Analysis and ChromatographicChromatographic
Separation of Oxygenates in yg
Hydrocarbon MatricesSimon JonesApplication EngineerFolsom, CAA t 20 2009August 20, 2009
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Agenda
WCOT vs. PLOT columns
OxyPlot A Unique stationary phaseOxyPlot – A Unique stationary phaseTrace oxygenates in reformulated gasoline
Capillary Flow Technology (CFT)Capillary Flow Technology (CFT)Heart cutting and back-flushing
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WCOT vs. PLOT
Type Stationary ChromatographicP
Stationary Type Phase Process Phases
WCOT Liquid orgum
Gas / Liquidpartition
PolysiloxanesPEG
PLOT Solid Gas solid Porous Polymers,So dadsorption
o ous o y e s,Al2O3,
Zeolites, etc.
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Film Thickness and Retention (WCOT): Isothermal
Thickness (µm) Retention Change0.10 0.400.25 1.001.0 4.003.0 12.05.0 20.0
Constant DiameterN li d t 0 25
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Normalized to 0.25 µm
Film Thickness and Resolution
Wh l t k 5 Rdf
When solute k < 5
or T(early eluters)
or T
RWhen solute k > 5 df
or T(later eluters)
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Capillary Column Types
P L O T b (PLOT)
Carrier Gas
Porous Layer Open Tube (PLOT)
Solid ParticlesCarrier Gas
W ll C t d O T b (WCOT)Wall Coated Open Tube (WCOT)
Liquid PhaseCarrier Gas
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PLOT Columns
"Solid"PorousPorousLayer
F d SiliFused Silica Tubing
Ideal for the anal sis of gases d e toIdeal for the analysis of gases due totheir increased retention (k) and uniqueselectivity (α) compared to WCOT
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selectivity (α) compared to WCOT
Selectivity Interactions in PLOT Phases
Shape / Size SurfaceZeolites Al2O3
Porous Polymers
Bonded Carbon Bonded SilicaMolecular Sieves
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Surface Interactions in PLOT Columns
+ + + + + + + + + + + + +
Gas Flow δ- δ- δ+δ+
neutral
+ + + + + + + + + + + + +
Vapor pressure always plays a leading role in solute interactions
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Vapor pressure always plays a leading role in solute interactions
Considerations for PLOT Column AnalysisColumn Analysis
• Inlet issues• split versus direct injection• gas sampling valves• low dead volume• column ID and flow rate
• Detector issues• particle generation or “spiking”; particle traps• column ID and flow rate
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Considerations for PLOT Column AnalysisColumn Analysis
• Column issues• selectivity• capacity; overloaded peaks• inertness• temperature limits• Elution order of major peak
• Column contamination • efficiency loss; “ghost peaks”; increase in bleed
water CO high molecular weight hydrocarbons?• water, CO2, high molecular weight hydrocarbons?• Carrier gas purifiers
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J&W / Agilent PLOT Columns
•GS-OxyPlot
GS Alumina
• HP-PLOT MoleSieve
• GS CarbonPLOT•GS-Alumina
• HP-PLOT Al2O3 “M”
• GS-CarbonPLOT
• HP-PLOT Q
• HP-PLOT Al2O3 “S”
• HP-PLOT Al2O3 “KCl
• HP-PLOT U
• GS-GasPro
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Application SummaryPetrochemical and Chemical companies have a need toPetrochemical and Chemical companies have a need to quantitatively measure low level oxygenates in petroleum products
Gas
Oil FieldsShipping Ctrs
Distribution CentersCrude Oil
Light HCsGasJet FuelDieselRefineries
Fuel Oil
Shipping Ctrs DieselFuel Oil
Diesel
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Application SummaryPetrochemical and Chemical companies have a need toPetrochemical and Chemical companies have a need to quantitatively measure low level oxygenates in petroleum products
