NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency & Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

This report is available at no cost from the National Renewable Energy

Laboratory (NREL) at www.nrel.gov/publications.

Contract No. DE-AC36-08GO28308

Technical Report

NREL/TP-5400-72341

May 2019

Metals Analysis of Biodiesel Blends

Teresa L. Alleman, Lisa Fouts, and Earl D. Christensen

National Renewable Energy Laboratory
NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency & Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

This report is available at no cost from the National Renewable Energy

Laboratory (NREL) at www.nrel.gov/publications.

Contract No. DE-AC36-08GO28308

National Renewable Energy Laboratory

15013 Denver West Parkway

Golden, CO 80401

303-275-3000 • www.nrel.gov

Technical Report

NREL/TP-5400-72341

May 2019

Metals Analysis of Biodiesel Blends

Teresa L. Alleman, Lisa Fouts, and Earl D. Christensen

National Renewable Energy Laboratory

Suggested Citation

Alleman, Teresa L., Lisa Fouts, and Earl D. Christensen. 2019. Metals Analysis of 

Biodiesel Blends. Golden, CO: National Renewable Energy Laboratory. 

NREL/TP-5400-72341. https://www.nrel.gov/docs/fy19osti/72341.pdf.
NOTICE

This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable 

Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding 

provided by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Vehicle 

Technologies Office and the National Biodiesel Board under Cooperative Research and Development Agreement 

CRD-15-593. The views expressed herein do not necessarily represent the views of the DOE or the U.S. 

Government.

This report is available at no cost from the National Renewable 

Energy Laboratory (NREL) at www.nrel.gov/publications.

U.S. Department of Energy (DOE) reports produced after 1991 

and a growing number of pre-1991 documents are available 

free via www.OSTI.gov.

Cover Photos by Dennis Schroeder: (clockwise, left to right) NREL 51934, NREL 45897, NREL 42160, NREL 45891, NREL 48097, 

NREL 46526.

NREL prints on paper that contains recycled content.
iii

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Acknowledgments

Co-funding for this work was provided by the National Biodiesel Board under CRADA No. 

CRD-15-593.

The authors wish to acknowledge Ted Sears from NREL’s Federal Fleet Program and the various 

EPAct fleets that provided samples to make this project possible. The authors also acknowledge 

Dr. Greg Gililland and Dr. Jenny Nelson from Agilent Technologies and Dr. Francisco LinaresLopez from Chevron for assistance running samples in this project.
iv

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Nomenclature or List of Acronyms

ASTM ASTM International

Bxx Biodiesel blend, where xx is the percent biodiesel, 

by volume, in the blend

Ca calcium

EPA U.S. Environmental Protection Agency

Fe iron

ICP-AES inductively coupled plasma atomic emission 

spectroscopy

ICP-MS inductively coupled plasma mass spectrometer

K potassium

LOD limit of detection

LOQ limit of quantitation

Mg magnesium

MP-AES microwave plasma atomic emission spectroscopy

Na sodium

NREL National Renewable Energy Laboratory

P phosphorus

ppm parts per million

vol% percent by volume
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Executive Summary

ASTM International (ASTM) Specification D6751 limits the concentrations of sodium + 

potassium and calcium + magnesium to 5 parts per million (ppm) maximum and phosphorus to 

10 ppm maximum. Metals are controlled because of the potential for abrasive solids to contribute 

to engine component wear, for soluble soaps to cause filter clogging and injector deposits, and

the additional diesel particle filter ash loading from biodiesel metals may be an issue.

ASTM D6751 relies on two methods for metals determination in biodiesel, both based on 

inductively-coupled plasma atomic emission spectroscopy (ICP-AES). The limits on metals are 

meant to be protective when biodiesel is used in blends. No limit exists on metals in the biodiesel 

blend specification, ASTM D7467 (6-20 percent biodiesel by volume). Current test methods 

have some significant limitations when trying to get the lowest possible detection limits, as the 

limit of detection is 1 ppm. 

The focus of this study was to measure the metal content in real-world biodiesel blends using a 

variety of analytical methodologies, selected for the lowest detection limits available. In this 

survey, we applied methods with lower detection limits to provide a more quantitative 

understanding of potential impacts on particle filter performance. Samples of B20 were collected 

from various fleets federally mandated to use B20 and public stations throughout the United 

States. It was assumed the B100 was solely responsible for the metal content in the Bxx1 blends. 

Using the biodiesel content, the metal content in the B100 was extrapolated to determine if the 

biodiesel likely met the limits in ASTM D6751 prior to blending with diesel fuel. The average 

biodiesel content in this study was 18 vol% (B18). 

Samples were analyzed by a variety of ICP-AES methods, an emerging microwave plasma 

(MP)-AES method, and an ion chromatography method. UOP-389, an ICP-AES wet ashing 

method, showed the best results of the ICP methods and was used to test all samples in this 

study. To provide a robust comparison, the samples were also run on MP-AES and ICP-mass 

spectrometric (MS) methods. 

All methods investigated provided lower limits of detection than those currently used for metals 

determination in biodiesel. Differences in the results between the methods may be caused by 

myriad factors, e.g., small differences in ionization efficiency may impact results at these very 

low levels for the elements of interest. Another key factor may be the different preparation 

techniques. Our work shows some disagreement may exist between methodologies that needs to 

be further investigated. 

With one exception, metal contents were very low and often at or below the detection limits of 

the methods. Good directional agreement was observed among the methods. Some variability 

was expected due to very low levels of metals present. Beyond one sample with very high 

calcium by all methods, the techniques showed some discrepancies for this element. Each 

method showed several samples with notable calcium content, although the agreement between 

methods was not as great as with the other elements. 

 1 Biodiesel blend, where xx is the percent biodiesel by volume in the blend.
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In total, thirty-five B20 samples collected from public stations and mandated fleets around the 

United States were tested for metal content using three different methods. Two of the methods 

were based on ICP, with one using ICP-AES after ashing and the other was direct analysis by 

ICP-MS. The third analytical method was MP-AES, an emerging alternative to ICP-AES. 

