ASTM D1768-89(2016)

Standard Test Method for Sodium Alkylbenzene Sulfonate in Synthetic Detergents by Ultraviolet Absorption

ABSTRACT
This test method covers commercial synthetic detergents and built detergent formulations that do not contain organic additives such as amides. This test method involves measurement of the ultraviolet absorbance of the sample at the maximum absorbance point for sodium alkylbenzene sulfonate and at a selected background point in order to determine the amount of active ingredient present. The percentage of alcohol-soluble matter, absorptivity value and percentage of active ingredient shall be calculated in accordance to the specified requirements.
SCOPE
1.1 This test method covers commercial synthetic detergents and built detergent formulations that do not contain organic additives such as amides. Optical dyes and materials normally found in formulated detergents do not interfere; however, materials other than sulfonates that possess strong ultraviolet absorptions must be absent. The indicated sample size and aliquoting scheme is based on samples containing 30 to 40% of active ingredient.  
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 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. Material Safety Data Sheets are available for reagents and materials. Review them for hazards prior to usage.

General Information

• Status: Published
• Publication Date: 30-Jun-2016
• ICS: 71.100.40 - Surface active agents
• Technical Committee: D12 - Soaps and Other Detergents
• Drafting Committee: D12.12 - Analysis and Specifications of Soaps, Synthetics, Detergents and their Components

Relations

• Replaces: ASTM D1768-89(2009) - Standard Test Method for Sodium Alkylbenzene Sulfonate in Synthetic Detergents by Ultraviolet Absorption
• Effective Date: 01-Jul-2016
• Refers: ASTM D3049-89(2016) - Standard Test Method for Synthetic Anionic Ingredient by Cationic Titration
• Effective Date: 01-Jul-2016
• Refers: ASTM D4251-89(2016) - Standard Test Method for Active Matter in Anionic Surfactants by Potentiometric Titration
• Effective Date: 01-Jul-2016
• Refers: ASTM D4251-89(2009) - Standard Test Method for Active Matter in Anionic Surfactants by Potentiometric Titration
• Effective Date: 01-Oct-2009
• Refers: ASTM D3049-89(2009) - Standard Test Method for Synthetic Anionic Ingredient by Cationic Titration
• Effective Date: 01-Oct-2009
• Refers: ASTM E275-08 - Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
• Effective Date: 15-Oct-2008
• Refers: ASTM D460-91(2005) - Standard Test Methods for Sampling and Chemical Analysis of Soaps and Soap Products
• Effective Date: 01-May-2005
• Refers: ASTM D1568-05 - Standard Test Methods for Sampling and Chemical Analysis of Alkylbenzene Sulfonates
• Effective Date: 01-May-2005
• Refers: ASTM E275-01 - Standard Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near-Infrared Spectrophotometers
• Effective Date: 10-Feb-2001
• Refers: ASTM E275-93 - Standard Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near-Infrared Spectrophotometers
• Effective Date: 10-Feb-2001
• Refers: ASTM D460-91(1997) - Standard Test Methods for Sampling and Chemical Analysis of Soaps and Soap Products
• Effective Date: 10-Mar-1997
• Refers: ASTM D1568-97 - Standard Test Methods for Sampling and Chemical Analysis of Alkylbenzene Sulfonates
• Effective Date: 10-Mar-1997
• Refers: ASTM D3049-89(1996)e1 - Standard Test Method for Synthetic Anionic Ingredient by Cationic Titration
• Effective Date: 01-Jan-1996
• Refers: ASTM D4251-89(1995)e1 - Standard Test Method for Active Matter in Anionic Surfactants by Potentiometric Titration
• Effective Date: 01-Jan-1995
• Refers: ASTM D4251-89(2003) - Standard Test Method for Active Matter in Anionic Surfactants by Potentiometric Titration
• Effective Date: 26-May-1989

Overview

ASTM D1768-89(2016) is the international standard published by ASTM International entitled "Standard Test Method for Sodium Alkylbenzene Sulfonate in Synthetic Detergents by Ultraviolet Absorption." This standard specifies a quantitative analytical procedure for determining sodium alkylbenzene sulfonate (SABS) content in commercial synthetic detergents and built detergent formulations, particularly those that exclude organic additives like amides. Relying on ultraviolet (UV) absorbance measurements, the method is recognized for its accuracy and reliability, facilitating quality control and regulatory compliance in detergent manufacturing and related industries.

