Liquid samples were withdrawn periodically and analyzed.
Nicotine was quantified by HPLC (Hewlett-Packard, mod. 1100)
using a Diode Array detector (HP G1315A) with a Chromolith
Performance column (monolithic silica in rod form, RP-18e 100-
4.6 mm) as the stationary phase and a 92.5/7.5 (v/v) mixture of
acetonitrile and water as the mobile phase. The flow rate of the mobile
phase was 1 mL min−1 and a UV detector was used at a wavelength of
210 nm.