A national laboratory of the U.S. Department of Energy

Office of Energy Efficiency & Renewable Energy

National Renewable Energy Laboratory 

Innovation for Our Energy Future 

2006 B100 Quality Survey Results 

Milestone Report 

T.L. Alleman, R.L. McCormick, and S. Deutch

Milestone Report 

NREL/TP-540-41549 

May 2007 

NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 
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Milestone Report 

NREL/TP-540-41549 

May 2007 

2006 B100 Quality Survey Results 

Milestone Report 

T.L. Alleman, R.L. McCormick, and S. Deutch 

Prepared under Task No. FC079400 
NOTICE

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Acknowledgments 

The authors thank the U.S. Department of Energy’s Office of FreedomCAR & Vehicle 

Technologies for funding support, Scott Fenwick at Archer Daniels Midland for conducting 

the methanol analysis, Tom Livingston of Robert Bosch for the Rancimat analysis, and Tom 

Carter at Eastman for oil stability index analysis. 

 i
Executive Summary 

In 2006, the National Renewable Energy Laboratory conducted a nationwide quality survey 

of pure biodiesel (B100) intended to be used as a blendstock. The study collected random 

samples throughout the United States and analyzed them for quality against the current and 

proposed ASTM D6751 fuel quality specifications. 

This report documents completion of the National Renewable Energy Laboratory’s Fiscal 

Year 2007 Annual Operating Plan Milestone 10.2. This milestone supports the U.S. 

Department of Energy, Fuels Technologies Program Multiyear Program Plan Goal of 

identifying fuels that can displace 5% of petroleum diesel by 2010. 

Samples were randomly collected from terminals throughout the Petroleum Area Defense 

Districts (PADDs), with a higher concentration of fuels collected in the Midwest, where 

biodiesel production is highest. The samples were sent to a subcontracted analytical 

laboratory for analysis. The same methodology was used to analyze all samples. 

Results of a telephone survey of the distributors revealed that most samples were soy 

derived. The sample set contained a few animal fat-derived samples, and one derived from 

palm stearin. Samples were typically stored at the distributors in aboveground tanks. 

The survey revealed the increasing prevalence of B99.9 in the marketplace, 6 of 37 U.S. 

samples were B99.9 rather than B100. As a group, the samples had a failure rate of 59% 

compared to the specifications. The B100 samples as a subset had an identical failure rate. 

Most often, the samples failed by exceeding the allowable total glycerin or by not meeting 

the minimum flash point specification. Several samples failed to meet requirements for 

multiple properties. The individual failure rates for total glycerin and flash point were 33% 

and 30%, respectively. The results of this study were not production volume weighted, but do 

show a significant fuel quality concern for B100 produced and distributed during 2006. 

 ii
Acronyms and Abbreviations 

AET atmospheric equivalent temperature 

ASTM ASTM International 

B boron 

Bxx Biodiesel blend composed of xx% biodiesel in diesel fuel 

Ca calcium 

°C degrees Celsius 

Cu copper 

EN European Normalization 

EPA U.S. Environmental Protection Agency 

FAME fatty acid methyl ester 

Fe iron 

GC gas chromatography 

GC-MS gas chromatography-mass spectrometry 

h hour, hours 

ICP-AES Inductively coupled plasma atomic emission spectroscopy 

K potassium 

mass% percent by mass 

max maximum 

Mg magnesium 

mgKOH/g milligrams potassium hydroxide per gram 

min minimum 

mm2

/s millimeters squared per second 

MSTFA N-methylN-trimethlsilyiltrifluoroacetamide 

Na sodium 

NREL National Renewable Energy Laboratory 

OSI oil stability index 

PADD Petroleum Area Defense District 

ppm parts per million 

S sulfur 

S15 15 ppm sulfur 

S500 500 ppm sulfur 

Si silicon 

UOP Universal Oil Products 

Zn zinc

 iii
Contents 

Figures..........................................................................................................................................................v 

Tables ..........................................................................................................................................................vi 

Acknowledgments........................................................................................................................................i 

Executive Summary ....................................................................................................................................ii 

Acronyms and Abbreviations....................................................................................................................iii 

Introduction..................................................................................................................................................1 

Methodology ................................................................................................................................................2 

Results..........................................................................................................................................................4 

Sample Collection and Telephone Survey.................................................................................4

ASTM D6751 Specification Results..........................................................................................5 

Flash Point...........................................................................................................................6 

Kinematic Viscosity..............................................................................................................9 

Sulfated Ash .........................................................................................................................9 

Sulfur Content......................................................................................................................9 

Cloud Point........................................................................................................................10 

Carbon Residue..................................................................................................................11 

Acid Number ......................................................................................................................11 

Free and Total Glycerin.....................................................................................................12 

Phosphorus ........................................................................................................................13 

Distillation T90 ..................................................................................................................14 

Sodium and Potassium.......................................................................................................15 

Results for Requirements Recently Included in ASTM D6751...............................................16 

Oxidation Stability .............................................................................................................16 

Calcium and Magnesium ...................................................................................................17 

Nonspecification Test Results..................................................................................................17 

Water Content ....................................................................................................................19 

Particulate Contamination.................................................................................................19 

Peroxide Number...............................................................................................................19 

Other Metals ......................................................................................................................21 

Fatty Acid Methyl Ester Profile .........................................................................................21 

Summary and Conclusions ......................................................................................................................24 

References .................................................................................................................................................25 

 iv
Figures 

Figure 1. Regional distribution of biodiesel samples collected .......................................... 4 

Figure 2. Flash point of B100 quality survey samples........................................................ 9 

Figure 3. Sulfur content for B100 quality survey samples ............................................... 10 

Figure 4. Cloud point of biodiesel quality survey samples............................................... 11 

Figure 5. Acid number for B100 samples......................................................................... 12 

Figure 6. Relationship between acid number and sample age .......................................... 13 

Figure 7. Free and total glycerin results for biodiesel samples......................................... 14 

Figure 8. Na+K results from B100 quality survey............................................................ 16 

Figure 9. Rancimat and OSI induction period results for a subset of the B100 

quality survey samples....................................................................................... 17 

Figure 10. D6304 water content for B100 quality survey samples................................... 19 

Figure 11. Peroxide number for B100 quality survey samples......................................... 20 

Figure 12. Relationship between peroxide number and sample age................................. 21 

 v
Tables

Table 1. Fuel Property Specifications for B100 Samples under ASTM D6751-03a.......... 2 

Table 2. Changes to D6751 in 2006 (D6751-06e1)............................................................ 2 

Table 3. Other Properties Tested ........................................................................................ 3 

Table 4. Storage Location Information for Biodiesel Samples........................................... 5 

Table 5. Fuel Property Test Results from B100 Quality Survey ........................................ 7 

Table 6. T90 Comparison of 10 Biodiesel Samples ......................................................... 15 

Table 7. ASTM Test Results for Properties Not Covered in D6751 ................................ 18 

Table 8. FAME Analysis of B100 Samples...................................................................... 23 

 vi
Introduction 

In 2004 the U.S. Jobs Creation Act set forth credits for biodiesel to encourage the domestic 

biodiesel market. A blender’s tax credit of $1.00/gal for agri-biodiesel and $0.50/gal for 

biodiesel from recycled oils went into effect January 1, 2005.1,2

 The Internal Revenue 

Service rule governing the tax credit states that blending one gallon of diesel fuel with 999 

gallons of biodiesel classifies as a “blending event.” Thus, many biodiesel producers sell 

B99.9 and claim the tax credit. As a result of these credits and industry growth, biodiesel 

production in the United States reached 75 million gallons in 2005 and about 250 million 

gallons in 2006.3

 Producers must ensure that the biodiesel meets the ASTM D6751 

specifications for neat biodiesel to meet U.S. Environmental Protection Agency fuel 

registration requirements and to obtain the tax credit. 