Follow-up work should continue to collect data on metal contents of field B20 samples. Having a 

better understanding of the overall quality of B20 should be useful going forward as one tool to 

assist in the investigation of the useful life of diesel aftertreatment. The MP-AES technique is not 

yet standardized through ASTM, and future work should develop a standard test method for use 

in industry. Lower detection limits are likely possible with optimization of instrument parameters 

specific to biodiesel blend samples. 
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Table of Contents

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

2 Methodology ......................................................................................................................................... 3

Sample Collection .................................................................................................................................. 3

Test Method Selection............................................................................................................................ 3

UOP-389................................................................................................................................................. 4

Microwave-Plasma Atomic Emission Spectroscopy (MP-AES) ........................................................... 4

Inductively-Coupled Plasma Mass Spectrometry (ICP-MS).................................................................. 6

3 Results................................................................................................................................................... 7

ICP-AES................................................................................................................................................. 8

MP-AES ............................................................................................................................................... 10

ICP-MS................................................................................................................................................. 14

Method Comparison ............................................................................................................................. 16

4 Conclusions ........................................................................................................................................ 18

References................................................................................................................................................. 19

Appendix A ................................................................................................................................................ 22
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List of Figures

Figure 1. State locations of B20 sampling. .................................................................................................. 3

Figure 2. Biodiesel blend content ................................................................................................................. 7

Figure 3. Na and K results for B20 samples by UOP-389............................................................................ 9

Figure 4. Ca and Mg results for B20 samples by UOP-389........................................................................ 10

Figure 5. MP-AES metals results for Na and K.......................................................................................... 12

Figure 6. MP-AES metals results for Ca and Mg ....................................................................................... 13

Figure 7. ICP-MS Na and K ....................................................................................................................... 14

Figure 8. ICP-MS Ca and Mg ..................................................................................................................... 15

Figure 9. ICP-MS Fe, semi-quantitative ..................................................................................................... 16

List of Tables

Table 1. Wavelengths for Detection of Ca, K, Mg, and Na using UOP-389................................................ 4

Table 2. MP-AES Instrument Conditions..................................................................................................... 5

Table 3. Wavelengths for Detection of Ca, K, Mg, and Na using MP-AES................................................. 5

Table 4. ICP-MS Instrument Conditions ...................................................................................................... 6

Table A-1. Biodiesel Blend Content Results.............................................................................................. 23

Table A-2. Analytical Results and Error Bars for Survey Samples............................................................ 24

Table A-3. UOP-389 Results...................................................................................................................... 26

Table A-4. MP-AES results........................................................................................................................ 27

Table A-5. ICP-MS Results. ....................................................................................................................... 28
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1 Introduction

The Renewable Fuels Standard mandated 2.1 billion gallons of biomass-based diesel in 2018, 2.1

billion gallons in 2019 and proposes 2.43 billion gallons in 2020 (U.S. Environmental Protection 

Agency [EPA] 2018b). Of those mandated gallons, EPA reports biodiesel production of 2.05

billion gallons and non-ester renewable diesel of 0.453 billion gallons in 2017, exceeding the 

mandate (EPA 2018a). These figures indicate strong growth in the biodiesel market over the past 

10 years (National Biodiesel Board 2018). Most biodiesel was used as a blend with petroleum 

diesel, typically a 20-volume percent (vol%) blend or less (biodiesel blends are designated Bxx, 

where xx is the volume percent biodiesel in the blend). 

The quality of biodiesel and its blends with diesel fuel has been widely reported (McCormick et 

al. 2004; McCormick et al. 2005; Alleman et al. 2007; Alleman and McCormick 2008; Tang et 

al. 2008; Geng et al. 2009; Alleman et al. 2010; Alleman et al. 2011; de Guzman et al. 2010; 

Alleman et al. 2013; Lopes et al. 2014; Legg and Legg, 2015). The surveys collected biodiesel 

samples, analyzed them for key properties, and compared them to the prevailing ASTM

International (ASTM) specifications at the time of the survey. The ASTM specifications have 

become increasingly stringent over the years as more experience in the use of biodiesel and 

biodiesel blends has been gained. 

Currently, one of the most significant questions about biodiesel quality concerns limits for trace 

metals. Alkali (sodium [Na] and potassium [K]) and alkaline earth (calcium [Ca] and magnesium 

[Mg]) metals can be present in biodiesel as residues from the production process. Specification

ASTM D6751 limits the combinations of Na+K and Ca+Mg to 5 parts per million (ppm)

maximum and phosphorus (P) to 10 ppm maximum. As discussed in the appendix to ASTM 

D6751, both groups of metals are controlled because of the potential for abrasive solids to 

contribute to engine component wear or for soluble soaps to cause filter clogging and injector 

deposits.

Alkali and alkaline earth metals may also impact diesel catalyst/filter emission control systems 

and this question is being examined in ongoing research (Williams et al. 2013; Williams et al. 

2014; Lance et al. 2016). Recent research (Lance et al. 2016) suggests for heavy-duty systems 

with a 435,000-mile full-useful-life requirement, the additional diesel particle filter ash loading 

from biodiesel metals may be an issue depending on the actual levels of Na and K found in 

biodiesel blends on the market. The test method currently used for this determination has a 

detection limit of 1 ppm. Previous surveys of B100 quality have shown most samples have Na 

and K levels below detection (Alleman et al. 2013). In this survey we are applying methods with 

lower detection limits to provide a more quantitative understanding of potential impacts on 

particle filter performance.

ASTM D6751 relies on two methods for metals determination in biodiesel, both based on 

inductively-coupled plasma atomic emission spectroscopy (ICP-AES). The specification 

measures Ca, Mg, Na, and K by EN14538, and P is measured by ASTM D4951. The limits on 

metals in ASTM D6751 are meant to be protective when biodiesel is used in blends. No metal 

limit exists in the biodiesel blend specification, ASTM D7467.
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ASTM D7467 allows for biodiesel content between 6 and 20 vol%. Previous surveys have found 

biodiesel content is slightly lower in the winter to allow blenders to meet regional cold flow 

requirements (Alleman et al. 2011). Federal fleets are required to use a minimum of 20 vol% 

biodiesel throughout the year to meet mandates for alternative fuel use. 

The current test methods have some significant limitations when trying to get the lowest possible 

detection limits. The limit of detection of EN14538 is 1 ppm for each metal, and the method 

includes a statement if the metal is below the limit of detection of the method, it is not included 

in the reporting calculation. The ASTM D4951 method was originally developed for lubrication 

oil with much higher metal content than biodiesel. The operating range of the method is 500 –

1,200 ppm P.

