Suresh Ralapati, batf/National Laboratory Center

End Determination. UV absorbance measurements of nicotine are performed using a Shimadzu Model UV-2501 PC UV-VIS recording spectrophotometer equipped with a data system using UVPC Personal Spectroscopy Software v. 3.9 (Shimadzu Scientific Instruments, Inc., Columbia, MD, USA). The UV spectral data are measured in the spectrum acquire mode at a wavelength range of 200-300 nm. After nicotine is extracted from the tobacco product, aliquots of the distillate are diluted, if necessary, with 0.05 N HCl such that the absorbance at 259 nm is between 0.5-0.8. Furthermore, the absorbance values at wavelengths 236, 259 and 282 nm are also read for background correction purposes.


UV absorbance measurements of nicotine are also obtained at times for capillary electrophoresis calibration studies. For quantitative CE studies, nicotine calibration standard concentrations are calculated using the molar extinction coefficient of 3016.92 M^-1cm^-1 for nicotine in water at 260 nm (15).
Nicotine Reporting Requirements. Current ATF regulatory classifications are based on qualitative information. As such, declaration of the presence or absence of nicotine in a particular sample is the only reporting requirement with this method. However, quantitative determination of nicotine in tobacco is also possible with the method. If quantitative results are reported, the percent total alkaloids, expressed as nicotine, are reported for samples on a dry weight basis. The percent total alkaloids (as nicotine) is calculated after correcting the absorbance at 259 nm as follows:
A_{259 corr} = 1,059 [A₂₅₉ - ½ (A₂₃₆ + A₂₈₂)]
Gas Chromatographic (GC) Analysis of Nicotine. Gas chromatography is very amenable to the analysis of nicotine in ATF regulated tobacco products, especially since the technique was originally applied to the analysis of nicotine in commercial tobacco products. As with spectrophotometry described above, there are disadvantages associated with this technique as well. Despite the rapid analysis times, gas chromatography also suffers in that the extraction step employs organic solvents such as chloroform and hexane in relatively large volumes, is tedious, time consuming and not environmentally friendly. The main features of the gas chromatographic method can be described as follows:
Method Scope. Tobacco is extracted with organic solvent and nicotine is determined by capillary gas chromatography with a polar stationary phase.