ASTM D7785-21

Standard Practice for Water in Lint Cotton by Oven Evaporation Combined with Volumetric Karl Fischer Titration

SIGNIFICANCE AND USE
5.1 The water content of raw or lint cotton determined by this practice, calculated from the required volume of reagent, may be greater, equal to or less than the moisture content measured by standard oven drying methods. These differences may be of significance in commercial transactions (1-3)4 (see also Appendix X2). Water content by this method is not to be considered the same attribute as moisture content.  
5.2 Standard test methods using volumetric and coulometric Karl Fischer reagent are two of the most widely used procedures for the determination of water.  
5.3 The volumetric method is typically used for the routine determination of water in the mass percent range of concentrations. If samples contain very low levels of water, the coulometric technique should be considered (see Test Methods D1533, E1064).  
5.4 This practice for testing the water content of cotton can be used for acceptance testing of commercial shipments of lint cotton, manufacturing control and calibration of fast, indirect sensors to measure water.  
5.5 Information on the water content of cotton is desirable since the physical properties of cotton are significantly affected by its water content. Variations in the amount of water present, or its regain, affect the mass and hence the market value of a lot of material.  
5.6 The observed volume of Karl Fischer reagent used in this practice to analyze a specimen represents the water in the absence of side reactions in an oven supplied with air (3).
Note 2: Side reactions in cotton that confound the actual weight loss due to water have been demonstrated in two laboratory ovens and a thermogravimetric analysis oven supplied with air (3). This results in an approximation regarding the actual amount of water in cotton based on mass loss by drying. If the moisture content by oven drying agrees with the water content measured by Karl Fischer titration, the one-to-one correspondence may be coincidental due to the presence of both negative a...
SCOPE
1.1 This practice covers the determination of the total amount of water (free and bound) in raw and lint cotton at moisture equilibrium from conditioning in the standard atmosphere for testing textiles.
Note 1: For other methods of determination of moisture in lint cotton that do not specify conditioning to moisture equilibrium, refer to Test Methods D2495 and D1348.  
1.2 This practice requires the use of oven evaporation to remove all of the water in the fiber matrix, volumetric Karl Fischer (KF) titration to determine water content and water regain, and control current potentiometry to detect the end point.  
1.3 This practice is not intended for use with potentiometric (zero current) and coulometric Karl Fischer titrators (see Test Methods D1533, D4377 and E1064), nor is this practice intended to be used with methanol extracts of cotton (See Test Methods D1348).  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific precautionary warnings see 9.1.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Dec-2020
• ICS: 59.080.01 - Textiles in general
• Technical Committee: D13 - Textiles
• Drafting Committee: D13.11 - Cotton Fibers

Relations

• Refers: ASTM D1441-12(2020) - Standard Practice for Sampling Cotton Fibers for Testing
• Effective Date: 01-Jul-2020
• Refers: ASTM D7139-20 - Standard Terminology for Cotton Fibers
• Effective Date: 01-Jul-2020