As part of an effort to help the biodiesel industry achieve engine manufacturer warranty 

approval for the use of biodiesel blends, the National Renewable Energy Laboratory (NREL), 

for the U.S. Department of Energy, has conducted nationwide surveys of biodiesel quality. 

NREL conducted a B100 quality survey in 2004, the results of which showed that 

approximately 85% of the samples met the quality standards of ASTM D6751-03a, the 

version of D6751 that was in effect at the time.4

 Beginning in late 2005 and continuing 

through mid-2006, NREL conducted a second nationwide B100 quality survey, which is the 

subject of this report. 

 1
Methodology 

B100 samples were collected from distributors throughout the 48 contiguous states. A 

contractor contacted each distributor to obtain a B100 sample. The contractor was 

constrained to obtain a certain number of samples within each Petroleum Area Defense 

District (PADD). The samples were collected from random points of distribution. Thus, the 

samples may not be wholly representative on a volume basis of biodiesel in use in the United 

States today. 

After the samples were collected, the contractor was instructed to conduct a telephone survey 

of the distributors, who were asked what the biodiesel feedstock was, how recently the load 

sampled had been delivered, the storage conditions, if any additives were in use, and if so, 

which ones. 

The samples were tested for a variety of properties, including those that make up the ASTM 

D6751 specification as well as other properties that were proposed for inclusion or are 

otherwise of interest. The samples were collected between November 2005 and July 2006. 

During this period, the ASTM fuel property specification for biodiesel was modified. The 

first set of samples was collected under ASTM D6751-03a (Table 1). An update to D6571 

was published in May 2006 as D6751-06. Table 2 lists the relevant modifications made in 

D6751-06 relative to D6751-03a. Properties not listed are identical for both versions of the 

standard. The impact of these changes to the fuel quality specifications will be discussed as 

appropriate. Other properties for which testing was also performed are listed in Table 3. 

Several of these properties and limits have been included in subsequent versions of D6751 

but were not in effect at the time of this study. 

Table 1. Fuel Property Specifications for B100 Samples under ASTM D6751-03a 

Property ASTM 

Method 

S15 Limits S500 Limits 

Flash point, closed cup, °C D93 130.0 min 130.0 min 

Water and sediment, vol% D2709 0.050 max 0.050 max 

Kinematic viscosity, 40°C, mm2/s D445 1.9-6.0 1.9-6.0 

Sulfated ash, mass% D874 0.020 max 0.020 max 

Sulfur, ppm D5453 0.0015 max 0.0500 max 

Cetane number D613 47 min 47 min 

Cloud point, °C D2500 Report Report 

Carbon residue, mass% D4530 0.050 max 0.050 max 

Acid number, mg KOH/g D664 0.80 max 0.80 max 

Free glycerin, mass% D6584 0.020 max 0.020 max 

Total glycerin, mass% D6584 0.240 max 0.240 max 

Phosphorus content, mass% D4951 0.001 max 0.001 max 

Distillation temperature, AET, 90% recovered, °C D1160 360 max 360 max 

Table 2. Changes to D6751 in 2006 (D6751-06e1) 

Property Test Method S15 Limits S500 Limits 

Acid number, mg KOH/g D664 0.50 max 0.50 max 

Sodium + potassium, combined, ppm UOP 391 5 max 5 max 

 2
Table 3. Other Properties Tested 

Property Method Limit if Proposed for Inclusion 

in D6751 

Oxidation stability, ha EN14112 3 min 

Calcium + magnesium, combined, ppma EN14538 5 max 

Methanol content, mass%a EN14110 0.20 maxb

Karl Fisher water, ppm D6304 500 max 

Particulate contamination, mg/L D6271 24 max 

Peroxide content, ppm D3703 Not proposed for inclusion in D6751, 

no proposed limit a Incorporated into D6751-07. Additionally, the test method for sodium+potassium was changed from UOP391 to 

EN14538. 

b Incorporated into D6751-07 with a minimum flash point of 93°C as an alternative to the 130°C minimum flash 

point requirement. 

 3
Results 

Sample Collection and Telephone Survey 

Each sample collected has been assigned a numeric identifier between 1 and 39 that is used 

consistently throughout this report. 

The goal of the sample collection was to include samples from every PADD, with an 

emphasis in areas where biodiesel use and/or production is highest. A total of 37 samples 

were collected from 23 of the 48 contiguous states. For comparison, two additional samples 

were included in the survey from outside the United States, one each from Canada and 

Germany. Figure 1 shows the collection location for each U.S. sample. 

Figure 1. Regional distribution of biodiesel samples collected 

The samples were collected over a period of 9 months. The samples had been in storage at 

the distributors for various lengths of time, from one day to about 10 months. The average 

age of the samples was 37 days and the median age was 12 days. The telephone survey did 

not include information about the producer or the age of the fuel before it was received at the 

distributor. 

The feedstock of the samples was predominantly soy (31 of the 39 samples). These results 

are similar to the results of the 2004 survey, showing that the United States still produces 

most of its biodiesel from soy. Animal fats composed four of the samples and there was one 

sample each of palm stearin and unknown origin. The two non-U.S. samples were produced 

from canola (Canada) and rapeseed (Germany). 

 4
The distributors held the biodiesel in a variety of storage containers and locations. Table 4

lists the storage conditions encountered and the frequency of each condition, along with 

applicable notes. Most of these samples were stored outside in aboveground tanks. No 

information was collected about whether these tanks were heated during the winter; however, 

outdoor B100 tanks are commonly heated to temperatures in the range of 10°C to 15°C. In 

most cases, the distributors did not report additive usage in the biodiesel. Two distributors 

reported use of additives: an additive described as Sure Flo in one sample, and additives 

described as Power Service Products plus an unspecified biodiesel antigel additive in the 

other. No specific product information or treat rates were given. 

Table 4. Storage Location Information for Biodiesel Samples 

Storage Type Frequency Notes 

Aboveground, outdoors 27 

Aboveground, indoors 4 

Underground 2 

Other 1 Fuel stored in 5-gal containers 

The sample collection contractor was specifically instructed to collect B100 samples. 