The goal of this study was to measure the metal content in real-world biodiesel blends using a 

variety of analytical methodologies. These analytical techniques were selected for the lowest 

detection limits available.
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2 Methodology

Samples of B20 were collected from various fleets federally mandated to use B20 and at public 

stations throughout the United States. Samples were collected in 1-gallon containers and shipped 

to the National Renewable Energy Laboratory (NREL) for analysis. 

Sample Collection

Thirty-five samples were collected from February through June 2016 throughout the contiguous 

United States. Nine samples were collected from fleets using B20, and the remaining 26 samples 

came from retail stations. Many of the retail stations were sampled in the last two weeks of June

2016. Each station was called to confirm they were selling a Bxx blend before a sample was 

collected. Figure 1 shows where the samples were collected. The blue markers identify retail 

stations, and the red markers identify fleet locations. 

Figure 1. State locations of B20 sampling. 

Test Method Selection

Initially, subsets of five samples were selected and sent for metal analysis by various 

methodologies. These methods included ICP-AES by UOP-389 and a method based on EPA 

6010C. Other potential techniques considered were ion chromatography and microwave plasma 
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(MP)-AES. Good improvements in the detection limit of the results were shown by the UOP-389 

and MP-AES methods, which are discussed in detail below. The EPA 6010C and ion 

chromatography methods did not achieve the detection limits necessary for this work, although 

the techniques are described in Appendix A. 

UOP-389

Based on the screening results, the UOP-389 method (Procedure A) was selected for testing all 

samples. The commercial lab selected to run the method is BQ-9000 accredited and claimed the

ability to provide improved detection limits. UOP-389 Procedure A uses digestion in a sulfur 

trioxide pyridine complex to produce ash, then dissolution in aqua regia and water prior to ICPAES analysis. Table 1 lists the wavelengths and applicable concentrations for the elements of 

interest from the UOP-389 method. 

Table 1. Wavelengths for Detection of Ca, K, Mg, and Na using UOP-389

Element Wavelength,

nm

Concentration

Range, ppm

Ca 393.366 0.8 – 5

K 766.491 0.05 – 500

Mg 279.553 0.04 – 200

Na 589.592 0.04 – 500

Microwave-Plasma Atomic Emission Spectroscopy (MP-AES)

An emerging alternative method for elemental analysis is MP-AES. In contrast to ICP-AES, MPAES uses microwaves to generate a nitrogen-based plasma. Sample introduction and detection 

are similar to ICP-AES. Samples were measured in-house for Na, K, Ca, Mg, and P. Instrument 

conditions are listed in Table 2. Table 3 lists the recommended detection wavelengths and 

applicable concentrations for the elements of interest. Additional details of the MP-AES 

methodology for biodiesel and diesel analysis can be found in Lowenstern and Reisman (2011).
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Table 2. MP-AES Instrument Conditions

Parameter Condition

Instrument Agilent 4200 

MP-AES

Nebulizer Inert, high solids

Spray chamber Cyclonic 

 double pass

Pump tubing Viton

Pump rate 5 mL/min

Uptake delay 60 s

Stabilization time 45 s

Read time 10 s

Air injection Yes

Background 

 correction

Auto

Internal standard 20 ppm yttrium

Table 3. Wavelengths for Detection of Ca, K, Mg, and Na using MP-AES

Element Wavelength,

nm

Concentration

Range, ppm

Ca 396.847 0 – 10

K 766.491 0 – 20

Mg 285.213 0 – 20 

Na 588.995 0 – 10 

P 213.618 1.0 – 20 
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Inductively-Coupled Plasma Mass Spectrometry (ICP-MS)

Although outside of the scope of this study, an inductively coupled plasma mass spectrometry 

(ICP-MS) technique was used to validate the other techniques presented in this study. ICP-MS 

can provide the best detection limits of any method studied, the cost of analysis makes it 

prohibitive for routine testing when other methods provide adequate detection limits. The results 

are presented here for comparison. The ICP-MS calibration was set to mirror the calibration used 

with the MP-AES. In addition to Na, Ca, K, Mg, and P, samples were tested semi-quantitatively 

for iron (Fe) by ICP-MS. Conditions for the ICP-MS are listed in Table 4. 

Table 4. ICP-MS Instrument Conditions

Parameter Condition

Instrument Agilent 7900

ICP-MS

Forward power 1,550 W

RF matching 1.8 V

Sample depth 8

Nebulizer gas 0.45 L/min

Option gas 10%

Nebulizer pump 0.04 rps

Spray chamber

 temperature

-2°C

Dilution gas 0.10 L/min

Collison cell

He mode

H2 mode

5.0 mL/min

6.0 mL/min

Element isotope

 and detection limit

40Ca 0.5 ppb

56Fe a

23Na 9.6 ppb

24Mg 1.6 ppb

39K 1.25 ppb

31P 1.24 ppb

ppb: parts per billion

a Fe results were semi-quantitative.
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3 Results

The primary focus of this work was to examine the metal content of the B20 samples; however,

other properties of interest were also measured. The biodiesel blend content, measured using 

ASTM D7371, is presented in Figure 2 (numerical results are in Table A-1. Data is arranged by 

Petroleum Area Defense District from I to V [top to bottom] and then alphabetically, with a line 

delineating each region). It was assumed the B100 was solely responsible for the metal content in 

the Bxx blends. Using the biodiesel content, the metal content in the B100 was extrapolated to 

determine if the biodiesel likely met the limits in ASTM D6751 prior to blending with diesel 

fuel. Other analytical properties for the Bxx blends are given in Table A-2. 

