Standard Test Method for Citrate in Detergents

SIGNIFICANCE AND USE
This test method is suitable in research, development, and manufacturing control to monitor the level of citrate, a sequestering agent, in powder and liquid detergents.
Accurate determination of sequestering agent is important in evaluating cost and performance of detergent products.
SCOPE
1.1 This test method covers a potentiometric titration procedure for the determination of citrate in liquid and powder detergents.
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. Specific safety precautions are given in Section 8.

General Information

Status
Historical
Publication Date
25-May-1989
Current Stage
Ref Project

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ASTM D4608-89(2003) - Standard Test Method for Citrate in Detergents
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D4608–89(Reapproved2003)
Standard Test Method for
Citrate in Detergents
This standard is issued under the fixed designation D4608; 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 5. Interferences
1.1 This test method covers a potentiometric titration pro- 5.1 Other complexing agents such as nitrilotriacetic acid
cedure for the determination of citrate in liquid and powder (NTA), ethylenedinitrilotetraacetic acid (EDTA), phosphates,
detergents. etc. will titrate as citrate in this method. For accurate citrate
1.2 This standard does not purport to address all of the determinations, such complexing agents must be absent.
safety concerns, if any, associated with its use. It is the
6. Apparatus
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 6.1 pH Meter, with millivolt capability.
6.2 Copper Ion Selective Electrode.
bility of regulatory limitations prior to use. Material Safety
Data Sheets are available for reagents and materials. Review 6.3 Calomel Reference Electrode.
6.4 Glass Electrode Triple Purpose.
them for hazards prior to usage. Specific safety precautions are
given in Section 8. 6.5 Buret, semi-micro, 25 mL capacity with 0.1 mL gradu-
ations.
2. Referenced Documents
6.6 Magnetic Stirrer, and TFE-fluorocarbon-coated mag-
2.1 ASTM Standards: netic stirring bars.
E70 Test Method for pH of Aqueous Solutions With the
7. Reagents
Glass Electrode
7.1 Purity of Reagents—Reagent grade chemicals shall be
E180 Practice for Determining the Precision of ASTM
Methods for Analysis and Testing of Industrial and Spe- used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to specifications of the Committee
cialty Chemicals
on Analytical Reagents of the American Chemical Society,
3. Summary of Test Method
where such specifications are available. Other grades may be
3.1 The sample is titrated in an aqueous solution buffered at used, provided it is first ascertained that the reagent is of
pH 8.5, with standard copper sulfate solution. The endpoint is sufficiently high purity to permit its use without lessening the
detected potentiometrically using a copper ion selective elec- accuracy of the determination.
trode. The citrate content is calculated from the amount of 7.2 Purity of Water—Unless otherwise indicated, reference
standard copper sulfate solution consumed. to water shall be understood to mean distilled water or water of
equal purity.
4. Significance and Use
7.3 Hydrochloric Acid Solution (1 + 1)—Slowly mix 1
4.1 This test method is suitable in research, development,
volume of concentrated hydrochloric acid (sp gr 1.19) with 1
and manufacturing control to monitor the level of citrate, a volume of water.
sequestering agent, in powder and liquid detergents.
7.4 Sodium Hydroxide Solution (20 %)—Prepare a 20 %
4.2 Accurate determination of sequestering agent is impor- aqueous solution of sodium hydroxide.
tant in evaluating cost and performance of detergent products.
An automatic titrator may be used.
1 5
This test method is under the jurisdiction of ASTM Committee D12 on Soaps Orion Model 94-29A or equivalent has been found suitable for this purpose.
and Other Detergents and is the direct responsibility of Subcommittee D12.12 on Available from Orion Inc.
Analysis of Soaps and Synthetic Detergents. Orion Model 90-22 or equivalent has been found suitable for this purpose.
Current edition approved May 26, 1989. Published July 1989. Originally Available from Orion Inc.
published as D4608 – 86. Last previous edition D4608 – 88. DOI: 10.1520/D4608- Corning Model No. 476022 or equivalent has been found suitable for this
89R03. purpose. Available from Corning Inc.
2 8
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Reagent Chemicals, American Chemical Society Specifications, American
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Standards volume information, refer to the standard’s Document Summary page on listed by the American Chemical Society, see Analar Standards for Laboratory
the ASTM website. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Withdrawn. The last approved version of this historical standard is referenced and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
on www.astm.org. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4608–89 (2003)
7.5 Sodium Hydroxide Solution (0.1 N)—Prepare a 0.1 N 9. Procedure
aqueous solution of sodium hydroxide.
9.1 Accuratelyweigh(tothenearest0.1mg)enoughsample
7.6 Hydrochloric Acid Solution (0.1 N)—Prepare a 0.1 N to contain about 150 mg citrate as sodium citrate or 100 mg as
citric acid. Quantitatively transfer to a 400-mL beaker with
aqueous solution of hydrochloric acid.
water and bring the volume to about 200 mL. While stirring
7.7 Borate Buffer Solution (pH 8.5)—Dissolve 12.8 g of
with a magnetic stirrer, adjust the pH between 8 and 9 with
sodium borate (Na B O ·10H O) and 16.6 g of boric acid
2 4 7 2
dropwise additions of HCl (1 + 1) or NaOH (20 %). Add 25
(H BO )inabout900mLofwater.AdjustpHto8.5with20 %
3 3
mLborate buffer (pH 8.5). If necessary, carefully adjust the pH
NaOH solution. Transfer quantitatively into a 1-L volumetric
to 8.5 with NaOH (0.1 N) or HCl (0.1 N). Remove the glass
flask. Dilute to volume with water. Mix well.
electrode and insert the copper ion selective
9 4
7.8 Sodium Thiosulfate Solution, Standard (0.1 N)—
electrode. Set the pH meter on millivolt and begin to add
Dissolve25gofsodiumthiosulfate(Na S O 5H O)crystalsin
...

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