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 attraction of mosquitoes to handled glass (c. 25%). Mr. Smith provides the highest 



attraction percentage on a consistent basis (c. 70%). Samples were analyzed in sets 



of two similar analyses, each involving beads handled by the two different subjects. 



In the morning session, five blank beads were analyzed prior to the arrival of the 



subjects. After arrival, 10-12 beads were handled by the first subject. A chosen 



number of beads, from 2-5 beads, were sampled immediately after handling. The 



number used remained consistent throughout the day. The remainder of the rubbed 



beads were placed in a 1/4" diameter tube at room temperature and open to ambient 



air. Fifteen minutes before the completion of the first analysis, the second subject 



handled 10-12 beads. Between 2 and 5 beads, consistent with the previous analysis, 



were sampled immediately; the remainder were stored in a second tube under the 



same conditions as previously described. TTie morning session involved either 



PPINCI or EI as the mode of ionization. The mode chosen to analyze at the 



beginning of the day was alternated for subsequent days. 



The TSQ70 was switched over to the complementary mode for the afternoon 



session; i.e. if PPINICI data was acquired in the morning session, EI data were 



acquired in the afternoon session. An analysis of 5 blank beads was performed prior 



to the return of the subjects. The subjects repeated the handling procedures. The 



beads were sampled and stored as described above for the morning session. After 



these sessions, the acquired data consisted of PPINICI and EI analyses from each 



subject. The analyses were repeated in the evening, with the same ionization mode 



used in the afternoon session, but with beads handled in the morning session. This 