Figure 2. Biodiesel blend content

Diesel fuel may contain up to 5 vol% biodiesel with no requirements for labeling or disclosure of 

the biodiesel content (16 Code of Federal Regulations [CFR] Part 306). Notable exceptions are 

the states of Minnesota and Oregon, which mandate B5 year-round, and Washington State, 

which mandates B2 (Transportation Environmental Resource Center undated). At the time of this 

work, Minnesota required B10 from April 1 through September 30, and only B10 was readily 

available during the study period (Minnesota Department of Agriculture 2018). The B20 

mandate for Minnesota was planned to go into effect May 1, 2018, but was temporarily 

suspended until June 30, 2018 (Minnesota Department of Commerce 2018).
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With no requirement to disclose the volume of biodiesel in conventional diesel fuel, blenders 

have three options when making biodiesel blends for retail. First, measure the biodiesel content 

of the diesel fuel being used in blending to precisely determine how much biodiesel is needed to 

make a B20 blend (samples that are B20). Second, assume the diesel fuel contains 5 vol%, and 

blend no more than 15 vol% additional biodiesel (samples that are ~B17, for example, were 

likely blended under this assumption, but the diesel fuel was a B2), or simply add 20 vol% 

biodiesel (samples slightly above B20). 

The average biodiesel content in this study was 18 vol%. Three stations had less than 2 vol% 

biodiesel. Each of these three stations was contacted prior to sample collection and confirmed 

they were selling biodiesel. It is unclear why these samples did not contain any biodiesel—

whether between the time of contact and collection (typically less than 2 weeks) the station 

stopped selling Bxx blends for whatever reason, whether there was some misunderstanding about 

the blend being sold when the station was contacted, etc. 

ICP-AES 

The UOP-389 method was developed for the analysis of petroleum products and blending 

components, including biodiesel blends. This, along with the improved detection limits, were the 

primary reasons the method was selected for this project. The commercial lab that ran the UOP389 method reported a detection limit of 0.1 ppm for all elements tested (Na, K, Ca, and Mg), 

although the method states slightly lower detection limits are possible (Table 1).

The first results provided by the laboratory showed the metal content of most samples below the 

limit of detection (LOD) of 0.1 ppm. However, the laboratory agreed to provide uncertified, “out 

of scope” results. These results were below the lowest calibration point of the method, but still 

showed a measurable peak above the signal to noise of the instrument (samples with results 

below the limit of quantitation [LOQ] of the method but having detectable metals content). 

These results are presented in Figures 3 and 4 and Table A-3.
9

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Figure 3. Na and K results for B20 samples by UOP-389
10

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Figure 4. Ca and Mg results for B20 samples by UOP-389.

Sodium was near or below the stated LOQ for every sample, with the exception of samples TN2, ID, and IN. None of the samples had K or Mg above the LOQ. Only samples ID and KS had 

detectable Ca present in the sample. Assuming the Ca present in the sample came only from the 

biodiesel, the Ca content of the KS B100 can be extrapolated to 2.65 ppm. While the KS B100 

would not be off specification at this level, detectable metals have not typically been observed in 

previous biodiesel blend quality survey work (Geng et al. 2009; Alleman et al. 2013; Alleman et 

al. 2011; Alleman et al. 2010). 

MP-AES

MP-AES is a new analytical technique emerging as an alternative to ICP-AES for metal 

detection. Currently, a standard method for analysis of metals in fuels does not exist although the 

method standardization process has begun through ASTM. 

Results from the MP-AES (Appendix Table A-4 and Figures 5 and 6) show similar results to the 

ICP-AES, with very low levels of metals for most samples. Phosphorus was not plotted due to 

only one sample having measured P content. 
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To determine the limit of blank (i.e. noise) on our instrument, the same blank sample was 

measured 10 times at each wavelength. Under these operating conditions, the limits of blank

were: 0.413 ppm for P, 0.045 ppm for Mg, and 0.023 ppm for Ca, K, and Na. With further 

modification of the instrument parameters, improved limits may be possible. Similar to the UOP389 method, several samples had measurable peaks and are reported here. 

Only sample KS had Na content above the LOQ/LOD of the method. The P content of the KS 

sample was measured by the instrument software, but was below the LOQ reported for this 

method. The K content of several samples was above the LOQ/LOD (GA, KS, IN, IA, CO, ID, 

OR-1, and CA-1) although in most cases the levels were very low. 

Fleet sample FL-1 had detectable K content below the LOQ, but is reported as 0 here due to 

uncertainty in the measurement. Samples KS, IN, and ID had at least 0.1 ppm K content. Similar 

results were observed for Ca and Mg, with samples that had detectable K content also having 

detectable Ca and Mg content. 

Similar to the ICP-AES results, sample KS was notable for having the highest total metal content 

of any sample tested by MP-AES. Although the sample contained K, the extrapolated levels in 

the B100 would still be well below the specification limits. In contrast to the results from the 

ICP-AES, the results from the MP-AES showed the extrapolated Ca+Mg content of sample KS 

would have been well in excess of the 5-ppm limit in D6751 (nearly 10 ppm). The sample from 

IN, a B10, had elevated K content of 2 ppm extrapolated to the B100. 
12

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Figure 5. MP-AES metals results for Na and K
13

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Figure 6. MP-AES metals results for Ca and Mg
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ICP-MS

ICP-MS offered the lowest LOQ/LOD of any technique studied, approximately 0.001 ppm for P, 

K, and Mg; 0.009 ppm for Na; and 0.0005 ppm for Ca. Table A-5 and Figures 7, 8, and 9

illustrate the results from the ICP-MS determination. The ICP-MS analysis included P and Fe, in 

addition to Na, K, Ca, and Mg. Phosphorus results are not shown because only two samples had 

detectable P content.

Figure 7. ICP-MS Na and K
15

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Figure 8. ICP-MS Ca and Mg 

Similar to the other analytical techniques, no samples contained measurable Na, and only 

samples KS and CO had P above the detection limit. Note the MP-AES did not measure P above 

the detection limit for these samples. While most samples contained measurable K, samples from

KS and IN had the highest levels by ICP-MS and are very similar to the levels measured by MPAES. 

Although several samples contained trace amounts of Ca and Mg (KS, MI, IN, and CO), the 

levels would have been very low in the B100, with the exception of sample KS. As with the 

other analytical techniques, sample KS had significant Ca content (1.37 ppm), making the B100 

Ca+Mg content significantly above the D6751 limits. The Mg content of sample KS by ICP-MS 

was roughly half of the level reported by MP-AES.
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Figure 9. ICP-MS Fe, semi-quantitative 

The Fe content of the samples was only tested by ICP-MS, and results are semi-quantitative. The 

metal content of sample KS as over 1.5 ppm, indicating an obvious quality problem with either 

the sample or the sampling location or both. Other samples with Fe content above 1 ppm were 

samples GA and MI. 

