ASTM D3227-04a(2010)
(Test Method)Standard Test Method for (Thiol Mercaptan) Sulfur in Gasoline, Kerosine, Aviation Turbine, and Distillate Fuels (Potentiometric Method)
Standard Test Method for (Thiol Mercaptan) Sulfur in Gasoline, Kerosine, Aviation Turbine, and Distillate Fuels (Potentiometric Method)
SIGNIFICANCE AND USE
Mercaptan sulfur has an objectionable odor, an adverse effect on fuel system elastomers, and is corrosive to fuel system components.
SCOPE
1.1 This test method covers the determination of mercaptan sulfur in gasolines, kerosines, aviation turbine fuels, and distillate fuels containing from 0.0003 to 0.01 mass % of mercaptan sulfur. Organic sulfur compounds such as sulfides, disulfides, and thiophene, do not interfere. Elemental sulfur in amounts less than 0.0005 mass % does not interfere. Hydrogen sulfide will interfere if not removed, as described in 9.2.
1.2 The values in acceptable SI units are to be regarded as the standard. The values in parentheses are for information only.
1.3 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. For specific warning statements, see Sections 6, 8, 9, and Appendix X1.
X1.1.1 This test method provides an alternative to using a cadmium sulfate acid solution. (WarningPoison. May be fatal if swallowed or inhaled. A known carcinogen (animal positive).) (WarningPoison. Causes severe burns. Harmful or fatal if swallowed or inhaled.)
X1.1.2 This test method uses lead acetate test paper (WarningPoison, health hazard, may be toxic by ingestion, inhalation, or absorption through the skin) to test for the presence of hydrogen sulfide and sodium hydrogen carbonate for the removal of hydrogen sulfide.
X1.1.3 This test method shall not be used when the sample is a referee sample or when QA/QC protocols specify the test method as written. Instances in which they can be used may be instances of routine refinery control samples.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D3227 − 04a(Reapproved 2010)
Designation: 342/00
Standard Test Method for
(Thiol Mercaptan) Sulfur in Gasoline, Kerosine, Aviation
Turbine, and Distillate Fuels (Potentiometric Method)
This standard is issued under the fixed designation D3227; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope D4177Practice for Automatic Sampling of Petroleum and
Petroleum Products
1.1 This test method covers the determination of mercaptan
D6299Practice for Applying Statistical Quality Assurance
sulfur in gasolines, kerosines, aviation turbine fuels, and
and Control Charting Techniques to Evaluate Analytical
distillate fuels containing from 0.0003 to 0.01 mass% of
Measurement System Performance
mercaptan sulfur. Organic sulfur compounds such as sulfides,
disulfides, and thiophene, do not interfere. Elemental sulfur in
3. Summary of Test Method
amountslessthan0.0005mass%doesnotinterfere.Hydrogen
3.1 The hydrogen sulfide-free sample is dissolved in an
sulfide will interfere if not removed, as described in 9.2.
alcoholic sodium acetate titration solvent and titrated potentio-
1.2 The values in acceptable SI units are to be regarded as
metrically with silver nitrate solution, using as an indicator the
the standard. The values in parentheses are for information
potential between a glass reference electrode and a silver/
only.
silver-sulfide indicating electrode. Under these conditions, the
1.3 This standard does not purport to address all of the
mercaptan sulfur is precipitated as silver mercaptide and the
safety concerns, if any, associated with its use. It is the
end point of the titration is shown by a large change in cell
responsibility of the user of this standard to establish appro-
potential.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. For specific 4. Significance and Use
warning statements, see Sections 6, 8, 9, and Appendix X1.
4.1 Mercaptan sulfur has an objectionable odor, an adverse
effect on fuel system elastomers, and is corrosive to fuel
2. Referenced Documents
system components.
