Determination of nicotine in tobacco leaves in northern Thailand by spectrophotometry
1984
Nivate Udomratana
Two methods were employed for determining nicotine in 20 tobacco leaf samples in Northern Thailand, namely, ultraviolet spectrophotometry and titrimetry. For both techniques, nicotine in the tobacco leaves was extracted by steam distillation prior to analysis. The optimal conditions for extracting the samples were as follows: the extractant consisted of 5 cm3 of 30 percent sodium hydroxide saturated with sodium chloride while the minimum time to complete distillation was found to be within 20 minutes. The ultraviolet spectrophotometric technique involved the measurement at wavelength max = 259 nm of the nicotine dichlorate formed in the reaction between nicotine in the distillate and dilute hydrochloric acid. The nicotine contents in the samples were 0.19-1.55 percent w/w. The relative standard deviation and the percentage recovery were 7.34 percent and 92.20 percent respectively. A comparison was also made by determining nicotine titrimetrically based on the reaction of the base in the distillate with standard hydrochloric acid (0.0200 mole/dm3) in the presence of methyl red indicator. It was found that the nicotine contents were 0.27-1.73 percent w/w, a value greater than that obtained by the spectrophotometric method. This was probably due to alkaloid bases other than nicotine which might be present in the sample. The relative standard deviation and the percentage recovery were 3.61 percent and 94.63 percent respectively
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