ASTM D2761-89(1998)

Standard Test Method for Analysis of Sodium Triphosphate by the Simplified Ion Exchange Method (Withdrawn 2001)

SCOPE
1.1 This test method covers the determination of ortho-, pyro-, and meta-phosphates in sodium triphosphate. It depends on direct flow elutriation through a column of ion exchange resin.  
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• Status: Withdrawn
• Publication Date: 09-Jan-1998
• Withdrawal Date: 09-Aug-2001
• ICS: 71.100.40 - Surface active agents
• Technical Committee: D12 - Soaps and Other Detergents

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 2761 – 89 (Reapproved 1998)
Standard Test Method for
Analysis of Sodium Triphosphate by the Simplified Ion
Exchange Method
This standard is issued under the fixed designation D 2761; 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.
1. Scope 4. Reagents
1.1 This test method covers the determination of ortho-, 4.1 Purity of Reagents—Reagent grade chemicals shall be
pyro-, and meta-phosphates in sodium triphosphate. It depends used in all tests. Unless otherwise indicated, it is intended that
on direct flow elutriation through a column of ion exchange all reagents shall conform to the specifications of the Commit-
resin. tee on Analytical Reagents of the American Chemical Society,
1.2 This standard does not purport to address all of the where such specifications are available. Other grades may be
safety concerns, if any, associated with its use. It is the used, provided it is first ascertained that the reagent is of
responsibility of the user of this standard to establish appro- sufficiently high purity to permit its use without lessening the
priate safety and health practices and determine the applica- accuracy of the determination.
bility of regulatory limitations prior to use. Material Safety 4.2 Purity of Water—Unless otherwise indicated, references
Data Sheets are available for reagents and materials. Review to water shall be understood to mean distilled water or water of
them for hazards prior to usage. equal purity.
4.3 Ammonium Molybdate Solution (100 g/L)—Dissolve
2. Summary of Test Method
100 g of ammonium molybdate ((NH ) Mo O ·4H O) in
4 6 7 24 2
2.1 A sample of sodium triphosphate is introduced into an
water and dilute to 1 L.
ion exchange resin column. The phosphate ions diffuse into the 4.4 Ion-Exchange Resin—Anion-exchange resin, 100 to
resin phase and are held by the resin cation. The anions are then
200-mesh, chloride form (Caution, see Note 1).
selectively eluted from the column using different strengths of
NOTE 1—Caution: This method as written is based on the use of
potassium chloride solutions. The ions with the least affinity
analytical grade Dowex AG-1X8 anion exchange resin. Comparable
are eluted first: ortho-, pyro-, tri-, and meta-phosphate, respec-
results may not be obtained with other resins.
tively. Colorimetric molybdenum blue procedure is used for
4.5 Phosphate, Standard Solution (1 mL 5 0.05 mg
phosphorus pentoxide (P O ) determinations of each fraction
2 5
P O )—Dissolve 0.9568 g of potassium dihydrogen phosphate
2 5
and of total phosphate.
(KH PO ) in water and dilute to 500 mL. Transfer 25 mL of
2 4
this solution to a 500-mL volumetric flask and dilute to
3. Apparatus
volume.
3.1 Separatory Funnel, 500-mL.
4.6 Potassium Acetate Stock Buffer Solution (78.5 g/L,
3.2 Ion Exchange Column, 31 cm (310 mm) long with
pH 5 5.0)—Dissolve 78.5 g of potassium acetate (KC H O )
2 3 2
28-mm inside diameter.
in water and dilute to 1 L. Adjust the pH to 5.0 with glacial
3.3 Tubing, vinyl (Tygon), ⁄4-in. (6-mm) inside diameter,
acetic acid.
⁄8-in. (9-mm) outside diameter.
3.4 Tubing, capillary, chemical-resistant glass, 1 ⁄2-mm in- NOTE 2—Add a pinch of mercuric iodide to inhibit mold growth.
side diameter, 7-mm outside diameter.
4.7 Potassium Chloride Solution (22.35 g/L)—Dissolve
3.5 Photometer—A spectrophotometer or filter photometer
22.35 g of potassium chloride (KCl) in water, add 5 mL of the
