AATCC TM149-2023 氨基多羧酸及其盐类螯合值测试法：草酸钙

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288 AATCC TM149-2023 AATCC Manual of International Test Methods and Procedures/2025

1. Foreword

1.1 The titration in this method yields a

value that includes partially-substituted

EDTA, HEDTA, DTPA, nitrilotriacetic

acid (NTA), iminodiacetic acid (IDA),

glycolate and other weak chelating agents

found in some commercial products. An

alternative procedure, excluding the ef-

fect of partially-substituted products, is

provided in AATCC TM168, Test

Method for Chelation Value of Polyami-

nopolycarboxylic Acids and Their Salts:

Copper PAN.

2. Purpose and Scope

2.1 The active content of ethylene-

diaminetetraacetic acid (EDTA), N-hy-

droxyethylethylenediaminetriacetic acid

(HEDTA) and diethylenetriaminepen-

taacetic acid (DTPA) and their salts is

usually expressed by the calcium chela-

tion value (CaCV). This value indicates

the amount of calcium (as calcium car-

bonate) which will be chelated by a

known weight of chelating agent.

3. Principle

3.1 The chelation value is determined

experimentally by titrating a weighed

sample of chelating agent with a calcium

ion solution of known concentration. A

precipitating anion (oxalate) is present

during the titration. As the calcium solu-

tion is added, the ions are chelated by the

chelating agent and no permanent precip-

itate is formed as long as there is free

chelating agent present. Beyond this

point, any excess calcium ion that is

added reacts with oxalate anion to form a

cloudy precipitate which is the endpoint.

3.2 The CaCV indicates the amount of

calcium (as calcium carbonate) that will

be sequestered by a known weight of

chelating agent and is expressed as milli-

grams of calcium carbonate (CaCO3) per

gram of chelating agent (mg calcium car-

bonate/g chelating agent).

4. Referenced Documents

NOTE: Use current versions of all

publications unless otherwise specified.

4.1 AATCC TM168, Test Method for

Chelation Value of Polyaminopolycarbox-

ylic Acids and Their Salts: Copper PAN.

5. Terminology

5.1 chelating agent, n.—in textile

chemistry, a chemical capable of deacti-

vating metal ions by formation of a water-

soluble complex. SYN.—sequestering

agent.

6. Safety Precautions

6.1 The safety precautions specified in

the method/procedure are ancillary to the

testing procedures and are not intended to

be all inclusive.

6.2 It is the user’s responsibility to ref-

erence applicable safety data sheets, use

safe and proper techniques, and wear ap-

propriate personal protective equipment

in handling materials in this standard.

7. Uses and Limitations

7.1 Analysis by this method will yield

a CaCV that includes partially-substituted

EDTA, HEDTA and DTPA as well as ni-

trilotriacetic acid (NTA), iminodiacetic

acid (IDA), glycolate and other weak

chelating agents. These compounds may

be present in some commercial products.

7.2 AATCC TM168 is an alternative

procedure that yields a CaCV that does

not include the partially-substituted prod-

ucts and weaker chelating agents.

8. Reagents

8.1 Calcium carbonate (CaCO3).

8.2 Sodium oxalate (Na2C2O4).

8.3 Diethylamine hydrochloride [(C2H5)2

NH · HCl]

8.4 Sodium hydroxide (NaOH) solu-

tion, 50% W/W.

8.5 Hydrochloric acid (HCl) conc.

9. Sampling

9.1 Conduct the test in triplicate; i.e.,

analyze 3 test specimens from a sample.

10. Specimens

10.1 Do not use aluminum or metallic

weighing pans.

10.2 If solid chelating agent is being

evaluated, dry a 2-g sample at the appro-

priate temperature for at least 2 h and

cool in desiccator before weighing speci-

mens.

10.2.1 Dry free acid forms of chelating

agents at 120°C.

10.2.2 Dry salt forms of chelating

agents at 80°C.

10.3 For analysis of solid EDTA,

HEDTA and DTPA (either free acid or

salt forms) weigh a 0.49-0.51 g specimen

of the dried chelating agent to an accu-

racy of 0.01 g.

10.4 For analysis of commercial solu-

tions of salts of the chelating agents (see

10.2) weigh a 1.00-1.20 g specimen of

the solution to an accuracy of 0.01 g.

11. Preparation of Reagents

11.1 Calcium Titrant Solution (0.250

M): Weigh 25.0 g of calcium carbonate to

an accuracy of 0.1 g and add it to 300 mL

of distilled water in a 600-mL beaker

with stirring on a magnetic stirrer. Dis-

solve by adding 43 mL of concentrated

hydrochloric acid. Add the hydrochloric

acid slowly and carefully to prevent bub-

bling over and excessive splattering. After

the calcium carbonate has dissolved (the

solution becomes clear), heat the solution

to boiling and allow it to boil for at least 5

min to expel carbon dioxide. Cool the so-

lution to room temperature, transfer it to

a 1-L volumetric flask and dilute it to 1 L.

Prepare a fresh solution monthly.

11.2 Sodium Oxalate Indicator: Dis-

solve 5 g of sodium oxalate in 250 mL of

distilled water. Prepare a fresh solution

monthly.

11.3 Sodium Hydroxide (50%): 50%

solution (W/W) of sodium hydroxide is

available from many laboratory supply

vendors. It can be prepared by dissolving

100 g of sodium hydroxide pellets in 100

mL of distilled water in a polyethylene

bottle. Let stand for a week to allow the

insoluble sodium carbonate to settle.

