Application Note
Energy and Chemicals

ASTM D8322: Elemental Analysis ofCrude Oil and Residual Fuels using
MP-AES
Simple, streamlined, and safe analysis ofpetrochemical samples using an Agilent
4210 MP-AESAuthors
Jenny Nelson,
Neli Drvodelic,
Agilent Technologies, Inc.

Introduction
Trace elements can adversely affect both the refinery of petroleum into different
products and the quality and value of those products (1). The most common
problematic elements are Fe, V, and Ni but other elements such as Zn, Si, Al, Ca, Na,and K are also often present, typically at lower concentrations. Fe, Ni, and V andother trace elements (including Si, Al, K, and Zn) can poison catalysts in the refinery
process or contribute to atmospheric emissions during the combustion of fuels.
Monitoring Na and Ca in crude and residual fuel oils is important to ensure that
efficient desalting of crude can be performed before distillation.

ASTM test method D8322-20 covers the determination of V,Ni, Ca, Na, Al, Si, Zn, and S in residual fuels and Fe, V, Ni, Ca,Na, K, and S in crude oils using MP-AES (2). Measuring thesame elements previously required multiple ASTM methods
and multiple techniques such as ICP-OES, flame AAS(FAAS), and X-ray spectrometry (3). D8322 streamlines theanalysis using a single technique and extends the scope andelemental range of test methods D5708 and D5863(4, 5), improving productivity. It uses simple ‘dilute and shoot’method compared with other ASTM or Energy Institute IP
test methods that use labor-intensive sample preparationsuch as ashing and fusion. Dilute and shoot reduces costs
and improves productivity, as it requires less equipment,fewer reagents, and is easier and faster to do. It also reduces
sources of error associated with sample ashing and fusion,
improving the accuracy of the data.
Agilent MP-AES instruments use a nitrogen‑based plasma as
an atomization source rather than argon or acetylene required
by ICP-OES and FAAS, respectively. The N2 can be produced
from air by an Agilent 4107 nitrogen generator, significantly
reducing the costs and time associated with the supply andhandling of gas bottles. MP-AES is often preferred over FAAS
where lab-safety is important because it does not requireflammable gases and can be used without close supervision,
including for overnight runs. MP-AES with a N2 generator canalso be used in the field or remote areas where the petroleum
industry operates.
The Agilent 4210 MP-AES is fully controlled using MP Expert
software that guides operators through typical workflows
using application-specific preset methods. The instruments
are quick to startup, and the plug-and-play torch ensures
reproducible performance, even between different operators.
The instrument also includes diagnostic software so thatanalysts can check for any problems quickly, maximizing
instrument uptime.
In this study, we report the average results obtained by threeAgilent laboratories for the analysis of crude and residual fueloil samples measured in accordance with the ASTM D832220 method.

2Experimental
Instrumentation
All measurements were performed using three Agilent 4210
MP‑AES instruments in three different laboratories. Dependingon each lab’s set up, the N2 was supplied from an Agilent 4107
Nitrogen Generator, an in-house gas supply, or a combinationof the two. Each MP-AES instrument was set up with anorganics kit comprising an External Gas Control Module(EGCM), inert OneNeb Series 2 nebulizer, and a double-pass
glass cyclonic spray chamber. The OneNeb nebulizer offers
increased nebulization efficiency and a narrow distributionof small droplets. This performance allows the analysis to be
performed at lower flow rates, reducing the solvent loading on
the plasma, while maintaining excellent sensitivity. The EGCM
injects air into the plasma preventing the build-up of carbon
in the torch. The samples were introduced to the MP-AESusing an Agilent SPS 4 autosampler. Instrument operating
conditions are given in Table 1.
Table 1. MP-AES operating conditions.
ParameterSetting

Read Time (s)3 (10 for Sulfur)

Number of Replicate

3

Sample Uptake Delay (s)60Stabilization (s)30

Rinse Time (s)Approximately 60 s (depends on lab)

Pump Speed (rpm)5Sample Pump Tubing*Orange/green (0.38 mm ID)

Internal Standard Tubing*Orange/green (0.38 mm ID)

Waste Pump Tubing*Blue/blue (1.65 mm ID)

Internal StandardYttrium

Background Correction

Auto

Air Injection RequiredYes*Solvent-resistant tubing made from a fluoropolymer elastomer and synthetic rubber compound.