2.1 ASTM Standards:
D1193Specification for Reagent Water 5. Apparatus
D1250Guide for Use of the Petroleum MeasurementTables
5.1 As described in 5.2-5.5; alternatively, any automatic
D1298Test Method for Density, Relative Density (Specific
titrationsystemmaybeusedthat,usingthesameelectrodepair
Gravity), or API Gravity of Crude Petroleum and Liquid
described in 5.3, is capable of performing the titration as
Petroleum Products by Hydrometer Method
described in Section 9 and selecting the endpoint specified in
D4052Test Method for Density, Relative Density, and API
11.1 with a precision that meets or is better than that given in
Gravity of Liquids by Digital Density Meter
Section 14.
D4057Practice for Manual Sampling of Petroleum and
5.2 Meter—An electronic voltmeter, operating on an input
Petroleum Products
−12
of less than 9×10 A and having a sensitivity of 62mV
over a range of at least 61 V. The meter shall be electrostati-
This test method is under the jurisdiction of ASTM Committee D02 on callyshielded,andtheshieldshallbeconnectedtotheground.
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
5.3 Cell System, consisting of a reference and indicating
D02.03 on Elemental Analysis.
Current edition approved May 1, 2010. Published May 2010. Originally electrode. The reference electrode should be a sturdy, pencil-
approved in 1973. Last previous edition approved in 2004 as D3227–04A. DOI:
type glass electrode, having a shielded lead connected to
10.1520/D3227-04R10.
ground. The indicating electrode shall be made from a silver
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Any apparatus that will give equal or better precision is acceptable.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3227 − 04a (2010)
NOTE 1—It is important to pass the propan-2-ol through a column of
wire, 2 mm (0.08 in.) in diameter or larger, mounted in an
activated alumina to remove peroxides that may have formed on storage;
insulated support. Silver billet electrodes can also be used.
failure to remove peroxides will lead to low results. It is not necessary to
5.4 Buret, 10-mL capacity, graduated in 0.05-mL intervals,
perform this step if the alcohol is tested and found free of peroxides.
withatipthatextendsapproximately120mm(5in.)belowthe
6.6.1 Standardization—Add six drops of concentrated
stopcock.
HNO (relative density 1.42) (Warning—Poison. Causes
5.5 Titration Stand,preferablybuiltasanintegralpartofthe
severe burns. Harmful or fatal if swallowed or inhaled) to 100
meter housing and provided with supports for the electrodes
mL of water in an appropriately sized beaker (for example, a
and electrical stirrer, all connected to ground. No permanent
200-, 250-, or 300-mL size beaker is typically large enough).
change in meter reading should be noticeable upon connecting
Remove oxides of nitrogen by boiling for 5 min. Cool to
or disconnecting the stirring motor.
ambient temperature. Pipet 5 mLof 0.1 mol/LKI solution into
the beaker and titrate with the AgNO solution choosing the
6. Reagents and Materials
end point at the inflection of the titration curve.
6.1 Purity of Reagents—Reagent grade chemicals shall be
6.7 Silver Nitrate, Standard Alcoholic Solution (0.010 mol/
used in all tests. Unless otherwise indicated, it is intended that
L)—Prepare daily when the test is being performed by dilution
all reagents shall conform to the specifications of the Commit-
of the 0.1 Nstandard. Pipet 100 mL of the 0.1 mol/L standard
tee onAnalytical Reagents of theAmerican Chemical Society,
into a 1-L volumetric flask and dilute to volume with propan-
where such specifications are available. Other grades may be
2-ol. Calculate the exact molarity.
used, provided it is first ascertained that the reagent is of
6.8 Sodium Sulfide Solution (10 g/L)—Dissolve 10 g of
sufficiently high purity to permit its use without lessening the
Na S in water and dilute to 1 L with water. Prepare fresh as
accuracy of the determination.
6.1.1 Commercially available solutions may be used in needed.
place of prepared laboratory solutions, when they are certified
6.9 Sulfuric Acid, dilute. Cautiously dilute five volumes of
to meet the required concentrations.
water with one volume of sulfuric acid (relative density 1.84).
