Abstract
Nicotine, a typical environmental pollutant, is released in large quantities along with other alkaloids during tobacco cultivation. However, there is limited research regarding the quantity, distribution, and environmental impact of these alkaloids in tobacco-planted soils. To elucidate the distribution of tobacco alkaloids in the soil environment, this study developed a rapid, accurate, and efficient analytical method for 10 alkaloids, which was subsequently applied to analyze soil samples from tobacco plantations and assess the associated risks. The method demonstrated satisfactory results in terms of extraction rate (92.0–102.6 %), recovery (85.6–111.0 %), matrix effect ( 10.4–12.8 %), limits of detection (LOD, 0.01–0.10 ng/g), limits of quantification (LOQ, 0.03–0.30 ng/g), intra-day repeatability (1.62–5.48 %), and inter-day repeatability (1.68–5.25 %). Moreover, the r values of the regression equations were greater than 0.9996. A total of 29 tobacco-planted soil samples from 12 townships in Kunming (Yunnan Province, China) were analyzed. The results showed that 10 alkaloids were present in the tobacco field, with nicotine identified as the most abundant compound, accounting for an average of 65.4 % of the total concentration. Risk quotients (RQs) were employed to evaluate the potential ecological risks of six alkaloids in the tobacco-planted soil. The result revealed that nicotine exhibited the highest RQ value, ranging from 653.58 to 17,760.12, suggesting that nicotine may be a potential risk factor for soil organisms. Furthermore, the presence of nornicotine, nicotyrine, and 2,3′-bipyridin in the soil also posed potential risks.
Notably, our study is the first to detect the residues of plant alkaloids other than nicotine in the soil. Overall, the results obtained confirm that our method is relatively rapid, accurate, and highly sensitive, which provides robust support for the study of alkaloid residues in subsequent crops and soil. These results also contribute to understanding the absorption, distribution, and risk assessment of alkaloids, which can be further developed in
future research.
