in an international smoking mode. Repeatability of the analytical results was high, that is, coefficient of variation was 4.9% for NDMA and 2.9% for NPYR. Furthermore, it was found that contents of these N-nitrosamines in side-streams varied from brands of cigarette, and ranged from 190 to 370 ng/cigarette for NDMA and 90 to 210 ng/cigarette for NPYR.