Bond Failure Analysis in Engine and Suspension Mounts
RTI adds Karl Fischer Volumetric Water Content Determination with Homogenization to the Paints and Coatings Analytical Group
RTI has developed and maintained expertise in EPA method 24 determination for many years. EPA method 24 determination involves direct measurement of several physical and chemical properties of a substance to ultimately report on its “VOC content” (volatile organic compounds). One of the required measurements for VOC determination is water content. Several methods are available to the laboratory for accurate determination of water content, however each method has it’s pros and cons for this determination based on factors such as nominal level (trace or waterborne), inferring substances (ketones, organo-sulfur), and matrix (viscosity, pastes). Karl Fischer titration is a long established method for accurate determination of water content with a wide variety of sample introduction techniques also available.
Karl Fischer titration is broken up into two distinct “types” of titration: coulometric and volumetric. Although coulometric titration is generally the most suitable method for trace water content analysis, the uncertainty associated with bulk water determinations can be the dominant factor in inaccuracies of the VOC determination as the water level increases. The uncertainties associated with volumetric titration are typically much less as the water content increases and is the method of choice for accurate determination of water content in waterborne and low VOC formulations.
The addition of the Mettler Toledo V30S volumetric titrator with HS-280 homogenizer completes the package offerings for water content determination in support of EPA method 24 analysis. The homogenizer addition also enables the rapid breakup and dissolution of solids and difficult matrices, furthering the accurate determination of water content. This addition complements our capability of water content by coulometric titration as well as by GC-TCD (gas chromatography – thermal conductivity detection).
The ASTM methods specifically referenced in EPA method 24 provide the individual measurements to the VOC content calculated value. These methodologies include:
- ASTM D1475 for density determination
- ASTM D2369 for volatile content
- ASTM D3792 for water content by GC-TCD
- ASTM D4017 for water content by Karl Fischer Titration
- ASTM D4457 for determination of exempt solvent content by GC
In addition, RTI also can provide for EPA method 24 values at modified temperatures (often used by facilities to determine at use temperature VOC exposures or air handling parameters), or provide further characterization of VOC components utilizing methods such as EPA method 311 for HAP (hazardous air pollutants) content. In addition, although outside of the scope of EPA method 24, RTI can also perform VOC content by TGA (ASTM E1868) which is more applicable to industrial matrices outside of paints and coatings and also for reporting per SCAQMD (South Coast Air Quality Management District) Rule 1144.
Written by Lloyd Kaufman
Director of Materials Sciences
RTI Laboratories, Inc.