ASTM D8322 method
Each laboratory used an MP Expert software method for
ASTM D8322 that was provided by the authors. An MPApplet for the ASTM D8322 can be created within the MP
Expert software, as shown in Figure 1. MP Expert Applet is abrowser-based software interface that is suitable for routine
operation of the 4210 MP-AES by users of all skill levels (6).

Reference materials and samples
Four National Institute of Standards and Technology (NIST,Gaithersburg, MD, USA) standard reference materials (SRMs)
and two third-party RMs (Analytical Services, Inc., ASI,Houston, Texas, USA) were used to verify the method. NIST
1634c Trace Elements in Crude Oil and the third-party crude
oil RM were used to validate the method for Ni, S, V, Ca, Na, K,and Fe in crude oil. NIST 2721 Crude Oil (Light-sour) and NIST
2722 (Heavy-sweet) were used to validate the method for S incrude oil. NIST 1619b Sulfur in Residual Fuel Oil and the thirdparty fuel oil RM were used to validate the method for Ni, S, V,Ca, Na, Fe, Zn, Si, and Al in fuel oil.
Fuel and crude oil samples were collected by ASI from various
large oil companies that were participating in the ASTM
interlaboratory study (ILS).

Figure 1. Applets created in MP Expert software.

Once an Applet has been created, it simplifies method setup
by loading predefined analytical parameters such as analytes,wavelengths, background correction technique, and EGCM
mode. It also ensures that operating conditions are quick toapply and are consistent from analyst-to-analyst. To ensure
the accuracy and precision of the analysis of residual fuelsand crude oils, the setting of the analyte nebulizer flow rateand EGCM are critical. Auto background correction was used
for the application to resolve the element emission line fromthe organic matrix. The acquisition parameters used for theASTM D8322 method are given in Table 2.

Table 2. MP-AES method acquisition parameters for the ASTM D8322
method.
Element

Wavelength(nm)Nebulizer
Flow Rate(L/min)EGCM Air
Injection
Flow Rate

Background
Correction

Iron

259.940

0.5

MediumAuto

Vanadium

311.070

0.5

HighAuto

Nickel341.476

0.5

High

Auto

Calcium396.847

0.5

High

Auto

Sodium588.995

0.5

High

Auto

Aluminum396.152

0.5

High

Auto

Silicon288.158

0.5

MediumAuto

Zinc

213.857

0.5

MediumAuto

Potassium

766.491

0.5

High

Auto

Sulfur181.972

0.5

Low

Auto

Yttrium*

371.029

0.5

MediumAuto* Internal standard

Standards and sample preparation
All calibration standards were prepared from Agilent A21+K
multi-element organometallic standard. Working standards
for V, Ni, Ca, Na, Al, Si, Zn, S, Fe, and K were prepared withfinal mass fractions of 0.1, 1.0, 10.0, 25.0, 50.0 and, 70 mg/kg.
Working standards for sulfur were prepared at 40.0, 200.0,500.0, 1000.0, and 2000.0 mg/kg from an Agilent single
element standard.
A blank calibration standard was used as the initial andcontinuing calibration blank (ICB and CCB). A 10 mg/kg
multi-element standard was used as a Continuing Calibration
Verification (CCV) solution for all elements except S, which
was prepared at 1000 mg/kg. Yttrium, which was used as
an internal standard (IS) at 20 mg/kg, was added to thesample line before the nebulizer using a mixing tee-connector.
Standards, blanks, spikes, QCs, and IS were matrix matched
to a constant viscosity with mineral oil (or 75 cts oil) anddiluted with o-xylene to give a total oil concentration of 10%(w/w) in each solution.
The residual fuel and crude oils covering a wide range of API
gravity and density were analyzed in this study. The samples
were prepared according to the ASTM D8322 method. The
samples were all diluted from 1:10 up to 1:20 in o-xylene byweight. The more viscous samples that did not readily flowat room temperature were heated in a hot block at 60 °C andshaken before being weighed and diluted with o-xylene. ASI
also prepared all the solutions used for the spike recovery testat the concentrations given in Table 4.

