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
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 Page 2
Usage and Source of ASTM/IP/EN methods used ASTM D 6591-06 and IP548/06 measure aromatic hydrocarbon groups in petroleum distillates having specified boiling point ranges of 150-400 o C. 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 Page 3
Related IP, EN and ASTM Methods IP Method and Revision Method Overview Special Parameters ASTM Method? Comments IP391/07 150-400 o C 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 IP548/06 150-400 o C diesel fuel backflush required D-6591-06 MAH, DAH, Tri+AH reported amino and/or cyano column FAME interferes with result IP436/01 50-300 o C aviation fuel, kerosene no backflush amino and/or cyano column D-6379-04 MAH and DAH reported not for samples with Tri+AH Page 4
General Conditions and Schematic of ASTM D 6591 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. 20-25 o C Detection: Refractive Index Special Feature: 6 port valve for backflushing the column to elute tri+ aromatics as a single peak Page 5
General Schematic of ASTM D 6591-06 Figure 1, Agilent publication 5965-9044E Page 6
Recent HGA Method Updates: ASTM D6591-06 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 Page 7
General Conditions and Schematic of D 6591-06 System Performance Standard 1. cyclohexane 2. o-xylene (dimethylbenzene) 3. dibenzothiophene 4. 9-methyl anthracene 1 2 3 4 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: 20 o C Detection: Refractive Index, 35 o C Page 8
General Conditions and Schematic of D 6591-06 Calibration Standards 1. cyclohexane 2. o-xylene (1,2-dimethylbenzene) 3. 1-methyl-naphthalene 4. phenanthrene with backflush at ~9 min. 1 2 3 4 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: 20 o C Detection: Refractive Index, 35 o C Page 9
Analysis of Petrodiesel, overlay of 3 injections 1. saturates 2. mono-aromatics 3. di-aromatics 4. tri+ aromatics t= <30 minutes Ultra Low Sulfur Diesel (ULSD), retail pump 1 2 3 4 Page 10
Analysis of Petrodiesel, overlay of 3 brands 1. saturates 2. mono-aromatics 3. di-aromatics 4. tri+ aromatics t= <30 minutes Ultra Low Sulfur Diesel (ULSD), retail pumps a winter blend, old retained sample summer blends 1 2 3 4 Page 11
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) SPS 1. cyclohexane 2. o-xylene (1,2-dimethylbenzene) 3. dibenzothiophene 4. 9-methyl anthracene 1 2 3 4 1ml/min heptane 20C column temp. 35C RID temp. 20ul SPS no backflush. 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
SPS Separation and Resolution Criteria SPS 1. cyclohexane 2. o-xylene (1,2-dimethylbenzene) 3. dibenzothiophene 4. 9-methyl anthracene 1 2 3 4 1ml/min heptane 20C column temp. 35C RID temp. 20ul SPS backflush 9.4 min... 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)
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(t 2 -t 1 ) (difference in retention time) R = ------------------------ 1.699(y 1 +y 2 ) (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 3500000 3000000 y = 812489.767010x + 963.112364 R 2 = 0.999995 RID Peak Area 2500000 2000000 1500000 1000000 Series1 Linear (Series1) 500000 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Conc. (g/100 ml). 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 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 Page 18
What to order, for consumables, ASTM D 6591-06 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) Page 19
Performance with Selected Samples 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 Page 20
Analysis of Petrodiesel, overlay of 3 brands 1. saturates 2. mono-aromatics 3. di-aromatics 4. tri+ aromatics t= <30 minutes Ultra Low Sulfur Diesel (ULSD), retail pumps a winter blend, old retained sample summer blends 1 2 3 4 Page 21
Analysis of Petrodiesel, n=3, Vendor 1 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% Vendor 1, Retail pump, summer MAH DAH Tri+AH Mobil Page 22
Analysis of Petrodiesel, n=3, Vendor 2 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% Vendor 2, Retail pump, summer MAH DAH Tri+AH Marathon Page 23
Analysis of BioPetrodiesel with ASTM D 6591-06 Amount units Group 21.75 g/100ml MAH 4.12 g/100ml DAH 3.59 g/100ml Tri+AH Vendor 3, consumer retail pump, summer, dispensing pump labeled diesel erroneous high Tri+AH due to FAME in sample Citgo Page 24
Analysis of BioPetrodiesel with ASTM D 6591-06 Amount units Group 26.21 g/100ml MAH 5.12 g/100ml DAH 4.12 g/100ml Tri+AH Vendor 4, commercial biodiesel blend, dispensing pump labeled diesel erroneous high Tri+AH due to FAME in sample RR Page 25
Analysis of Biodiesel B-11 with Method IP391/07 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% Vendor 4, ULSD-based biodiesel blend retail auto/light truck Results are n=3 by IP391/07 method approved for diesel and biodiesel blends Tri+AH region FAME resolved RR Page 26
ASTM D 6591-06 Observations 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 Page 27
Summary ASTM D 6591-06 Status 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) Page 28
References 1. IP391/07 / EN12916:2006, Energy Institute, UK 2. Agilent application note 5965-9044E 3. ASTM Methods D6591-06, D6379-04 Page 29
Appendix and supplemental slides may be used depending on audience and need. Page 30
Acknowledgements 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 Page 31