This survey contains a very limited number of samples, and no correlations can be made between 

Fe content and any other parameter in the study. Iron is not a metal used for biodiesel 

production, and any Fe in the samples was most likely picked up in the distribution system or 

during sample collection, though every effort was made to minimize contamination during 

collection and analysis. 

Method Comparison

All methods investigated provided lower limits of detection than those currently used for metal 

determination in biodiesel. Differences in the results between the methods may be caused by 

myriad factors. Each element has a unique ionization efficiency, and small differences may 

impact results at these very low levels for the elements of interest. Another key factor may be the 

different preparation techniques, with the UOP-389 method using digestion and ashing, while 

MP-AES and ICP-MS used a simpler preparation of sample dilution and direct analysis. 
17

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Sodium was only detected by the UOP-389 method and was not observed above the detection 

limits for either the MP-AES or ICP-MS methods. The work by Lance et al. (2016) suggests the 

need for highly accurate Na determination in biodiesel blends. Our work shows there may be 

some disagreement between methodologies that needs to be further investigated. 

The ICP-MS and UOP-389 methods both found very low levels of K in a majority of samples. 

The MP-AES found K in 25% of the samples (FL-1, GA, KS, IN, IA, CO, ID, OR-1, and CA-1). 

Using the UOP-389 method, the sample from IN had the highest K content. This sample from 

IN, as well as the sample from KS, had elevated K using ICP-MS and MP-AES.

All three methods showed the sample from KS sample having Ca content well above every other 

sample tested. The UOP-389 method showed the lowest Ca (0.53 ppm) compared to the MPAES and ICP-MS (~1.5 ppm) in this sample. Beyond this sample with very high Ca, the 

techniques showed some discrepancies. Each method showed several samples with notable Ca 

content, and the agreement between methods was not as great as with the other elements. 

The Mg determination showed good agreement between methods, with all three techniques 

showing elevated Mg in the sample from KS. Absolute agreement among the methods was poor, 

with the UOP-389 method showing the lowest Mg content (0.06 ppm), ICP-MS having 

intermediate levels (0.17 ppm), and MP-AES having the highest level at 0.36 ppm, although 

these levels are very low in any case. 

Only the MP-AES and ICP-MS methods were used to determine P content of the samples. 

Phosphorus determination at these levels is difficult on the MP-AES, and the reported results are 

below the detection limit of our instrument. The ICP-MS offered a significantly lower detection 

limit than the MP-AES for samples and may be necessary if ultra-low P detection is necessary in 

the future. 
18

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4 Conclusions

Thirty-five B20 samples were collected from public stations and mandated fleets throughout the 

United States. The samples were tested for metal content using three different methods. Two 

methods were based on ICP, with one using ICP-AES after ashing and the other was direct 

analysis by ICP-MS. The third analytical method was MP-AES, an emerging alternative to ICPAES.

All three methods were used successfully to determine the metal content of the biodiesel blend 

samples. With the exception of one sample (KS), metal contents were very low and often at or 

below the detection limits of the methods. Good directional agreement was observed between the 

methods and some variability was expected due to the very low levels of metals present. 

Due to the nature of the methods, not all metals will have the same limits of detection, and some 

metals are inherently more difficult to measure due to high ionization potentials. This is 

especially true for P, though reasonable agreement was achieved between the methods for all 

samples tested. 

Only the B20 sample from KS showed significant metal content in this study. The source of the 

metal was not investigated, as it was beyond the scope. The levels of metals in this sample were 

some of the highest observed in recent quality survey work, and it is highly likely the biodiesel 

was out of specification when blended with the diesel fuel. 

Follow-up work should continue to collect data on the metal content of field B20 samples. Due 

to the long useful life of diesel vehicles, it may be impossible outside of controlled tests to 

determine direct cause and effect of metals on emission control devices. However, having a 

better understanding of the overall quality of B20 should be useful to the industry going forward. 

The MP-AES technique is not yet standardized through ASTM, and future work should develop 

a standard test method for use in industry. Lower detection limits are likely possible with 

optimization of instrument parameters specific to biodiesel blend samples. 
19

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References 

Alleman, T.L., and R.L. McCormick. 2008. Results of the 2007 B100 Quality Survey. Golden, 

CO: National Renewable Energy Laboratory. Technical report NREL/TP-540-42787.

http://www.nrel.gov/docs/fy08osti/42787.pdf. 

Alleman, T.L., L. Fouts, and G. Chupka. 2013. Quality Parameters and Chemical Analysis for 

Biodiesel Produced in the United States in 2011. Golden, CO: National Renewable Energy 

Laboratory. Technical report NREL/TP-5400-57662.

http://www.nrel.gov/docs/fy13osti/57662.pdf. 

Alleman, T.L., L. Fouts, and R.L. McCormick. 2011. “Quality Analysis of Wintertime B6-B20 

Biodiesel Blend Samples Collected in the United States.” Fuel Processing Technology 92, no. 7: 

5407-5415.

Alleman, T.L., R.L. McCormick, and S. Deutch. 2007. 2006 B100 Quality Survey Results: 

Milestone Report. Golden, CO: National Renewable Energy Laboratory. Technical report 

NREL/TP-540-41549. http://www.nrel.gov/docs/fy07osti/41549.pdf. 

Alleman, T.L., L. Fouts, and R.L. McCormick. 2010. Analysis of Biodiesel Blend Samples 

Collected in the United States in 2008 (Revised). Golden, CO: National Renewable Energy 

Laboratory. Technical report NREL/TP-540-46592. 

http://www.nrel.gov/docs/fy11osti/46592.pdf. 

Bock, R., A Handbook of Decomposition Methods in Analytical Chemistry. T.&A. Constable 

Ltd., Edinburgh. 1979.

de Guzman, R.C., H. Tang, S. Wadumesthrige, T. Zhou, M.D. Garcia-Perez, K.Y.S. Ng, and 

S.O. Salley. 2010. “2009 Quality Survey of Retail Biodiesel Blends in Michigan.” Fuel 89:

3662–3667. https://doi.org/10.1016/j.fuel.2010.07.035

Federal Trade Commission, 16 CFR Part 306, “Automotive Fuel Ratings, Certification, and 

Posting,” https://www.ftc.gov/sites/default/files/documents/federal_register_notices/automotivefuel-rating-certification-and-posting-16-cfr-part-306/080311automotivefuelratings.pdf, accessed 

August 24, 2016. 

