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Meeting the Requirements of ASTM D 6591-06 ( IP548/06 ) with Agilent 1200 LC Systems
M.Woodman, Chemical Analysis Solutions Unit, Wilmington, Delaware, USA
M.Sierocinska, European Field Support Centre, Waldbronn, Germany
EN12916/IP391 Update
September, 2009
Agenda
• What is the source and application for ASTM D 6591-06 (and IP548/06)?
• Description of Recent ASTM D 6591-06 Method Updates • New D 6591-06 / IP548/06 Method Requirements • Alternate methods for biodiesel blends • Recommendations for the best configuration • Results from locally collected diesel samples • Summary
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Usage and Source of ASTM/IP/EN methods used
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ASTM D 6591-06 and IP548/06 measure aromatic hydrocarbon groups in petroleum distillates having specified boiling point ranges of 150-400oC. These methods are mainly applied to fuel analysis, particularly diesel motor fuel. Kerosene based fuels for aviation are covered by another related method
ASTM (www.astm.org) is the source of ASTM methods. The Energy Institute (www.energyinst.org.uk) is the source of the IP (sometimes referenced as EI) methods
IP (or EI) and EN methods (European Committee for Standardization http://www.cen.eu/cen/pages/default.aspx ) often have parallel ASTM methods
The method revision designation is very important
Related IP, EN and ASTM Methods
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IP Method and Revision
Method Overview
Special Parameters
ASTM Method?
Comments
IP391/07 150-400oC diesel fuel petro/bio blends up to B-5
no backflush
amino and/or cyano column
no equivalent available at this time
same as method EN12916:2006
MAH, DAH, Tri+AH reported
IP548/06 150-400oC diesel fuel
backflush required
amino and/or cyano column
D-6591-06 MAH, DAH, Tri+AH reported
FAME interferes with result
IP436/01 50-300oC
aviation fuel, kerosene
no backflush
amino and/or cyano column
D-6379-04 MAH and DAH reported
not for samples with Tri+AH
General Conditions and Schematic of ASTM D 6591
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Mobile phase: n-heptane at 1ml/min flow rate
Column: Amino-propyl and/or Amino-Cyano-propyl bonded phases. Amino-propyl 4.6x250mm 5um is commonly used
Column Temperature: approx. 20-25oC
Detection: Refractive Index
Special Feature: 6 port valve for backflushing the column to elute tri+ aromatics as a single peak
General Schematic of ASTM D 6591-06
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Figure 1, Agilent publication 5965-9044E
Recent HGA Method Updates: ASTM D6591-06
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• Terms redefined • more specific description of polyaromatics adopted
• Designate a new IP method correlation • IP391-95 (used with ASTM D 6591-00) replaced by IP548/06
• Exclusion or warning regarding Bio/Petrodiesel Blends • the method recognizes difficulties with biodiesel fuel blends and
refers the analyst to IP391/07 (EN12916:2006) for samples containing biodiesel (FAME) components
• due to inclusion of FAME components in the tri+AH backflush peak, erroneously high tri+ aromatic results are reported if D6591-06 is used with biodiesel blends
• unusually high tri+AH results with this method should be investigated to determine if unsuspected FAME is present due to fuel contamination or mislabeling
General Conditions and Schematic of D 6591-06
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ASTM D 6591-06 System Performance Std., Agilent p/n 5190-0483
Mobile phase: n-heptane at 1ml/min flow rate
Column: ZORBAX NH2 4.6x250mm, 5um
Column Temperature: 20oC
Detection: Refractive Index, 35oC
1. cyclohexane 2. o-xylene (dimethylbenzene) 3. dibenzothiophene 4. 9-methyl anthracene
1 2 3 4
System Performance Standard
General Conditions and Schematic of D 6591-06
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ASTM D 6591-06 Calibration Standard A-D, Agilent kit p/n 5190-0482
Mobile phase: n-heptane at 1ml/min flow rate
Column: ZORBAX NH2 4.6x250mm, 5um
Column Temperature: 20oC
Detection: Refractive Index, 35oC
1. cyclohexane 2. o-xylene (1,2-dimethylbenzene) 3. 1-methyl-naphthalene 4. phenanthrene with backflush at ~9 min.
1 2 3 4
Calibration Standards
Analysis of Petrodiesel, overlay of 3 injections
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1. saturates 2. mono-aromatics 3. di-aromatics 4. tri+ aromatics
t= <30 minutes
1 2 3 4
Ultra Low Sulfur Diesel (ULSD), retail pump
Analysis of Petrodiesel, overlay of 3 brands
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1. saturates 2. mono-aromatics 3. di-aromatics 4. tri+ aromatics
t= <30 minutes
1 2 3 4
Ultra Low Sulfur Diesel (ULSD), retail pumps a winter blend, old retained sample summer blends
ASTM D 6591-06 Separation Criteria
The official method clearly describes the appearance and statistical evaluation of method conditions for the new revision Resolution, selectivity, precision and calibration linearity are clearly stated In the following slides we review the performance of the Agilent approach to this method indicates that Agilent meets requirements .
