Milton E. Parrish

Measurement of Formaldehyde in a Single Puff of Cigarette Smoke Using Tunable Diode Laser Infrared Spectroscopy

A method has been developed for measuring formaldehyde in single puffs of mainstream (MS) and per cigarette in sidestream (SS) smoke with the use of tunable diode laser (TDL) infrared spectroscopy. Thirty to fifty percent of the total MS formaldehyde delivery per cigarette is generated in the lighting puff. This phenomenon is unique to formaldehyde compared to most other gaseous smoke components. The effect of the lighting technique, packing density of the tobacco in the cigarette rod, flow rate of air (heating rate) through the cigarette coal (burning zone), and tobacco type on the formaldehyde levels were studied. Calibration was based on measuring the second-derivative spectral response of formaldehyde generated from certified paraformaldehyde permeation tubes. The accuracy of the measured value of this standard was determined to be within ±0.7% of the certified formaldehyde delivery by performing periodic gravimetric measurements. In addition, the formaldehyde standard was collected in a water trap and analyzed by using a colorimetric analytical technique, providing an agreement of ± 2% with the TDL measurement. The TDL method precision was ≤ 1% with the use of the permeation standard. The MS formaldehyde deliveries for a Philip Morris monitor and Kentucky Reference 1R4F cigarette were 37 ± 5 and 27 ± 5 μg/cigt., respectively. The 1R4F value was in close agreement with results found by using an HPLC method reported in the literature. The MS sampling system can be quickly modified to determine formaldehyde levels in sidestream smoke. The SS formaldehyde delivery for the Philip Morris monitor cigarette was 2.1 ± 0.1 mg/cigt. (i.e., 0.27 ± 0.01 mg/min). The range of SS deliveries for reference, experimental, and commercial brands was much less than that observed for the MS smoke deliveries of similar cigarettes.

Formaldehyde in the gas phase of mainstream cigarette smoke

Abstract Formaldehyde deliveries in the gas phase of the mainstream cigarette smoke of a single puff were studied using Fourier transform infrared (FTIR) spectroscopy. The lighting puff (first puff) has significantly more formaldehyde than subsequent puffs. The differences between the first puff and later puffs in cigarette smoking, such as tobacco rod length, smoke condensate on tobacco rod and filter, and whether or not the tobacco has been exposed to the previous puff(s), were explored in this study. It was found that while the mainstream gas phase formaldehyde deliveries vary with cigarette rod length and amount of smoke condensate on the tobacco rod and filter, the heat exposure of tobacco through previous puff(s) shows a more significant effect on formaldehyde levels observed in different puffs. The results of this study seek to explain the higher level of formaldehyde detected in the first puff. Exploring the smoking process on a per puff basis will provide more insight into the smoke chemistry and increase our understanding of combustion and pyrolysis in cigarette smoking.

Puff-by-puff and intrapuff analysis of cigarette smoke using infrared spectroscopy

Abstract This paper reports new techniques for smoke analysis for single puffs and during a puff (intrapuff) with minimal adverse effects due to sampling. These new sampling techniques, combined with Fourier transform infrared (FTIR) spectroscopy, offer excellent approaches for measuring gaseous combustion products from burning cigarettes in real time. Near-infrared (NIR) laser scattering also is shown to provide a physical measurement of smoke based on aerosol visibility (AV) that can be related to chemical composition using FTIR in intrapuff smoke research. The absorbance of simple gases such as carbon dioxide (CO 2 ), carbon monoxide (CO), acetaldehyde (CH 3 CHO), nitric oxide (NO), hydrogen cyanide (HCN), and carbonyl sulfide (COS) are determined on a puff-by-puff basis using FTIR spectroscopy. The aerosol portion of the smoke is separated from the gas phase by a Cambridge pad prior to the gas flowing into the gas cell for analysis. A decrease in HCN and CH 3 CHO as a result of the effect of a Cambridge pad is lessened by decreasing the diameter of the pad and by replacing the pad between puffs. Each puff is trapped in a gas cell and analyzed between puffs. These results are compared with those measured using the conventional Cambridge filter pad and for whole smoke (no pad). In addition, the effect of the heat source and the lighting procedure on the lighting puff delivery of selected smoke components was studied. The absorbance of smoke constituents during a puff is determined using a flow-cell interface designed specifically for this measurement. Evolution profiles are reported for carbon dioxide, carbon monoxide, methane, and glycerine. Aerosol visibility is determined by NIR laser scattering using a separate flow cell located upstream. The evolution profile of the aerosol matches that of the glycerine profile demonstrating that an aerosol component can be monitored during the puff as well as purely gas phase components.

Hydrazine detection limits in the cigarette smoke matrix using infrared tunable diode laser absorption spectroscopy.

Infrared absorption lines of hydrazine are broad and typically not baseline resolved, with line strengths approximately 100 times weaker than the more widely studied compound ammonia. Hardware and software improvements have been made to a two-color infrared tunable diode laser (IR-TDL) spectrometer in order to improve the limit of detection (LOD) of hydrazine (N2H4) in the cigarette smoke matrix. The detection limit in the smoke matrix was improved from 25 parts-per-million-by-volume (ppmv) to 4.2 ppmv using a 100 m pathlength cell with acquisition of background spectra immediately prior to each sample and 100 ms temporal resolution. This study did not detect hydrazine in cigarette smoke in the 964.4-964.9 cm(-1) spectral region, after mathematically subtracting the spectral contributions of ethylene, ammonia, carbon dioxide, methanol, acrolein, and acetaldehyde. These compounds are found in cigarette smoke and absorb in this spectral region. The LOD is limited by remaining spectral structure from unidentified smoke species. The pseudo random noise (root mean square) in the improved instrument was 2 x 10(-4) absorbance units (base e) which is equivalent to a 0.09 ppmv hydrazine gas sample in the multipass cell. This would correspond to a detection limit of 0.44 ppmv of hydrazine, given the dilution of the smoke by a factor of 5 by the sampling system. This is a factor of 10 less than the 4.2 ppmv detection limit for hydrazine in the smoke matrix, and indicates that the detection limit is primarily a result of the complexity of the matrix rather than the random noise of the TDL instrument.

Tunable Diode Laser Applications To Cigarette Smoke Analysis

High resolution infrared tunable diode laser spectroscopy (TDL) has been applied to the study of cigarette smoke for qualitative and quantitative determinations involved in tobacco blend and cigarette filter developments. As examples of the different types of application of this work, several TDL studies are presented. The measurements of smoke components on a puff-by-puff basis in confined sample chambers and flowing streams were used to study the smoke component deliveries and the effects of filter dilution. The study of isotopes generated during combustion of chemically treated tobaccos was another application of the TDL system to complex gas mixtures without prior separation of compo-nents. The application of the TDL to the study of cigarette filters and smoke delivery simultaneously was demonstrated by using two well resolved absorption lines of two different gases which occur on a single TDL wavelength scan.