In the Laboratory
An Undergraduate Field Experiment for Measuring Exposure to Environmental Tobacco Smoke in Indoor Environments
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Adam M. Marsella, Jiping Huang, David A. Ellis, and Scott A. Mabury* Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada; *
[email protected] The focus of this experiment is to familiarize students with techniques and equipment frequently employed in the measurement of gases and vapors in the environment and workplace; this experiment is an extension of a lab-based investigation of aldehydes produced from cigarette smoke (1). By applying current and reliable methods to the field sampling of nicotine and aldehydes, students are able to examine the real-world problem of environmental tobacco smoke (ETS) exposure in common indoor urban environments such as cafes, restaurants, and nightclubs. By measuring both nicotine (2) and aldehydes (3, 4), students can critically compare the use of these two methods for the estimation of ETS exposure. Finally, the experiment illustrates common variables often encountered when assessing indoor ETS concentrations, including ventilation and the number of people smoking.
Carbonyls
Nicotine XAD-2
2,4-DNPH
Ethyl acetate extraction
Acetonitrile extraction
GC-NPD analysis
Sampling pump (1 L/min)
Sampling pump (0.5 L/min)
HPLC-UV (370 nm) analysis
Figure 1. Sampling, extraction and analysis schematic for nicotine and aldehydes.
Methods Each group of students was supplied with two personal i.d. Simplicity-1 column, polydimethylsiloxane bonded sampling pumps (Buck I.H. Pump, A.P. Buck Inc., Orlando, phase; He carrier at 5 mL/min, makeup H2–air 1.7 and 100 FL), one for aldehydes and one for nicotine (Fig. 1). These mL/min, respectively). A flame ionization detector (FID) is pumps were battery operated and lightweight to facilitate the not recommended for the nicotine analysis, for reasons of field sampling. Both pumps were fitted with a suitable length both inadequate sensitivity and selectivity. External calibraof Tygon tubing to attach each sampling cartridge. After pump tion was used for both nicotine and aldehyde extracts. calibration, students were given two silica SPE cartridges impregnated with 2,4-dinitrophenylhydrazine (2,4-DNPH) Results and Discussion for aldehyde sampling (Supelco, Oakville, ON) and two Most groups found detectable levels of aldehydes (Table XAD-4 (Supelco, Oakville, ON) tubes for sampling nicotine. 1) in their control cartridge extracts, likely arising from One of each sampling device was used as a control and the aldehydes emitted from sources other than ETS. In contrast, other for sample collection. From the “sample location”, sidenicotine was detected in only 2 of the 12 groups’ control by-side sampling for nicotine and aldehydes was conducted for XAD-4 extracts, and in both cases could be attributed to the approximately 1 h (1 L/min for nicotine and 500 mL/min choice of control location (for example, the nonsmoking for aldehydes), which generally resulted in an adequate signal for each of the analytes. Next, students sampled from a “control location” for the same length of Table 1. Tracer Compounds in Samples and Controls time and at the same flow rates. Samples and conFormaldehyde/µg m{3 Acetaldehyde/µg m{3 Nicotine/µg m{3 Location trols were usually taken from different locations, Sample/Control Sample Control Sample Control Sample Control depending on the students’ intentions. Students Nightclub/lab 30 50 59 nd 913
