Table 2.

Values of α_fb by h-SPME for Selected Commercial E-Liquids at ~20 °C along with pH_1:10 and the Corresponding Inferred α_fb,w,1:10 Values for 1:10 Dilution with CO₂-Free Water at ~20 °C^a

		e-liquid by h-SPME
			ammonia as a base				1:10 water dilution
brand, flavorb	nicotine label concn clabel (mg/mL)	${\alpha }_{\text{fb}}^{\text{est}.}$	vammonia (mL)	αfb (mean ± 1s) (final)	CV (%)c	m (final)	pHw,1:10d	α fb,w,1:10 d,e
Sour Vape, “Atomic Apple”	6	0.007	3	0.003 ± 0.00	26	3.4	3.37	0.000
OKAMI, “Bubble Gang, Sour Menace Green Sour Apple”	6	0.006	3	0.012f	NAf	3.4	3.55	0.000
Artist Collection, “Hedon’s Bite”	12	0.03	2 × 3	0.032 ± 0.00	6.8	3.5	4.90	0.001
OMG, “WTF Ice”	3	0.072	3	0.11 ± 0.01	10	7.6	4.76	0.001
Cloud Nurdz, “Watermelon Apple”	3	0.13	3	0.27 ± 0.01	2.6	9.3	7.34	0.16
Bombies, “Tiger Style”	3	0.47	3	0.40 ± 0.03	6.8	11	7.62	0.26
The Milkman, “Churrios”	6	0.31	3	0.40 ± 0.03	8.6	5.6	6.48	0.03
ANML, “Carnage”	6	0.34	3	0.51 ± 0.01	1.8	6.9	7.79	0.34
Glas, “Pound Cake”	6	0.47	3	0.51 ± 0.01	2.8	6.9	6.96	0.07
NicQuid, “Midnight Express”	6	0.48	3	0.59 ± 0.03	5.6	8.3	8.12	0.53
The Standard, “Cell Block Four”	6	0.50	3	0.59 ± 0.05	8.9	8.3	7.68	0.29
Beard Vape, “No. 5”	18	0.42	2 × 3 + 2	0.69 ± 0.02	2.9	9.8	7.86	0.38
Charlie Noble, “Charlie’s Custard”	12	0.76	2 × 3	0.69 ± 0.01	1.2	11	7.67	0.28
Sengoku, “Kendo Man”	6	0.95	3	0.77 ± 0.02	2.6	14	8.66	0.80
Nerdz, “Premium Blend”	6	0.66	3	0.83 ± 0.02	1.9	20	8.56	0.76
Teleos, “Delta Cloud Science”	6	0.90	3	0.84 ± 0.05	5.7	21	8.85	0.86
The Mad Alchemist, Twice in a Blue Moon”	12	0.85	2 × 3	0.93 ± 0.01	0.8	50	8.70	0.81
Caesar, “Seduce Juice”	18	0.90	2 × 3 + 2	1.03 ± 0.03	3.3	>100	NA	NA
		e-liquid by h-SPME
			triethylamine as a base				1:10 water dilution
brand, flavorb	nicotine label concn clabel (mg/mL)	${\alpha }_{\text{fb}}^{\text{est}.}$	vPOLB (μL)	αfb (mean ± 1s) (final)	CV (%)c	m (final)	pHw,1:10d	α fb,w,1:10 d,e
Cloud Nurdz, “Watermelon Apple”	3	0.21	12	0.26 ± 0.04	17.0	6.3	7.34	0.16

^aNumber of replicates N = 3 except as noted.

^bFrom the product label.

^cCV = coefficient of variation.

^dAssumes calibration with aqueous buffers is sufficiently accurate.

^eAssumes pK_a = 8.07 at ~20 °C for NicH⁺ and that α_fb,1:10 = 10^−pK_a/(10^−pK_a + 10^−pH), which neglects NicH₂²⁺.

^fNumber of replicates N only 2: standard deviation and CV not available (NA).