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7785 − 21
Standard Practice for
Water in Lint Cotton by Oven Evaporation Combined with
1
Volumetric Karl Fischer Titration
This standard is issued under the fixed designation D7785; 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 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This practice covers the determination of the total
D123 Terminology Relating to Textiles
amount of water (free and bound) in raw and lint cotton at
D1193 Specification for Reagent Water
moisture equilibrium from conditioning in the standard atmo-
D1348 Test Methods for Moisture in Cellulose (Withdrawn
sphere for testing textiles.
3
2017)
NOTE 1—For other methods of determination of moisture in lint cotton
D1441 Practice for Sampling Cotton Fibers for Testing
that do not specify conditioning to moisture equilibrium, refer to Test
D1533 Test Method for Water in Insulating Liquids by
Methods D2495 and D1348.
Coulometric Karl Fischer Titration
1.2 This practice requires the use of oven evaporation to
D1776 Practice for Conditioning and Testing Textiles
remove all of the water in the fiber matrix, volumetric Karl
D2495 Test Method for Moisture in Cotton by Oven-Drying
Fischer (KF) titration to determine water content and water
D4377 Test Method forWater in Crude Oils by Potentiomet-
3
regain, and control current potentiometry to detect the end
ric Karl Fischer Titration (Withdrawn 2020)
point.
D7139 Terminology for Cotton Fibers
E177 Practice for Use of the Terms Precision and Bias in
1.3 This practice is not intended for use with potentiometric
ASTM Test Methods
(zero current) and coulometric Karl Fischer titrators (see Test
E203 Test Method for Water Using Volumetric Karl Fischer
Methods D1533, D4377 and E1064), nor is this practice
Titration
intended to be used with methanol extracts of cotton (See Test
E691 Practice for Conducting an Interlaboratory Study to
Methods D1348).
Determine the Precision of a Test Method
E1064 Test Method for Water in Organic Liquids by Coulo-
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this metric Karl Fischer Titration
standard.
3. Terminology
1.5 This standard does not purport to address all of the
3.1 Definitions:
safety concerns, if any, associated with its use. It is the
3.2 For all terminology relating to D13.11, Cotton Fibers,
responsibility of the user of this standard to establish appro-
refer to Terminology D7139.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3.3 The following terms are relevant to this standard: bound
For specific precautionary warnings see 9.1. water, free water, test specimen, water content, water regain.
1.6 This international standard was developed in accor-
3.4 FordefinitionsofallothertextiletermsseeTerminology
dance with internationally recognized principles on standard-
D123.
ization established in the Decision on Principles for the
4. Summary of Practice
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
4.1 A0.1gtestspecimenissealedinaglassvial,positioned
Barriers to Trade (TBT) Committee.
on the sample turntable and lowered into the single sample
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
1
ThispracticeisunderthejurisdictionofASTMCommitteeD13onTextilesand contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
is the direct responsibility of Subcommittee D13.11 on Cotton Fibers. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Jan. 1, 2021. Published February 2021. Originally the ASTM website.
3
published in 2012. Last previous edition approved in 2012 as D7785-12. DOI: The last approved version of this historical standard is referenced on
10.1520/D7785-21. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7785 − 21
oven where dry nitrogen transports the water vapor that is automaticovenevaporatorcombinedwiththecoulometricKarl
rapidly evaporated from the fibers into a titration cell. The Fischer method demonstrate the need to validate the proce-
amount of water is determined by volumetric titration with dures (5,6).
Karl Fischer reagent
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7785 − 12 D7785 − 21
Standard Test Method Practice for
Water in Lint Cotton by Oven Evaporation Combined with
1
Volumetric Karl Fischer Titration
This standard is issued under the fixed designation D7785; 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
1.1 This test method covers the determination of the total amount of water (free and bound) in raw and lint cotton at moisture
equilibrium from conditioning in the standard atmosphere for testing textiles.
NOTE 1—For other methods of determination of moisture in lint cotton that do not specify conditioning to moisture equilibrium, refer to Test Methods
D2495 and D1348.
1.2 This test method requires the use of oven evaporation to remove all of the water in the fiber matrix, volumetric Karl Fischer
(KF) titration to determine water content and water regain, and control current potentiometry to detect the end point.
1.3 This test method is not intended for use with potentiometric (zero current) and coulometric Karl Fischer titrators (see Test
Methods D1533, D4377 and E1064), nor is this test method intended to be used with methanol extracts of cotton (See Test Methods
D1348).
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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. For specific precautionary warnings see 9.1.
2. Referenced Documents
2
2.1 ASTM Standards:
D123 Terminology Relating to Textiles
D1193 Specification for Reagent Water
3
D1348 Test Methods for Moisture in Cellulose (Withdrawn 2017)
D1441 Practice for Sampling Cotton Fibers for Testing
D1533 Test Method for Water in Insulating Liquids by Coulometric Karl Fischer Titration
D1776 Practice for Conditioning and Testing Textiles
D2495 Test Method for Moisture in Cotton by Oven-Drying
3
D4377 Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration (Withdrawn 2020)
1
This test method practice is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.11 on Cotton Fibers.
Current edition approved Feb. 1, 2012Jan. 1, 2021. Published March 2012February 2021. DOI: 10.1520/D7785-12.Originally published in 2012. Last previous edition
approved in 2012 as D7785-12. DOI: 10.1520/D7785-21.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7785 − 21
D7139 Terminology for Cotton Fibers
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E203 Test Method for Water Using Volumetric Karl Fischer Titration
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1064 Test Method for Water in Organic Liquids by Coulometric Karl Fischer Titration
3. Terminology
3.1 Definitions:
3.2 For all terminology relating to D13.11, Cotton Fibers, refer to Terminology D7139.
3.3 The following terms are relevant to this standard: bound water, free water, test specimen, water content, water regain.
3.4 For definitions of all other textile terms see Terminology D123.
4. Summary of Test Method
4.1 A 0.1 g test specimen is sealed in a glass vial, positioned on the sample turntable and lowered into the single sample oven
where dry nitrogen transports the water vapor that is rapidly evaporated from the fibers into a titration cell. The amount of water
is determined by volumetric titration with Karl Fischer reagent with the end point determined by electrodes that measure a sharp
change in potential when the iodine in the reagent is reduced by sulfur dioxide in the presence of water. The volume of reagent
required to titrate the wet gas stream i
...