An Analytical Perspective on Determination of Free Base Nicotine in E-Liquids

Table 1

Determination of free base nicotine in e-liquids by potentiometric titration (Henderson–Hasselbalch method).

e-Liquid flavor (80 mg/mL)	e-Liquid category	pH of 10x dilution in water	% free base nicotine by Henderson–Hasselbalch equation	Experimental % free base nicotine	% difference	Mean % difference	Std. dev.
Unflavored	PG : VG	10.22	99.12	100.00	0.88	0.52	0.33
		10.20	99.07	99.47	0.41
		10.15	98.97	99.21	0.25
Maui menthol	Menthol	9.48	95.31	94.42	0.93	0.67	0.37
		9.41	94.52	94.75	0.24
		9.15	90.46	91.21	0.83
Element tobacco	Tobacco	8.90	84.24	82.53	2.03	0.77	1.09
		8.84	82.39	82.31	0.09
		8.82	81.85	81.69	0.19
Motley brew	Fruit	8.89	83.96	81.61	2.80	1.97	1.08
		8.87	83.43	81.46	2.36
		8.84	82.39	81.76	0.76
Milkman milky cloud	Sweet	8.87	83.43	80.58	3.42	1.87	1.61
		8.72	78.01	77.85	0.21
		8.72	78.05	76.50	1.99
Hazelnut coffee	Coffee	9.63	96.68	95.38	1.34	0.90	0.38
		9.55	96.01	95.28	0.76
		9.54	95.89	95.30	0.61
					Avg.	1.12 ± 0.64