G
Oil FieldsDistribution
C tCrude Oil
Light HCsGas
Gas
Fuel Oil FieldsShipping Ctrs
CentersOilJet FuelDieselFuel Oil
Refineries Oil
Diesel
The need to measure trace oxygenates from 10to 1000 ppm in Gasoline
• Problems with MTBE in reformulated gasoline• MTBE causing groundwater contamination• Desire to use ethanol as a renewable, green fuel additive
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Oxygenates in Gasoline and NaphthaWhy is this measurement neededy• Oxygenated additives in reformulated gasoline
– Needed for clean air regulations and petroleum fuel extenders• Problems with groundwater contamination
– Ethers in gasoline (MTBE, ETBE, TAME) in underground tanks– Greater toxicity than alcohol additives
– Move toward biofuels– Fuels derived from renewable agricultural products– Ethanol from fermentation of biomass– Lower toxicity than other alcohols
• Improve quality of feedstocks– Gasoline and naphtha used as feedstock for other HPI productsp p– Traces of oxygenates poison catalyst
• lower production yields• lower product quality
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lower product quality
Traditional Oxygenates Methods
ASTM D4815• Valve based using TCEP packed/ DB 1 capillary column• Valve based using TCEP packed/ DB-1 capillary column• Used to measure oxygenated additives (0.1 wt% to 15 wt%)• ASTM study shows that D4815 has interference problems
– TCEP column cannot separate trace oxygenates from trace olefins
ASTM D5599ASTM D5599• Single column method using oxygen selective detector (OFID)• Expensive system that is dedicated to only one application• Expensive system that is dedicated to only one application• Selectivity and sensitivity may not be good enough for low ppm
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New Method Under Development by ASTM D2Method ScopeMethod Scope
• Trace oxygenates in finished gasoline from 10 ppm to 1000 ppm (wt/wt)• Oxygenates include:
– methanol, n-propanol, i-propanol, n-butanol, s-butanol, t-butanol, s-butanol, t-pentanol
– MTBE, ETBE, DIPE, TAME– Ethanol additive from 1 to 15 wt%– Internal standard: 1,2-dimethoxyethane (DME)
Other capabilitiesOther capabilities
• can measure other oxygenate contaminants– ketones and other alcohols and ethers
• can be used for naphthas• sensitivity range can be lowered to 1 ppm with no changes in method conditions
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New Proposed ASTM Method Instrumentation ConfigurationConfiguration
• Uses valve switching 2-D GC
• DB-1 column separates oxygenates/light hydrocarbons from heavy hydrocarbons
• New Agilent GS-OxyPLOT column separates light g y p ghydrocarbons from oxygenates
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Proposed ASTM Methods Uses 2-D GC with Oxygenate Selective PLOT ColumnOxygenate Selective PLOT Column
FIDS/SLFlowSource
DB-1
Vent
OxyPLOT1
2
3
4
5
61. Sample introduction of gasoline onto DB-1 pre-column GS-
30m x 0.53mmid x 5um
AuxEPC
10m x 0.53mmidof gasoline onto DB-1 pre-column.
FIDS/SLFlowSource
DB-130m x 0.53mmid x 5um
Vent
OxyPLOT10m x 0.53mmid
1
2
3
4
5
6
2. Oxygenates and light hydrocarbons transfer to GS-OxyPlot. Heavy hydrocarbons remain on DB-1 pre-
lGS-
AuxEPC
Vent
column.
FIDS/SLFlowSource
DB-130m x 0.53mmid x 5um
OxyPLOT10m x 0.53mmid
1
2
3
4
5
6
3. Heavy hydrocarbons vented from DB-1 pre-column. Oxygenates resolved on GS-OxyPlot column.
GS-
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AuxEPC
What Is GS-OxyPLOT?A 10 0 53 I D 10 fil thi k P L O• A 10 m x 0.53 mm I.D., 10 µm film thickness, Porous Layer Open Tubular (PLOT) Capillary Column. New Agilent p/n 115-4912.
