steam or classic distillation for proofing?
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Steam or classic distillation for proofing?
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Alex White [email protected] 800-722-7556 x129
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Vapor Pressure
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▸All liquids exist naturally in equilibrium w/ their vapor ▸Amount of vapor measured by pressure it exerts…thus “vapor
pressure” ▸ Increasing temp increases speed of molecules and gives more
molecules energy to become gas (vap press ↑)
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Boiling
▸When liquid heated to temp where vapor press = atm press (760 torr), liquid boils. ▸ If press = 1 atm, temp = “normal boiling pt”
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Retrieved from :https://www.bing.com/images/search?q=Boiling+Point&view=detailv2&qft=%
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Raoult’s Law
▸Psoln = (X) (Ppure) ▸X=1 (pure solvent) ▸X<1 for all solutions ▸Psoln < Psolvent
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Retrieved from: https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Raoultov_zakon.png/220px-Raoultov_zakon.png
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Vapor Pressure
Ptotal = PA + PB
PA = (XA) PA pure
PB = (XB) PB pure Each substance lowers the vapor pressure of the other (when pure).
The vapor above mixtures of liquids is more enriched in the more volatile component(s)
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▸Water = 3 torr ▸Ethanol = 50 torr
▸50% ethanol/water total vapor pressure = ? Ptotal = PA + PB
PA = (XA) PA pure
PB = (XB) PB pure
Ex: 50% ethanol/water @ room temp
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Ethanol = 25 torr Water = 1.5 torr total = 26.5 torr
%vap ethanol = Pvap /Ptotal
= 25 torr / 26.5 torr = 94 mol% ethanol (vapor)
answer
Ptotal = PA + PB PA = (XA) PA pure PB = (XB) PB pure
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Distillation = boiling + transporting + condensing
▸Distilling creates a liquid with a
greater purity ▸ Distillate enriched but not completely
pure ▸How would you get a distillate of
higher purity?
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http://www.chemhelper.com/images/pictures/simpledist.gif
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Sequential Simple Distillation (Batch)
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http://chemistry.about.com/od/chemistryglossary/g/Steam-Distillation-Definition.htm
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Fractional distillation
https://en.wikipedia.org/wiki/Fractional_distillation#/media/File:Fractional_distillation_lab_apparatus.svg
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Fractional still (column, continuous) vs simple still (pot)
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http://www.stillcooker.com/patent-still.php
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Steam Distillation
▸Typically used two immiscible liquids which are heat sensitive and may decompose before reaching bp ▸ Often used to extract essential oils
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Retrieved from: http://3.bp.blogspot.com/--7Npvyc_Es0/URI1Ll6pNHI/AAAAAAAAAIY/HfIJpYh9LB8/s1600/steam-distillation.jpeg
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methods
▸Apparent proof: solids ≤ 400 mg/100 ml
▸True Proof by Distillation: any sample
▸True Proof by Obscuration: spirits w/ 80-100 proof w/ solids ≤ 600 mg/100 ml ▸ ie apparent proof and solids by evaporation
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Other approved devices
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Retrieved from:http://www.ttb.gov/pdf/2014-7-21-device-approval-guidlines.pdf
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▸Must distill spirits with > 600 mg/100 ml dissolved solids ▸Recommend apparatus specified in AOAC 942.06
▸ Flask, column, condenser, Class A volumetric flask ▸Do not approve or disapprove distillation units ▸Distillation should take 30 min – 1 hr ▸Sample must be same temp before and after distillation ▸Condenser coolant stay below 25°C ▸ http://www.ttb.gov/spirits/proofing.shtml
TTB distillation guidelines
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distillation
1. Fill vol flask a bit beyond graduation mark 2. Equilibrate in water bath 3. Remove excess sample to grad mark 4. Place in distillation flask 5. Collect a bit less than grad mark 6. Equilibrate 7. Bring to volume with water (at temp)
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▸Only ethanol/water mixtures (about 40%) used ▸no influence from other components ▸concentration measurements made with TTB-approved density meter before and after distillation
Steam vs classic comparison
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Results
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
1 3 5 7 9 11 13 15 17 19 21 23 25
Steam Distillation: difference (%v/v)
-0.02
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
1 3 5 7 9 11 13 15 17 19 21 23 25
Classic Distillation: difference (%v/v)
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▸Steam Distillation ▸ Mean difference = 0.09 %v/v, Std Dev = 0.03
▸Classic Distillation
▸ Mean difference = 0.02 %v/v, Std Dev = 0.02
▸TTB Tolerances (27CFR 5.37): ▸ 0.25 %v/v (>600mg/100ml) ▸ 0.15 %v/v (<600mg/100ml)
Results
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▸Tested 154 distilled spirits ▸62 found non-complaint
▸48 non-compliant due to alcohol content (40 over)
TTB 2015 Alcoholic Beverage Sampling Program
From www.TTB.gov, “TTB Alcohol Beverage Sampling Program p1. http://www.ttb.gov/pdf/2015-03-08-fy2016-results.pdf
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Thank you for your attention !