11.4 pH 12.0 Buffer Solution: Dissolve

41.0 g of diethylamine hydrochloride in

400 mL of distilled water. Add 40 mL of

50% sodium hydroxide and dilute to 500

mL. Store in a polyethylene bottle. Pre-

pare a fresh solution monthly.

12. Procedure

12.1 Transfer the specimen into a 250-

mL Erlenmeyer flask and add 85 mL of

distilled water. Wash any residual chelat-

ing agent from the weighing paper or dish

into the flask.

12.2 Add 5 drops of 50% sodium hy-

droxide (10 drops if the free acid form of

a chelating agent is being analyzed) and

swirl to dissolve and/or mix the chelating

agent.

12.3 Add 1 mL of pH 12.0 buffer solu-

tion and swirl to mix.

AATCC TM149-2023

Test Method for Chelation Value of Aminopolycarboxylic

Acids and Their Salts: Calcium Oxalate

Provided by Accuris under license with AATCC

No reproduction or networking permitted without license from Accuris Not for Resale, 2025-04-14 18:24:10 UTC

Sold to: Nawal Analytical Labs India Private limited

Order Number: 00015024

AATCC Manual of International Test Methods and Procedures/2025 AATCC TM149-2023 289

12.4 Add 10 mL of sodium oxalate so-

lution and swirl to mix.

12.5 Using a 10-mL burette, titrate

with calcium titrant solution until a drop

produces a slight turbidity that persists

for at least 30 s.

12.5.1 Turbidity is easier to observe

when a piece of black paper is placed be-

neath and behind the flask, and the flask

is illuminated from the side by a white

fluorescent light. Add the calcium titrant

dropwise once the turbidity begins to per-

sist for more than 2-3 s. The endpoint is

the first sign of turbidity that persists for

at least 30 s. If there is uncertainty as to

whether a slight turbidity has been ob-

tained, compare the appearance of the

flask to that of one containing only water,

which has a distinct clear appearance.

13. Calculation

13.1 Calculate the CaCV for each

specimen to 3 significant digits using

Equation 1:

(Eq. 1)

where:

CaCV= Calcium chelation value, ex-

pressed as mg CaCO3/g

chelating agent

CaCV 100.1()0.250()V()

---------------------------------------------=

100.1 = Molecular weight of CaCO3

expressed in mg/mmole

0.250 = Molarity of calcium titrant so-

lution expressed in mmoles/

V= Volume of calcium titrant so-

lution in mL

W= Weight of specimen in grams

13.2 Average the CaCV values for the

3 specimens tested.

14. Report

14.1 Report for each sample tested:

14.1.1 A description or identification

of the sample.

14.1.2 Report that the sample was

tested using AATCC TM 149-2022.

14.1.3 Average CaCV, to 3 significant

digits.

14.1.4 Describe any modifications of the

test method.

15. Precision and Bias

15.1 Summary. An interlaboratory

study was conducted in March 1990 to

establish the precision of the test method.

Four chelating agents (EDTA, tetraso-

dium salt; EDTA, 40% solution of tetra-

sodium salt; DTPA, free acid; and DTPA,

40% solution) were evaluated.

15.2 Precision. The components of

variance as standard deviations of CaCV

were calculated as follows:

Single Operator Component 1.46

Interlaboratory Component 0.00

15.3 Critical Differences. For the com-

ponents of variances reported in 13.2,

two averages of observed values should

be considered significantly different at

the 95% probability level if the difference

is equal to or exceeds the following criti-

cal differences:

Single Operator 4.04

Interlaboratory 4.04

15.4 Bias. Based on the theoretical cal-

cium chelation values of the four materi-

als used in the interlaboratory study, the

average bias of the five laboratories was

2.24%. The individual biases for the four

materials and five laboratories ranged

from 2.50-4.25%.

16. History

16.1 Revised in 2023 to clarify and align

with prescribed AATCC style guidelines.

16.2 Editorially revised 2019; revised 2018;

reaffirmed 2012; editorially revised 2010; re-

affirmed 2007; reaffirmed 2002; editorially re-

vised and reaffirmed 1997; revised 1992;

editorially revised 1988, 1986; editorially re-

vised and reaffirmed 1985; editorially revised

1984; reaffirmed 1980; editorially revised and

reaffirmed 1977.

16.3 Developed in 1976 by AATCC Com-

mittee RR90. Maintained by RA99.

Provided by Accuris under license with AATCC

No reproduction or networking permitted without license from Accuris Not for Resale, 2025-04-14 18:24:10 UTC

Sold to: Nawal Analytical Labs India Private limited

Order Number: 00015024

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摘要：

AATCC TM149-2023 是纺织与化学行业广泛参考的标准方法，专门用于测定氨基多羧酸及其盐类在草酸钙体系中的螯合值。该测试通过评估螯合剂对钙离子的结合能力，帮助制造商和质检机构在水处理、纺织印染及清洁剂配方中精准控制螯合剂的性能。标准采用草酸钙沉淀法，详细规定了试剂配制、滴定步骤及结果计算，确保不同实验室间的结果可比性。对于从事工业水软化、织物前处理或金属离子控制的专业人员，掌握AATCC TM149-2023 能优化工艺、减少硬水影响并提升产品稳定性。本测试方法的最新2023版更新了操

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