ASTM D5185-97
(Test Method)Standard Test Method for Determination of Additive Elements, Wear Metals, and Contaminants in Used Lubricating Oils and Determination of Selected Elements in Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
Standard Test Method for Determination of Additive Elements, Wear Metals, and Contaminants in Used Lubricating Oils and Determination of Selected Elements in Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
SCOPE
1.1 This test method covers the determination of additive elements, wear metals, and contaminants in used lubricating oils by inductively coupled plasma atomic emission spectrometry (ICP-AES). The specific elements are listed in Table 1.
1.2 This test method covers the determination of selected elements, listed in Table 1, in re-refined and virgin base oils.
1.3 For analysis of any element using wavelengths below 190 nm, a vacuum or inert-gas optical path is required. The determination of sodium and potassium is not possible on some instruments having a limited spectral range.
1.4 This test method uses oil-soluble metals for calibration and does not purport to quantitatively determine insoluble particulates. Analytical results are particle size dependent, and low results are obtained for particles larger than a few micrometers.
1.5 Elements present at concentrations above the upper limit of the calibration curves can be determined with additional, appropriate dilutions and with no degradation of precision.
1.6 For elements other than calcium, sulfur, and zinc, the low limits listed in Table 2 and Table 3 were estimated to be ten times the repeatability standard deviation. For calcium, sulfur, and zinc, the low limits represent the lowest concentrations tested in the interlaboratory study.
1.7 The values stated in SI (metric) units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 6.1, 8.2, and 8.4
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Designation: D 5185 – 97 An American National Standard
Standard Test Method for
Determination of Additive Elements, Wear Metals, and
Contaminants in Used Lubricating Oils and Determination of
Selected Elements in Base Oils by Inductively Coupled
Plasma Atomic Emission Spectrometry (ICP-AES)
This standard is issued under the fixed designation D 5185; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
INTRODUCTION
Costs associated with maintenance due to engine and machine wear can be significant. Therefore,
diagnostic methods for determining the condition of engines and other machinery can be important.
This test method is intended to quantify, for the purpose of equipment monitoring, the concentration
of metals in used lubricating oils. Although the precision statement was determined by analyzing a
variety of used oils this test method can, in principle, be used for the analysis of unused oils to provide
more complete elemental composition data than Test Methods D 4628, D 4927 or D 4951.
1. Scope 1.7 The values stated in SI (metric) units are to be regarded
as the standard. The inch-pound units given in parentheses are
1.1 This test method covers the determination of additive
for information only.
elements, wear metals, and contaminants in used lubricating
1.8 This standard does not purport to address all of the
oils by inductively coupled plasma atomic emission spectrom-
safety concerns, if any, associated with its use. It is the
etry (ICP-AES). The specific elements are listed in Table 1.
responsibility of the user of this standard to establish appro-
1.2 This test method covers the determination of selected
priate safety and health practices and determine the applica-
elements, listed in Table 1, in re-refined and virgin base oils.
bility of regulatory limitations prior to use. Specific precau-
1.3 For analysis of any element using wavelengths below
tionary statements are given in Note 1, Note 2, and Note 3.
190 nm, a vacuum or inert-gas optical path is required. The
determination of sodium and potassium is not possible on some
2. Referenced Documents
instruments having a limited spectral range.
2.1 ASTM Standards:
1.4 This test method uses oil-soluble metals for calibration
C 1109 Test Method for Analysis of Aqueous Leachates
and does not purport to quantitatively determine insoluble
from Nuclear Waste Materials Using Inductively Coupled
particulates. Analytical results are particle size dependent, and
Plasma-Atomic Emission Spectrometry
low results are obtained for particles larger than a few
2 D 1552 Test Method for Sulfur in Petroleum Products
micrometers.
(High-Temperature Method)
1.5 Elements present at concentrations above the upper limit
D 4057 Practice for Manual Sampling of Petroleum and
of the calibration curves can be determined with additional,
Petroleum Products
appropriate dilutions and with no degradation of precision.
