Isotopically-labeled solvents and the use of same in testing e-cigarettes
Isotopically-labeled species of propylene glycol and glycerol are provided as solvents for use in electronic nicotine delivery systems (e.g., as disposed in a cartridge in an e-cigarette). The isotopically-labeled species are distinguishable from the non-isotopically-labeled species (e.g., by mass spectrometry). Thus, methods are provided for the measurement of the quantity of solvent or of a solvent heating by-product (e.g., formaldehyde, acetaldehyde), or of a metabolite of the drug, delivered to a user by analysis of blood samples taken subsequent to dosing by use of the electronic nicotine delivery system. An example of an isotopically-labeled species of propylene glycol for use in such measurement methods is [ 13 C] 3 H 8 O 2 . A clinical study of e-cigarettes loaded with this isotopically-labeled species resulted in the following blood plasma concentration profiles in “vaping” subjects.
1. A method of determining a quantity of a compound delivered to a user of an e-cigarette comprising:
providing a user with an e-cigarette including an e-cigarette cartridge loaded with a liquid that includes a predetermined quantity of an isotopically-labeled solvent that is propylene glycol of the form [ 13 C] 3 H 8 O 2 ;
dosing the user with said e-cigarette;
obtaining a bodily fluid sample from the user;
measuring the levels of unlabeled and isotopically-labeled species of propylene glycol in the bodily fluid sample; and,
determining the level of propylene glycol in the bodily fluid sample that was delivered by the e-cigarette based on the difference between measured levels of unlabeled and isotopically-labeled species of propylene glycol in the bodily fluid sample.
2. The method according to claim 1 , wherein said liquid further comprises nicotine.
3. The method according to claim 2 , wherein the concentration of said nicotine in said liquid is between about 1.4 and about 2.2 v/v %.
4. The method of claim 1 , wherein:
the bodily fluid sample is a blood sample;
the levels of unlabeled and isotopically-labeled species of propylene glycol in the blood plasma are measured; and
the level of propylene glycol in the blood plasma that was delivered by the e-cigarette is determined based on the difference between measured levels of unlabeled and isotopically-labeled species of propylene glycol in the blood plasma.
5. The method of claim 4 , wherein the levels of unlabeled and isotopically-labeled species of propylene glycol in the blood plasma are measured using mass spectrometry.
6. The method of claim 1 , wherein:
the bodily fluid sample is a saliva sample;
the levels of unlabeled and isotopically-labeled species of propylene glycol in the saliva sample are measured; and
the level of propylene glycol in the saliva sample that was delivered by the e-cigarette is determined based on the difference between measured levels of unlabeled and isotopically-labeled species of propylene glycol in the saliva sample.
7. The method of claim 6 , wherein the levels of unlabeled and isotopically-labeled species of propylene glycol in the saliva sample are measured using mass spectrometry.
8. The method of claim 1 , wherein:
the bodily fluid sample is a urine sample;
the levels of unlabeled and isotopically-labeled species of propylene glycol in the urine sample are measured; and
the level of propylene glycol in the urine sample that was delivered by the e-cigarette is determined based on the difference between measured levels of unlabeled and isotopically-labeled species of propylene glycol in the urine sample.
9. The method of claim 8 , wherein the levels of unlabeled and isotopically-labeled species of propylene glycol in the urine sample are measured using mass spectrometry.