ASTM D 4373 is an essential standard for the geotechnical engineer’s toolkit. It sacrifices the pinpoint chemical accuracy of wet chemistry titration for the sake of speed, economy, and portability. It provides a reliable "index" value for carbonate content that is sufficient for most construction material selection, soil stabilization design, and corrosivity assessments. However, for geochemical research or soils with complex mineralogy, users must be wary of interferences from organic matter and sulfides.