ASTM D 6591-06 Criteria – Column Selection Column Descriptions: 4.6 x 250 mm, stainless steel column packed with 5um ZORBAX NH2 (p/n 880952-708)
. 6.4 Column System—Any stainless steel HPLC column(s) packed with an approved amino-bonded (or polar amino/cyano-bonded) silica stationary phase is suitable…
1. cyclohexane 2. o-xylene (1,2-dimethylbenzene) 3. dibenzothiophene 4. 9-methyl anthracene
1 2 3 4
SPS
1ml/min heptane 20C column temp. 35C RID temp. 20ul SPS no backflush
SPS Separation and Resolution Criteria
.
.
6.4 …provided it meets the resolution requirements laid down in 9.4.3. 9.4.1 Ensure that baseline separation is obtained between all components of the SPS. [without backflush] 9.6 Calculate the backflush time, B, in seconds, using the following equation: B = tA + 0.4(tB – tA)
1. cyclohexane 2. o-xylene (1,2-dimethylbenzene) 3. dibenzothiophene 4. 9-methyl anthracene
1 2 3 4
SPS 1ml/min heptane 20C column temp. 35C RID temp. 20ul SPS backflush 9.4 min.
.
Calculation of Resolution (Cyclohexane to 1,2 dimethylbenzene (o-xylene))
.
9.4.3 Ensure that the resolution between cyclohexane and 1,2 dimethylbenzene is not less than 5.
9.4.3.1 Column Resolution -- Calculate the resolution, R, between cyclohexane and 1,2 dimethylbenzene using the following equation. 2(t2-t1) (difference in retention time) R = ------------------------ 1.699(y1+y2) (averaging of peak widths)
Name R. Time width (hh) Rsln. 1. cyclohexane 3.307 0.059 2. 1,2-dimethylbenzene) 4.477 0.097 8.79
3. dibenzothiophene 8.907 0.186
4. 9-methyl anthracene 18.905 0.282
Linearity (section 9.4: R = >0.999, Intercept <0.01g/100ml) RID peak area vs. Std.Conc., o-xylene
y = 812489.767010x + 963.112364R2 = 0.999995
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Conc. (g/100 ml)
RID
Peak A
rea
Series1
Linear (Series1)
. …correlation coefficients all >0.999 (fits are nominally 1), linear fit of the calibration points Intercepts all =<0.005g/100ml
Reproducibility for Retention and Area, Cal. A-D Calibrant A
Analyte R.T. Avg., n=3 R.T. Stdev R.T.RSD% Area Avg., n=3 Area Stdev Area.RSD%
xylene 4.44 0.0005774 0.01% 3.29E+06 755.932096 0.02%
1-Me-naphthalene 5.96 0.001 0.02% 5.76E+06 2299.268 0.04%
phenanthrene 20.14 0.0020817 0.01% 7.12E+05 8351.82533 1.17%
Calibrant B
Analyte R.T. Avg., n=3 R.T. Stdev R.T.RSD% Area Avg., n=3 Area Stdev Area.RSD%
xylene 4.55 0.0020817 0.05% 8.33E+05 5263.96922 0.63%
1-Me-naphthalene 6.24 0.0041633 0.07% 1.46E+06 14197.7087 0.97%
phenanthrene 20.13 0.0023094 0.01% 3.55E+05 849.500049 0.24%
Calibrant C
Analyte R.T. Avg., n=3 R.T. Stdev R.T.RSD% Area Avg., n=3 Area Stdev Area.RSD%
xylene 4.63 0.0017321 0.04% 2.06E+05 536.395687 0.26%
1-Me-naphthalene 6.44 0.0036056 0.06% 3.66E+05 1830.77315 0.50%
phenanthrene 20.12 0.0040415 0.02% 8.87E+04 139.006199 0.16%
Calibrant D
Analyte R.T. Avg., n=3 R.T. Stdev R.T.RSD% Area Avg., n=3 Area Stdev Area.RSD%
xylene 4.67 0.0005774 0.01% 4.03E+04 214.794072 0.53%
1-Me-naphthalene 6.65 0.0020817 0.03% 2.96E+04 334.193512 1.13%
phenanthrene 20.10 0.0025166 0.01% 1.76E+04 176.541808 1.00%
Average RSD% All Runs 0.028% 0.555%
Recommendations for the best configuration
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• Agilent pump, minimum isocratic G1311A • Agilent sampler, minimum G1329A • Agilent thermostatted column compartment (TCC) with 6
port 2 position switching/backflush valve • Agilent RID G1362A • Agilent ChemStation B.04.02 or EZChrom software,
or third party compatible control/data software • Agilent ZORBAX NH2 4.6x250mm 5um column equilibrated
to heptane mobile phase • Agilent calibrants for system performance and calibration • HPLC grade n-heptane, 2-propanol
What to order, for consumables, ASTM D 6591-06
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ASTM D 6591-06 (IP548/06) System Performance Standard (SPS)
Agilent p/n 5190-0483
ASTM D 6591-06 (IP548/06) System Calibration Solutions A-D
Agilent p/n 5190-0482
Column(s):
ZORBAX NH2 4.6x250mm, 5um, Agilent p/n 880952-708
guard cartridge (pk/4) 4.6x12.5mm, 5um, Agilent p/n 820950-908
guard hardware (holder) kit, 4.6mm, Agilent p/n 820888-901
Normal phase pump seals, (pk/2), Agilent p/n 0905-1420
