ASTM D3598-89(1995)e1

Standard Test Method for Citrate in Synthetic Detergents

SCOPE
1.1 This test method covers the enzymatic determination of citrate in both liquid and solid synthetic detergents. The test method is applicable to most detergents containing citrate at a minimum concentration of approximately  % (1-8).  
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: 31-Dec-1994
• Technical Committee: D12 - Soaps and Other Detergents
• Drafting Committee: D12.12 - Analysis and Specifications of Soaps, Synthetics, Detergents and their Components

Relations

• Replaced By: ASTM D3598-89(2003) - Standard Test Method for Citrate in Synthetic Detergents
• Effective Date: 26-May-1989

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.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.
e1
Designation: D 3598 – 89 (Reapproved 1995)
Standard Test Method for
Citrate in Synthetic Detergents
This standard is issued under the fixed designation D 3598; 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 a-ketoglutaric, oxalic, succinic, or tartaric acids, do not inter-
fere.
1.1 This test method covers the enzymatic determination of
4.2 Although low levels of zinc or magnesium, or both, are
citrate in both liquid and solid synthetic detergents. The test
required as an activator for the enzyme citrate lyase, exces-
method is applicable to most detergents containing citrate at a
sively high levels of divalent metallic ions including zinc and
minimum concentration of approximately 5 % (1-8).
magnesium will cause inactivation of the enzyme and poten-
1.2 This standard does not purport to address all of the
tially interfere with the test method (7).
safety concerns, if any, associated with its use. It is the
4.3 The test method is not applicable to those detergents
responsibility of the user of this standard to establish appro-
containing components with excessive absorptivity at 340 nm
priate safety and health practices and determine the applica-
such that ultraviolet measurements are inappropriate at 340 nm
bility of regulatory limitations prior to use. Material Safety
under test conditions.
Data Sheets are available for reagents and materials. Review
them for hazards prior to usage.
5. Apparatus
2. Referenced Documents 5.1 Interval Timer.
5.2 Micropipet, suitable Eppendorf pipets for dispensing 10
2.1 ASTM Standards:
and 100-μL volumes and with disposable tips.
D 501 Test Methods of Sampling and Chemical Analysis of
3 5.3 Spectrophotometer, suitable for measuring ultraviolet
Alkaline Detergents
absorbance at 340 nm and equipped with 1-cm matched quartz
D 1193 Specification for Reagent Water
cells with tapered TFE-fluorocarbon stoppers and a minimum
3. Summary of Test Method
volume of 4 mL.
3.1 This test method employs an enzyme system that is
6. Reagents
based upon the selective cleavage of citrate by citrate lyase
6.1 Purity of Reagents—Reagent grade chemicals shall be
(citrate oxaloacetate-lyase; EC 4.1.3.6) (1). One of the prod-
used in all tests. Unless otherwise indicated, it is intended that
ucts, oxaloacetate, is reduced to malate by malic dehydroge-
all reagents shall conform to the specifications of the Commit-
nase (L-malate: NAD oxidoreductase; EC 1.1.1.37) with the
tee on Analytical Reagents of the American Chemical Society,
simultaneous oxidation of reduced b-nicotinamide adenine
where such specifications are available. Other grades may be
dinucleotide to b-nicotinamide adenine dinucleotide, oxidized
used, provided it is first ascertained that the reagent is of
form. The course of the reaction is measured spectrophoto-
sufficiently high purity to permit its use without lessening the
metrically. The decrease in absorbance at 340 nm caused by the
accuracy of the determination.
formation of b-nicotinamide adenine dinucleotide, oxidized
6.2 Purity of Water—Unless otherwise indicated, references
form, is directly proportional to the concentration of citrate.
to water shall be understood to mean Type II reagent water
4. Interferences conforming to Specification D 1193.
6.3 Citrate Lyase Solution (40 units/mL)—Add sufficient
4.1 The test method is highly specific for citrate. Other
cold water to a vial of citrate lyase containing a premeasured
organic acids, for example, cisand trans-aconitic, d,l-isocitric,
weight of enzyme protein such that the resulting solution will
contain 40 units/mL; for example, 2.0 mL of water is added to
This test method is under the jurisdiction of ASTM Committee D-12 on Soaps
a vial containing 5 mg of enzyme protein with an activity of 16
and Other Detergents, and is the direct responsibility of Subcommittee D12.12 on
Analysis of Soaps and Synthetic Detergents.
Current edition approved May 26, 1989. Published July 1989. Originally
Reagent Chemicals, American Chemical Society Specifications, American
published as D 3598 – 77 T. Last previous edition D 3598 – 80 (1988). Chemical Society, Washington, DC. For suggestions on the testing of reagents not
The boldface numbers in parentheses refer to the references at the end of this listed by the American Chemical Society, see Analar Standards for Laboratory
test method. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 15.04. and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 11.01. MD.
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 3598
units/mg of enzyme protein. One unit of activity will convert 7. Sampling
1.0 μmol of citrate to oxaloacetate per minute at pH 7.6 at
7.1 Collect the sample in accordance with Test Methods
25°C. The citrate lyase solution should be maintained in an ice
D 501.
bath for the duration of the analyses and can be used for 5 days
if refrigerated. Citrate lyase (EC 4.1.3.6) from Aerobacter
8. Procedure
aerogenes is commercially available as a lyophilized powder
8.1 Dissolve an accurately weighed detergent sample
containing approximately 24 % citrate lyase, 24 % albumin,
equivalent to approximately 300 mg of trisodium citrate
48 % saccharose and 4 % magnesium sulfate (MgSO ·7H O).
4 2
dihydrate in distilled water and dilute to 200 mL. Dilute a 3.0
The citrate lyase powder should be stored as specified by the
mL aliquot of this solution to 100 mL with water. This is the
supplier.
sample test solution.
6.4 Disodium b-Nicotinamide Adenine Dinucleotide, Re-
8.2 During the following steps, use the appropriate micropi-
duced Form Solution (0.0032 M)—Dissolve 10 mg of diso-
pet for the 10 and 100-μL volumes, replacing the tip after each
diumb -nicotinamide adenine dinucleotide, reduced form,
addition. Standard volumetric pipets can be used for the 1.0
(b-NADH) in 4.0 mL of water. The b-NADH should be
and 2.0-mL additions.
approximately 98 % pure and essentially free of the alpha
8.3 Into a 1-cm quartz cell, pipet 1.0 mL of either a water
isomer. The b-NADH solution should be protected from light
blank, standard Solutions I or II, or a sample test solution.
and maintained in an ice
...