However, a number of biodiesel blends were collected. Of the 37 U.S. samples, six were 

B99.9 blends and one (sample #28) was a B50 blend. These samples were identified as B99.9 

during the D6584 glycerin analysis, as discussed in the glycerin section. Fourier transform 

infrared spectroscopy with an attenuated total reflectance cell was used to measure the 

biodiesel content of the B50 sample. This method for blend level quantification was 

developed at ASTM by a work group under the D02.04.F subcommittee on Adsorption 

Spectroscopy. The number of samples collected that were B99.9 rather than B100 for the 

2005–2006 survey contrasts with the 2004 survey, where no B99.9 was encountered. The fact 

that several distributors submitted B99.9 instead of B100 indicates a lack of specificity in 

differentiating between these products in the marketplace. 

ASTM D6751 Specification Results 

Samples 1–24 were collected under the D6751-03a fuel property specification from 

November 2005 to March 2006 and were tested for all the properties listed in Table 1. 

Samples 25–39 were collected after D6751-06 was published in May 2006, and were tested 

against the properties listed in Table 1 plus additional properties or limits listed in Table 2. 

Based on the results of the 2004 B100 quality survey (where every sample met the water and 

sediment, copper corrosion, and cetane limits) these tests were not performed in the current 

survey.4

Results from the D6751 properties are listed in Table 5. The results in boldface type failed to 

meet the D6751 standard in effect at the time of sample collection. Excluding the samples 

from outside the United States, the failure rate of the samples collected in this survey is 59%. 

The failure rate is the same regardless of whether the B99.9 samples are included with the 

B100 samples (assuming that all the B99.9 samples met the glycerin standards). The failure 

rates for individual test methods vary and will be discussed in the subsequent sections; the 

highest single failure rate was observed for total glycerin; 10 of 30 B100 samples did not 

meet the specifications (33% failure rate). The next most significant test method in terms of 

failure rate is the flash point, with an 18% failure rate for the B100 samples and a combined 

 5
 6

failure rate (B100 and B99.9) of 30%. For the other requirements failure rates were much 

lower. 

Flash Point 

Flash point is the temperature to which a fuel must be heated to produce a fuel/air mixture 

that is ignitable by a flame. It is an important safety and handling parameter for fuels. The 

flash point of biodiesel was required to be >130°C during the period of sample collection for 

this study. This limit ensures that residual alcohol, typically methanol, from the production 

process is below 0.20 mass% in the finished fuel. The current specification, D6751-07 

includes two options for limiting methanol content. In the first option, the flash point must be 

>130oC as before. In the second option, the flash point must be >93°C and methanol content 

<0.20 mass%. The methanol content is measured by EN14110, a gas chromatography (GC) 

method that employs head-space sampling, meaning the vapors above the fuel are sampled 

under specified conditions and analyzed chromatographically. This second option was not 

available at the time these samples were collected. 

Figure 2 shows the flash point of the B100 samples and indicates a 30% failure rate 

compared to the standard of >130°C. Three of the samples with low flash points were 

analyzed for methanol content by EN14110. All three contained residual methanol in excess 

of 0.20 mass% and would not meet the updated flash point specification. 

Compared to the 2004 survey, where no samples failed the flash point specification, the 

greatly increased failure is noteworthy. Methanol in biodiesel is a remnant of the production 

process, indicating that a significant fraction of fuels entering the marketplace are not being 

postprocessed adequately to meet the current specifications. 

Five of six B99.9 blends had flash point below the 130°C limit. Blending with such a small 

amount of diesel fuel would be unlikely to reduce the flash point of biodiesel below the 

130°C limit. This is illustrated within the data set by sample #36, a B99.9 blend that readily 

met the 130°C flash point minimum and by the blend flash point study results shown in the 

Appendix. More likely possibilities are that the B99.9 failed because of high methanol 

content in the B100 or because of cross contamination with other, more volatile products 

(such as gasoline or ethanol) at the distributor. These low boiling products could significantly 

reduce the flash point of biodiesel. 
Table 5. Fuel Property Test Results from B100 Quality Survey 

(boldface type indicates the sample failed the property specification in effect at the time of sample co

Sample ID 

Feedstock 

Date Collected 

Sample Age, days 

Comments 

Cloud Point, 

D2500, °C 

Flash Point, 

D93,°C 

Sulfated Ash, 

D874, mass% 

Sulfur, 

D5453, ppm 

Carbon Residue, 

D524, mass% 

Acid Number, 

D664, mg KOH/g 

Rancimat, 

EN14112, h 

Viscosity, 

D445, mm2

/s 

Free Glycerin, 

D6584, mass% 

Total Glycerin, 

D6584mass% 

1 Soy 11/10/2005 1 0 130 <0.001 6.9 0.03 0.14 3.12 4.131 0.002 0.272 Soy 11/10/2005 35 -1 146 <0.001 4.4 0.04 0.57 2.09 4.119 0.002 0.173 Soy 11/10/2005 8 -1 159 <0.001 1.8 0.04 0.47 0.43 4.107 0.002 0.184 Soy 11/10/2005 54 -1 141 <0.001 7.1 0.05 0.31 0.53 4.118 0.004 0.175 Soy 11/11/2005 18 0 150 <0.001 7 <0.01 0.57 0.52 4.173 0.001 0.276 Soy 11/10/2005 86 0 166 <0.001 16.1 0.03 0.39 1.08 4.27 0.003 0.277 Soy 11/15/2005 0 -1 138 <0.001 1.1 0.05 0.14 0.80 4.099 0.003 0.218 Soy 11/13/2005 6 0 168 0.02 8.3 0.08 <0.05 4.26 4.377 0.074 0.629 Soy 11/15/2005 1 0 122 0.03 53.3 0.03 0.58 4.12 4.098 0.012 0.19

10 Soy 11/21/2005 19 

B99.9, 

Sure Flo 

additive 

-6 93 <0.001 45.2 0.02 0.07 0.56 3.729 - - 

11 Canola 11/29/2005 U Canadian -5 167 <0.001 2.2 0.05 0.23 - 4.432 0.009 0.1012 Palm Stearin 11/29/2005 U 12 151 <0.001 0.5 0.02 0.69 - 4.672 <0.001 0.1213 Rapeseed 12/16/2005 U European -3 165 <0.001 2.2 0.04 0.08 - 4.480 <0.001 0.1614 Animal fat 12/20/2005 U 10 183 <0.001 34.7 0.03 0.41 - 4.731 <0.001 0.0815 Soy 2/10/2006 101 -2 58 <0.001 8.4 0.05 0.94 - 4.081 0.003 0.4116 Soy 2/10/2006 9 -3 136 <0.001 3.1 0.05 0.39 - 4.160 <0.001 0.2817 Animal fat 2/7/2006 7 9 176 <0.001 17.2 0.06 0.53 - 4.712 0.007 0.2018 Soy 2/3/2006 33 -2 161 <0.001 0.7 0.04 0.08 - 4.099 0.009 0.2119 Soy 2/9/2006 9