D 4307 Practice for Preparation of Liquid Blends for Use as
1.6 For elements other than calcium, sulfur, and zinc, the
Analytical Standards
low limits listed in Table 2 and Table 3 were estimated to be ten
D 4628 Test Method for Analysis of Barium, Calcium,
times the repeatability standard deviation. For calcium, sulfur,
Magnesium, and Zinc in Unused Lubricating Oils by
and zinc, the low limits represent the lowest concentrations
Atomic Absorption Spectrometry
tested in the interlaboratory study.
D 4927 Test Methods for Elemental Analysis of Lubricant
and Additive Components—Barium, Calcium, Phospho-
rus, Sulfur, and Zinc by Wavelength-Dispersive X-Ray
This test method is under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.03.0B on Spectrometric Methods.
Annual Book of ASTM Standards, Vol 12.01.
Current edition approved Apr. 10, 1997. Published October 1997. Originally
Annual Book of ASTM Standards, Vol 05.01.
published as D 5185 – 91. Last previous edition D 5185 – 95.
2 Annual Book of ASTM Standards, Vol 05.02.
Eisentraut, K. J., Newman, R. W., Saba, C. S., Kauffman, R. E., and Rhine, W.
E., Analytical Chemistry, Vol 56, 1984.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 5185
A
TABLE 1 Elements Determined and Suggested Wavelengths TABLE 3 Reproducibility
A
Element Wavelength, nm Element Range, mg/kg Reproducibility, μg/g
0.26
Aluminum 308.22, 396.15, 309.27 Aluminum 6–40 3.8 X
0.92
Barium 233.53, 455.40, 493.41 Barium 0.5–4 0.59 X
0.01
Boron 249.77 Boron 4–30 13 X
1.3
Calcium 315.89, 317.93, 364.44, 422.67 Calcium 40–9000 0.015 X
0.61
Chromium 205.55, 267.72 Chromium 1–40 0.81 X
Copper 324.75 Copper 2–160 0.24 X
0.80
Iron 259.94, 238.20 Iron 2–140 0.52 X
0.36
Lead 220.35 Lead 10–160 3.0 X
0.77
Magnesium 279.08, 279.55, 285.21 Magnesium 5–1700 0.72 X
1.2
Manganese 257.61, 293.31, 293.93 Manganese 5–700 0.13 X
0.71
Molybdenum 202.03, 281.62 Molybdenum 5–200 0.64 X
0.50
Nickel 231.60, 277.02, 221.65 Nickel 5–40 1.5 X
0.50
Phosphorus 177.51, 178.29, 213.62, 214.91, 253.40 Phosphorus 10–1000 4.3 X
0.29
Potassium 766.49 Potassium 40–1200 6.6 X
0.39
Sodium 589.59 Silicon 8–50 2.9 X
Silicon 288.16, 251.61 Silver 5–50 0.35 X
0.71
Silver 328.07 Sodium 7–70 1.1 X
0.75
Sulfur 180.73, 182.04, 182.62 Sulfur 900–6000 1.2 X
0.62
Tin 189.99, 242.95 Tin 10–40 2.1 X
0.47
Titanium 337.28, 350.50, 334.94 Titanium 5–40 2.5 X
1.1
Vanadium 292.40, 309.31, 310.23, 311.07 Vanadium 1–50 0.28 X
1.1
Zinc 202.55, 206.20, 313.86, 334.58, 481.05 Zinc 60–1600 0.083 X
A A
These wavelengths are only suggested and do not represent all possible Where: X = mean concentration, μg/g.
choices.
TABLE 2 Repeatability 3.2.2 analyte—an element whose concentration is being
A
determined.
Element Range, mg/kg Repeatability, μg/g
0.41 3.2.3 Babington-type nebulizer—a device that generates an
Aluminum 6–40 0.71 X
0.66
Barium 0.5–4 0.24 X aerosol by flowing a liquid over a surface that contains an
Boron 4–30 0.26 X
orifice from which gas flows at a high velocity.
