The Heat of. Vaporization of Nicotine from Tobacco

Transcription

1 The Heat of Vaporization of Nicotine from Tobacco Kelley St.Charles 1, Serban Moldoveanu 2 1) Consultant to R.J. Reynolds Tobacco Company 2) R.J. Reynolds Tobacco Company, Winston-Salem, NC 1

2 Introduction Follow up to 2014 TSRC Paper* Nicotine vapor pressure at 23 ºC measured Pure nicotine and multiple tobacco types Vapor pressure since measured at higher temperatures *K. St.Charles & S. Moldoveanu, Nicotine activity in tobacco. Paper # 40. 2

3 Introduction Clausius-Clapeyron Equation ln(p) = - ΔHvap /RT + C P = Vapor Pressure (any pressure units) ΔHvap = Heat of vaporization* (J/mol) R = Gas Constant (8.314 J/K/mol) T = Absolute Temperature (K) C = Unitless constant * Enthalpy of Vaporization or Sublimation 3

4 Experimental 4

5 Rearranged Clausius-Clapeyron Eqn. ln(p) = (-ΔHvap/R) * 1/T + C Vapor P measured at 23, 30, 40 ºC Linear regression of ln(p) versus 1/T Slope = -ΔHvap/R ΔHvap = - Slope * R 5

6 Experimental summary Details in 2014 presentation Used pure nicotine and multiple tobacco types Samples stored in Al-foil lined gas bags with septum Diaphragm pump to sample 2 L headspace (HS) from tobacco 10 ml gas-tight syringe to sample pure nicotine HS HS sampled through XAD-4 cartridge similar to ETS nicotine Pure nicotine HS also sampled directly in syringe containing extraction solution 6

7 Experimental summary (cont.) Analysis by GC/MS/MS Ethyl acetate solvent with 5000 ppm triethylamine Deuterated nicotine (methyl -d3) internal standard MRM Nicotine m/z & m/z +3 for internal standard 30 minute run time Calibration from ng/ml nicotine Signal to noise = 8.3 ng/ml 7

8 Foil-lined gas bag modified 1/8 stainless steel Swagelok union replaced Restek polypropylene septum holder Bulkhead union nut inside bag PTFE lined septum replaced back ferrule outside bag Outer changed to Sorbent Systems bag 5 mil (127 µm) thick, 4-layer film: PET/PE/Al foil/pe ~20 x 25 cm (nicotine HS) & 40 x 50 cm (tobacco HS) Heavy-duty Al foil (~23.5 µm) inner liner Added Al tape to reinforce foil at union penetration Edges double folded and reinforced with Al tape Tested heavier gauge foil with pure nicotine 8

9 Tobacco headspace sampling Needle ½ of size 6D Silicone Stopper 4.8 ID x 7.9 OD mm Tubing XAD-4 Cartridge 4.8 x 7.9 mm Tubing 9

10 Tobacco types Conditioned to water activity = 0.61 Used 50+ g per bag Bags filled with nitrogen 10

11 Results 11

12 Pure nicotine vapor pressure XAD-4 = 62% of in-syringe sampling 12

13 Pure nicotine results In-syringe comparison to published results Linear Regression of ln P vs 1/T R 2 = ΔHvap = 56.6 kj/mol A. Harlan & Hixon. Ind Eng Chem. 1928, 20(7): B. Walker et al. Chem Senses. 1990, 15(2): C. Norton et al. J Amer Chem Soc. 1940, 62: D. Boldridge & Kelly Eqn E. Johnson. 1990, Eqn F. Banyasz Eqn. 2. in: Analytical determination of nicotine and related compounds and their metabolites. p.153 Ref A = 64.4 kj/mol Ref D = 72.3 kj/mol Ref E = 82.4 kj/mol Ref F = 65.0 kj/mol 13

14 Nicotine vapor from tobacco *Activity = Vapor Pressure / Pure Nicotine Vapor Pressure 14

15 Nicotine vapor pressure Pure nicotine vapor pressure X > Burley X > Flue Cured X > Oriental Vapor P Burley 6 10 X > Flue Cured 4-5 X > Oriental Vapor P Cigarette blends Flue Cured Tobacco nicotine activity slightly with temperature (i.e. relative vapor pressure increases more than pure nicotine) 15

16 Nicotine activity in tobacco Un-protonated calculated using: 1. Tobacco % nicotine (DWB) 2. Tobacco extract ph 3. pka as f(temperature)* *Clayton et al. 2013, Anal. Methods, Polynomial Regression Y = X 5542 X 2 Intercept term not significant R 2 = Std. Error = 0.04% Activity 16

17 Heat of vaporization - ΔHvap No obvious trends with respect to: Tobacco origin, type, stalk position, or nicotine concentration Wide range of nicotine activities 17

18 Combined heat of vaporization Mean ΔHvap = 86.7 kj/mol, SD = 5.6 kj/mol 30 kj/mol more endothermic than pure nicotine ΔH for mono-protonated un-protonated nicotine reported as 34 A & 41 B kj/mol* Property of nicotine rather than tobacco type Supports 2-step vaporization process from tobacco 1. Dissociation of mono-protonated to un-protonated nicotine 2. Vaporization of un-protonated nicotine A. Banyasz.1999 in: Analytical determination of nicotine and related compounds and their metabolites. p.159 B. Clayton et al. 2013, Anal. Methods,

19 Conclusions Pure nicotine vapor P & ΔHvap similar to literature (foil lined gas bags + in-syringe extraction) Pure nicotine vapor P X greater than that from tobacco Nicotine activity of Burley > Flue Cured > Oriental Activity appears a function of un-protonated nicotine concentration and temperature Tobacco moisture can also influence nicotine activity (Observed but not quantified). 19

20 Conclusions ΔHvap from tobacco ΔHvap did not depend on tobacco origin, type, stalk position, nicotine concentration or activity ΔHvap depends on the nicotine properties rather than tobacco properties Mean ΔHvap = 86.7 kj/mol, RSD = 6.5% Supports 2-step vaporization process from tobacco 1. Dissociation of mono-protonated to un-protonated nicotine (~30 kj/mol) 2. Vaporization of un-protonated nicotine (~57 kj/mol) 20

21 Thanks to R.J. Reynolds Tobacco Company Research and Development You for listening Questions? 21