Results and discussion
Calibration
Figure 2 shows representative calibration curves for Fe, Ni, Si,and V obtained from the analysis of the standard solutions
under optimized conditions. Linear calibration curves wereobtained for all elements.
3

Quality control
To check the ongoing validity of the calibration during theanalysis of crude and residual fuel oil samples over four days,three CCV standards were analyzed after every 10 samples.
In accordance with the ASTM ILS guidance, the MP-AES wascalibrated at the beginning of every day. The QC stability plot
in Figure 3 shows the recovery of all elements to be within±20%. The results demonstrate the excellent robustness,stability, and precision of the 4210 MP-AES over four days.
ASTM D8322 does not specify acceptance criteria for therecovery of elements in the QC samples, allowing labs to set
their own limits.

Figure 3. Recovery data for three QC samples measured every 10 samples
for approximately four hours.

Recoveries of certified elements in crude oil and fuelRMs
Fe, V, and Ni are important elements in the assay of crude
oil as they are usually present at the highest concentrations,and they can adversely affect catalytic cracking, productyields, and product quality/value. Ni, S, V, Ca, Na, K, and Fe
were measured in the crude oil RMs and Ni, S, V, Ca, Na, Fe,Zn, Si, and Al were measured in a fuel oil RM in each lab overfour days. The results in Table 3 show excellent recoveries
within ±10% of the certified values or information values forall elements, apart from Ca in the fuel oil RM. Ca was within±20% of the reproducibility test described in the ASTM D8322.
The data demonstrates the accuracy, reproducibility, andreliability of the method.

Figure 2. Calibration curves for Fe, Ni, Si, and V.

4

Table 3. Average recoveries for results from three Agilent laboratories of multiple elements in NIST SRM, a crude oil RM, and a residual fuel oil RM. All recoveries
are within the reproducibility test criteria described in ASTM D8322.
Crude OilNIST 1634c

Third-Party Crude Oil RM

Element and Wavelength(nm)Measured Value(mg/kg)

Certified Value(mg/kg)

Recovery (%)

Measured Value(mg/kg)

Certified Value(mg/kg)

Recovery (%)

Ni 341.476

17.25±1.7

17.54

98

5.05±0.5

5.00

101

S 181.972

20159±6250

20000

101

1038±139

1000

104

V 311.837

28.57±0.1

28.19

101

5.33±0.5

5.00

107

IV

Ca 396.152

48.9±4.3

50.00

98

Na 588.995

49.6±8.3

50.00

99

K 766.491

45.8±1.050.00

92

Fe 259.940

23.62±1.1

25.00

94

NIST 2721 Crude Oil (Light-Sour)
S 181.972

17101±556

15832

NIST 2722 (Heavy-Sweet)
1082015 ± 276

2103.70

96

Measured Value(mg/kg)

Certified Value(mg/kg)

Recovery (%)

7427±1641

6960.0107

Residual Oil
Third-Party Fuel Oil RM

NIST 1619b

Element and Wavelength(nm)Measured Value(mg/kg)

Certified Value(mg/kg)Recovery (%)

Ni 341.476

10.66±1.1

10.00

107

S 181.9724940±631.9

5000

99

V 311.837

10.31±1.7

10.00

103

Ca 396.152

23.51±0.2

20.00

118

Na 588.995

10.55±1.1

10.00

106

Fe 259.940

6.26±0.2

6.00

104Zn 213.618

20.93±2.1

20.00

105

Si 288.158

20.02±3.4

20.00

100

Al 396.152

20.22±0.1

20.00

101

IV=Information value

5

Spike recovery test
The average of the spike recovery results for multiple elements in four crude oil and five residual fuel samples obtained by thethree labs are shown in Table 4. All recoveries were all within ±20% of the reproducibility test described in ASTM D8322. The
recovery data demonstrates the accuracy of the method for the analysis of Fe, V, Ca, Na, K, and S in crude oils and V, Ni, Ca, Na, Al,Si, Zn, and S in residual fuels by MP-AES.