• The stationary phase is a “proprietary, salt deactivated adsorbent”.K h t i ti• Key characteristics are:– Strong selectivity to oxygenated hydrocarbons.– Methanol (BP 65 °C) elutes after Tetradecane (BP 254°C)
Solute MTBE Iso-Butylaldehyde
Methanol Acetone
RI* 1236 1368 1418 1450RI* 1236 1368 1418 1450
– Upper temperature limit 350°C with no column bleed
*150°C
pp p– Stabilized phase coating, minimizing particle generation and
detector spiking
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GS-Oxy-PLOT “Electronic” Selective Interactions
Distinct Advantages• Adsorption interactions are much stronger than the polar/non-polar
interactions in “liquid” stationary phasesinteractions in liquid stationary phases. – Oxygenated hydrocarbons, un-retained in a WCOT column even at
sub-ambient temperatures can exhibit high retention in a PLOT column at GC oven temperatures above ambientcolumn at GC oven temperatures above ambient
– Non-polar solutes are essentially un-retained except for their vapor pressure interaction at a given oven temperature.
– Ideal column for selective solute-value cut applications
• Column phase is surprisingly inert to the polar compounds it so stronglyColumn phase is surprisingly inert to the polar compounds it so strongly interacts with.– Good for low concentration, quantitative GC analysis
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OxyPlot Column Separation of Trace Oxygenates and Ethanol Additive in Reformulated Gasolineand Ethanol Additive in Reformulated Gasoline
Light HydrocarbonsEthanolEthanol
EthersMethanol
C3 to C5 Alcohols
5 10 15 20 25 min.
Methanol
BE
E nol
ETB
EM
TBD
IPE TA
ME
OH
Pro
pano
l
t,s,i-
But
a n
But
anol
-Pen
tano
l
E(IS
)
E D
MeO
i,n-P n-B t-
1,2-
DM
E
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min12.5 13.5 14.5 15.5 min22 23 24 25 26 27
Ethanol Influenced Retention Time Shifts
12 wt% ethanol
1 wt% ethanol
12 14 16 18 20 22 24 min.
ETBE12.498
MTBE12.660 DIPE
12.789
TAME13.755
MeOH15.463
12.753 13.852
min12 12 5 13 13 5 14 14 5 15 15 5
12.601 12.886 15.687
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min12 12.5 13 13.5 14 14.5 15 15.5
Excellent Quantitative Precision
Expected Avg Std Dev RSD(ppm)* (ppm)* (ppm)*
High Concentration QA/QC Check SampleExpected Avg Std Dev RSD
(ppm)* (ppm)* (ppm)*
Low Concentration QA/QC Check Sample
(pp ) (pp ) (pp )ETBE 780 758 1.3 0.2%MTBE 795 816 1.5 0.2%DIPE 795 758 1.1 0.2%TAME 779 779 1.4 0.2%
(pp ) (pp ) (pp )ETBE 49 48 0.7 1.4%MTBE 49 46 1.0 2.1%DIPE 49 93 0.7 0.8%TAME 48 48 0.3 0.6%
Methanol 802 759 1.6 0.2%Ethanol* 12.0% 11.3% 0.0 0.4%i,n-Propanol 1619 1566 14.7 0.9%t,s,i-Butanol 2399 2372 4.4 0.2%n-Butanol 798 791 1 7 0 2%
Methanol 50 67 0.6 0.8%Ethanol* 1.0% 0.9% 0.0 2.2%i,n-Propanol 101 95 1.3 1.4%t,s,i-Butanol 150 152 2.4 1.6%n-Butanol 50 47 0 8 1 6%
*ethanol results are in wt%
n-Butanol 798 791 1.7 0.2%t-Pentanol 801 766 0.6 0.1%
n-Butanol 50 47 0.8 1.6%t-Pentanol 50 47 0.2 0.5%
Each QA/QC sample prepared in reformulated gasolineEach QA/QC sample prepared in reformulated gasolineFive consecutive runs of each sample
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New Method Under Development by ASTM D2 for Analysis of Oxygenates in Ethene, Propene, C4Analysis of Oxygenates in Ethene, Propene, C4 and C5 Hydrocarbon Matrices
Method ScopeMethod Scope
•Oxygenates in these light hydrocarbon matrices from 500 ppb to 100 ppm (wt/wt)•Oxygenates include 25 alcohols, ketones, aldehydes and ethers (e.g.):
–methanol, ethanol, n-propanol, n-butanol, s-butanol, t-butanol, s-butanol–DME, MTBE, DIPE, TAME–Acetone, acetaldehyde Liquid
SampleGas
Sample
Similar in principle to Fused Silica
Restrictor
1 mL
2 µLp pthe oxygenates in gasoline method DB-1
25 m X 0.53mm I.D., 1.0 µm GS-OxyPLOT
