ASTM D1768-89(2003)

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 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: Historical
• Publication Date: 25-May-1989
• 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(1995)e1 - Standard Test Method for Sodium Alkylbenzene Sulfonate in Synthetic Detergents by Ultraviolet Absorption
• Effective Date: 26-May-1989
• Replaced By: ASTM D1768-89(2009) - Standard Test Method for Sodium Alkylbenzene Sulfonate in Synthetic Detergents by Ultraviolet Absorption
• Effective Date: 01-Oct-2009
• Referred By: ASTM D820-93(2023) - Standard Test Methods for Chemical Analysis of Soaps Containing Synthetic Detergents
• Effective Date: 26-May-1989

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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(Reapproved 2003)
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 of active ingredient present. The percentage of active ingredi-
ent is calculated from the above absorbances and data on the
1.1 This test method covers commercial synthetic deter-
pure active ingredient.
gents and built detergent formulations that do not contain
organic additives such as amides. Optical dyes and materials
4. Apparatus
normally found in formulated detergents do not interfere;
4.1 Spectrophotometer, equippedforliquidsamplesandfor
however, materials other than sulfonates that possess strong
measurements in the ultraviolet region.The instrument shall be
ultraviolet absorptions must be absent. The indicated sample
capable of measuring absorbance with a repeatability of
size and aliquoting scheme is based on samples containing 30
60.5 % or better from an average at the 0.4 absorbance level
to 40% of active ingredient.
in the spectral region between 220 and 270 nm. The spectral
1.2 This standard does not purport to address all of the
positions shall be accurate to 60.5 nm and repeatable to 60.2
safety concerns, if any, associated with its use. It is the
nm.
responsibility of the user of this standard to establish appro-
4.2 Absorption Cells, silica, matched pairs of optical path
priate safety and health practices and determine the applica-
length 1.000 6 0.005 cm.
bility of regulatory limitations prior to use. Material Safety
Data Sheets are available for reagents and materials. Review
5. Reagent
them for hazards prior to usage.
5.1 Ethyl Alcohol (95 %)—Conforming to either Formula
No. 3A or No. 30 of the U.S. Bureau of Internal Revenue.
2. Referenced Documents
2.1 ASTM Standards:
6. Reference Standard
D460 Test Methods for Sampling and ChemicalAnalysis of
2 6.1 A previously analyzed sample or solution may be used
Soaps and Soap Products
to check performance of the cell and instrument. Guard such
D1568 Test Methods for Sampling and Chemical Analysis
2 reference samples from contamination and renew periodically
of Alkylbenzene Sulfonates
(quarterly).
D3049 Test Method for Synthetic Anionic Ingredient by
Cationic Titration 4
7. Calibration and Standardization of Cells
D4251 Test Method for Active Matter in Anionic Surfac-
7.1 The cells in a pair, when filled with distilled water,
tants by Potentiometric Titration
should match within 1 % transmittance at 224 nm. Otherwise,
E275 Practice for Describing and Measuring Performance
calibrate the cells as directed by the manufacturer and use a
of Ultraviolet and Visible Spectrophotometers
correction factor for each cell.
7.2 Before each day of operation, load the quartz cells with
3. Summary of Test Method
distilledwaterandmakecertainthatthecellsmatchwithin1 %
3.1 This test method involves measurement of the ultravio-
transmittance. This practice is necessary to check cleanliness
let absorbance of the sample at the maximum absorbance point
of the cells. Clean cells, if necessary, using dichromate
for sodium alkylbenzene sulfonate (224 nm) and at a selected
cleaning solution, until the desired transmittance is obtained.
background point of 270 nm in order to determine the amount
NOTE 1—All glassware must be rinsed with freshly prepared distilled
water before use. Do not dry the rinsed glassware. This is necessary,
This test method is under the jurisdiction of ASTM Committee D12 on Soaps
and Other Detergents and is the direct responsibility of Subcommittee D12.12 on
Analysis of Soaps and Synthetic Detergents. Forinformationonperformancetestingofspectrophotometers,refertoPractice
Current edition approved May 26, 1989. Published July 1989. Originally pub- E275.
lished as D1768 – 60 T. Last previous edition D1768 – 83. DOI: 10.1520/D1768- One-centimetre silica cells manufactured by either the Pyrocell Manufacturing
89R03. Co., 270 E. 84th St., New York, NY, Catalog No. S22-240, or by Beckman
Annual Book of ASTM Standards, Vol 15.04. Instruments, Inc., Fullerton, CA, Catalog No. 40736 have been found satisfactory
Annual Book of ASTM Standards, Vol 03.06. for this purpose.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1768–89 (2003)
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
instruments having scanning capability, scan from 300 down to
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
NOTE 4—Caution: There is danger of contamination of the sample
(or particular alkylbenzene sulfonate being determined) in
with detergent dust in the production laboratory air; therefore, these
accordance with 8.2-8.5.
measurements must be made immediately after the procedure described in
9.3. Contamination is evident when a high reading (above 0.1 absorbance)
NOTE 2—The purity of the standard, or percentage of active ingredient,
at 270 nm is obtained. Discard such contaminated samples and start with
can also be determined by the cationic titration of Test Method D3049 or
a new aliquot (9.3, Note 5 and Note 6).
by the specific ion electrode titration of Test Method D4251.
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
8.3 Determine alcohol-insoluble matter in accordance with
must be made with a sample of the sodium alkylbenzene sulfonate being
Sections 19 to 20 (Total Matter Insoluble in Alcohol) of Test quantitatively measured. See also Note 7.)
Methods D460 orTotal Matter Insoluble inAlcohol 20 to 22 of
NOTE 6—When analyzing samples of doubtful origin, the absorption
maximum at 224 nm should be checked. Measure the absorbance at 220,
Test Methods D1568.
224, 228, and 270 nm. The absorbance at 224 nm should be greater than
8.4 Determine chlorides calculated as sodium chloride in
...