ASTM_D_1768_-_89_2016.pdf

Designation:D176889(Reapproved 2016)Standard Test Method forSodium Alkylbenzene Sulfonate in Synthetic Detergents byUltraviolet Absorption1This standard is issued under the fixed designation D1768;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers commercial synthetic deter-gents and built detergent formulations that do not containorganic additives such as amides.Optical dyes and materialsnormally found in formulated detergents do not interfere;however,materials other than sulfonates that possess strongultraviolet absorptions must be absent.The indicated samplesize and aliquoting scheme is based on samples containing 30to 40%of active ingredient.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Material SafetyData Sheets are available for reagents and materials.Reviewthem for hazards prior to usage.2.Referenced Documents2.1 ASTM Standards:2D460 Test Methods for Sampling and Chemical Analysis ofSoaps and Soap ProductsD1568 Test Methods for Sampling and ChemicalAnalysis ofAlkylbenzene SulfonatesD3049 Test Method for Synthetic Anionic Ingredient byCationic TitrationD4251 Test Method forActive Matter inAnionic Surfactantsby Potentiometric TitrationE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible Spectrophotometers3.Summary of Test Method3.1 This test method involves measurement of the ultravio-let absorbance of the sample at the maximum absorbance pointfor sodium alkylbenzene sulfonate(224 nm)and at a selectedbackground point of 270 nm in order to determine the amountof active ingredient present.The percentage of active ingredi-ent is calculated from the above absorbances and data on thepure active ingredient.4.Apparatus4.1 Spectrophotometer,3equipped for liquid samples and formeasurements in the ultraviolet region.The instrument shall becapable of measuring absorbance with a repeatability of60.5%or better from an average at the 0.4 absorbance levelin the spectral region between 220 and 270 nm.The spectralpositions shall be accurate to 60.5 nm and repeatable to 60.2nm.4.2 Absorption Cells,4silica,matched pairs of optical pathlength 1.000 6 0.005 cm.5.Reagent5.1 Ethyl Alcohol(95%)Conforming to either FormulaNo.3A or No.30 of the U.S.Bureau of Internal Revenue.6.Reference Standard6.1 A previously analyzed sample or solution may be usedto check performance of the cell and instrument.3Guard suchreference samples from contamination and renew periodically(quarterly).7.Calibration and Standardization of Cells37.1 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 acorrection factor for each cell.1This test method is under the jurisdiction of ASTM Committee D12 on Soapsand Other Detergents and is the direct responsibility of Subcommittee D12.12 onAnalysis and Specifications of Soaps,Synthetics,Detergents and their Components.Current edition approved July 1,2016.Published August 2016.Originallyapproved in 1960 as D1768 60 T.Last previous edition approved in 2009 asD1768 89(2009).DOI:10.1520/D1768-89R16.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3For information on performance testing of spectrophotometers,refer to PracticeE275.4One-centimetre silica cells manufactured by either the Pyrocell ManufacturingCo.,270 E.84th St.,New York,NY,Catalog No.S22-240,or by BeckmanInstruments,Inc.,Fullerton,CA,Catalog No.40736 have been found satisfactoryfor this purpose.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.2 Before each day of operation,load the quartz cells withdistilled water and make certain that the cells match within 1%transmittance.This practice is necessary to check cleanlinessof the cells.Clean cells,if necessary,using dichromatecleaning solution,until the desired transmittance is obtained.NOTE1All glassware must be rinsed with freshly prepared distilledwater before use.Do not dry the rinsed glassware.This is necessary,especially after the first dilution,to avoid errors due to contamination.8.Determination of Purity of Sodium AlkylbenzeneSulfonate Standard from its Organic Alcohol-SolubleMatter8.1 D