suitable for measurements at approximately 650 nm with
stock buffer solution (4.6), and dilute to 1 L (Note 2).
10-mm cells.
4.8 Potassium Chloride Solution (44.7 g/L)—Dissolve 44.7
g of KCl in water, add 5 ml of the stock buffer solution (4.6),
and dilute to 1 L (Note 2).
This test method is under the jurisdiction of ASTM Committee D-12 on Soaps
and Other Detergents and is the direct responsibility of Subcommittee D12.14 on
Analysis of Inorganic Alkaline Detergents.
Reagent Chemicals, American Chemical Society Specifications, American
Current edition approved May 26, 1989. Published July 1989. Originally
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
published as D 2761 – 68. Last previous edition D 2761 – 85.
listed by the American Chemical Society, see Analar Standards for Laboratory
Fischer and Porter, Model No. 1320, available from Scientific Glass Apparatus
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Co., Inc., Bloomfield, NJ as Catalog No. C4225X, has been found satisfactory for
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
this purpose.
MD.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 2761
4.9 Potassium Chloride Solution (74.5 g/L)—Dissolve 74.5 aliquot of the solution to the separatory funnel. Open both
g of KCl in water, add 5 mL of stock buffer solution (4.6), and stopcocks and allow the sample to drain into the column. Rinse
dilute to 1 L (Note 2). the separatory funnel with 20 mL of water. Discard the elute
4.10 Reducing Solution—Dissolve7gof sodium sulfite collected to this point. Add 375 mL of KCl solution (22.35 g/L)
(Na SO ) and 1.5 g of 1-amino-2-naphthol-4-sulfonic acid in to the column and collect the elute in consecutive 25-mL
2 3
75 mL of water. Add this to a solution of 90 g of sodium portions. Repeat this procedure with 250 mL of KCl solution
bisulfite (NaHSO ) in 700 mL of water. Dilute the mixture to (44.7 g/L) and with 100 mL of KCl solution (74.5 g/L).
1 L. Mix thoroughly and keep in a low-actinic bottle. Hydrolyze the collected fractions, develop the blue color, and
4.11 Sulfuric Acid (225+775)—Carefully dilute 225 mL of analyze for micrograms of P O per fraction. Based on the
2 5
concentrated sulfuric acid (H SO , sp gr 1.84) to 1 L with resulting elution curve, choose the desired portions to be
2 4
water. collected in each fraction to give good separation.
8. Separation of Sample into Fractions
5. Preparation of Standard Curves
5.1 Add 3 mL of H SO (225+775) to each of six 100-mL 8.1 Prepare an aqueous solution of the sample containing
2 4
about 1 mg of P O /mL and make up to a convenient volume.
volumetric flasks marked as No. 1, No. 2, No. 3, No. 4, No. 5,
2 5
and No. 6. To No. 2 flask add 2 mL (0.10 mg P O ) of standard For example, dissolve 0.5 g of sodium triphosphate in water
2 5
and dilute to 250 mL.
phosphate solution; to No. 3 flask, 5 mL (0.25 mg P O ); to No.
2 5
4 flask, 10 mL (0.50 mg P O ); to No. 5 flask, 20 mL (1.0 mg 8.2 Transfer a 10-mL aliquot of this solution to the separa-
2 5
tory funnel. Open both stopcocks and allow the solution to
P O ); and to No. 6 flask, 30 mL (1.5 mg P O ). Add 1 mL of
2 5 2 5
ammonium molybdate solution and 2 mL of reducing solution drain onto the column. Follow this with 20 mL of water to
to each of the six flasks and dilute to volume. Mix and allow to rinse, also added through the funnel. Discard the elute that has
stand 10 min. Then read the absorbance at 650 nm, using a come through the column to this point.
10-mm cell. Use the No. 1 solution as a blank. Prepare a 8.3 Add 370 mL of KCl solution (22.35 g/L) to the
calibration curve for micrograms of P O per millilitre versus separatory funnel with both stopcocks closed. Open both
2 5
absorbance. stopcocks and catch the elute coming through the column as
follows:
6. Preparation of Ion-Exchange Column
8.3.1 The first fraction in a graduated cylinder marked
6.1 Clamp the clean column in a vertical position to a tall “blank,”
ring stand so that the bot
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