Key Topics

• Principle of the Method: This test method measures the UV absorbance of a detergent sample at 224 nm, corresponding to the maximum absorbance for sodium alkylbenzene sulfonate, and at a background wavelength of 270 nm. The difference in absorbance at these two points is used to accurately determine the SABS content.
• Sample Applicability: The method is suitable for commercial synthetic detergents and formulated detergents without amide-type organic additives. Common additives like optical brighteners do not interfere, but substances with strong UV absorbance other than sulfonates should be absent.
• Precision: The test yields a repeatable and reproducible determination of SABS in detergent samples. It features specific guidance on sample sizes, suitable for 30-40% active ingredient content.
• Calculation and Reporting: The standard details the required calculations for alcohol-soluble matter, absorptivity, and percentage of active ingredient, ensuring consistent and standardized reporting across laboratories.
• Safety and Compliance: Users are responsible for employing appropriate safety and health practices and consulting Material Safety Data Sheets for used chemicals.

Applications

• Quality Control in Detergent Manufacturing: This test method is critical for manufacturers seeking to verify the SABS content during production, ensuring batch-to-batch consistency and adherence to product specifications.
• Regulatory Compliance: The ability to accurately quantify sodium alkylbenzene sulfonate assures compliance with industry regulations and customer requirements, especially where product labeling or composition limits are enforced.
• Research and Development: Chemical laboratories and R&D departments use the ASTM D1768 method for developing new detergent formulations, optimizing sulfonate levels, and comparing surfactant performance.
• Third-party and Independent Laboratories: Independent test labs utilize this recognized method to provide reliable detergent analysis services for manufacturers, importers, or regulatory bodies.
• Interlaboratory Comparisons: The standard’s reproducibility data support interlaboratory performance checks, helping organizations benchmark analytical quality.

Related Standards

• ASTM D460: Test Methods for Sampling and Chemical Analysis of Soaps and Soap Products.
• ASTM D1568: Test Methods for Sampling and Chemical Analysis of Alkylbenzene Sulfonates.
• ASTM D3049: Standard Test Method for Synthetic Anionic Ingredient by Cationic Titration.
• ASTM D4251: Test Method for Active Matter in Anionic Surfactants by Potentiometric Titration.
• ASTM E275: Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers.

Practical Value

Implementing ASTM D1768-89(2016) supports detergent producers and laboratories in delivering high-precision analytical results for sodium alkylbenzene sulfonate in detergent formulations. Its adoption enhances product quality, ensures regulatory conformance, facilitates fair trade, and maintains consumer confidence in cleaning products. The UV absorption method stands out for its simplicity, speed, and effectiveness in surfactant quantification, making it a foundational analytic standard in the detergents industry.

