HI all
I ask Kevin knight from (:http://www.cig-eliquid.co.uk) how long can you store nicotine and this what he says


Best way to store 52mg base liquid is in glass bottle with little or no head room
my larger bottles are fluorinated HDPE to prevent nicotine and PG from leaching plasticizers from them, but glass is a far better as HDPE oxygen transmission rate hdpe is poor

Keep it cool and away from light
Best color glass to use to stop the light damage is brown then blue then green 
Boots will sell you brown glass bottles with CRC if you ask at the dispensing counter.
How long will it keep for is a hard one, 
I see no reason if left unflavoured it should go off to the point you would not be able to use it
If stored unflavoured in dark glass bottles after some years it would be quite dark and would not taste as good as fresh but you would be able to use it ! unless it smelt rank
The strength will drop down a few mg from 52mg 
As no long term tests have been done this is just a guess and I would think that PG+ nicotine would store better than VG+ nicotine 
Regards Kev
Just found this by Kurt

Credit to: ECF
Author: Kurt (ECF Member)
As a professional chemist, I would recommend storing long term in glass. Nic in high concentration will slowly dissolve plastic, and PG will leach plasticizers from plastic. VG might too.
Sun’s fridge issues were with flavored juices stored six months, some of which were not even opened. I believe they were early Johnson Creek. The culprit was probably water in the JC recipe. I think decomp would have happened anyway, regardless. I do not think it was necessarily the fridge itself.
A sealed glass bottle of unflavored nic juice will not allow water in. The only reactant here is O2, which if there is little head room is negligible. O2 is very slightly soluble in PG or VG, and will be present in trace quantities in the solution no matter what you do, but it is not enough to make any appreciable change in 100 mg juice, even if it all reacts.
I use glass bottles from specialtybottles.com for storage of my unflavored 35-100 mg VG nic juice. The ones with eurodropper inserts, since I use them for syringe dispensing. Just stick an 18 gauge blunt needle through the center hole. With these inserts, accidental spill, which is a DISASTER with 100 mg juice, is eliminated. I use 50 mL bottles (although given how fast I go through them, I should have used 30 mL), fill them almost to the rim, put in the insert and screw on the cap.
I store them in the freezer. As long as they are brought to room temp before opening them, the liquid will not absorb much water from the air. I pull out one bottle at a time for juice making. I just pulled out a 100 mg VG bottle stored since January, and it has not even discolored compared to the original very slightly yellow, as in VERY slightly yellow. In my freezer, PG and VG do not freeze (I have some DV PG juice stored too), nor do they expand. VG becomes VERY thick, like rubber cement at the temp of my freezer. I have not tested for nic content, but the juices I make now are in my opinion no less potent than when I got the juice fresh.
Cool, dark, and dry is appropriate for a bottle opened and being actively used for DIY. Sealed is sealed, and extreme cold almost eliminates the kinetics of any O2 reactions and mold or bacteria growth, which is also almost eliminated by nic itself, PG or VG. I keep many 50 mL bottles in a sealed container in the freezer (actually a pet food container).
From what I know about these chemicals, I expect the juice to last certainly much much longer than 24 months, and probably many years.
This long term storage is for unflavored, and undiluted nic-juice only. I do not store flavored DIYs this way. I make them in relatively small quantities and vape them up before making more. Flavors are probably the most unstable part of e-juice, and the presence of water in them will hasten their decomposition into nasty tasting products. Fridge cold does not really change this a lot, it is dependent on the flavor itself. Fruits are especially prone, since they are esters that tend to hydrolyze to organic acids (sour, vinegar, vomit taste) and organic alcohols (wet-dog, funky taste).
Even unfrozen, liquid PG nic-juice in the freezer will still have slower reaction kinetics than room temperature liquid. Increased viscosity, such as VG nic-juice, will further lower kinetics of reactions of nic with O2: the molecules do not move around much to find each other. But all reactions slow down with cold regardless of viscosity changes. The fact that neither of these liquids freeze solid in the freezer is good. Solid is chrystalline, and is generally not the same composition as the liquid, in other words, freezing solid will promote separations…although after it melts to room temp, it can be mixed back to original uniform composition.
Is freezer storage overkill? Maybe. As I said, sealed is sealed, and the total reactions possible if its sealed are low. But I get a singular pleasure from taking one of those 50 mL bottles out, knowing it will be as fresh and potent as the day I bought it, even years down the line.
Based on my decades of chemical knowledge, I do honestly think this is the best option for long-term unflavored nic-juice storage.