8l, gas chromatography (gc)...2019/06/08 · 2.5 cm 60 sec 1 min quethe • khlyl iii.is little)...
TRANSCRIPT
-
8L, Gas Chromatography (GC)
L3-1
CHEM 8L, Lecture 3 Experiment 2, Day 2 – Gas Chromatography (GC) Analysis of Citrus Oil
Last time… Exp 2, Day 2 - Steam distillation (AKA Co-Distillation) of Terpenes (Citrus Oil) *Green (Environmentally-Friendly)*
- Water-based extraction of terpenes - Minimized waste (you eat the oranges, we compost the peels) - Alternative to solvent-based extraction (toxic, wasteful; more on that in Exp 3)
Citrus Oil Analysis Week 1 - Percent Recovery: (mass of oil) / (mass of peels) x 100% = very low!! Typical recovery of 0.5 – 3 g, 1-10% recovery or less Week 2 - Terpene Identification and Percent Composition by GC CHROMATOGRAPHY - family of techniques for separating components from a mixture based on distribution between a mobile & stationary phase
Stationary Phase (S) Mobile Phase (M)
Metric Sample Mixture Separated by…
Selectively binds to components in
sample Selectively pushes sample along (S)
Gas, GC (Exp 2) Liquid
Gas
Retention Time (tR)
Boiling Point ↓bp, faster (smaller) tR
Thin-Layer, TLC
(Exp 3) Solid
Liquid
Retention Factor (Rf)
Polarity ↓polar, higher Rf Column
(8M, Exp 1)
How does GC help you understand citrus oil? 1. Analyze known standard terpenes - How long does each terpene spend on the column? Retention Time (tR)
Ex. limonene has specific tR on specific instrument, no matter whether it’s pure limonene or mixture containing limonene, based on boiling point
2. Terpene components of citrus oil separate in heated GC column 3. What’s in your oil?
- Compare tR of peaks in oil to tR of standards 4. Quantitative Analysis of Your Citrus Oil - Calculate the area under each peak - Relative Percent Composition: xx% α-pinene, xx% β-pinene, xx% limonene
-
8L, Gas Chromatography (GC)
L3-2
Inner Workings of Gas Chromatograph
B has ↓ bp, moves faster, ↓ tR A has ↑ bp, moves slower, ↑ tR
-
8L, Gas Chromatography (GC)
L3-3
Chromatograph Analysis Corrected Retention Time (tR’) for Peak Identification
Peak Integration and Percent Composition
Integration: Peak Area = h x wh/2
% Composition of A = Area of component A Total area of all components
air
solvent
sample
injection baseline
distance from air to sample
(cm)
8L, Gas Chromatography (GC)
L3-3
Chromatograph Analysis 1. Corrected Retention Time (tR’) for Peak Identification
2. Peak Integration for Sample Composition
Integration: Peak Area = h x wh/2 % Composition of A = Area of component A Total area of all components
Next week in lab: Exp 2, Day 2 ** Coordinate with partner – bring freshly prepared citrus peels ** Due at the door:
- Exp 2, Day 1 pre-lab questions & notebook pages - Exp 1 report – cover page (last pg of Exp 1 PDF), typed responses to post-lab
questions, carbon copies of notebook pages
air
solvent
sample
injection baseline
distance from air to sample
(cm)
tR' (sec) =
distance from air to sample
(cm) x
chart speed1 min
2.5 cmx
60 sec
1 min
•
thequeylKhliii.is
( too little ) In
c. :µWL
Ii
:¥¥knIe
•
8L, Gas Chromatography (GC)
L3-3
Chromatograph Analysis 1. Corrected Retention Time (tR’) for Peak Identification
2. Peak Integration for Sample Composition
Integration: Peak Area = h x wh/2 % Composition of A = Area of component A Total area of all components
Next week in lab: Exp 2, Day 2 ** Coordinate with partner – bring freshly prepared citrus peels ** Due at the door:
- Exp 2, Day 1 pre-lab questions & notebook pages - Exp 1 report – cover page (last pg of Exp 1 PDF), typed responses to post-lab
questions, carbon copies of notebook pages
air
solvent
sample
injection baseline
distance from air to sample
(cm)
tR' (sec) =
distance from air to sample
(cm) x
chart speed1 min
2.5 cmx
60 sec
1 min
•
thequeylKhliii.is
( too little ) In
c. :µWL
Ii
:¥¥knIe
•
tR' (sec) =
distance from air to sample
(cm) x
chart speed1 min
2.5 cmx
60 sec
1 min
8L, Gas Chromatography (GC)
L3-3
Chromatograph Analysis 1. Corrected Retention Time (tR’) for Peak Identification
2. Peak Integration for Sample Composition
Integration: Peak Area = h x wh/2 % Composition of A = Area of component A Total area of all components
Next week in lab: Exp 2, Day 2 ** Coordinate with partner – bring freshly prepared citrus peels ** Due at the door:
- Exp 2, Day 1 pre-lab questions & notebook pages - Exp 1 report – cover page (last pg of Exp 1 PDF), typed responses to post-lab
questions, carbon copies of notebook pages
air
solvent
sample
injection baseline
distance from air to sample
(cm)
tR' (sec) =
distance from air to sample
(cm) x
chart speed1 min
2.5 cmx
60 sec
1 min
•
thequeylKhliii.is
( too little ) In
c. :µWL
Ii
:¥¥knIe
•
-
8L, Gas Chromatography (GC)
L3-4
3rd Lab Meeting: Exp 2, Day 1 ** Coordinate with partner – bring freshly prepared citrus peels ** Due at the door:
- Exp 2, Day 1 pre-lab questions & notebook pages - Exp 1 report – cover page (last pg of Exp 1 PDF), typed responses to post-lab
questions, carbon copies of notebook pages
Biosynthesis of Terpenes and Cannabinoids
High Performance Liquid Chromatography (HPLC): Quality Control (QC) in Cannabis Industry
OP2O73-
Isopentyl diphosphate(IPP)
2 x
α-Pinene155 oC
β-Pinene165 oC
Limonene175 oC
γ-Terpinene183 oC
PP i
CO2HOH
O
H
H
CO2OH
O
H
H
Tetrahydrocannabinolic acid (THCA, decarb 120 oC)
Tetrahydrocannabinol (THC Δ-9), bp 155 oC
Decarboxylation (decarb)
PP i
OH
HO
CO2H
Olivetolic Acid
OH
HO
CO2H
Cannabigerolic Acid(CBGA)
Plants, esp. citrus
Cannabis
MONOTERPENESCollect via steam distillation
OP2O73-
Geranyl diphosphate (GPP)
HO
HOH H
CBDA, decarb 130 oC
OH
O
CBNA, decarb 140 oC
CO2H
CO2H
CANNABINOIDSCollect via CO2, EtOH, or butane extraction