Power 

Service 

additive 

0 193 <0.001 5.6 0.02 0.11 - 4.182 0.001 0.23

20 Animal fat 2/20/2006 U 0 172 <0.001 0.7 0.02 0.22 - 3.991 0.011 0.07

U: Unknown sample age 7
 8

Sample ID 

Feedstock 

Date Collected 

Sample Age, days 

Comments 

Cloud Point, 

D2500, °C 

Flash Point, 

D93, °C 

Sulfated Ash, 

D874, mass% 

Sulfur, 

D5453, ppm 

Carbon Residue, 

D524, mass% 

Acid Number, 

D664, mg KOH/g 

Viscosity, 

D445, mm2/s 

Free Glycerin, 

D6584, mass% 

Total Glycerin, 

D6584, mass% 

P, D5185, ppm 

21 Soy 2/8/2006 102 1 169 <0.001 6.4 0.05 0.24 4.153 0.008 0.325 <1 22 Soy 2/7/2006 98 B99.9 -5 103 <0.001 74.4 0.05 0.19 3.922 - - <1 23 Soy 2/10/2006 40 -4 157 0.04 1.0 0.04 0.34 4.061 0.001 0.012 <1 24 Soy 3/16/2006 2 0 113 <0.001 2.1 0.06 0.22 4.163 0.004 0.219 <1 25 Soy 6/16/2006 U -3 119 <0.001 15.2 0.03 0.46 4.082 0.004 0.180 <1 26 Soy 6/15/2006 0 3 171 <0.001 5.7 0.03 0.12 4.115 0.004 0.187 <1 27 Soy 6/6/2006 0 0 169 <0.001 5.7 0.05 0.46 4.24 0.002 0.151 <1 28 Soy 7/18/06 290 B50 -1 126 <0.001 101.5 0.04 0.27 4.085 - - 2 29 Soy 7/18/2006 1 0 138 <0.001 0.4 0.03 0.13 4.08 0.002 0.095 <1 30 Soy 7/19/2006 171 2 155 <0.001 0.8 0.03 0.17 2.855 0.012 0.242 <1 31 Unknown 7/19/2006 2 B99.9 3 105 <0.001 26.8 0.03 0.11 4.027 - - <1 32 Soy 7/18/2006 43 B99.9 1 100 <0.001 15.3 0.03 0.16 4.088 0.004a 0.166 a <1 33 Soy 7/20/2006 0 0 172 <0.001 1.3 0.04 0.55 4.153 0.016 0.251 <1 34 Soy 7/19/2006 5 0 163 <0.001 1.4 0.03 0.05 4.125 0.014 0.229 <1 35 Soy 7/20/2006 1 B99.9 -2 84 0.008 51.1 0.04 0.34 4.061 0.014 a 0.192 a 10 36 Soy 7/21/2006 U B99.9 2 160 <0.001 13.6 0.03 0.32 4.183 0.009 a 0.231 a <1 37 Animal fat 7/19/2006 1 -2 161 <0.001 5.4 0.03 0.07 4.293 0.002 0.041 <1 38 Soy 7/24/2006 -1 122 <0.01 2.7 0.03 0.34 4.089 0.002 0.162 <1 39 Soy 7/28/2006 12 0 90 <0.001 0.7 0.05 0.26 4.131 0.019 0.274 <1 

Table 5. Fuel Property Test Results from B100 Quality Survey (continued) 

U: Unknown sample age 

 a: Estimated (discussed below) 
Kinematic Viscosity 

Kinematic viscosity is determined by the D445 method, which measures the time required for 

a given volume of fuel to flow through a capillary tube viscometer under force of gravity at a 

fixed temperature. For biodiesel the kinematic viscosity is limited to 1.9-6.0 mm2

/s. This 

limit is set to ensure adequate lubrication without causing either leakage in metal-to-metal 

contact regions or excessively high resistance to flow during cold temperature operation. All 

samples met this limit, with an average for the set of 4.18 mm2

/s. One outlier (sample #30) 

exhibited viscosity of 2.855 mm2

/s and had a slightly elevated total glycerin content (0.242 

mass%, failing to meet the specification), but met all the other property specifications. 

Sulfated Ash 

The sulfated ash, measured by D874, determines the amount of ash, soluble metallic soaps, 

and residual catalyst in the biodiesel. In this test the sample is burned to form ash, which is 

then treated with sulfuric acid to form metal sulfates. These components can lead to deposits, 

wear, and filter plugging. Only two of the 37 U.S. samples did not meet the sulfated ash 

specification of <0.02 mass%. One of the failing samples did not meet multiple properties; 

the other failed to meet only the D874 sulfated ash content. 

Sample ID

0 5 10 15 20 25 30 35 40

Flash Point, oC, D93

40

60

80

100

120

140

160

180

200

220

Methanol Content, mass%, EN14110

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

M

M

M

Soy

Canola

Palm Stearin

Rapeseed

Animal Fat

Soy B50

Soy B99

Unknown B99

M Methanol Content

Figure 2. Flash point of B100 quality survey samples. Methanol content has been measured 

for selected samples and shown on the right hand axis. 

Sulfur Content 

The sulfur content of biodiesel produced from virgin oils is expected to be inherently low 

because these oils naturally contain few sulfur compounds. Recycled cooking oils can 

 9
acquire sulfur from the foods fried in them and thus may have significant sulfur content 

(higher than 15 ppm). In these cases, the sulfur must be removed during production to allow 

the finished fuel to meet the specifications for on-highway diesel in effect today. However, at 

the time these samples were collected (before October 2006), 15 ppm sulfur was not required 

for on-highway diesel fuel. The sulfur content of the sample was not specified when the 

samples were collected. Thus, any sample meeting the on-highway requirement of 500 ppm 

in effect at that time is regarded as meeting the specification. Sulfur is determined by 

method D5453, where the sample is burned in a high temperature oven and the sulfur dioxide 

formed is quantified by ultraviolet fluorescence. 

Figure 3 shows the results obtained for sulfur content of the samples collected in this study. 

The significant sulfur content of several of the B100 samples is not readily explained, but 

seems most likely to have been caused by contamination during handling and storage and 

will need to be addressed as the 15 ppm sulfur limit has come into effect. 

Sample ID

0 5 10 15 20 25 30 35 40

Sulfur Content, ppm, D5354

0

20

40

60

80

100

120

Soy

Canola

Palm Stearin

Rapeseed

Animal Fat

Soy B50

Soy B99

Unknown B99

Figure 3. Sulfur content for B100 quality survey samples 

Cloud Point 

The cloud point by method D2500, wherein the sample is cooled at a specified rate and the 

temperature at which crystals first begin to form, is measured. Cloud point is used as a 

predictor of the low temperature performance of biodiesel in a blend and for the samples 

included in this study ranged from −6°C to 12°C (see Figure 4), with the highest cloud point 

 10
recorded for palm stearin-derived biodiesel. The average soy biodiesel cloud point was 

−0.8°C. The animal fat derived biodiesels had a higher average cloud point, 4°C. 

The cold weather operability of biodiesel is influenced by the cloud point, although very little 

biodiesel is used as B100. The impact of cold weather operability of blends is more important 

because of the differences between petroleum diesel and biodiesel properties at low 

temperatures. 

Sample ID

0 5 10 15 20 25 30 35 40

Cloud Point, oC, D2500

-8

-6

-4

-2

0

2

4

6

8

10

12

14

Soy

Canola

Palm Stearin

Rapeseed

Animal Fat

Soy B50

Soy B99

Unknown B99

Figure 4. Cloud point of biodiesel quality survey samples 

Carbon Residue 

D524, the carbon residue indicates the carbon deposit-forming potential of a fuel in the 

combustion chamber. It is measured by heating the biodiesel to a high temperature to drive 

off volatiles and volatile pyrolysis products. A high carbon residue may lead to combustion 

chamber deposits. Three of the samples failed to meet this specification; two of these also 

failed on at least one other property. 

