Real time gas phase puff-by-puff profile
An automated puff-by-puff mainstream smoke system is developed to monitor real time gas phase in mainstream cigarette smoke. Simple and sensitive, the real-time analysis delivers, without pre-treatments, a rapid fingerprint of the volatile profile as the cigarette is consumed. Sample generation is provided by a customized single-port smoking machine. iltered mainstream smoke is analyzed on a continuous basis using a RTGA→ system which consists of a modified 5973N mass selective detector (MSD). Instead of smoking valve (which would distort smoke profile); the gas phase entering the MSD is carefully controlled through precision orifices in two stages using differential pumping: 1) process orifice, and 2) MSD sampling orifice. Unlike the traditional GC/MS systems, separation of the components does not occur prior to entering the MSD. With response times as fast as 2 to 5 seconds, the system can monitor and capture rapid transients that could be missed by other monitoring equipment. The occurrence of peak tailing decreased with a gentle helium back flush system to exhibit low carryover of volatile smoke constituents. Preliminary data for volatile fingerprint has been collected with the Kentucky Reference 2R4F cigarette. Both scan (m/z 55 to 115) and selected ion monitoring (SIM) modes on m/z 67/68/78 and 92 with dwell times of 500 ms were found to yield approximately the same sensitivities providing good linearity and good day-to-day variability (CoV <8%)Drawbacks of this method: not selective and today limited to the analysis of gaseous compounds compared with accurate puff-by-puff GC-MS method. Nevertheless, such rapid and easy-to hand evaluation would provide analytical information for testing the efficiency of vapour phase filters. Improvements of statistic exploitation are on the way to establish methods of investigation as well as provide guidance for further investigations of prototype cigarette under development.