Investigation of the Method to Determine Carboxyhaemoglobin in Blood

摘要

The current method for determining blood carboxyhemoglobin concentration by gas chromatography has been critically evaluated and compared to spectrophotometric analysis methods. The major sources of bias in the method accuracy have been found to be in the measurement of blood volume and in the separate determination of total hemoglobin concentration in the blood. The method is estimated to have a coefficient of variation of 6.2% over the range of 0.5 to 20 vol % COHb. Standardization procedures which have been examined are the use of a 500 ppm carbon monoxide in nitrogen gas mixture and carbon monoxide-saturated blood solutions as external standards. Also, methods of saturating blood with carbon monoxide have been examined, with the use of an impinger or tonometer held at 37 C giving the most effective results. Studies of long-term storage of carbon monoxide blood have been carried out and have revealed that the concentration remains stable for up to nine days if the blood is stored anaerobically at refrigerator temperatures. Blood containing 10% or less carboxyhemoglobin has been found to be stable up to 60 days.