Section 864.7425 - Carboxyhemoglobin assay(a)Identification. A carboxyhemoglobin assay is a device used to determine the carboxyhemoglobin (the compound formed when hemoglobin is exposed to carbon monoxide) content of human blood as an aid in the diagnosis of carbon monoxide poisoning. This measurement may be made using methods such as spectroscopy, colorimetry, spectrophotometry, and gasometry.(b)Classification. Class II (performance standards).45 FR 60619, Sept. 12, 1980