6.1.2 Alternate volumes of solutions and solvents may be
(Warning—Adding the acid will generate heat: mix well. If
prepared, when an equivalent concentration is maintained.
water begins to boil, cool before adding more acid.) Note that
6.2 Water—Reagent grade, Type I, Specification D1193.
only limited volumes are required because only 10 mL are
needed for each litre of cadmium sulfate solution.
6.3 Cadmium Sulfate, Acid Solution (150 g/L)—Dissolve
150 g of cadmium sulfate (3CdSO ·8H O) in water.
4 2
6.10 Titration Solvent—Low molecular weight mercaptans,
(Warning—Poison. May be fatal if swallowed or inhaled. A
as usually found in gasoline, are readily lost from the titration
known carcinogen (animal positive).) Add 10 mL of dilute
solution if an acidic titration solvent is used. For the determi-
H SO (Warning—Poison. Causes severe burns. Harmful or
2 4
nation of the higher molecular weight mercaptan as normally
fatal if swallowed or inhaled) and dilute to 1 L with water.
encountered in kerosines, aviation turbine fuels, and distillate
fuels, the acidic titration solvent is used to achieve more rapid
6.4 Potassium Iodide, Standard Solution(approximately0.1
equilibrium between successive additions of the titrant.
mol/L)—Dissolve 17 g of KI (weigh to 0.01 g) in 100 mL of
water in a 1-Lvolumetric flask and dilute to 1 L. Calculate the
6.10.1 Alkaline Titration Solvent—Dissolve2.7gofsodium
exact molarity.
acetate trihydrate (NaC H O ·3H O) or 1.6 g of anhydrous
2 3 2 2
sodium acetate (NaC H O ) in 25 mL of water free of
2 3 2
6.5 Propan-2-ol—( Warning—Flammable. Warning—
dissolved oxygen and pour into 975 mLof propan-2-ol (99%)
Unless inhibited against it, peroxides can form in propan-2-ol
(Note 1). When necessary, remove dissolved oxygen by purg-
when stored in the same container that is exposed to air.When
ingthesolutionwitharapidstreamofnitrogenfor10mineach
this happens and the propan-2-ol evaporates to dryness, an
day prior to use; keep protected from the atmosphere. To
explosion can occur. When peroxides are suspected, they may
minimize oxygen from dissolving in the solution during
be removed by percolation through an activated alumina
storage, an option exists to nitrogen blanket the solution prior
column.)
to sealing the solvent container.
6.6 Silver Nitrate, Standard Alcoholic Solution (0.1 mol/
6.10.2 Acidic Titration Solvent—Dissolve 2.7 g of
L)—Dissolve 17 g of AgNO in 100 mL of water in a 1-L
NaC H O ·3HOor1.6gofNaC H O in20mLofwaterfree
2 3 2 2 2 3 2
volumetricflaskanddiluteto1Lwithpropan-2-ol(99%)(see
of dissolved oxygen and pour into 975 mL of propan-2-ol
Note 1). Store in a dark bottle and standardize at intervals
(99%) (Note 1) and add 4.6 mL of glacial acetic acid. When
frequent enough to detect a change of 0.0005 or greater in
necessary, remove dissolved oxygen by purging the solution
molarity.
with a rapid stream of nitrogen for 10 min each day prior to
use; keep protected from the atmosphere.To minimize oxygen
from dissolving in the solution during storage, an option exists
Reagent Chemicals, American Chemical Society Specifications, American
to nitrogen blanket the solution prior to sealing the solvent
Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
container.
listed by the American Chemical Society, see Annual Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
6.11 Polishing Paper or Cloth, 6–20 µm average particle
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. size abrasive.