Acid Number 

Acid number is measured by method D664 using potentiometric titration. Figure 5 shows the 

results of the acid number determination for the samples. In the left half of the figure, the 

samples were collected when D6751-03a was in effect with a limit of 0.80 mg KOH/g. On 

the right half of the figure, the acid number limit was 0.50 mg KOH/g under D6751-06. Only 

two samples failed to meet the appropriate standard at the time of collection. 

 11
Sample ID

0 5 10 15 20 25 30 35 40

Acid Number, mg KOH/g, D664

0.0

0.2

0.4

0.6

0.8

1.0

Soy

Canola

Palm Stearin

Rapeseed

Animal Fat

Soy B50

Soy B99

Samples collected under Unknown B99

0.8 mgKOH/g limit

Samples collected under

0.5 mgKOH/g limit

Figure 5. Acid number for B100 samples 

Acid number is one of the first parameters to increase as biodiesel begins to oxidize and age. 

During the telephone survey, the distributors were asked when the biodiesel being sampled 

was delivered. Property analysis was completed within weeks of sample receipt to ensure the 

accuracy of the analyses. There is no relationship between sample age, as given by the fuel 

distributor, and acid number (Figure 6). The samples with an unknown age have been shown 

as a negative value to artificially separate the data in the figure.

Free and Total Glycerin 

Samples with high free glycerin can result in fuel separation and materials compatibility 

issues. High total glycerin, measured as the sum of free glycerin and glycerin in unreacted 

and partially reacted fats, are high boiling compounds that can lead to deposit formation and 

fuel filter plugging. 

The free and total glycerin are measured with GC per ASTM D6584, which is a significantly 

more complex test to implement than any of the others required by the D6751 specification. 

The free hydroxyl groups in the mixture are derivitized with N-methyl N-(trimethylsilyl) 

trifluoroacetamide (MSTFA). The derivitized sample mixture is separated using GC. The 

free glycerin is measured directly, and the mono-, di-, and triglycerides are determined with 

conversion factors to internal standards. 

 12
# of days from delivery to distributor and 

sample collection by contractor

0 50 100 150 200 250 300 350

Acid Number, D664, mg KOH/g

0.0

0.2

0.4

0.6

0.8

1.0

Negative sample age represents

samples that do not have delivery

date information available

Figure 6. Relationship between acid number and sample age. Samples with no data on time at 

distributor are shown as a negative value. 

One of the major shortcomings of the D6584 method is its sensitivity to diesel fuel. Diesel 

fuel components react differently on the column used in the GC—they make determination 

of free glycerin very difficult and damage the column. Thus, free and total glycerin cannot be 

determined in samples with even small amounts of diesel fuel, such as B99.9. 

Seven of the 39 samples contained at least small amounts of diesel fuel. Currently, many 

commercial laboratories do not report free and total glycerin results for biodiesel blends. For 

the purposes of this study, three of these blends were analyzed by D6584 but, because of the 

interference of diesel fuel with the free glycerin peak in the chromatogram, the results for 

free glycerin in these samples are not quantitative. 

All but one of the 30 U.S. B100 samples passed the free glycerin specification of <0.02 

mass% (Figure 7). For the total glycerin, a much higher percentage of B100 samples (33%) 

failed to meet the <0.240 mass% limit. Seven of the 11 failing samples also did not meet 

other quality requirements. 

 13
Sample ID

0 5 10 15 20 25 30 35 40

Free Glycerin, D6584, mass%

0.00

0.02

0.04

0.06

0.08

Total Glycerin, D6584, mass%

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Soy

Canola

Palm Stearin

Rapeseed

Animal Fat

B99 Samples

Hollow symbols are free glycerin

Filled symbols are total glycerin

Figure 7. Free and total glycerin results for biodiesel samples. Hollow symbols are total 

glycerin using the left axis and the filled symbols are total glycerin using the right axis. 

Phosphorus 

In this study phosphorus was determined by D5185, a method that uses inductively coupled 

plasma-atomic emission spectrometry for elemental analysis. Phosphorus must be limited to 

protect the particle filters and catalysts that are important components of advanced emission 

control systems. All samples met the limit of 10 ppm maximum. One sample was right at the 

limit, containing 10 ppm of phosphorus. This sample (#35) also had high Ca, Zn, and S, 

indicating possible contamination and/or poor purification after processing. 

Distillation T90 

Biodiesel, being essentially a pure component, has a distillation “curve” that is very different 

than a typical petroleum diesel fuel. The temperature at which 90% of the sample has been 

distilled, the T90, is measured by a reduced pressure distillation with method D1160. The 

distillation requirement ensures that the fuel is pure biodiesel and has not been contaminated 

with other high boiling compounds. 

The D1160 distillation method was not developed for biodiesel, and appropriate 

modifications for reproducibility and repeatability have not been developed; however, D1160 

was the best method available for distillation at the time D6751 was adopted. ASTM is 

working to determine whether a simulated distillation, per D2887, is appropriate for 

biodiesel. The results from this study illustrate the difficulty with the D1160 test method. The 

first 10 samples of the survey were analyzed for T90 by two test laboratories. Table 6 shows 

the results from these laboratories for these 10 samples. 

 14
Table 6. T90 Comparison of 10 Biodiesel Samples 

Sample # T90, °C, Laboratory A T90, °C, Laboratory B 

1 368 352 

2 365 351 

3 367 351 

4 367 352 

5 367 354 

6 368 355 

7 367 351 

8 366 371 

9 366 355 

10 365 351 

In every case but one, Laboratory A recorded higher T90 temperatures than Laboratory B. 

Laboratory A found the samples to fail this requirement and Laboratory B found the samples 

to pass. The differences reported between these laboratories show that a more reliable 

method needs to be considered. Because of this discrepancy in testing results, we do not 

include T90 in the evaluation of percent of samples passing or failing the standard. 

Sodium and Potassium 

The sodium and potassium (Na+K) standard went into effect in May 2006 in the middle of 

the sample collection period. Sodium and potassium come from the hydroxide catalyst used 

in the reaction to convert fats and oils into biodiesel. High levels of these metals can lead to 

the formation of deposits, poison advanced emission control equipment, or act as catalysts in 

the formation of undesired products. 

The samples in this study were analyzed for Na+K using D5185 instead of Universal Oil 

Products (UOP) 391, which is rarely used. Both methods use inductively coupled plasma 

atomic emission spectroscopy (ICP-AES). The D5185 method uses the same techniques to 

introduce and analyze samples as the UOP 391 method and with an appropriate calibration 

for the low levels of metals in biodiesel, so the results from D5185 reported in this study are 

reliable and accurate. 

The field samples collected before the 5 ppm limit was included in D6751 have a wide range 

of Na+K contents (Figure 8). In particular, sample #8, with extremely high Na+K (82 ppm) 

failed multiple other properties and is an example of a fuel with a serious quality problem. 