Geng, P.Y., A.E. Buczynsky, and A. Konzack. 2009. “US and EU Market Biodiesel Blends 

Quality Review – An OEM Perspective.” SAE Int. J. Fuels Lubr. 2, no. 1: 860–869. 

doi:10.4271/2009-01-1850.

Lance, M., T. Toops, R. Ancimer, R., H. An, J. Li, A. Williams, P. Sindler, A. Ragatz, and R.L. 

McCormick. 2016. “Evaluation of Fuel-Borne Sodium Effects on DOC-DPF-SCR Heavy-Duty 

Engine Emission Control System: Simulation of Full-Useful Life.” SAE Technical Paper No. 

2016-01-2322, doi:10.4271/2016-01-2322.

Legg, R.R., and M.T. Legg. 2015. “Survey of Biodiesel Content at Retail Diesel Fuel Outlets in 

Illinois and Minnesota.” CRC Project No. E-112, www.crcao.org. 
20

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Lopes, S.M., P. Geng, and A. Konzack. 2014. “Review of 2013 U.S. Retail Biodiesel Blends 

Quality Survey.” SAE Technical Paper 2014-01-1379, doi:10.4271/2014-01-1379.

Lowenstern, P., and E. Reisman. 2011. Analysis of Diesel using the 4100 MP-AES. Application 

Note. Melbourne, Australia: Agilent Technologies. Publication number: 5990-9005EN, 

September 1, 2011. https://www.agilent.com/cs/library/applications/5990-

9005EN_AppNote_4100MP-AES_Diesel.pdf. 

McCormick, R.L., T.L. Alleman, M. Ratcliff, L. Moens, and R. Lawrence. 2005. Survey of the 

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

CO: National Renewable Energy Laboratory. Technical report NREL/TP-540-38836. 

http://www.nrel.gov/docs/fy06osti/38836.pdf.

Minnesota Department of Agriculture. 2018. “About the Minnesota Biodiesel Program.” 

http://www.mda.state.mn.us/environment-sustainability/minnesota-biodiesel, accessed August 

17, 2018. 

Minnesota Department of Commerce. 2018. “Temporary Suspension of Biodiesel Minimum 

Content Requirement as authorized under Minn. Stat. 239.77, subd. 2(d).” 

http://mn.gov/commerce-stat/pdfs/temporary-suspension-biodiesel-minimum-requirement.pdf, 

accessed June 8, 2018. 

National Biodiesel Board. 2018. “Production Statistics.” 

http://biodiesel.org/production/production-statistics, accessed May 4, 2018. 

Tang, H., N. Abunasser, A. Wang, B.R. Clark, K. Wadumesthrige, S. Zeng, M. Kim, S.O. Salley, 

G. Hirschlieb, J. Wilson, K.Y.S. Ng. 2008. “Quality Survey of Biodiesel Blends Sold at Retail 

Stations.” Fuel 87: 2951–2955.

Transportation Environmental Resource Center. Undated. “Alternative Fuels – State Regulations 

Listed by Topic.” http://www.tercenter.org/pages/altfuelcompare.htm, accessed June 8, 2018.

U.S. Environmental Protection Agency. 2007. “Method 6010C (SW-846): Inductively Coupled 

Plasma-Atomic Emission Spectrometry.” Revision 3.

U.S. Environmental Protection Agency. 2018a. “Proposed Volume Standards for 2019, and the 

Biomass-Based Diesel Volume for 2020.” https://www.epa.gov/renewable-fuel-standardprogram/proposed-volume-standards-2019-and-biomass-based-diesel-volume-2020, accessed 

August 13, 2018.

U.S. Environmental Protection Agency. 2018b. “2017 Renewable Fuel Standard data.”

https://www.epa.gov/fuels-registration-reporting-and-compliance-help/2017-renewable-fuelstandard-data, access August 13, 2018.

USP XXIV <231>, Heavy Metals, Method II.

Williams, A., J. Burton, R.L. McCormick, T. Toops, A.A. Wereszczak, E.E. Fox, M.J. Lance, G.

Cavataio, D. Dobson, J. Warner, R. Brezny, D.W. Brookshear, and K. Nguyen. 2013. “Impact of 
21

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Fuel Metal Impurities on the Durability of a Light Duty Diesel Aftertreatment System.” SAE 

Technical Paper No. 2013-01-0513, doi: 10.4271/2013-01-0513.

Williams, A., R.L. McCormick, M.J. Lance, C. Xie, T. Toops, and R. Brezny, R. “Effect of the 

Acceleration Factor on the Capture and Impact of Fuel-Borne Metal Impurities on Emissions 

Control Devices.” 2014. SAE Int. J. Fuels Lubr. 7 no. 2, doi:10.4271/2014-01-1500.
22

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications.

Appendix A

To fully explore the various metal analysis methods available, subsets of samples were tested 

using a variety of methods to determine the methods with the lowest detection limit. The three 

methods that had the lowest detection limits, UOP-389, ICP-MS, and MP-AES, are discussed 

above. The other methods used are discussed in more detail here. 

A standard digestion and analysis by ICP-AES was also used, although not following ASTM 

methods for fuels (Bock 1979; USP XXIV). The test laboratory followed standard ICP-AES 

techniques (EPA 2007) for the analysis. Fuels, being a relatively dirtier matrix, will have a 

higher limit of detection than water, although some improvement over current ASTM methods 

may be possible. Results from the EPA 6010C method (EPA 2007) show improved detection 

limits for P, with a detection limit of <0.9 ppm, although results for the other elements of interest 

are comparable to current methods at approximately 1 ppm. 

