ASTM D1318-23

Standard Test Method for Sodium in Residual Fuel Oil (Flame Photometric Method)

SIGNIFICANCE AND USE
5.1 Excessive amounts of sodium can indicate the presence of materials that cause high wear of burner pumps and valves, and contribute to deposits of boiler heating surfaces.
SCOPE
1.1 This test method covers the determination of sodium in residual fuel oil by means of a flame photometer. Its precision in low ranges limits its application to samples containing more than 15 mg/kg sodium. Other elements commonly found in residual fuel oil do not interfere.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements see 7.3, 7.5, 7.7, 9.2, 7.8, 7.9, and Note 3.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Apr-2023
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.03 - Elemental Analysis

Relations

• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D6299-17b - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Dec-2017
• Refers: ASTM D6299-17a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Nov-2017
• Refers: ASTM D6299-17 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Jan-2017
• Refers: ASTM D6299-13e1 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Oct-2013
• Refers: ASTM D4057-06(2011) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• Effective Date: 01-Jun-2011
• Refers: ASTM D6299-10 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Mar-2010
• Refers: ASTM D6299-10e2 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Mar-2010
• Refers: ASTM D6299-09 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Nov-2009
• Refers: ASTM D6299-08 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Oct-2008
• Refers: ASTM D6299-07 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Nov-2007
• Refers: ASTM D6299-07e1 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Nov-2007
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006

Overview

ASTM D1318-23, "Standard Test Method for Sodium in Residual Fuel Oil (Flame Photometric Method)," provides a reliable procedure for quantifying sodium content in residual fuel oils using flame photometry. This internationally recognized petroleum testing standard addresses the presence of sodium, an element that, in excessive quantities, can result in high wear of burner pumps and valves and contribute to problematic deposits on boiler heating surfaces.

The flame photometric method described in ASTM D1318-23 is applicable to samples containing more than 15 mg/kg sodium and is recognized for its high specificity, as commonly occurring elements in residual fuel oils do not interfere with the results. All measurements are based on SI units, ensuring global consistency.

Key Topics

• Significance of Sodium Detection

  • High sodium levels in fuel oil can signal contamination, leading to increased maintenance costs and unplanned downtime in combustion systems.
  • Monitoring sodium helps operators maintain fuel quality and protect infrastructure.

• Flame Photometric Method

  • Employs a flame photometer, focusing on the sodium doublet at 589 nm, for reliable sodium detection in residual fuel oil samples.
  • The method involves sample preparation by ashing, dissolution in acids, and dilution prior to photometric measurement.
  • Requires strict adherence to safety, health, and environmental precautions due to potentially hazardous reagents.

• Precision, Quality Control, and Reporting

  • The method is designed for accuracy with defined limits for repeatability and reproducibility, especially in the sodium range of 15-90 mg/kg.
  • It incorporates regular analysis of quality control (QC) samples and guidance for statistical quality assurance.
  • Results are reported to the nearest 1 mg/kg, supporting regulatory and contractual requirements.

Applications

ASTM D1318-23 is utilized widely in industries dependent on residual fuel oils, including:

• Power Generation: Ensures boiler and turbine protection by identifying sodium contamination that could cause scaling and mechanical wear.
• Maritime and Shipping: Monitors fuel oil quality to avoid engine damage and inefficiency caused by sodium-induced deposits.
• Refinery Operations: Supports quality control and compliance in the blending, storage, and shipment of heavy fuel oils.
• Third-Party Testing Laboratories: Used for commercial fuel certification, customer dispute resolution, and adherence to environmental standards.

Routine sodium monitoring using ASTM D1318-23 helps optimize maintenance schedules, reduce operational risks, and comply with internal and regulatory standards for fuel quality.

