Environ. Sci. Techno/. 1995, 29, 975-978
Phase Distribution of Nicotine in Real Environments As Determined by Two Sampling Methods GORAN LOFROTH* Environmental Health Unit, Nordic School of Public Health, Box 12133, S-402 42 Gothenburg, Sweden
In order to clarify earlier failure to collect nicotine in environmental tobacco smoke (ETS) on acid-treated filters downstream of a particle filter, samples were collected using t w o methods that could differentiate between particle- and gas-phase nicotine. Sampling with a device consisting of a particle filter followed by acid-treated filters showed that fresh ETS nicotine is collected as an apparent gas-phase component whereas nicotine in aged ETS, commonly encountered in the environment, is partly or completely adsorbed to the particle filter. The filter adsorption could be abolished with a pretreatment, making the filter basic. In contrast, sampling with acid-treated denuders followed by a particle filter showed that ETS nicotine to a large extent is collected by the denuders as a gas-phase component in agreement with other studies. All parts of a sampling device should be analyzed so that ETS nicotine concentrations are not underestimated, and gas-phase nicotine should be collected with acid-treated denuders upstream of the particle filter.
Introduction Passive smoking, i.e., inhalation of environmental tobacco smoke (ETS), is a frequently occurring exposure that has no social or personal benefits but is linked to a number of health hazards (1). In the exposure assessment of ETS, airborne nicotine is a major chemical indicator (2) that is used directly by air analysis or indirectly by determination of cotinine in body fluids of exposed persons. Methods for the collection and analysis of airborne nicotine have been assessed with samples collected in an environmental chamber (3). Two methods have been introduced to distinguish between gas-phase and particlebound nicotine; one using glass fiber filters in series in which the first filter collects particles and the following filters, which are acid-treated, collect gas-phase nicotine (4) and one using acid-coated annular denuders for gasphase collection followed by a glass fiber filter for particles (5,s).It is generallyagreed that nicotine in fresh ETS mainly is in the gas phase (2). The original study by Hammond et al. (4) using filtersin series reported that only a few percent of the airborne nicotine was in the particulate phase; this was later confirmed in a collaborativestudyusingthe same experimentalchamber and freshlyprepared tobacco smoke (3)*
We have in the past used the Ames Salmonella1 microsome mutagenicity assay to characterize ETS and to compare indoor tobacco aerosol pollution with outdoor ambient particulate matter (7-10). The mutagenicity of particulate matter is, however, not diagnostic for ETS. The reported presence of nicotine in the gas phase and its collectionon treated filters downstreamof a filter collecting particulate matter (4) indicated that one sampler could be used for the determination of nicotine as well as one or more parameters associated with particulate matter, e.g., mutagenic activity. Such studies have been reported (11, 121, but they were conducted in environments where smoking was performed in the immediate vicinity of the samplers. In a program aimed at characterizationof ETS exposure in restaurants and shopping malls (13, 141, it was found that the apparent concentrations of gas-phase nicotine, collected on acid-treated filters downstream the glass fiber filter collectingparticles, were suspiciously low. While the applied study continued with the use of separate samplers for nicotine and for mutagenicity of particulate matter, action was taken to compare two methods that may differentiate between gas-phase and particle-bound nicotine. In this study, which is presented here, samples were collected simultaneously in different environments with samplers equipped either with the filterlfilter system (4) and the denuderlfilter system (a. The results show that ETS nicotine to a large extent behaves as a gas-phase component as collected with the denuderlfilter system but that it is increasingly collected on the particle flter in the filterlfilter system as it ages. * Telephone: 46-31-69-39-35; FAX: 46-31-69-17-77; e-mail address:
[email protected].
0013-936X/95/0929-0975$09.00/0
0 1995 American Chemical Society
VOL. 29, NO. 4, 1995 / ENVIRONMENTAL SCIENCE & TECHNOLOGY rn 975
TABLE 1
Total Nicotine Concentrations and Fractions Collected as Gas Rase Using Sampling Heads with a Particulate Filter Follswed by Two NaHSO,=Treated Filted nicotine sampling location apartmentd living room bedroom study room housee living room kitchen bedroom attic smoking room during smoking'
total (palm3)
apparent gas phasebrC(YO)
33 22 8.7
60 f 1 30 1 4 615
75 26 10 10 27
68 f 9 30 f 20 131 11 1 4 f 13 97 f 1
a The samples represent ETS of different ages. Fraction collected on NaHSOdreated filters. SD of two sampling occasions. Samples collected in an apartment with smoking in the living room; data from ref 15. e Samples collected in a three-story house with smoking in the living room;datafrom ref 15. fSamplescollectedduring working hours in a small smoking room with a high ventilation rate, > 1 0 ach.
H120WW, Pallflex Products Corp., Putnam, PA) in 37-mm Millipore aerosol cassettes (MilliporeAB,Vtistra FrBlunda, Sweden). Three filters were arranged in series, and the top filter was untreated while the two bottom filters had been pretreated with NaHS04 (4) to collect gas-phase nicotine. The top filter was in some studies pretreated with a 4 % aqueous solution of tris(hydroxymethy1)aminomethane (Tris) (Sigma). Denuder sampling was performed with two serially connected 75-mm denuders (URG-2000, University Research Glass, Carrboro, NC) treated with benzenesulfonic acid (6).The denuders were either preceeded by one or followed by two 25-mm Teflon-coated glass fiber filters; the filters were also pretreated with NaHS04 when they were used downstream of the denuders. Nicotine Analysis. The desorption and the analysis of nicotine by gas chromatography were performed as described earlier (14,15). The limit of detection was about 0.05pglsample part, giving a detectable concentrationlimit of 0.04-0.4 pglm3 depending on sample volume and number of sample parts.
Results A nicotine sampling system consistingof a particle filter as
Sampling and Analysis of Nicotine Sampling. The sampling in diverse environments was made with battery-operated personal pumps (Aircheck sampler, SKC Inc., Eighty Four, PA) at a rate of 2 Llmin. The sampling times were mainlyin the range of 1.5-4 h, except the overnight samplings in a smoking room which lasted 10h. Nicotine was collected on sample heads that consisted of either only filters or of denuders and filter. Filter collection of nicotine was performed as described earlier (14,15) on Teflon-coated glass fiber filters (TX40-
the first part of a sampling head collects a variable and often a substantial fraction of the airborne nicotine on the particle filter, giving the appearance that ETS nicotine is largely not in the gas phase (Tables 1 and 2). A sampling system with denuders as the first part gives the result that a major part of airborne nicotine is in the gas phase. Pretreatment of the particle filter with an aqueous ammonia solution to remove potential filter acidity did not change the collection on the particlefilter (data not shown), but pretreatment of the filter with an aqueous Tris solution,
TABLE 2
Total Nicotine Concentrations and Fractions Collected as Gas Phase Using D mSampling Heads filter/NaHSOa-treated filter Tris-treated filter/NaHSO&eated filter sampling location
total (pg/m3)
apparent gas phase' (%)
14 10
29 17
total (pg/m3)
shopping mallb
1211 0123
-f
-
apparent gas phase' (%)
-
restaurantC
021 1 0219 1005 1028 1119 1130 0111 jazz clubd
0224 0331 smoking room during nonsmokinge
1121 1205 1212 01 16 0206 0123
8.3 6.4
-
1 .o
1.4 1.3 2.6 2.3 1.7
12 98 >96
-
-
-
36
>99
41
>99