Another method explored was matrix elimination ion chromatography. Samples were prepared 

by shaking in warm water for 15 minutes and allowed to settle. The aqueous phase was removed 

and filtered. The metal-containing aqueous phase was injected onto an ion chromatograph with 

non-suppressed conductivity detection and analyzed for Na. The method detection limit was 0.34 

ppm Na, which represented an improvement over current methods, but the long run times (~40 

minutes) made this a less attractive method for this study. 
23

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Table A-1. Biodiesel Blend Content Results

State Biodiesel Content, vol% Error, vol%

FL-1 (fleet) 22.01 1.76

FL-2 18.38 1.59

GA 19.36 1.63

NC-1 (fleet) 20.40 1.68

NC-2 0.00 0.71

PA-1 17.73 1.56

PA-2 (fleet) 20.31 1.68

MA 21.35 1.73

VA (fleet) 18.56 1.60

IA (fleet) 16.10 1.48

IL 15.30 1.44

IN 20.34 1.68

KS 17.27 1.53

KY 20.11 1.67

MI 20.51 1.69

MN-1 10.68 1.22

MN-2 10.61 1.22

MO 19.44 1.64

OH-1 20.40 1.68

OH-2 8.84 1.13

TN-1 20.24 1.68

TN-2 (fleet) 20.02 1.67

LA 12.26 1.30

TX-1 17.14 1.53

TX-2 1.40 0.78

TX-3 1.20 0.77

CO 21.99 1.76

ID (fleet) 19.64 1.65

AZ (fleet) 20.39 1.68

CA-1 (fleet) 18.84 1.61

CA-2 22.12 1.77

CA-3 19.90 1.66

NM 19.61 1.65

OR-1 20.10 1.67

OR-2 20.15 1.67
24

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Table A-2. Analytical Results and Error Bars for Survey Samples