Mobile phase: n-heptane, HPLC grade, minimum 4 Liter or 2.5 Liter bottles, 2-propanol, HPLC grade, 1 Liter (installation, maintenance)
Performance with Selected Samples
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Samples were collected from retail and commercial diesel and biodiesel distribution centers around the Chicago area
One older sample was collected in the cold winter months, all others in recent warm summer months. Fuel blends vary seasonally in this area, with change occurring around early September and April
Sample preparation: Accurately weigh ~1g fuel and dilute to 10ml with
n-heptane. Mix thoroughly and inject 10ul. Calculations: Determine sample concentrations from calibration curves
using 1,2 dimethylbenzene for MAH, 1-methyl-naphthalene for DAH and phenanthrene for Tri+AH. Correct for sample weight and dilution variables.
Conditions: as described in previous slides
Analysis of Petrodiesel, overlay of 3 brands
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1. saturates 2. mono-aromatics 3. di-aromatics 4. tri+ aromatics
t= <30 minutes
1 2 3 4
Ultra Low Sulfur Diesel (ULSD), retail pumps a winter blend, old retained sample summer blends
Analysis of Petrodiesel, n=3, Vendor 1
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MAH DAH Tri+AH
Mobil
Vendor 1, Retail pump, summer
Group Avg., n=3 RSD% MAH 29.26 g/100ml 0.68% DAH 4.74 g/100ml 2.77%
Tri+AH 0.70 g/100ml 6.63%
Analysis of Petrodiesel, n=3 , Vendor 2
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Vendor 2, Retail pump, summer
Marathon
Group Avg., n=3 RSD% MAH 29.38 g/100ml 0.12% DAH 5.10 g/100ml 0.60%
Tri+AH 0.77 g/100ml 1.52%
MAH DAH Tri+AH
Analysis of BioPetrodiesel with ASTM D 6591-06
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Vendor 3, consumer retail pump, summer, dispensing pump labeled “diesel “
Citgo
Amount units Group 21.75 g/100ml MAH
4.12 g/100ml DAH 3.59 g/100ml Tri+AH
erroneous high Tri+AH due to FAME in sample
Analysis of BioPetrodiesel with ASTM D 6591-06
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Vendor 4, commercial biodiesel blend, dispensing pump labeled “diesel”
RR
Amount units Group 26.21 g/100ml MAH
5.12 g/100ml DAH 4.12 g/100ml Tri+AH
erroneous high Tri+AH due to FAME in sample
Analysis of Biodiesel B-11 with Method IP391/07
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RR
Vendor 4, ULSD-based biodiesel blend retail auto/light truck Results are n=3 by IP391/07 method approved for diesel and biodiesel blends
Group Avg., n=3 RSD%
MAH 24.74 g/100ml 5.06% DAH 5.15 g/100ml 3.38%
Tri+AH 0.72 g/100ml 4.58%
FAME resolved
Tri+AH region
ASTM D 6591-06 Observations
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The method retention time stability is very sensitive to column activity, as noted in the official method. This is typical for many normal phase separation methods
Moisture in solvents or samples is problematic and affects column activity
Variable retention is primarily due to moisture and temperature, though good system maintenance is essential
Use of normal phase seals in the pump is very important
Summary ASTM D 6591-06 Status
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Specialized all-Agilent column arrangement meets SPS resolution requirements for cyclohexane and 1,2-dimethylbenzene (o-xylene)
Adding the 6-port valve to the system configuration is required, however it is possible to easily switch between current IP391/07 (no backflush, for biodiesel blends) and ASTM D 6591 (with backflush, no FAME content)
References
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1. IP391/07 / EN12916:2006, Energy Institute, UK
2. Agilent application note 5965-9044E
3. ASTM Methods D6591-06, D6379-04
Appendix and supplemental slides
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…may be used depending on audience and need.
Acknowledgements
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Cynthia – guidance, resources and encouragement
Maggie – continued technical support and for persistence in keeping this development on the road map
Melanie/Georgia/Phil – standards packaging and work with the Ultra Scientific team
Andre – creating the opportunity and motivation
Ultra Scientific – too many to name, once again committed to a successful development with Agilent