Table 4. Average spike recovery results for duplicate measurements of elements in crude oil and in residual fuel samples measured using MP-AES in three labs
over four days, n=6.
Crude Oil
Spiked Sample-D
Element and Wave-

Measured Value

Spiked Value

length (nm)(mg/kg)(mg/kg)

S 181.972

20997±1303

20000

Spiked Sample-K
Recovery (%)

Spiked Sample-N

Measured Value

Spiked Value

RecoveryMeasured Value

Spiked Value

Recovery(mg/kg)(mg/kg)(%)(mg/kg)(mg/kg)(%)

2236±308.9

2610.0863.27±0.2

3.6789Ca 396.152

3.83±2.0

3.50

110

Na 588.995

100.9±13.8

100.0101

64.71±8.9

70.00

92

138.1±8.6150.092

105

V 311.837

K 766.491

11.73±0.8

12.00

98

24.51±4.2

25.00

98

Fe 259.940

Residual Oil
Spiked Sample-D
Ni 341.476

0.48±0.00.40

Spiked Sample-H
119

51.12±1.650.00

Spiked Sample-L102

S 181.972

12627±1690

12000

105

376.4±3.8

400.0

94

93.99±8.1

100.0

94

45.56±1.1

40.00

114

102.2±1.6

100.0102

30.00

97

Ca 396.152

66.45±2.3

70.00

95

Zn 213.618

1.98±0.22.00

99

Si 288.158

49.04±2.5

45.00

109

156.3±19.7

158.9

98

243.9±19.2

250.0

98

Al 396.152

3.71±0.0

3.30

113

94.12±2.8

90.00

105

148.5±5.2

150.099670.82

99

101

29.23±4.175.21±1.7

250.0

70.00

V 311.837

Na 588.995

247.13±7.6

70.65±4.1

106Quantitative results
Quantitative results for various elements in crude oil and residual fuel samples measured over four days by MP-AES are shownin Tables 5 and 6 respectively. All measured values have been corrected for the wt/wt dilution factors to obtain the concentrationin the original sample. The results show some variation in concentration for each element between the different samples. The
greatest difference was for V, which ranged from 1 to over 360 ppm in both the crude oil and residual oil samples.

Table 5. Average quantitative results for six elements in crude oil samples measured using MP-AES in three labs in duplicate over four days. All data mg/kg.
Crude Oil

APIFeVNiCaNaSKSample A212.08

283.0

58.89

NDND

37858

3.38

Sample B

40.2

0.951.59

0.81

ND

0.65

1893

1.18

Sample C

50.4

0.98

0.71

NDND

1.07

1198

1.45

Sample D

41.6

31.77

0.92

0.54

2.81

17.21

1479

2.27

Sample E

44.6

4.00

2.09

0.82

1.33

2.40

2132

1.69

Sample F

27.8

26.67

102.3

21.81

12.43

90.79

22277

6.20

Sample G

21

12.12

303.8

56.77

4.21

3.42

29648

6.97

Sample H

40.2

67.41

34.48

10.35

103.5

6.46

1628

7.91

Sample I

50.4

6.83

7.59

99.84

64.77

11.82

991.7

21.73

Sample J

41.6

4.28

0.28

1.00

29.77

61.93

1310.634.25Sample K

44.6

173.5

383.5

1.87

ND

3.09

1686

3.65

Sample L30

23.14

4.74

5.05

48.92

53.89

1038

45.81

Sample M

Unknown

26.55

20.89

17.73

8.85

29.45

24145

5.98

Sample N

27.8

2.42

118.9

31.20

ND

0.40

27779

1.60

ND = below valid test range.