With the inclusion of the Na+K specification in D6751 (samples 25–39), all fuels met the <5 

ppm standard. 

 15
Sample ID

0 5 10 15 20 25 30 35 40

Na+K, ppm, D5185

0

10

20

80

100

Soy

Canola

Palm Stearin

Rapeseed

Animal Fat

Soy B50

Soy B99

Unknown B99

Samples collected when

5 ppm limit was in effect

Figure 8. Na+K results from B100 quality survey 

Results for Requirements Recently Included in ASTM D6751 

Oxidation Stability 

When the samples were collected, a limit on oxidation stability by Rancimat (EN14112) was 

not yet included in D6751. Because of a larger stability study already underway,5 oxidation 

stability was not measured for all of the samples collected for this study. However, the first 

10 samples collected (Samples 1-10) were analyzed for the Rancimat induction period and 

oil stability index (OSI) at 110oC. The Rancimat and OSI are instruments from two different 

manufacturers that perform essentially the same experiment. Nevertheless, there has been 

concern that these instruments will not produce identical results. The Rancimat results are 

the average of four measurements—two automatic and two manual—and the OSI results are 

the average of two measurements. The results show slightly shorter induction times with the 

OSI than with Rancimat, although this might be due to differences in the age of samples 

when they were tested and slight differences between methods, such as a larger sample size 

with the OSI. 

The range of Rancimat induction period in these samples was 0.43 to 4.26 h and the OSI 

induction period was 0.13 to 3.92 h (Figure 9). The correlation between OSI and Rancimat is 

0.95. At the time of this writing, ASTM D6751-07 includes an oxidation stability standard of 

3 h minimum on the Rancimat or OSI test performed at 110oC. 

 16
OSI at 110C

012345

Rancimat at 110C

0

1

2

3

4

5

6

OSI vs Rancimat (Manual)

OSI vs Rancimat (2nd Derivative)

OSI v Rancimat (Manual)

f(x) = 0.54+1.03X

r

2

 = 0.96

OSI v Rancimat (2nd Derivative)

f(x) = 0.41+1.15x

r

2

 = 0.94

Figure 9. Rancimat and OSI induction period results for a subset of the B100 quality survey 

samples 

Calcium and Magnesium 

Calcium and magnesium (Ca+Mg) contamination in biodiesel can also lead to deposits, 

poison emission control systems, and catalyze side reactions. Calcium and magnesium in 

biodiesel occur from washing with hard water or contamination from adsorbents used to 

remove polar compounds during product purification. ASTM D6751-07 currently limits 

Ca+Mg to a maximum of 5 ppm. 

Only one sample from this study did not meet the 5 ppm combined limit for Ca+Mg (Sample 

#39). This limit was not in effect at the time these samples were collected. This sample was a 

B99.9 that also failed to meet the phosphorus and flash point specifications. The failure of 

this sample to meet the specifications suggests possible contamination from other products.

Nonspecification Test Results 

In addition to the ASTM D6751 properties that were tested, other properties not part of the 

specification were included in the analysis. These properties included dissolved water 

content, particulate contamination, peroxide number, and other metals (Zn, Fe, and Cu). 

Results from testing are presented in Table 7. 

 17
Table 7. ASTM Test Results for Properties Not Covered in D6751 

(samples in italics are biodiesel blends) 

Sample ID Water 

Content 

D6304, ppm

Particulate 

Contamination, 

D6217, mg/L 

Peroxide 

Number, 

D3703, ppm 

Fe, D5185, 

ppm 

Cu, D5185, 

ppm 

Zn, D5185, 

ppm 

1 1238 4.1 160. <1 <1 <1 

2 776 2.8 223 <1 <1 <1 

3 636 0.6 40 <1 <1 <1 

4 585 5.1 25 <1 1 <1 

5 691 2 264 <1 <1 <1 

6 596 2.9 215 <1 <1 1 

7 204 13.9 64 <1 <1 <1 

8 276 4.4 64 <1 <1 <1 

9 255 2.5 127 <1 <1 <1 

10 252 3 280 <1 <1 <1 

11 78 3.6 217 <1 <1 <1 

12 162 6.4 105 <1 <1 <1 

13 185 6.5 55 <1 <1 <1 

14 85 93.2 9 <1 <1 <1 

15 1096 2.1 199 <1 <1 2 

16 1706 5.2 134 <1 <1 <1 

17 536 6.3 56 3 <1 <1 

18 1031 5.9 51 <1 <1 <1 

19 846 1.4 167 <1 <1 <1 

20 416 6.7 208 <1 <1 <1 

21 604 6.7 160 <1 <1 <1 

22 1072 1.0 136 <1 <1 <1 

23 201 3.4 127 <1 <1 <1 

24 666 1.2 274 <1 <1 <1 

25 1857 4.4 64 <1 <1 <1 

26 781 3.6 50 <1 <1 <1 

27 199 9.4 87 <1 <1 <1 

28 789 2.8 364 <1 <1 <1 

29 133 1.2 61 <1 <1 <1 

30 627 12.0 296 <1 <1 <1 

31 1148 3.8 119 <1 <1 <1 

32 1231 18.0 218 <1 <1 1 

33 934 8.8 438 <1 <1 <1 

34 738 2.2 206 <1 <1 <1 

35 1031 23.8 385 <1 <1 9 

36 819 1.4 103 <1 <1 <1 

37 914 0.8 38 <1 <1 <1 

38 1117 7.4 82 <1 <1 <1 

39 1375 2.6 56 <1 <1 3 

 18
Water Content 

Water in biodiesel can corrode fuel systems and promote degradation and microbial growth. 

A 500 ppm limit on dissolved water, measured by the Karl Fisher method (D6304), has been 

proposed. However, because there is currently no limit for water via D6304 in the 

specifications, there are no controls within the industry to limit the dissolved water in the 

fuel. Thus, the fuels collected show a wide range of water content (Figure 10), and less than 

one-third contain <500 ppm dissolved water. An analysis of the time in storage compared to 

the water content showed no correlation (r2

 = 0.005, data not shown). Should this 

requirement be implemented in a future version of D6751, biodiesel producers and blenders 

will have to take steps to remove dissolved water during production and maintain a relatively 

dry environment during handling and storage. 

Sample ID

0 5 10 15 20 25 30 35 40

Water, ppm, D6304

0

250

500

750

1000

1250

1500

1750

2000

Soy

Canola

Palm Stearin

Rapeseed 

Animal Fat

Soy B50

Soy B99

Unknown B99

Figure 10. D6304 water content for B100 quality survey samples 

Particulate Contamination 

The particulate contamination was measured via D6217 and is an indicator of the quantity of 

solids in the biodiesel. The D6217 method measures the mass of particulate (solids) collected 

on a filter after vacuum filtration at specified conditions. A high mass of particulate can lead 

to excessive wear of fuel injection equipment because of the mass, type, and number of 

particles present. All the samples but one passed the proposed limit of 24 ppm. The failing 

sample had a particulate content almost 4 times greater than the standard and also failed the 

proposed Na+K limit. 