State Date

Collected

Cloud 

Point, °C

D5773

Error

Water, 

ppm

D6304

Error

Rancimat, 

Hours

EN15751

Error

Acid 

Number,

mgKOH/g

D664

Error

Peroxide 

Number, ppm

AOCS Cd8b-90

Error

FL-1 (fleet) 4/15/16 -9.9 0.9 155 8.7 21.3 4.4 0.07 0.06 4.9 5.0

FL-2 6/24/16 -2.3 0.9 224 10.9 10.9 2.5 0.12 0.08 34.8 9.2

GA 6/20/16 -0.9 0.9 216 10.7 3.2 1.0 0.12 0.07 39.7 9.9

NC-1 (fleet) 3/24/16 -10.7 0.9 119 7.5 18.2 3.8 0.05 0.05 2.0 4.5

NC-2 6/22/16 -12.7 0.9 80 5.9 10.1 2.3 0.09 0.07 0.2 4.3

PA-1 5/5/16 -10.8 0.9 71 5.5 21.2 4.4 0.03 0.04 1.6 4.5

PA-2 (fleet) 5/5/16 -10.6 0.9 130 7.9 17.9 3.8 0.06 0.06 10.5 5.8

MA 6/23/16 -12.2 0.9 141 8.3 12.4 2.7 0.13 0.08 14.3 6.3

VA (fleet) 7/7/16 -6.5 0.9 249 11.6 17.4 3.7 0.08 0.06 12.9 6.1

IA (fleet) 7/28/16 -10.8 0.9 117 7.4 27.04 5.5 0.04 0.05 1.5 4.5

IL 4/26/16 -14.3 0.9 64 5.1 19.8 4.1 0.06 0.06 3.4 4.7

IN 6/23/16 -9.8 0.9 121 7.5 29.5 6.0 0.08 0.07 5.0 5.0

KS 6/22/16 -3.5 0.9 209 10.5 7.6 1.8 0.18 0.09 32.7 8.9

KY 5/11/16 -9.3 0.9 186 9.8 6.6 1.6 0.15 0.08 30.6 8.6

MI 6/23/16 -14.4 0.9 233 11.2 1.7 0.7 0.12 0.08 144.3 24.8

MN-1 6/2/16 -17.9 0.9 65 5.2 54.6 10.8 0.03 0.05 0.3 4.3

MN-2 6/2/16 -16.3 0.9 44 4.1 56.5 11.1 0.03 0.04 0.2 4.3

MO 2/29/16 -18.7 0.9 65 5.2 14.6 3.1 0.09 0.07 8.0 5.4

OH-1 2/29/16 -9.3 0.9 49 4.4 7.9 1.9 0.02 0.04 15.6 6.5

OH-2 6/22/16 -15.5 0.9 95 6.5 13.5 3.0 0.08 0.06 1.5 4.5

TN-1 3/18/16 -10.0 0.9 182 9.6 2.3 0.8 0.14 0.08 96.3 18.0

TN-1 (fleet) 5/20/16 -11.0 0.9 145 8.4 3.2 1.0 0.16 0.09 68.4 14.0

LA 6/17/16 -6.9 0.9 101 6.8 33.3 6.7 0.12 0.08 1.1 4.4

TX-1 4/4/16 -8.0 0.9 115 7.3 21.4 4.4 0.02 0.04 11.3 5.9

TX-2 6/19/16 -10.5 0.9 58 4.8 24 4.9 0.08 0.06 0.5 4.3

TX-3 6/20/16 -11.1 0.9 67 5.3 24 4.9 0.04 0.05 3.7 4.8
25

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State Date

Collected

Cloud 

Point, °C

D5773

Error

Water, 

ppm

D6304

Error

Rancimat, 

Hours

EN15751

Error

Acid 

Number,

mgKOH/g

D664

Error

Peroxide 

Number, ppm

AOCS Cd8b-90

Error

CO 3/4/16 -11.9 0.9 77 5.7 8.8 2.1 0.05 0.05 13.6 6.2

ID (fleet) 6/10/16 -17.5 0.9 71 5.5 28.7 5.8 0.11 0.07 5.0 5.0

AZ (fleet) 4/22/16 -6.0 0.9 72 5.5 32.0 6.5 0.06 0.06 2.3 4.6

CA-1(fleet) 5/13/16 -13.8 0.9 89 6.3 21.9 4.5 0.07 0.06 4.1 4.8

CA-2 6/22/16 0.7 0.9 136 8.1 7.9 1.9 0.12 0.08 7.5 5.3

CA-3 6/23/16 -6.8 0.9 151 8.6 2.4 0.8 0.30 0.11 35.4 9.3

NM 6/26/16 -12.8 0.9 173 9.3 4.6 1.2 0.08 0.06 0.9 4.4

OR-1 4/29/16 -11.0 0.9 135 8.1 26.4 5.4 0.04 0.05 1.4 4.5

OR-2 6/20/16 -7.3 0.9 137 8.1 23.6 4.9 0.10 0.07 3.3 4.7
26

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Table A-3. UOP-389 Results 

State Na, ppm K, ppm Ca, ppm Mg, ppm

FL-1 (fleet) 0.14 0.04 0.08 0.01

FL-2 0.04 0.01 0.05 0.01

GA 0.06 0.02 0.06 0.01

NC-1 (fleet) 0.06 0.01 0.09 0.02

NC-2 0.02 0.01 0.02 0.01

PA-1 0.09 0.01 0.05 0.02

PA-2 (fleet) 0.08 0.02 0.04 0.03

MA 0.04 0.01 0.04 0.01

VA (fleet) 0.08 0.02 0.06 0.02

IA (fleet) 0.09 0.03 0.04 0.01

IL 0.07 0.01 0.03 0.01

IN 0.2 0.07 0.1 0.03

KS 0.09 0.02 0.53 0.06

KY 0.05 0.01 0.03 0.01

MI 0.11 0.02 0.06 0.01

MN-1 0.04 0.01 0.04 0.01

MN-2 0.02 0.01 0.03 0.01

MO 0.09 0.01 0.05 0.01

OH-1 0.05 0.01 0.05 0.01

OH-2 0.01 0.01 0.03 0.01

TN-1 0.1 0.01 0.06 0.01

TN-2 (fleet) 0.24 0.02 0.08 0.01

LA 0.04 0.01 0.03 0.01

TX-1 0.06 0.01 0.08 0.01

TX-2 0.07 0.01 0.04 0.01

TX-3 0.04 0.01 0.03 0.01

CO 0.09 0.01 0.05 0.01

ID (fleet) 0.22 0.03 0.12 0.03

AZ (fleet) 0.07 0.01 0.04 0.01

CA-1 0.05 0.02 0.03 0.01

CA-2 0.07 0.01 0.04 0.01

CA-3 (fleet) 0.06 0.01 0.04 0.01

NM 0.1 0.02 0.05 0.01

OR-1 0.06 0.02 0.03 0.02

OR-2 0.05 0.01 0.05 0.01
27

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Table A-4. MP-AES results 

State Na, ppm K, ppm Ca, ppm Mg, ppm P, ppm

FL-1 (fleet) ND 0.015 0.03 0.015 ND

FL-2 ND ND ND 0.01 ND

GA ND 0.055 0.055 0.08 ND

NC-1 (fleet) ND ND ND ND ND

NC-2 ND ND ND ND ND

PA-1 ND ND ND ND ND

PA-2 (fleet) ND ND ND ND ND

MA ND ND ND ND ND

VA (fleet) ND ND ND ND ND

IA (fleet) ND 0.04 ND ND ND

IL No Data No Data No Data No Data No Data

IN ND 0.205 ND 0.005 ND

KS 0.1 0.26 1.575 0.355 0.17

KY ND ND ND ND ND

MI ND ND 0.01 0.005 ND

MN-1 ND ND ND ND ND

MN-2 ND ND ND ND ND

MO ND ND ND ND ND

OH-1 No Data No Data No Data No Data No Data

OH-2 ND ND ND ND ND

TN-1 ND ND ND ND ND

TN-2 (fleet) ND ND ND ND ND

LA ND ND ND ND ND

TX-1 ND ND ND ND ND

TX-2 ND ND ND 0.005 ND

TX-3 ND ND ND ND ND

CO ND 0.03 0.045 0.01 ND

ID (fleet) ND 0.095 0.075 0.025 ND

AZ (fleet) ND ND ND ND ND

CA-1 ND 0.035 ND ND ND

CA-2 ND ND ND ND ND

CA-3 (fleet) ND ND ND ND ND

NM ND ND ND ND ND

OR-1 ND 0.03 ND ND ND

OR-2 ND ND ND ND ND
28

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Table A-5. ICP-MS Results. 

State Na, ppm K, ppm Ca, ppm Mg, ppm Fe, ppm

FL-1 (fleet) 0.029 0.021 0.008 0.026 0.065

FL-2 0.029 0.033 0.002 0.014 0.146

GA 0.029 0.034 0.002 0.011 1.44

NC-1 (fleet) 0.029 0.02 0.002 0.01 0.004

NC-2 No Data No Data No Data No Data No Data

PA-1 0.029 0.014 0.002 0.009 0.012

PA-2 (fleet) 0.029 0.031 0.002 0.019 0.017

MA 0.029 0.02 0.002 0.015 0.016

VA (fleet) 0.029 0.028 0.012 0.011 0.086

IA (fleet) 0.029 0.1 0.017 0.014 0.249

IL 0.029 0.02 0.007 0.019 0.005

IN 0.029 0.237 0.106 0.031 0.075

KS 0.029 0.11 1.366 0.166 1.557

KY 0.029 0.022 0.002 0.015 0.069

MI 0.029 0.045 0.122 0.025 3.117

MN-1 0.029 0.016 0.002 0.025 0.172

MN-2 0.029 0.016 0.002 0.048 0.003

MO 0.029 0.034 0.01 0.012 0.019

OH-1 0.029 0.013 0.002 0.011 0.033

OH-2 0.029 0.015 0.002 0.007 0.003

TN-1 0.029 0.019 0.003 0.006 0.085

TN-2 (fleet) 0.029 0.029 0.012 0.009 0.361

LA No Data No Data No Data No Data No Data

TX-1 0.029 0.01 0.002 0.005 0.003

TX-2 0.029 0.012 0.002 0.006 0.004

TX-3 0.029 0.011 0.002 0.005 0.004

CO 0.029 0.023 0.094 0.035 0.037

ID (fleet) 0.029 0.085 0.065 0.034 0.044

AZ (fleet) 0.029 0.085 0.065 0.034 0.044

CA-1 (fleet) 0.029 0.016 0.002 0.019 0.009

CA-2 0.029 0.016 0.002 0.011 0.03

CA-3 0.029 0.033 0.002 0.018 0.005

NM 0.029 0.025 0.002 0.005 0.284

OR-1 0.029 0.012 0.002 0.005 0.009

OR-2 0.029 0.021 0.002 0.005 0.011