10 m X 0.53mm I.D., 10 µm
2 µL
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Hydrocarbons and Oxygenates Separation Using DB-1 Stripper Column and GS-OxyPLOT Separation Column
Isooctane
Benzene
1. Dimethyl ether
2. Diethyl ether
3. Acetaldehyde
4. Ethyl t-butyl ether
13. Acetone14. Isovaleraldehyde15. Valeraldehyde16. MEK17 Ethanol
Column 1: DB1, 25 m x 0.53 mm x 1 um
P/N 125-102J
Column 2: GS-Oxy-PLOT, 10 m x 0.53 mmP/N 115-4912
Carrier gas: Helium, 40 cm/s @ 50°C
8 5. Methyl t-butyl ether
6. Diisopropyl ether
7. Propionaldehyde
8. Tert-amyl methyl ether
9 P l th
17. Ethanol18. 1-Propanol19. Isopropyl Alcohol20. Allyl Alcohol21. Isobutyl Alcohol
Carrier gas: Helium, 40 cm/s @ 50 CInjection volume: 1 uLInlet: Split, 250
• Temperature: 225 oC• Split Ratio: 10:1• Column flow: 11 mL/min
n-Octane
2
3
4
5 6
9
21,22,23
9. Propyl ether
10. Isobutylaldehyde
11. Butylaldehyde
12. Methanol
22. t-Butyl Alcohol23. s-Butyl Alcohol24. n-Butyl Alcohol25. 2-Methyl-2-pentanol
3
7
10
11
12
13
14
15
1819
2017Backflush occurs here
Oven
• Initial temp 50 oC• Initial hold 5 min• Ramp rate: 10 oC/min• Final temp 240 oC
1
11 13 15
16 24 25
Final temp 240 C
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SummaryA New Proposed ASTM Method for Trace Oxygenates inA New Proposed ASTM Method for Trace Oxygenates in Reformulated Gasoline• designed to measure 10 to 1000 ppm oxygenates in gasoline with 1 to 15
wt% ethanol additive
Agilent 7890A GC System with GS-OxyPlot Column meets method requirementsmethod requirements• excellent separation of oxygenates from light hydrocarbons• resolves all ethers (ETBE, MTBE, DIPE, and TAME)• high quantitative precision for both high and low concentrations in the
presence of percent ethanol
A New Proposed ASTM Method for Trace Oxygenates in LightA New Proposed ASTM Method for Trace Oxygenates in Light Hydrocarbon Matrices• designed to measure 500 ppb to 100 ppm oxygenates in matrices with
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g pp pp ygBPts less than 200°C
Old vs. New Switching Technology
Previous Slides depicted “Old-school” method of switching column flow
Newer method uses Capillary Flow Technology (CFT)No moving partsNo moving partsLow dead volumeLow thermal mass
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Challenges For Inside the Oven Devices
– Inertness (it is in the sample path)L d d l (i i i h i h)– Low dead volume (it is in the separation path)
– Leak free (especially with repeated temp cycling)– Fast thermal response (follow rapid oven ramping)– High temp tolerance (GC oven can go over 350C)– Reliable and easy to use
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Types of Connectors Used In The GC OvenLi it ti
Metal Packed columns, Not inert, no ferrule
Advantages Limitations
Fittings reliable for capillary columns
Press Fit Glass
Low dead volume, inert, low cost
Difficult to assemble, comes apart
Graphite High temperature Sheds active graphite particles into sample path
Polyimide Low initial leakage
path
Loosens and leaks with oven cycling,
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y gsolvent tailing
IF We Only Had A Technology That Provided Easy, Reliable Flow Structures In The GC Oven...Reliable Flow Structures In The GC Oven...It would open up many new (and old) capabilities for GC
– Column connections (connect pre-column)– Column connections (connect pre-column) – Change MSD columns (without venting) – Backflush (Reverse flow through column)– Detector splitter (effluent split to two or more detectors)– Merge flows (2 columns to 1 MSD)
Deans switch (heart cut select peaks to 2nd column)– Deans switch (heart cut select peaks to 2nd column)– Comprehensive 2-D GC (cut all peaks to 2nd column) – etc.