Peroxide Number 

The peroxide content of biodiesel is not limited as part of the quality specifications. The 

peroxide number is a measure of fuel degradation by oxidation as peroxides are the initial 

 19
products formed. These ultimately degrade to acids and aldehydes, or couple to form 

oligomers that ultimately lead to the formation of gums and deposits. Peroxide is measured 

through D3703, a method developed for aviation fuels with peroxide contents up to 15 ppm. 

The D3703 method is therefore not wholly applicable to samples with the high peroxide 

numbers found in many B100 samples, and an interlaboratory study is underway to 

determine the applicability of this method to biodiesel. From this study, the average peroxide 

number for biodiesel is 157 ppm (Figure 11). The B50 sample had a peroxide number of 363 

ppm, suggesting that the biodiesel used in the blend had a peroxide number higher than 700 

ppm, the highest value observed. When the samples were collected, D6751 had no oxidation 

stability requirement. 

Sample ID

0 5 10 15 20 25 30 35 40

Peroxide Number, ppm, D3703

0

100

200

300

400

500 Soy

Canola

Palm Stearin

Rapeseed

Animal Fat

Soy B50

Soy B99

Unknown B99

Figure 11. Peroxide number for B100 quality survey samples 

Figure 12 shows the peroxide number compared to how long the samples were stored at the 

distributors before collection. There is not a good correlation for time in storage and peroxide 

number, as measured by D3703. Two of the samples that had been in storage for a long time 

had high peroxide, but so did several samples that were collected when relatively fresh. 

 20
# of days from delivery to distributer

and sample collection by contractor

0 50 100 150 200 250 300 350

Peroxide Number, D3703, ppm

0

100

200

300

400

500

Soy

Canola

Palm Stearin

Rapeseed

Animal Fat

Soy B50

Soy B99

Unknown B99

Negative sample age represents

samples that do not have delivery

date information available

Figure 12. Relationship between peroxide number and sample age. Note that samples with no 

data on time at distributor are shown as a negative value. 

Other Metals 

In addition to the metals in D6751, the samples were analyzed for Fe, Cu, and Zn. The 

analysis was performed using the same ICP-AES technique as the other metals. The Fe, Cu, 

and Zn may come from contamination with lubrication oil or contact with copper or 

galvanized pipe and containers. These metals can catalyze oxidative degradation of vegetable 

oils even at below ppm levels. For example, Gordon and Musri report on a rapeseed oil that 

exhibited a 14.4 h Rancimat induction time (at 100oC). Treating with only 0.05 ppm of Cu2+

reduced the induction time to 6.4 h.6

 Frankel indicates that as little as 0.01 ppm of Cu can 

degrade soybean oil.7 These considerations should also apply to fatty acid methyl esters. The 

lower detection limit of the method employed here is 1 ppm. All but one sample contained 

less than 1 ppm of Fe and 1 ppm of Cu. Three samples contained more than 1 ppm of Zn 

with sample #35, a B99.9 blend exhibiting 9 ppm and having high levels of other metals 

discussed previously. Notably, this sample also exhibited one of the highest levels of 

peroxides. 

 21
 22

Fatty Acid Methyl Ester Profile 

Each sample was examined by gas chromatography-mass spectrometry (GC-MS) to 

determine the fatty acid profile. The GC-MS method was developed in-house and details are 

given in Reference 4. The results from the B100 samples are shown in Table 8. Mass 

recovery for these samples was only 80%–90%. The chromatographic conditions were such 

that other components in biodiesel, like the mono-, di-, and triglycerides, were not eluted 

under these conditions and may contribute to the lost mass. The fatty acid profiles are 

consistent with the feedstock information collected in the telephone survey and comparison 

to published literature on the makeup of various feedstocks.8

 The animal fat samples, except 

#20, are consistent with tallow derived samples. Sample #20, an animal fat derived sample, 

may be a mixed poultry fat, rather than a straight chicken fat. The fatty acid profile observed 

in this testing does not exactly match any one poultry fat source (chicken, hen, turkey, or 

egg).8
Sample 

ID 

C8:0 

C10:0 

C12:0 

C14:0 

C16:0 

C16:1 

(9) 

C18:0 

18:1(9) 

C18:2 

(9,12) 

C18:3 

(9,12,15 

C20:0 

C20:1 

(11) 

11 0.00% 0.00% 0.00% 0.04% 4.44% 0.15% 1.51% 46.08% 22.38% 7.06% 0.45% 0.99% 0.2612 0.00% 0.08% 0.11% 1.27% 21.94% 1.89% 11.77% 33.55% 10.88% 0.85% 0.14% 0.63% 0.0013 0.00% 0.00% 0.00% 0.00% 3.08% 0.13% 1.37% 47.68% 19.61% 8.79% 0.49% 1.13% 0.2814 0.00% 0.00% 0.00% 0.00% 15.54% 0.00% 13.34% 48.01% 9.00% 0.60% 0.86% 0.12% 0.1015 0.00% 0.00% 0.00% 0.06% 9.35% 0.00% 3.89% 19.14% 40.32% 5.39% 0.26% 0.12% 0.2416 0.00% 0.00% 0.00% 0.06% 10.22% 0.00% 3.74% 21.89% 44.67% 5.50% 0.27% 0.15% 0.2817 0.00% 0.06% 0.11% 1.23% 20.91% 2.03% 11.11% 33.59% 10.94% 1.17% 0.15% 0.57% 0.0018 0.00% 0.00% 0.00% 0.06% 10.35% 0.00% 3.87% 20.70% 44.95% 5.54% 0.27% 0.14% 0.2719 0.00% 0.00% 0.00% 0.06% 9.86% 0.00% 3.77% 20.56% 43.24% 5.70% 0.26% 0.14% 0.2720 0.00% 0.00% 0.00% 0.06% 10.36% 0.00% 4.04% 21.06% 43.50% 5.76% 0.24% 0.12% 0.0921 0.00% 0.00% 0.00% 0.06% 10.13% 0.00% 3.99% 18.83% 43.99% 7.24% 0.26% 0.11% 0.2522 0.00% 0.00% 0.00% 0.05% 8.26% 0.00% 3.16% 16.49% 38.33% 5.49% 0.21% 0.11% 0.2123 0.15% 0.08% 0.13% 0.23% 8.26% 0.00% 4.28% 21.70% 42.74% 2.04% 0.23% 0.13% 0.1124 0.00% 0.00% 0.00% 0.06% 10.31% 0.00% 3.98% 20.18% 45.03% 7.00% 0.26% 0.12% 0.2325 0.00% 0.00% 0.00% 0.05% 9.89% 0.00% 4.01% 20.32% 44.38% 6.15% 0.26% 0.12% 0.2426 0.00% 0.00% 0.00% 0.06% 10.38% 0.00% 3.96% 20.78% 45.55% 5.82% 0.29% 0.15% 0.2927 0.00% 0.00% 0.03% 0.23% 11.92% 0.57% 4.46% 23.31% 40.95% 5.97% 0.23% 0.14% 0.2028 0.00% 0.00% 0.00% 0.06% 9.66% 0.00% 3.71% 18.87% 42.84% 6.09% 0.25% 0.12% 0.2429 0.00% 0.00% 0.00% 0.05% 10.10% 0.00% 3.89% 20.90% 44.75% 7.03% 0.26% 0.11% 0.2430 0.00% 0.00% 0.00% 0.05% 10.30% 0.00% 3.94% 20.99% 45.39% 6.65% 0.26% 0.12% 0.2531 0.00% 0.00% 0.00% 0.05% 9.57% 0.00% 3.68% 18.75% 43.46% 5.06% 0.25% 0.13% 0.2532 0.00% 0.00% 0.00% 0.06% 10.25% 0.00% 3.80% 19.91% 44.69% 5.77% 0.27% 0.14% 0.2733 0.00% 0.00% 0.00% 0.06% 10.54% 0.00% 4.08% 21.25% 45.95% 6.37% 0.27% 0.13% 0.2634 0.00% 0.00% 0.00% 0.05% 10.14% 0.00% 4.30% 20.04% 45.23% 5.57% 0.30% 0.13% 0.2935 0.00% 0.00% 0.00% 0.05% 9.44% 0.00% 3.59% 18.78% 42.12% 6.07% 0.23% 0.12% 0.2236 0.00% 0.00% 0.00% 0.06% 9.93% 0.00% 3.82% 19.07% 43.18% 6.59% 0.25% 0.11% 0.2437 0.00% 0.00% 0.13% 0.61% 20.86% 6.13% 4.79% 37.37% 19.08% 1.25% 0.04% 0.24% 0.0038 0.00% 0.00% 0.00% 0.05% 10.05% 0.00% 4.04% 21.12% 45.19% 6.02% 0.26% 0.12% 0.2439 0.00% 0.00% 0.00% 0.06% 10.45% 0.00% 4.03% 20.78% 45.42% 6.16% 0.27% 0.13% 0.25