Related Standards

Several ASTM standards complement or are referenced by ASTM D1318-23 for comprehensive fuel oil analysis and sampling:

• ASTM D1193 – Specification for Reagent Water (ensures reagent quality in analyses)
• ASTM D4057 – Practice for Manual Sampling of Petroleum and Petroleum Products (for representative sampling)
• ASTM D4175 – Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• ASTM D4177 – Practice for Automatic Sampling of Petroleum and Petroleum Products
• ASTM D6299 – Practice for Applying Statistical Quality Assurance and Control Charting Techniques

Organizations involved in fuel production, testing, and utilization often reference these standards to assure data reliability and maintain quality across analytical operations.

In summary, ASTM D1318-23 is an essential tool for the accurate determination of sodium in residual fuel oils, informing operational decisions, ensuring equipment longevity, and assisting compliance efforts across the energy and maritime sectors.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1318 − 23
Standard Test Method for
Sodium in Residual Fuel Oil (Flame Photometric Method)
This standard is issued under the fixed designation D1318; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* Measurement System Performance
1.1 This test method covers the determination of sodium in
3. Terminology
residual fuel oil by means of a flame photometer. Its precision
3.1 Definitions:
in low ranges limits its application to samples containing more
3.1.1 For definitions of terms used in this test method, refer
than 15 mg ⁄kg sodium. Other elements commonly found in
to Terminology D4175.
residual fuel oil do not interfere.
1.2 The values stated in SI units are to be regarded as
4. Summary of Test Method
standard. No other units of measurement are included in this
4.1 A weighed sample is reduced to a carbonaceous ash
standard.
under controlled conditions. The residual carbon is removed by
1.3 This standard does not purport to address all of the
heating in a muffle furnace at 550 °C. The ash is dissolved,
safety problems associated with its use. It is the responsibility
diluted to volume, and the sodium determined by means of a
of the user of this standard to establish appropriate safety,
flame photometer.
health, and environmental practices and determine the appli-
5. Significance and Use
cability of regulatory limitations prior to use. For specific
hazard statements see 7.3, 7.5, 7.7, 9.2, 7.8, 7.9, and Note 3.
5.1 Excessive amounts of sodium can indicate the presence
1.4 This international standard was developed in accor-
of materials that cause high wear of burner pumps and valves,
dance with internationally recognized principles on standard-
and contribute to deposits of boiler heating surfaces.
ization established in the Decision on Principles for the
6. Apparatus
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
6.1 Flame Photometer, capable of isolating the sodium
Barriers to Trade (TBT) Committee.
doublet at 589 nm and stable enough to give repeatable
measurements that do not vary more than 5 % of their mean in
2. Referenced Documents
the 2 mg ⁄kg to 20 mg ⁄kg range of sodium.
2.1 ASTM Standards:
6.2 Platinum Dish, 100 mL capacity, approximately 35 mm
D1193 Specification for Reagent Water
in depth.
D4057 Practice for Manual Sampling of Petroleum and
6.3 Electric Muffle Furnace, capable of operating over a
Petroleum Products
variable range from 200 °C to 600 °C and of maintaining a
D4175 Terminology Relating to Petroleum Products, Liquid
temperature of 550 °C 6 50 °C.
Fuels, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and
7. Reagents and Materials
Petroleum Products
7.1 Purity of Reagents—Reagent grade chemicals shall be
D6299 Practice for Applying Statistical Quality Assurance
used in all tests. Unless otherwise indicated, it is intended that
and Control Charting Techniques to Evaluate Analytical
all reagents shall conform to the specifications of the Commit-
tee on Analytical Reagents of the American Chemical Society,
where such specifications are available. Other grades can be