Table 6. Average quantitative results for nine elements in residual fuel samples measured using MP-AES by three labs in duplicate over four days. All data reported
as mg/kg.
Fuel OilFeVNiCaNaAlSiZnS

Sample A

2.69

4.81

1.41

0.64

0.812.65

3.00

ND

5574

Sample B

1.95

1.74

0.49

0.75

0.87

ND

5.14

4.05

10420

Sample C

3.63

17.87

5.41

0.86

1.23

9.02

5.97

0.117142

Sample D

2.11

ND

ND

ND

4.17

ND

ND

0.18

3121

Sample E

2.95

ND

0.27

1.46

11.71

1.37

2.35

ND

3359

Sample F

6.84

11.28

11.73

23.54

10.55

14.69

15.70

20.93

4940

Sample G

1.52

364.9

104.9

95.04

98.39

120.0

211.6

106.9

2002

Sample H

2.33

ND

2.78

50.59

74.56

50.81

153.3

72.68

1878

Sample I

2.20

ND

1.11

3.32

5.8447.55

99.45

10.57

1243

Sample J

1.63

6.03

0.97

12.28

6.90

2.89

6.58

1.08

2377

Sample K

7.25

159.5

44.03

1.68

7.61

9.92

19.87

ND33222

ND = below valid test range.

7Conclusion

The publication of the first ASTM D8322-20 method for MPAES provides the petroleum industry with a viable technique
for the direct analysis of complex samples. D8322-20
relates to the quantification of V, Ni, Ca, Na, Al, Si, Zn, and S
in residual fuels and Fe, V, Ni, Ca, Na, K, and S in crude oils
following dilution in o-xylene. Previously, measuring theseelements required using multiple ASTM methods and multipletechniques. D8322 streamlines the analysis using a single
technique and simplifies sample preparation, ensuring greater
productivity and more accurate results.
Excellent accuracy was demonstrated with good recoveries
for certified elements in various crude and fuel referencematerials, and good spike recoveries of actual samples. A QC
stability test over four days showed the excellent robustness,stability, and precision of the 4210 MP-AES, with no need torecalibrate.
The simplicity, accuracy, and reproducibility of the method,plus the low running costs and safety of MP-AES make itsuitable for routine use in the petroleum industry.

www.agilent.com/chem
DE44284.6363425926
This information is subject to change without notice.
© Agilent Technologies, Inc. 2021
Printed in the USA, May 4, 2021
5994-3230EN

References
1.

S. Rand and A. Verstuyft, eds., Significance of Tests
for Petroleum Products: 9th ed. J. Nelson, Chapter
23, Analytical Methods for Determination of InorganicSpecies in Petroleum Products and Lubricants: A Focuson New Technologies and Techniques in the Petroleum
Industry, West Conshohocken, PA: ASTM International,
2018, https://www.astm.org/DIGITAL_LIBRARY/MNL/SOURCE_PAGES/MNL1-9TH.htm

2.

ASTM D8322-20, Standard Test Method for
Determination of Elements in Residual Fuels andCrude Oils by Microwave Plasma Atomic Emission
Spectroscopy (MP-AES), ASTM International, WestConshohocken, PA, 2020, https://www.astm.org/Standards/D8322.htm

3.

Measuring Elements in Residual Fuels and Crude Oil perMethod ASTM D8322 Using an Agilent 4210 MP-AES,Agilent publication, 5994-2460EN

4.

ASTM D5708-15(2020)e1, Standard Test Methods for
Determination of Nickel, Vanadium, and Iron in Crude
Oils and Residual Fuels by Inductively Coupled Plasma(ICP) Atomic Emission Spectrometry, ASTM International,West Conshohocken, PA, 2020, https://www.astm.org/
Standards/D5708.htm

5.

ASTM D5863-00a(2016) Standard Test Methods for
Determination of Nickel, Vanadium, Iron, and Sodiumin Crude Oils and Residual Fuels by Flame Atomic
Absorption Spectrometry, ASTM International, WestConshohocken, PA, 2016, https://www.astm.org/
Standards/D5863.htm

6.

Agilent MP Expert Software, Agilent publication, 59908975EN