ASTM D1768-89(1995)e1
(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
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.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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e1
Designation: D 1768 – 89 (Reapproved 1995)
Standard Test Method for
Sodium Alkylbenzene Sulfonate in Synthetic Detergents by
Ultraviolet Absorption
This standard is issued under the fixed designation D 1768; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Keywords were added editorially in February 1995.
1. Scope background point of 270 nm in order to determine the amount
of active ingredient present. The percentage of active ingredi-
1.1 This test method covers commercial synthetic deter-
ent is calculated from the above absorbances and data on the
gents and built detergent formulations that do not contain
pure active ingredient.
organic additives such as amides. Optical dyes and materials
normally found in formulated detergents do not interfere;
4. Apparatus
however, materials other than sulfonates that possess strong
4.1 Spectrophotometer, equipped for liquid samples and for
ultraviolet absorptions must be absent. The indicated sample
measurements in the ultraviolet region. The instrument shall be
size and aliquoting scheme is based on samples containing 30
capable of measuring absorbance with a repeatability of
to 40% of active ingredient.
60.5 % or better from an average at the 0.4 absorbance level
1.2 This standard does not purport to address all of the
in the spectral region between 220 and 270 nm. The spectral
safety concerns, if any, associated with its use. It is the
positions shall be accurate to 60.5 nm and repeatable to 60.2
responsibility of the user of this standard to establish appro-
nm.
priate safety and health practices and determine the applica-
4.2 Absorption Cells, silica, matched pairs of optical path
bility of regulatory limitations prior to use. Material Safety
length 1.000 6 0.005 cm.
Data Sheets are available for reagents and materials. Review
them for hazards prior to usage.
5. Reagent
5.1 Ethyl Alcohol (95 %)—Conforming to either Formula
2. Referenced Documents
No. 3A or No. 30 of the U.S. Bureau of Internal Revenue.
2.1 ASTM Standards:
D 460 Test Methods for Sampling and Chemical Analysis
6. Reference Standard
of Soaps and Soap Products
6.1 A previously analyzed sample or solution may be used
D 1568 Test Methods for Sampling and Chemical Analysis
2 to check performance of the cell and instrument. Guard such
of Alkylbenzene Sulfonates
reference samples from contamination and renew periodically
D 3049 Test Method for Synthetic Anionic Ingredient by
2 (quarterly).
Cationic Titration
D 4251 Test Method for Active Matter in Anionic Surfac- 4
7. Calibration and Standardization of Cells
tants by Potentiometric Titration
7.1 The cells in a pair, when filled with distilled water,
E 275 Practice for Describing and Measuring Performance
should match within 1 % transmittance at 224 nm. Otherwise,
of Ultraviolet, Visible, and Near Infrared Spectrophotom-
calibrate the cells as directed by the manufacturer and use a
eters
correction factor for each cell.
7.2 Before each day of operation, load the quartz cells with
3. Summary of Test Method
distilled water and make certain that the cells match within 1 %
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.
This test method is under the jurisdiction of ASTM Committee D-12 on Soaps
and Other Detergents and is the direct responsibility of Subcommittee D12.12 on For information on performance testing of spectrophotometers, refer to Practice
Analysis of Soaps and Synthetic Detergents. E 275.
Current edition approved May 26, 1989. Published July 1989. Originally pub- One-centimetre silica cells manufactured by either the Pyrocell Manufacturing
lished as D 1768 – 60 T. Last previous edition D 1768 – 83. 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, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1768
NOTE 1—All glassware must be rinsed with freshly prepared distilled
9.4 Using 1-cm cells in the spectrophotometer, measure the
water before use. Do not dry the rinsed glassware. This is necessary,
absorbance at 224 and 270 nm versus a water blank. With
especially after the first dilution, to avoid errors due to contamination.
instruments having scanning capability, scan from 300 down to
8. Determination of Purity of Sodium Alkylbenzene 210 nm. This facilitates obtaining the absorbance at the peak
Sulfonate Standard from its Organic Alcohol-Soluble maximum near 224 nm. (Caution, Note 4. See also Note 5 and
Matter Note 6).
8.1 Determine triplicate values for the percentage of organic
NOTE 4—Caution: There is danger of contamination of the sample
alcohol-soluble matter in the alkylbenzene sulfonate standard with detergent dust in the production laboratory air; therefore, these
measurements must be made immediately after the procedure described in
(or particular alkylbenzene sulfonate being determined) in
9.3. Contamination is evident when a high reading (above 0.1 absorbance)
accordance with 8.2-8.5.
at 270 nm is obtained. Discard such contaminated samples and start with
NOTE 2—The purity of the standard, or percentage of active ingredient,
a new aliquot (9.3, Note 5 and Note 6).
can also be determined by the cationic titration of Test Method D 3049 or
NOTE 5—The observed absorbance readings should be between 0.2 and
by the specific ion electrode titration of Test Method D 4251.
0.9; otherwise weigh a new sample or take a new or different aliquot and
dilute to a known volume. (A calibration curve in this absorbance range
8.2 Determine moisture in accordance with Moisture by the
must be made with a sample of the sodium alkylbenzene sulfonate being
Distillation Method sections of Test Methods D 1568.
quantitatively measured. See also Note 7.)
8.3 Determine alcohol-insoluble matter in accordance with
NOTE 6—When analyzing samples of doubtful origin, the absorption
Sections 19 to 20 (Total Matter Insoluble in Alcohol) of Test
maximum at 224 nm should be checked. Measure the absorbance at 220,
Methods D 460 or Total Matter Insoluble in Alcohol 20 to 22
224, 228, and 270 nm. The absorbance at 224 nm should be greater than
of Test Methods D 1568.
the absorbance at either 220 nm or 228 nm. If the 224-nm absorption is not
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