ASTM D1768-89(2009)
(Test Method)Standard Test Method for Sodium Alkylbenzene Sulfonate in Synthetic Detergents by Ultraviolet Absorption
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
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D1768 − 89 (Reapproved2009)
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 Oct. 1, 2009. Published December 2009. Originally
approved in 1960 as D1768 – 60 T. Last previous edition approved in 2003 as Forinformationonperformancetestingofspectrophotometers,refertoPractice
D1768 – 89(2003). DOI: 10.1520/D1768-89R09. 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 service@astm.org. 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 (2009)
7.2 Before each day of operation, load the quartz cells with volumetric flask. Mix well. Pipet a 50-mL aliquot of each
distilledwaterandmakecertainthatthecellsmatchwithin1 % solution into a 500-mL volumetric flask, dilute to volume with
transmittance. This practice is necessary to check cleanliness water at room temperature, and mix well. Treat each of the
of the cells. Clean cells, if necessary, using dichromate three sample solutions as directed in 9.3 and 9.4.
cleaning solution, until the desired transmittance is obtained.
9.3 Pipet a 5-mLaliquot of the solution from 9.1 or 9.2 into
a 250-mL volumetric flask and dilute to volume with water at
NOTE 1—All glassware must be rinsed with freshly prepared distilled
water before use. Do not dry the rinsed glassware. This is necessary,
room temperature. Mix well.
especially after the first dilution, to avoid errors due to contamination.
9.4 Using 1-cm cells in the spectrophotometer, measure the
absorbance at 224 and 270 nm versus a water blank. With
8. Determination of Purity of Sodium Alkylbenzene
instrumentshavingscanningcapability,scanfrom300downto
Sulfonate Standard from its Organic Alcohol-Soluble
210 nm. This facilitates obtaining the absorbance at the peak
Matter
maximum near 224 nm. (Caution, Note 4. See also Note 5 and
8.1 Determinetriplicatevaluesforthepercentageoforganic
Note 6).
alcohol-soluble matter in the alkylbenzene sulfonate standard
NOTE4—Caution:Thereisdangerofcontaminationofthesamplewith
(or particular alkylbenzene sulfonate being determined) in
detergent dust in the production laboratory air; therefore, these measure-
accordance with 8.2-8.5.
ments must be made immediately after the procedure described in 9.3.
NOTE 2—The purity of the standard, or percentage of active ingredient, Contamination is evident when a high reading (above 0.1 absorbance) at
can also be determined by the cationic titration of Test Method D3049 or 270 nm is obtained. Discard such contaminated samples and start with a
by the specific ion electrode titration of Test Method D4251. new aliquot (9.3, Note 5 and Note 6).
NOTE 5—The observed absorbance readings should be between 0.2 and
8.2 Determine moisture in accordance with Moisture by the
0.9; otherwise weigh a new sample or take a new or different aliquot and
Distillation Method sections of Test Methods D1568.
dilute to a known volume. (A calibration curve in this absorbance range
must be made with a sample of the sodium alkylbenzene sulfonate being
8.3 Determine alcoh
...
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