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United States Department of Agriculture

Agricultural Research Service

Research Project: Influence of Structure and Moisture on Cotton Fiber Properties

Location: Cotton Structure and Quality Research

Title: Standard test method for water in lint cotton by oven evaporation combined with volumetric Karl Fischer Titration

Authors
item Montalvo, Joseph
item von Hoven, Terri

Submitted to: American Society for Testing and Materials
Publication Type: Other
Publication Acceptance Date: February 1, 2012
Publication Date: March 14, 2012
Citation: Montalvo Jr, J.G., Von Hoven, T.M. 2012. Standard test method for water in lint cotton by oven evaporation combined with volumetric Karl Fischer Titration. American Society for Testing and Materials. D7785-12 p.1-7.

Interpretive Summary: Water in cotton is important because the fiber properties (mechanical, dimensional and electrical) are dependent on the water content. The standard test methods for water in lint cotton are based on oven drying at 105oC; all of the loss in weight is attributable to moisture. A more accurate reference method was developed at the request of the cotton industry and is based on oven drying in combination with Karl Fischer Titration of the water vapor from the dried cotton. Karl Fischer Titration, used in standard test methods worldwide, involves titrating water with an iodine reagent. From the information gathered in developing this method, all of the variables could be optimized and this resulted in excellent water content values that were validated by other techniques. Furthermore, it is possible to calibrate, package and distribute to collaborators standard reference cottons certified for water content.

Technical Abstract: The referenced test method for total water content and water regain in lint cotton was developed by USDA scientists in New Orleans at the request of the cotton industry. The method covers the determination of the total water (free and bound) in raw and lint cotton at moisture equilibrium from conditioning in the standard atmosphere for testing textiles. The use of oven evaporation is required 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. This test method eliminates all of the biases in the standard oven-drying method. An ASTM Intralaboratory Study (ILS) #519 was conducted in an effort to establish repeatability. Additionally, this test method will enable the calibration, packaging, and distribution of standard reference cottons for total water content and water regain.

Last Modified: 8/22/2014
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