780 



316 



CXDRl AND LYNCH 



SOr 



ts 



10 



QfUspondantt 



M 



Ji 







iu 



2 1 sT* 1 sTe I tTi r» iioTnTuI iVliVliVi wTiVi ui uTaO'f 



FTCT«r(nv) 

 FKj. 1. Distribution of sampled smokers venus actual market share, based on FTC lar yidd of cigarettes. 



Blood Samples 



Blood samples were drawn with EDTA as an anti<x>agulant; plasma was immediately 

 frozen without preservatives. Samples were blind coded and stored frozen at -20''C 

 or below. 



Cigarette Consumption 



Volunteers reported the number of cigarettes smoked each day (CPD), by day of 

 week. Approximately 20% of the volunteers were asked to bring all cigarette butts 

 from the previous day to the test facility, and the verbal reports were consistently 

 verified. The overall CPD was taken as the daily average for all days of the week, 

 rounded to the nearest integer. 



Colin ine and Sicotine Analysis 



Nicotine and cotinine levels in plasma were determined, using methods developed 

 by Jacob et al. (26). Standard curves were constructed and repeated e\ery 40 deter- 

 minations, using the internal standards iV-eihylnomicotine for nicotine, and .V-<2- 

 methoxyethyl)norcolinine for cotinine. The peak height correlation was linear over 

 the range 5 to 600 ng/ml for cotinine, and 1 to 100 ng/ml for nicotine. Throughout 

 the procedure, precautions were taken to avoid exogenous contamination ( 13). 



As a test of consistency, 167 samples were reanalyzed for nicotine and 88 separate 

 samples reanalyzed for cotinine. The mean values for nicotine were 31.1 ng/ml for 

 the onginal analyses and 31.5 ng/ml for duplicate analyses. The mean difference of 

 0.4 ng/ml had a SEM of 0.2 ng'ml. The corresponding values for cotinine were 244.7 