D3227 − 04a (2010)
7. Sampling solution. Again draw off the aqueous phase, and wash the
sample with three 25 to 30-mLportions of water, withdrawing
7.1 Take the sample in accordance with Practice D4057 or
the water after each washing. Filter the hydrocarbon through a
Practice D4177.
rapidpaper.Testasmallportionofthewashedsample,suchas
7.2 Methanethiol (methyl mercaptan) has a boiling point of
in a test tube or vial, with a few millilitres of the CdSO
6.2°C and may be expected to be present in light untreated
solution as described previously. If no further precipitate is
gasolines. Therefore, when the presence of this low boiling
formed, proceed as directed in 9.3. If a precipitate appears,
thiol (mercaptan) is known or expected, specimen to be tested
repeat the extraction with the CdSO solution until all of the
shall be kept below 4°C to prevent the loss of mercaptan from
H S has been removed. (Warning—Certain straight run gaso-
such samples.
lines can contain significant amounts of both low molecular
weight mercaptans and dissolved elemental sulfur, which,
8. Preparation of Apparatus
whenheatedundertotalrefluxconditions,mayproduceH Sby
8.1 Glass Electrode—After each manual titration, or batch
the inter-reaction of both. This phenomenon is particularly
oftitrations,inthecaseofautomatictitrationsystems,wipethe
noticed in straight run gasolines produced from some natural
electrode with a soft, clean tissue and rinse with water. Clean
gas condensates. Therefore, it is advisable that during the
the electrode at frequent intervals (at least once a week) by
removal of H S (and after all H S has been extracted), that no
2 2
stirring in cold chromic acid solution ( Warning—Causes
heat should be applied to the sample.)
severe burns. A recognized carcinogen. Strong oxidizer—
9.2.1 When the test results obtained are not for referee
contact with other material may cause fire. Hygroscopic. An
purposes and Quality Assurance/Quality Control (QA/QC)
equivalent, chromium-free cleaning solution may be used) for
protocolpermits,analternativetestfor,andaprocedureforthe
a few seconds (10 s maximum). When not in use, keep lower
removal of, hydrogen sulfide can be used. This process uses
half of the electrode immersed in water.
lead acetate paper and sodium hydrogen carbonate and is
8.2 Silver/Silver-Sulfide Electrode—Each day prior to use,
described in Appendix X1.
orastriggeredbytheanalysisofaqualitycontrol(QC)sample
9.2.2 There are available automated instruments that elimi-
(see Section 12), prepare a fresh silver sulfide coating on the
nate the necessity to remove H S when present, prior to
electrode by the following method:
performing the analysis, since the H S titration curve does not
8.2.1 Burnish electrode with polishing paper or cloth until a
interfere with the titration curve of the thiol or mercaptan
clean, polished silver surface shows.
determination. Such equipment may be used when the test is
8.2.2 Placeelectrodeinoperatingpositionandimmerseitin
not for referee purposes. The precision statement does not
100 mL of titration solvent containing 8 mL of Na S solution.
include data obtained from this alternate procedure.
8.2.3 Add slowly from a buret, with stirring, 10 mL of 0.1
9.2.3 For referee purposes, the protocol, as detailed in 9.2,
mol/LAgNO solution over a period from 10 to 15 min.
shall be used. A possible non-referee situation may be the
8.2.4 Removeelectrodefromsolution,washwithwater,and
instance of routine refinery control.
wipe with a soft, clean tissue.
8.2.5 Between manual titrations, or batches of titrations in 9.3 Measure with a pipet (or other suitable transfer device)
the case of automatic titration systems, store the electrode a
or weigh 20 to 50 mLof the original or treated sample into an
minimumof5minin100mLoftitrationsolventcontaining0.5 appropriatelysizedbeaker(forexample,a200,250,or300mL
mL of the 0.1 mol/LAgNO solution.
sizebeakeristypicallylargeenough)containing100mLofthe
appropriate titration solvent. Place the beaker on the titration
9. Procedure
stand or on the auto-sampler of an automatic titration system.
If an automatic titration system is used, set up the system to
9.1 Determin
...
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