Table 8. FAME Analysis of B100 Samples

 23
Summary and Conclusions 

In the marketplace, where biodiesel is an emerging fuel, fuels must meet or exceed the 

prevailing fuel property specifications. Ensuring that biodiesel is of adequate quality is 

necessary both to comply with federal law (fuel registration and tax credit requirements) and 

to provide consumers with the reliability that they have come to expect from petroleum 

products and modern vehicles. The 59% failure rate observed for this study shows significant 

and serious quality issues at the time these samples were collected. The primary failures were 

for total glycerin (33%) and flash point (30%). Even considering that the failure rate 

observed in this study applies only to the samples we collected and is not based on 

production volume, the results are still alarming. The 2004 study, conducted when biodiesel 

production was estimated at 25 million gallons, showed only a 15% failure rate.4 

Ensuring biodiesel quality is critical for the future growth of the biodiesel market. To that 

end, the National Biodiesel Board has begun to stress fuel quality and has released several 

informational documents to assist its members in this area.9

With the increase of B99.9 blends in the marketplace to take advantage of the tax credit 

available, the ability to ensure the B100 quality before blending becomes even more 

important. In particular, with D6584 (Test Method for Determination of Free and Total 

Glycerin in B-100 Biodiesel Methyl Esters by Chromatography) not being applicable to fuels 

with diesel content, even at 0.1%, the measurement of glycerin content is clearly an area for 

concern. The test methods will need to be adapted or new methods developed to allow for 

determination of glycerin content in B99.9 blended fuels. 

 24
References 

 

1 The Library of Congress, H.R. 4520, accessed on March 27, 2007, 

http://thomas.loc.gov/cgi-bin/bdquery/z?d108:HR04520:@@@L&summ2=m&. 

2 National Biodiesel Board Web site, accessed March 27, 2007, 

www.biodiesel.org/resources/pressreleases/gen/20041022_tax_Incentive_Passage.pdf.

3

 National Biodiesel Board Web site, “Estimated US Biodiesel Sales,” accessed March 27, 

2007, www.biodiesel.org/pdf_files/fuelfactsheets/Biodiesel_Sales_Graph.pdf. 

4

 McCormick, R.L.; Alleman, T.L.; Ratcliff, M.; Moens, L.; Lawrence, R. Survey of the 

Quality and Stability of Biodiesel and Biodiesel Blends in the United States in 2004. NREL 

Technical Report NREL/TP-540-38836, October 2004. 

5 McCormick, R.L.; Alleman, T.L.; Waynick, J.A.; Westbrook, S.R.; Porter, S. Stability of 

Biodiesel and Biodiesel Blends: Interim Report. NREL/TP-540-39721, April 2006. 

6 Gordon, M.H., Musri, E. “A Comparison of Oil Stability Based on the Metrohm Rancimat 

with Storage at 20oC.” J. Am. Oil. Chem. Soc. 71 649-651 (1994). 

7 Frankel, E.N. 2005. Lipid Oxidation, 2nd Edition. The Oily Press, Ltd, Bridgewater. 

8 Fats and Oils Handbook, AOCS Press, 1998. 

9

 National Biodiesel Board Web site, Fuel Quality Enforcement Guide, accessed on March 

27, 2007, www.biodiesel.org/resources/fuelqualityguide/. 

 25
 

Appendix 

To investigate the impact of small amounts of diesel fuel on the flash point of biodiesel 

blends, a typical No. 2 diesel fuel and biodiesel were used to produce B99 and B99.9 blends. 

These blends were analyzed for flash point using D93. The results are shown in the table. As 

the data illustrates, the presence of small amounts of diesel fuel in biodiesel (such as a B99 or 

B99.9 blend), does not impact the flash point significantly. 

Fuel Flash point, C 

Diesel fuel 72 

B100 124 

B99.9 124 

B99 124 

 

 26
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OMB No. 0704-0188

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PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION.

1. REPORT DATE (DD-MM-YYYY)

May 2007 

2. REPORT TYPE

Milestone Report 

3. DATES COVERED (From - To)

 

5a. CONTRACT NUMBER

DE-AC36-99-GO10337 

5b. GRANT NUMBER

4. TITLE AND SUBTITLE

2006 B100 Quality Survey Results: Milestone Report 

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

NREL/TP-540-41549 

5e. TASK NUMBER

FC079400 

6. AUTHOR(S)

T.L. Alleman, R.L. McCormick, and S. Deutch 

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Renewable Energy Laboratory 

1617 Cole Blvd. 

Golden, CO 80401-3393 

8. PERFORMING ORGANIZATION 

REPORT NUMBER

NREL/RP-540-41549 

10. SPONSOR/MONITOR'S ACRONYM(S)

NREL 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

11. SPONSORING/MONITORING 

AGENCY REPORT NUMBER

12. DISTRIBUTION AVAILABILITY STATEMENT

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

In 2006, the National Renewable Energy Laboratory conducted a nationwide quality survey of pure biodiesel (B100) 

intended to be used as a blendstock. The study collected random samples throughout the United States and 

analyzed them for quality against the current and proposed ASTM D6751 fuel quality specifications. 

15. SUBJECT TERMS

biodiesel; B100; quality survey; blendstock 

16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON 

a. REPORT 

Unclassified 

b. ABSTRACT 

Unclassified

c. THIS PAGE 

Unclassified

17. LIMITATION 

OF ABSTRACT

UL 

18. NUMBER 

OF PAGES 

19b. TELEPONE NUMBER (Include area code)

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18