Hi all,
I am planning a research project for next summer that investigates the effects of high temperature exposure for different lengths of time on the percent nicotine concentration in tobacco leaves. The setup is as follows:
Tobacco growing conditions
3 experimental groups of 10 or more will be grown in a chamber with a peak daytime temperature of 35oC and a minimum nighttime temperature of 26oC.
- group 1: 3 days exposure to heat
- group 2: 5 days exposure to heat
- group 3: 7 days exposure to heat.
3 control groups of 10 or more plants will be grown in a chamber with a peak daytime temperature of 30oC and a minimum nighttime temperature of 21oC.
- group 1: remove after 3 days
- group 2 remove after 5 days
- group 3 remove after 7 days
When the plants are removed from the temperature controlled growth chamber, I will dry the leaves in a 40 c oven until they are dry enough to powder. I plan to extract nicotine from leaf powder with methanol in an ultrasonic bath. Once I filter the resulting solution to remove particulate matter, I need to find percent nicotine. My school has a Hewlett-Packard GC-MS (NSF 9851032) with an autosampler. I am an undergrad with more background in bio than chem, and I am unfamiliar with gc-ms. Could I use this equipment to quantify nicotine in the leaves, or does this equipment only work for identification? If I can use this equipment for quantification, what general procedures should I follow? Any additional advice on methods would be much appreciated as well.
Amelia,
You'll probably find info about GCMS analysis of nicotine here:
Article Development and validation of a GC–MS method for nicotine de...
There are also a dozen of studies on such a analysis on Google Scholar.
Yes you can use it, however you need a proper sample preparation.
You can think about liquid extraction - like LLE or DLLME (check my papers on many groups of analytes) or "gas extraction" - like static or dynamic headspace (also check my papers).
best regards,
GB
Use a nicotine (alkaloid) selective, or a general extraction procedure, concentrate your extracts, weigh them all carefully, prepare a sample of known concentration (mg/ml) for injection, serially dilute to required levels of concentration (check GC-MS analysis of nicotine procedure, sample pre and injected micro litre sample quantity), the weight of the extract in the injectable volume is a must here! Run your sample, if need be use spiking techniques, record GC and (GC-MS comes later, MS another confirmation for Nicotine, but just don't rely on this info only, compare and see in known nicotine spiking to the injected sample!), identify the nicotine peak from the known column, concentration, and RI (not the RT- Retention Time) values, so the spiking for nicotine confirmation is necessary. Get total peak are, nicotine peak are, calculate the peak % for the nicotine, and correlate with your sample quantities. Repeat for all extracts, and get to know your concentration of the nicotine in the sample - each extract! Precaution: record all weight, volumes, procedure in stepwise manner, including GC-Conditions!
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