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5 Key Developments in Capillary Flow Technology
Easy to use, do not loosen or leak with oven cycling to 400°C
Metal Ferrules
Complex flow structures with low thermal massManifold Plates
Makes metal surfaces as inert as columnDeactivation of Metal
Backflushing now possible, change MSD columns without venting, known column outlet pressure
EPCpressure
Accurately predict flows and pressures BEFORE installing devicesCalculators
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BEFORE installing devices
Capillary Flow Technology- Design a proprietary Agilent Technology
• Photolithographic chemical milling for low dead volume
… a proprietary Agilent Technology
g p g
• Diffusion bond two halves to form a single flow plate
• Small, thin profile provides fast thermal response
• Projection welded connections for leak tight fittings
• Deactivation of all internal surfaces for inertness
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The Metal FerruleDoes not loosen (leak) even with thousands of runs to 350C
Seal region
Does not loosen (leak) even with thousands of runs to 350CDoes not shed particles
Square cut is
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not critical
Capillary Flow Technology
Column 1 In
Restrictor 1
out to vent
Restrictor 2
or Column 2out to vent
Nut
or Column 2
Ferrule
Channel
Plate
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Plate
Comparison of New Fitting with Polyimide Fitting
PolyimidePolyimide Fitting
Exposure to polyimide and unpurged annular spaces is greatly reduced
New Fitting
Ferrule Ejector Hole
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Ferrule Ejector Hole
Pentane test chromatogramFitting Design Minimizes Tailing
6
PolyimideFID direct
4
5
FID directCapillary Flow fitting
2
3
0
1
Capillary Flow Technology fittings avoid tailing with ll b t ll t d d l
1.1 1.15 1.2 1.25 1.3
0
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small but well swept dead volume
Capillary Flow Technology- Capabilities
Solvent Bypass
Heart Cutting (Deans Switch)
D S li i
Backflush
Detector Splitting
QuickSwapQuickSwap
Modulation (GCXGC)
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Modulation (GCXGC)
Dean SwitchHeartcutting 2-D GC provides extremely high
Cut
Heartcutting 2-D GC provides extremely high chromatographic resolution
Auto-sampler
Deans Switch
FID1 FID2
Switch
Column 1 Column 2
7890A GC
Column 1 Column 2
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2-D Separation of Sulfur Compound in Diesel FuelCompound is completely resolved and can be analyzed
Heart Cut to Column 2
Compound is completely resolved and can be analyzed with FID
Heart Cut to Column 2
Column 1 - FID 1
Diesel Fuel
Trace Sulfur Compound(4,6-DMDBT)
C l 2 FID 2Hydrocarbon
MatrixColumn 2 – FID 2 Matrix
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0 2 4 6 8 10 12 14 16 18 min.
QuickSwapChange MSD columns without ventingChange MSD columns without ventingBackflush heavy components out split vent
MSD TransferlineAuto-sampler
AUX EPC4 psig
171 mm X 0 121 mm id
Column
0.121 mm id restrictor
7890A GC
5975C InertMSD
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QuickSwap MSD Interface
Remove column w/o venting– Air & H2O blocked2
Safe disconnection of column from inlet for inlet maintenance
Column Effluent
– Reversed flow through column during inlet maintenance
BackflushingMSD TransferLiBackflushing
– Removes heavies from column
Maintain constant flow to MSD
Line
Maintain constant flow to MSD
Aux EPC In
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(flow rates exceeding 2 mL/min require an MSD with Performance Turbo)
Thank you!y
Questions?
Feel free to contact Agilent Application Support at:
1-800-227-9770 Option 3.3.1….or…..
via e-mail at:
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