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of used, provided it is first ascertained that the reagent is of
Subcommittee D02.03 on Elemental Analysis.
Current edition approved May 1, 2023. Published June 2023. Originally
approved in 1954. Last previous edition approved in 2016 as D1318 – 16. DOI: ACS Reagent Chemicals, Specifications and Procedures for Reagents and
10.1520/D1318-23. Standard-Grade Reference Materials, American Chemical Society, Washington,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or DC. For suggestions on the testing of reagents not listed by the American Chemical
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
Standards volume information, refer to the standard’s Document Summary page on U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
the ASTM website. copeial Convention, Inc. (USPC), Rockville, MD.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1318 − 23
sufficiently high purity to permit its use without lessening the sure of the gases (Warning—Dangerous.) used for flame
accuracy of the determination. combustion in the order described by the manufacturer until
optimum control is achieved. Select a standard approximately
7.2 Purity of Water—Unless otherwise indicated, references
in the middle of the optimum range of the instrument being
to water shall be understood to mean reagent water as defined
used. While atomizing this medium-range standard, adjust the
by Type II or III of Specification D1193.
wavelength selector to the greatest response for the sodium
7.3 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
doublet at about 589 nm and adjust all controls of the instru-
chloric acid (HCl). (Warning—Poison. Causes severe burns.
ment to optimum performance. Finally, adjust the sensitivity
Harmful or fatal if swallowed or inhaled.)
control to give a proper scale reading.
7.4 Hydrochloric Acid (1+9)—Mix 1 volume of HCl (sp gr
9.3 Atomize each of the standard solutions and record the
1.19) with 9 volumes of water.
scale response for each. Run repeat checks on the medium-
7.5 Hydrofluoric Acid (48 %)—Concentrated hydrofluoric range standard selected in 7.2 after each of these standards to
determine whether the flame photometer is functioning prop-
acid (HF). (Warning—Poison. Causes severe burns. Harmful
or fatal if swallowed or inhaled.) erly. Make the indicated adjustments, if required, and rerun the
standards.
7.6 Sodium Solution, Standard (1000 mg Na/L)—Dissolve
9.4 Prepare a working curve by plotting the milligrams of
3.088 g 6 0.005 g of dried sodium sulfate (Na SO ) in water
2 4
and dilute to 1 L in a volumetric flask. Store in a polyethylene sodium per litre against the scale readings.
bottle.
10. Procedure
7.7 Sulfuric Acid (1+1)—Carefully add, while stirring, 1
10.1 Preparation of Sample:
volume of concentrated sulfuric acid (H SO , sp gr 1.84) to 1
2 4
10.1.1 Weigh into a thoroughly clean, dry 100 mL platinum
volume of water. (Warning—Poison. Causes severe burns.
dish the appropriate size sample (8.3) with an accuracy of at
Harmful or fatal if swallowed or inhaled.)
least 1 part per 100 parts of sample (Note 2). Samples larger
7.8 Ethyl Alcohol, C H O, 95 % reagent grade. (Warning—
2 6
than 75 g require a second filling of the platinum dish; for such
Flammable.)
samples, obtain the sample weight from the difference between
7.9 2-Propanol, C H O, 99 % reagent grade (Warning—
the initial and final weights of the sample bottle. Place the
3 8
Flammable.)
platinum dish containing the fuel oil on a silica triangle
properly supported, and heat with a bunsen burner until the
8. Sampling
contents ignite and burn readily (Note 3). Continue heating
8.1 Sampling shall be done in accordance with Practices
with the burner in such a manner that the sample burns at a
D4057 or Test Method D4177.
uniform and moderate rate and only ash and carbon remain
after burning ceases. For samples larger than 75 g, cool the dish
8.2 Use a clear, clean glass pint bottle, previously rinsed
and fill it approximately two-thirds full with additional well-
twice with HCl (1+9) and once with water and allowed to dry,
shaken sample, and burn as above.
for sampling the bulk material or plant streams. Obtain a