1.4
Calcium 40–9000 0.0020 X
0.75 3.2.4 calibration—the process by which the relationship
Chromium 1–40 0.17 X
0.91
Copper 2–160 0.12 X between signal intensity and elemental concentration is deter-
0.80
Iron 2–140 0.13 X
mined for a specific element analysis.
0.32
Lead 10–160 1.6 X
0.86 3.2.5 calibration curve—the plot of signal intensity versus
Magnesium 5–1700 0.16 X
1.3
Manganese 5–700 0.010 X
elemental concentration using data obtained by making mea-
0.70
Molybdenum 5–200 0.29 X
surements with standards.
0.49
Nickel 5–40 0.52 X
0.58
3.2.6 contaminant—a foreign substance, generally undesir-
Phosphorus 10–1000 1.3 X
0.33
Potassium 40–1200 3.8 X
able, introduced into a lubricating oil.
0.26
Silicon 8–50 1.3 X
3.2.7 detection limit—the concentration of an analyte that
0.83
Silver 0.5–50 0.15 X
0.66
results in a signal intensity that is some multiple (typically two)
Sodium 7–70 0.49 X
0.81
Sulfur 900–6000 0.49 X times the standard deviation of the background intensity at the
0.17
Tin 10–40 2.4 X
measurement wavelength.
0.37
Titanium 5–40 0.54 X
3.2.8 inductively-coupled plasma (ICP)—a high-
Vanadium 1–50 0.061 X
0.88
Zinc 60–1600 0.15 X
temperature discharge generated by flowing an ionizable gas
A
through a magnetic field induced by a load coil that surrounds
Where: X = mean concentration, μg/g.
the tubes carrying the gas.
Fluorescence Spectroscopy 3.2.9 linear response range—the elemental concentration
D 4951 Test Method for Determination of Additive Ele- range over which the calibration curve is a straight line, within
ments in Lubricating Oils by Inductively Coupled Plasma the precision of the test method.
Atomic Emission Spectrometry 3.2.10 profiling—a technique that determines the wave-
E 135 Terminology Relating to Analytical Chemistry for length for which the signal intensity measured for a particular
Metals, Ores, and Related Materials analyte is a maximum.
3.2.11 radio frequency (RF)—the range of frequencies be-
3. Terminology
tween the audio and infrared ranges (3 kHz to 300 GHz).
3.1 Definitions:
3.2.12 wear metal—an element introduced into the oil by
3.1.1 emission spectroscopy—refer to Terminology E 135.
wear of oil-wetted parts.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 additive element—a constituent of a chemical com- 4. Summary of Test Method
pound that improves the performance of a lubricating oil.
4.1 A weighed portion of a thoroughly homogenized used
oil is diluted ten-fold by weight with mixed xylenes or other
suitable solvent. Standards are prepared in the same manner.
Annual Book of ASTM Standards, Vol 05.03.
Annual Book of ASTM Standards, Vol 03.05. An optional internal standard can be added to the solutions to
D 5185
compensate for variations in test specimen introduction effi- 6.1.2 The empirical method of spectral interference correc-
ciency. The solutions are introduced to the ICP instrument by tion uses interference correction factors. These factors are
free aspiration or an optional peristaltic pump. By comparing
determined by analyzing the single-element, high-purity solu-
emission intensities of elements in the test specimen with tions under conditions matching as closely as possible those
emission intensities measured with the standards, the concen-
used for test specimen analysis. Unless plasma conditions can
trations of elements in the test specimen are calculable.
be accurately reproduced from day to day, or for longer
periods, interference correction factors found to affect the
5. Significance and Use
results significantly must be redetermined each time specimens
5.1 This test method covers the rapid determination of 22
are analyzed.
elements in used lubricating oils and in base oils, and it
6.1.3 Interference correction factors, Kia, are defined as
provides rapid screening of used oils for indications of wear.
