代做CHEM 740 Assignment 3代做留学生SQL语言

日期：2024-10-14 05:34

CHEM 740 Assignment 3

1.          In 2020, some suppliers of nicotine-based cigarette alternatives in the US began using synthetic nicotine in their products, to circumvent regulations that controlled “any product made or derived from tobacco that is intended for human consumption” .  This loophole was closed by the US Congress as of 2022. During that time period, analytical chemists investigated methods for distinguishing between synthetic and tobacco-derived nicotine.  Other countries, such as China, have banned the use of synthetic nicotine in e-cigarettes.

a)          Explain how synthetic and tobacco-derived nicotine could be distinguished using stable isotope analyses. Your answer should include potential synthetic pathways and any challenges for the analysis. (6 marks)

b)          Explain how synthetic and tobacco-derived nicotine could be distinguished using accelerator mass spectrometry (AMS) as per ASTM standard D6866. Your answer should include consideration of potential synthetic pathways.  (6 marks)

2.          A recent authentication study of wintergreen essential oil reported that one of the samples (#17 in their paper) showed evidence of being adulterated with 14C-labelled synthetic methyl salicylate.

Explain how the authors identified that this was a synthetic sample, how they determined it had been adulterated with 14C labelled methyl salicylate, and explain why this particular adulteration might have been done.  (8 marks)

Useful references

Analysis and differentiation of tobacco-derived and synthetic nicotine products: addressing an urgent regulatory issue A. G. Cheetham, S. Plunkett, P. Campbell, J. Hilldrup, B. G. Coffa, S. Gilliland, S. Eckard, PloS ONE, 2022, 17(4) e0267049

Stable isotope characterisation of tobacco products: a determination of synthetic or natural nicotine authenticity, S. Han, L. Cui, H. Chen, Y. Fu, H. Hou, Q. Hu, Y. Yuan, Rapid Communications in Mass Spectrometry, 2022, 37, e9441

A systematic review of analytical methods for the separation of nicotine enantiomers and evaluation of nicotine sources, S. Salam, F. E-H. Moussa, R. El-Hage, A. El-Hellani, N. A. Saliba, Chemical Research in Toxicology, 2023, 36, 334-341

Authentication of the naturalness of wintergreen (Gaultheria genus) essential oils by gas chromatography, isotope mass spectrometry and radiocarbon assessment, A. Cuchet, P. Jame, A. Anchisi, F. Schiets, C. Oberlin, J-C. Lefevre, E. Carenini, H. Casabianca, Industrial Crops & Products, 2019, 142, 111873