representative sample but do not fill the bottle more than about
NOTE 2—Handle the platinum dish only with platinum-tip tongs and do
two-thirds full. Warm viscous samples until they can be mixed not touch it with the fingers during the test. Carefully dust the bottom of
the dish with a clean camel-hair brush before each weighing.
readily. Stir up any material that has settled out and shake the
NOTE 3—If sample contains an appreciable amount of water, as
sample for 3 min just prior to weighing it out.
indicated by spattering when heated, add a few millilitres of ethyl-alcohol
8.3 Optimum sample size for most instruments is that which (95 %) (Warning—Flammable) or isopropyl alcohol (99 %) (Warning—
Flammable) before heating. Include the alcohol in the blank determina-
contains from 0.5 mg to 1.0 mg of sodium. Estimate the sample
tion.
size as follows (see Note 1):
10.1.2 Place the dish in a muffle furnace at no more than
Sample size, g 5 750/estimated sodium content, mg/kg (1)
200 °C (Note 3). Slowly raise the temperature to 550 °C 6
NOTE 1—An estimate of the maximum amount of sodium in a sample
50 °C. Leave the muffle door slightly ajar until only a little
can be obtained from its ash value. For example, an ash of 0.01 % would
undoubtedly have less than 0.005 % sodium (50 ppm). If there is no
carbon remains in the dish; then close the door and continue the
estimate as to the probabl
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D1318 − 16 D1318 − 23
Standard Test Method for
Sodium in Residual Fuel Oil (Flame Photometric Method)
This standard is issued under the fixed designation D1318; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers the determination of sodium in residual fuel oil by means of a flame photometer. Its precision in low
ranges limits its application to samples containing more than 15 mg ⁄kg sodium. Other elements commonly found in residual fuel
oil do not interfere.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the
user of this standard to establish appropriate safety and healthsafety, health, and environmental practices and determine the
applicability of regulatory limitations prior to use. For specific hazard statements see 6.37.3, 6.57.5, 6.77.7, 8.29.2, 6.87.8, 6.97.9,
and Note 3.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
4. Summary of Test Method
4.1 A weighed sample is reduced to a carbonaceous ash under controlled conditions. The residual carbon is removed by heating
in a muffle furnace at 550 °C. The ash is dissolved, diluted to volume, and the sodium determined by means of a flame photometer.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of Subcommittee
D02.03 on Elemental Analysis.
Current edition approved July 1, 2016May 1, 2023. Published July 2016June 2023. Originally approved in 1954. Last previous edition approved in 20112016 as
D1318 – 00D1318 – 16. (2011). DOI: 10.1520/D1318-16.10.1520/D1318-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1318 − 23
5. Significance and Use
5.1 Excessive amounts of sodium can indicate the presence of materials that cause high wear of burner pumps and valves, and
contribute to deposits of boiler heating surfaces.
6. Apparatus
6.1 Flame Photometer, capable of isolating the sodium doublet at 589 nm and stable enough to give repeatable measurements that
do not vary more than 5 % of their mean in the 2 mg ⁄kg to 20 mg ⁄kg range of sodium.
6.2 Platinum Dish, 100 mL capacity, approximately 35 mm in depth.
6.3 Electric Muffle Furnace, capable of operating over a variable range from 200 °C to 600 °C and of maintaining a temperature
of 550 °C 6 50 °C.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades can be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type
II or III of Specification D1193.
7.3 Hydrochloric Acid (sp gr 1.19)—Concentrated hydrochloric acid (HCl). (Warning—Poison. Causes severe burns. Harmful or
fatal if swallowed or inhaled.)
7.4 Hydrochloric Acid (1+9)—Mix 1 volume of HCl (sp gr 1.19) with 9 volumes of water.
7.5 Hydrofluoric Acid (48 %)—Concentrated hydrofluoric acid (HF). (Warning—Poison. Causes severe burns. Harmful or fatal