follows: For analyte a, we have:
Test times approximate a few minutes per test specimen, and
Ca 5 Ia/Ha (1)
detectability for most elements is in the low mg/kg range. In
addition, this test method covers a wide variety of metals in
where:
virgin and re-refined base oils. Twenty-two elements can be
Ca = concentration of analyte a,
determined rapidly, with test times approximating several
Ia = net line intensity (that is, background corrected) of
minutes per test specimen.
analyte a, and
5.2 When the predominant source of additive elements in
Ha = sensitivity.
used lubricating oils is the additive package, significant differ-
6.1.3.1 Similarly, for an interferent i at the same wave-
ences between the concentrations of the additive elements and
length:
their respective specifications can indicate that the incorrect oil
Ci 5 Ii/Hi (2)
is being used. The concentrations of wear metals can be
indicative of abnormal wear if there are baseline concentration
where:
data for comparison. A marked increase in boron, sodium, or
Ii = contribution from the peak or wing of the interferent
potassium levels can be indicative of contamination as a result
line to the peak intensity of the analyte a.
of coolant leakage in the equipment. This test method can be
6.1.3.2 The correction factor, Kia is defined as:
used to monitor equipment condition and define when correc-
Kia 5 Hi/Ha 5 Ii/~Ci 3 Ha! (3)
tive actions are needed.
5.3 The concentrations of metals in re-refined base oils can
6.1.3.3 Analysis of high-purity stock solutions with a cali-
be indicative of the efficiency of the re-refining process. This
brated instrument gives Ii/Ha, the concentration error that
test method can be used to determine if the base oil meets
results when analyzing a solution containing an interferent of
specifications with respect to metal content.
concentration Ci. Dividing by Ci gives the dimensionless
correction factor Kia. To apply these correction factors:
6. Interferences
Ca, apparent 5 ~Ia 1 Ii!/Ha (4)
6.1 Spectral—Check all spectral interferences expected
from the elements listed in Table 1. Follow the manufacturer’s
Ca, apparent 5 Ca 1 Ii/Ha (5)
operating guide to develop and apply correction factors to
Ca 5 Ca, apparent 2 Ii/Ha (6)
compensate for the interferences. To apply interference correc-
Ca 5 Ca, apparent 2 Kia * Ci (7)
tions, all concentrations must be within the previously estab-
lished linear response range of each element listed in Table 1.
and, for more than one interferent:
Ca 5 Ca, apparent 2 K1a 3 C1 2 K2a 3 C2 2 . (8)
NOTE 1—Caution: Correct profiling is important to reveal spectral
interferences from high concentrations of additive elements on the spectral
6.1.4 Interference correction factors can be negative if
lines used for determining wear metals.
off-peak background correction is employed for element i.A
6.1.1 Spectral interferences can usually be avoided by
negative Kia can result when an interfering line is encountered
judicious choice of analytical wavelengths. When spectral
at the background correction wavelength rather than at the peak
interferences cannot be avoided, the necessary corrections
wavelength.
should be made using the computer software supplied by the
6.2 Viscosity Effects—Differences in the viscosities of test
instrument manufacturer or the empirical method described
specimen solutions and standard solutions can cause differ-
below. Details of the empirical method are given in Test
ences in the uptake rates. These differences can adversely affect
Method C 1109 and by Boumans. This empirical correction
the accuracy of the analysis. The effects can be reduced by
method cannot be used with scanning spectrometer systems
using a peristaltic pump to deliver solutions to the nebulizer or
when both the analytical and interfering lines cannot be located
by the use of internal standardization, or both. When severe
precisely and reproducibly. With any instrument, the analyst
viscosity effects are encountered, dilute the test specimen and
must always be alert to the possible presence of unexpected
standard 20-fold rather than 10-fold while maintaining the
elements producing interfering spectral lines.
same concentration of the internal standard.
6.3 Particulates—Particulates can plug the nebulizer
Boumans, P. W. J. M., “Corrections for Spectral Interferences in Optical
thereby causing low results. Use of a Babington type high-
Emission Spectrometry with Special Reference to the RF Inductively Coupled
Plasma,” Spectrochimica Acta, 1976, Vol 31B, pp. 147–152. solids ne
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