INTRODUCTION
Validating the concentration of nicotine in your DIY juice is by far one of the most important steps you should take before vaping anything you have concocted! A small miscalculation can leave you seriously hurt or dead (nicotine is horribly poisonous!).
That being said, titration is one of the most accessible and accurate methods for finding out whether you did your chemistry right. I recommend using a standard 0.12N (0.06M) solution of sulfuric acid that you can get as part of pool testing kits to keep your measurements relatively free of error. But if you have the equipment and now-how to make your own precisely concentrated acid solution, then go right ahead!
Titration of nicotine by hydrochloric acid can be used to determine the concentration of nicotine present in solution. Previous studies conducted by Hubert et al. use sodium hydroxide to neutralize the hydrochloride form of nicotine as shown in Figure 1. The resulting Henderson-Hasselbalch graph reveals a sharp drop in pH at the equivalence point between the di-protonated nicotine and NaOH with a pH rage of 5-6. That sharp drop in pH and the fact that it occurs at 1:1 equivalence with nicotine HCl and NaOH means we can use this to find the concentration of nicotine present.
In addition, Hubert et al. report the first and second apparent dissociation constants of nicotine as shown in Table 1.
MATERIALS
- bottle of 0.12N (0.06M) solution of sulfuric acid
- distilled water
- Indicator (I recommend Bromocresol purple, but phenol red which is pool indicator will work)
- 1ml polyethylene syringe
- clean glass container (around 50ml)
- 1ml of your DIY e-liquid
PROCEDURE
1. Prepare 0.06M solution of H2SO4(aq) or other strong acid.
2. Add 1ml of “E-Liquid” to 10ml of distilled H2O.
3. Add 2-3 drops of Bromocresol Purple (pH range = 5.2-6.8) to the solution and stir/shake. NOTE: you can use pool test indicator (Phenol red) with a harder end point to detect; bromocresol purple turns purple to yellow and is obvious, phenol red turns orange to yellow and is a bit harder to visually see.
4. Add 0.12N (0.06M) H2SO4(aq) using a 1mL syringe until solution turns from purple to yellow, which is the end point of the titration. MAKE SURE TO SHAKE AND STIR WITH A CLEAN ROD
5. Use equation: 19.46 x (Volume added) to determine concentration of nicotine in mg/ml.
CALCULATIONS
Ct x Vt x M=Ca
Va
Ca= unknown ([Nicotine])
M= 2 (molar equivalent): because it’s the di-protonated form we are evaluating! we need double the strong acid to get it to the proper pH.
Ct = 0.06M ([H2SO4(aq)] )
Va= 1mL (Volume of analyte)
Vt= Recorded value (Volume of titrant added)
2 x 0.06mol/L x 162.23g/mol(nic) x 1000mg/g x 1L/1000ml x Vt = [Nicotine](mg/ml)
(1mL)
= 19.46 x Vt
***THIS RIGHT HERE IS WHAT IT BOILS DOWN TO! TAKE THE VOLUME OF ACID YOU ADDED AND SIMPLY MULTIPLY IT BY 19.46 TO GET THE NICOTINE CONCENTRATION IN MG/ML***
Validating the concentration of nicotine in your DIY juice is by far one of the most important steps you should take before vaping anything you have concocted! A small miscalculation can leave you seriously hurt or dead (nicotine is horribly poisonous!).
That being said, titration is one of the most accessible and accurate methods for finding out whether you did your chemistry right. I recommend using a standard 0.12N (0.06M) solution of sulfuric acid that you can get as part of pool testing kits to keep your measurements relatively free of error. But if you have the equipment and now-how to make your own precisely concentrated acid solution, then go right ahead!
Titration of nicotine by hydrochloric acid can be used to determine the concentration of nicotine present in solution. Previous studies conducted by Hubert et al. use sodium hydroxide to neutralize the hydrochloride form of nicotine as shown in Figure 1. The resulting Henderson-Hasselbalch graph reveals a sharp drop in pH at the equivalence point between the di-protonated nicotine and NaOH with a pH rage of 5-6. That sharp drop in pH and the fact that it occurs at 1:1 equivalence with nicotine HCl and NaOH means we can use this to find the concentration of nicotine present.
In addition, Hubert et al. report the first and second apparent dissociation constants of nicotine as shown in Table 1.
MATERIALS
- bottle of 0.12N (0.06M) solution of sulfuric acid
- distilled water
- Indicator (I recommend Bromocresol purple, but phenol red which is pool indicator will work)
- 1ml polyethylene syringe
- clean glass container (around 50ml)
- 1ml of your DIY e-liquid
PROCEDURE
1. Prepare 0.06M solution of H2SO4(aq) or other strong acid.
2. Add 1ml of “E-Liquid” to 10ml of distilled H2O.
3. Add 2-3 drops of Bromocresol Purple (pH range = 5.2-6.8) to the solution and stir/shake. NOTE: you can use pool test indicator (Phenol red) with a harder end point to detect; bromocresol purple turns purple to yellow and is obvious, phenol red turns orange to yellow and is a bit harder to visually see.
4. Add 0.12N (0.06M) H2SO4(aq) using a 1mL syringe until solution turns from purple to yellow, which is the end point of the titration. MAKE SURE TO SHAKE AND STIR WITH A CLEAN ROD
5. Use equation: 19.46 x (Volume added) to determine concentration of nicotine in mg/ml.
CALCULATIONS
Ct x Vt x M=Ca
Va
Ca= unknown ([Nicotine])
M= 2 (molar equivalent): because it’s the di-protonated form we are evaluating! we need double the strong acid to get it to the proper pH.
Ct = 0.06M ([H2SO4(aq)] )
Va= 1mL (Volume of analyte)
Vt= Recorded value (Volume of titrant added)
2 x 0.06mol/L x 162.23g/mol(nic) x 1000mg/g x 1L/1000ml x Vt = [Nicotine](mg/ml)
(1mL)
= 19.46 x Vt
***THIS RIGHT HERE IS WHAT IT BOILS DOWN TO! TAKE THE VOLUME OF ACID YOU ADDED AND SIMPLY MULTIPLY IT BY 19.46 TO GET THE NICOTINE CONCENTRATION IN MG/ML***
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