if swallowed or inhaled.)
7.6 Sodium Solution, Standard (1000 mg Na/L)—Dissolve 3.088 g 6 0.005 g of dried sodium sulfate (Na SO ) in water and dilute
2 4
to 1 L in a volumetric flask. Store in a polyethylene bottle.
7.7 Sulfuric Acid (1+1)—Carefully add, while stirring, 1 volume of concentrated sulfuric acid (H SO , sp gr 1.84) to 1 volume
2 4
of water. (Warning—Poison. Causes severe burns. Harmful or fatal if swallowed or inhaled.)
7.8 Ethyl Alcohol, C H O, 95 % reagent grade. (Warning—Flammable.)
2 6
7.9 2-Propanol, C H O, 99 % reagent grade (Warning—Flammable.)
3 8
8. Sampling
8.1 Sampling shall be done in accordance with Practices D4057 or Test Method D4177.
8.2 Use a clear, clean glass pint bottle, previously rinsed twice with HCl (1+9) and once with water and allowed to dry, for
Reagent Chemicals, American Chemical Society Specifications, ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC),
Rockville, MD.
D1318 − 23
sampling the bulk material or plant streams. Obtain a representative sample but do not fill the bottle more than about two-thirds
full. Warm viscous samples until they can be mixed readily. Stir up any material that has settled out and shake the sample for 3 min
just prior to weighing it out.
8.3 Optimum sample size for most instruments is that which contains from 0.5 mg to 1.0 mg of sodium. Estimate the sample size
as follows (see Note 1):
Sample size, g5 750/estimated sodium content, mg/kg (1)
NOTE 1—An estimate of the maximum amount of sodium in a sample can be obtained from its ash value. For example, an ash of 0.01 % would
undoubtedly have less than 0.005 % sodium (50 ppm). If there is no estimate as to the probable sodium range in a sample, it is more expedient to weigh
out a large amount, for example 60 g, because the test method provides for dilution of sample solutions that are more concentrated than the standards.
9. Calibration
9.1 Dilute the sodium solution (1000 mg Na ⁄L) so as to obtain solutions containing 2 mg ⁄L, 4 mg ⁄L, 6 mg ⁄L, 8 mg ⁄L, 10 mg ⁄L,
12 mg ⁄L, 15 mg ⁄L, 18 mg ⁄L, and 20 mg ⁄L (approximately equivalent to mg/kg). Store all dilute sodium solutions in polyethylene
bottles.
9.2 Prepare the flame photometer for use as described in the manufacturer’s instruction manual. Carefully adjust the pressure of
the gases (Warning—Dangerous.) used for flame combustion in the order described by the manufacturer until optimum control
is achieved. Select a standard approximately in the middle of the optimum range of the instrument being used. While atomizing
this medium-range standard, adjust the wavelength selector to the greatest response for the sodium doublet at about 589 nm and
adjust all controls of the instrument to optimum performance. Finally, adjust the sensitivity control to give a proper scale reading.
9.3 Atomize each of the standard solutions and record the scale response for each. Run repeat checks on the medium-range
standard selected in 6.27.2 after each of these standards to determine whether the flame photometer is functioning properly. Make
the indicated adjustments, if required, and rerun the standards.
9.4 Prepare a working curve by plotting the milligrams of sodium per litre against the scale readings.
10. Procedure
10.1 Preparation of Sample:
10.1.1 Weigh into a thoroughly clean, dry 100 mL platinum dish the appropriate size sample (7.38.3) with an accuracy of at least
1 part per 100 parts of sample (Note 2). Samples larger than 75 g require a second filling of the platinum dish; for such samples,
obtain the sample weight from the difference between the initial and final weights of the sample bottle. Place the platinum dish
containing the fuel oil on a silica triangle properly supported, and heat with a bunsen burner until the contents ignite and burn
readily (Note 3). Continue heating with the burner in such a manner that the sample burns at a uniform and moderate rate and only
ash and carbon remain after burning ceases. For samples larger than 75 g, cool the dish and fill it approximately two-thirds full
with additional well-shaken sample, and burn as above.
NOTE 2—Handle the platinum dish only with platinum-t
...