Volumen 7 (1974): Edición 5 (September 1974)

During the attempt to transfer to tobacco a method commonly used to determine metobromuron in foodstuffs, it became apparent that only very small amounts of metobromuron and less than 0.1 ppm 4-bromoanilin were found. Nor did the modification of this method produce better results, because metobromuron, apparently linked to tobacco components, cannot be extracted with aqueous acetonitrile. The tobacco was then distilled under hydrolysing conditions and the 4-bromoanilin released was bound as hydrochloride. After gas-chromatographic separation 4-bromoanilin is determined specifically with the microcoulometer (bromine) and with the Coulson detector (nitrogen). The amount of metobromuron is calculated from the 4-bromoanilin. With this method no difference can be made between intact metobromuron and 4-bromoanilin already metabolised from metobromuron. Recovery is 90 % for 4-bromoanilin and 92 % for metobromuron, the coefficient of variation is 3.0 %. In cigarettes whose tobacco had grown in soil which had been treated with 4 kg of Patoran per hectare before transplanting, a mean of 5.8 ppm metobromuron was found by this procedure.

The screening procedure for the determination of pesticide residues in tobacco (organochlorine, organophosphorus and carbamate insecticides) published in 1970 has been improved by introduction of the dry-column chromatography as cleanup procedure. A new procedure has been developed for the detection of carbaryl and propoxur by gas chromatography. The extraction and cleanup method developed can be used to determine 11 organochlorine, 11 organophosphorus and 3 carbamate insecticides. The procedure can be applied to determine further insecticides and, in addition, fungicides, herbicides and metabolites. The recoveries of added pesticides at 0.5 ppm level are between 75 and 102 %. The coefficient of variation detected with parathion is 4.4 %

The present paper shows and discusses microphotographs of the structural composition of reconstituted tobacco sheet. So far as the biological activity of the sheets' smoke condensate had been investigated (5), the authors try to find a relation between the said activity and the microscopic structure.

Thermocouples were used in the past, with a few exceptions, for cigarette coal temperature measurements. The main shortcomings of this technique are: the cigarette is disturbed by insertion of the thermocouple, the position of the bead does not necessarily coincide with the location of the puff, heat transfer between tobacco shred and bead is poor, heat capacity and conductivity are orders of magnitude different for tobacco and metals. Methods employing x-ray observations of fusions of metal inclusions or cinematographic optical pyrometry also possess serious shortcomings. These shortcomings are eliminated by a non-contact technique based on radiometry. This method is applicable only to the measurement of surface temperature of the cigarette coal. By measuring the intensity of the emitted radiation, the temperature can be calculated or can be obtained by calibration with an artificial blackbody. Since the coal temperature is not stable even during the 2-second duration of a puff, the instantaneous response of an infra-red detector has to be coupled with a very fast recording system. An AGA Scanning Infra-red Camera was selected for the coal temperature measurements. The electronic system of the camera generates a waveform proportionaI to the 2-5.4 AAµ band of the infra-red radiation emitted by the coal. The peak value of the video signal, representing the hottest point of the coaI, is stored. At a command, given automatically by the smoking machine, the signal is digitized and printed out. Although the peak signal decreases with very small targets, evaluation of the system indicates acceptable accuracy for target sizes down to 3 mm in width. The cigarette coal fulfills this condition.

An investigation is described concerning the effect of tipping perforations on the yield of a variety of smoke components. The degree of ventilation covered the 20-70 % range. Tipping ventilation reduces the amount of air drawn past the cone during the puff and thereby compresses the thermaI profile of the cone. The yield of gaseous smoke components which have unique precursors is a function of time-at-temperature conditions in and near the cone and the effect on the yield differs between precursors as the amount of air flow is varied. Compounds that depend on distillation or sublimation to get into mainstream smoke are much less affected by tipping ventilation, i.e., condensation of these materials onto smoke particles becomes more efficient as the air flow past the cone is reduced and less particulate smoke is produced

Both the vapour and particulate phases of tobacco smoke have been shown to retard benzoyI-peroxide-initiated polymerisation of vinyl acetate by interception of the radicals involved in the polymerisation process. The extent of inhibition of polymerisation by test compounds is estimated by measuring time taken for a mixture of monomer and benzoyl peroxide, immersed in a water-bath at 70°C, to reach a spontaneous boil and comparing it with the time required for a similar mixture with added retarder to reach boiling point. Units are expressed as minutes of inhibition per part per million of inhibitor × 10³. Inhibition by the vapour phase can be attributed to conjugated unsaturated compounds, chiefly isoprene which has an inhibition factor of 788 min. ppm^-1 × 10³ respectively. To trace the groups of compounds responsible for the inhibitory activity of the particulate phase, the particulate matter was fractionated by the method of Stedman et al. The fractions containing the highest activities were ether-soluble weak acids, methanol-soluble neutrals and nitromethane-soluble neutrals with inhibition factors of 83, 122 and 135 min. ppm^-1 × 10³ respectively. Since the nitromethane fraction contains most of the aromatic hydrocarbons produced on smoking and some polyaromatics are known to have high inhibition factors, it was subfractionated after the method of Grimmer but no subfraction with activity appreciably higher than the crude nitromethane fraction was obtained. The distribution of activity in the major fractions of the particulate phase of the smoke from a number of different tobacco types and smoking vehicles has been examined. These results and the mechanism by which smoke inhibits polymerisation are discussed.

The examined components in the volatile phase of cigarette smoke increase with the puff number, in the same way as does the smoke condensate. The variation progresses similarly whether sampling with the Grob syringe or the smoking machine. However, when using the syringe we obtain lower values.

The amount of particulate matter on a Cambridge filter has little or no effect on the retention of the volatile phase components by this particulate matter, at least after the smoking of the first cigarette.

The volatile phase, resulting from the total phase collected in the syringe, gives, with the exception of benzene and toluene, higher values than those obtained by direct sampling through a Cambridge filter, both in the complete cigarette smoke test and in the puff-by-puff test.

By sampling the different puffs each time through a new Cambridge filter we observe that values are systematically lower than those obtained by aspiration of the respective puffs through one and the same Cambridge filter.

A method for the determination of trace transition metals in cigarette smoke is described. The smoke particulate matter is digested in nitric acid, the acid is neutralized, and metal ions are complexed with ammonium 1-pyrrolidinecarbodithioate and extracted with methyl isobutyl ketone. The metals are then determined in the organic solvent by atomic absorption spectroscopy. The sensitivity of the method is enhanced by the use of the methyl isobutyl ketone extraction. The method was evaluated for the determination of manganese, copper, iron, and zinc in the total particulate matter of smoke from University of Kentucky reference cigarettes and from commercial cigarettes. The amounts of these metals found in the smoke of a typical commercial filter cigarette are: 0.04 µg Mn, 0.10 µg Cu, 0.8 µg Fe, and 0.6 µg Zn. The method was used to show that cellulose acetate cigarette filters remove about the same percentage of metals as total particulate matter from smoke