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: D1768 − 89 (Reapproved 2016)
Standard Test Method for
Sodium Alkylbenzene Sulfonate in Synthetic Detergents by
Ultraviolet Absorption
This standard is issued under the fixed designation D1768; 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 3. Summary of Test Method
1.1 This test method covers commercial synthetic deter- 3.1 This test method involves measurement of the ultravio-
gents and built detergent formulations that do not contain let absorbance of the sample at the maximum absorbance point
organic additives such as amides. Optical dyes and materials for sodium alkylbenzene sulfonate (224 nm) and at a selected
normally found in formulated detergents do not interfere; background point of 270 nm in order to determine the amount
however, materials other than sulfonates that possess strong of active ingredient present. The percentage of active ingredi-
ultraviolet absorptions must be absent. The indicated sample ent is calculated from the above absorbances and data on the
size and aliquoting scheme is based on samples containing 30 pure active ingredient.
to 40% of active ingredient.
4. Apparatus
1.2 The values stated in SI units are to be regarded as
4.1 Spectrophotometer, equipped for liquid samples and for
standard. No other units of measurement are included in this
measurements in the ultraviolet region.The instrument shall be
standard.
capable of measuring absorbance with a repeatability of
1.3 This standard does not purport to address all of the
60.5 % or better from an average at the 0.4 absorbance level
safety concerns, if any, associated with its use. It is the
in the spectral region between 220 and 270 nm. The spectral
responsibility of the user of this standard to establish appro-
positions shall be accurate to 60.5 nm and repeatable to 60.2
priate safety and health practices and determine the applica-
nm.
bility of regulatory limitations prior to use. Material Safety
4.2 Absorption Cells, silica, matched pairs of optical path
Data Sheets are available for reagents and materials. Review
length 1.000 6 0.005 cm.
them for hazards prior to usage.
5. Reagent
2. Referenced Documents
5.1 Ethyl Alcohol (95 %) —Conforming to either Formula
2.1 ASTM Standards:
No. 3A or No. 30 of the U.S. Bureau of Internal Revenue.
D460 Test Methods for Sampling and Chemical Analysis of
Soaps and Soap Products
6. Reference Standard
D1568 TestMethodsforSamplingandChemicalAnalysisof
Alkylbenzene Sulfonates 6.1 A previously analyzed sample or solution may be used
D3049 Test Method for Synthetic Anionic Ingredient by
to check performance of the cell and instrument. Guard such
Cationic Titration reference samples from contamination and renew periodically
D4251 TestMethodforActiveMatterinAnionicSurfactants
(quarterly).
by Potentiometric Titration
7. Calibration and Standardization of Cells
E275 Practice for Describing and Measuring Performance of
Ultraviolet and Visible Spectrophotometers
7.1 The cells in a pair, when filled with distilled water,
should match within 1 % transmittance at 224 nm. Otherwise,
calibrate the cells as directed by the manufacturer and use a
This test method is under the jurisdiction of ASTM Committee D12 on Soaps
correction factor for each cell.
and Other Detergents and is the direct responsibility of Subcommittee D12.12 on
Analysis and Specifications of Soaps, Synthetics, Detergents and their Components.
Current edition approved July 1, 2016. Published August 2016. Originally
approved in 1960 as D1768 – 60 T. Last previous edition approved in 2009 as Forinformationonperformancetestingofspectrophotometers,refertoPractice
D1768 – 89(2009). DOI: 10.1520/D1768-89R16. E275.
2 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or One-centimetre silica cells manufactured by either the Pyrocell Manufacturing
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Co., 270 E. 84th St., New York, NY, Catalog No. S22-240, or by Beckman
Standards volume information, refer to the standard’s Document Summary page on Instruments, Inc., Fullerton, CA, Catalog No. 40736 have been found satisfactory
the ASTM website. for this purpose.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1768 − 89 (2016)
7.2 Before each day of operation, load the quartz cells with 9.2 Slurry Sample—Weigh, to the nearest 1 mg, three
distilledwaterandmakecertainthatthecellsmatchwithin1 % approximately 20-g portions of a representative sample. Add
transmittance. This practice is necessary to check cleanliness 50 mL of alcohol and mix to disperse the sample. Dissolve
of the cells. Clean cells, if necessary, using dichromate each portion of the sample in water (Note 3) and dilute to 1000
cleaning solution, until the desired transmittance is obtained.
mL with water at room temperature, employing a 1000-mL
volumetric flask. Mix well. Pipet a 50-mL aliquot of each
NOTE 1—All glassware must be rinsed with freshly prepared distilled
solution into a 500-mL volumetric flask, dilute to volume with
water before use. Do not dry the rinsed glassware. This is necessary,
water at room temperature, and mix well. Treat each of the
especially after the first dilution, to avoid errors due to contamination.
three sample solutions as directed in 9.3 and 9.4.
8. Determination of Purity of Sodium Alkylbenzene
9.3 Pipet a 5-mLaliquot of the solution from 9.1 or 9.2 into
Sulfonate Standard from its Organic Alcohol-Soluble
a 250-mL volumetric flask and dilute to volume with water at
Matter
room temperature. Mix well.
8.1 Determinetriplicatevaluesforthepercentageoforganic
9.4 Using 1-cm cells in the spectrophotometer, measure the
alcohol-soluble matter in the alkylbenzene sulfonate standard
absorbance at 224 and 270 nm versus a water blank. With
(or particular alkylbenzene sulfonate being determined) in
instrumentshavingscanningcapability,scanfrom300downto
accordance with 8.2 – 8.5.
210 nm. This facilitates obtaining the absorbance at the peak
NOTE 2—The purity of the standard, or percentage of active ingredient,
maximum near 224 nm. (Caution, Note 4. See also Note 5 and
can also be determined by the cationic titration of Test Method D3049 or
Note 6).
by the specific ion electrode titration of Test Method D4251.
NOTE4—Caution:Thereisdangerofcontaminationofthesamplewith
8.2 Determine moisture in accordance with Moisture by the
detergent dust in the production laboratory air; therefore, these measure-
Distillation Method sections of Test Methods D1568.
ments must be made immediately after the procedure described in 9.3.
Contamination is evident when a high reading (above 0.1 absorbance) at
8.3 Determine alcohol-insoluble matter in accordance with
270 nm is obtaine
...