Haems as potential reagents for carbon monoxide

A study of the potential of a myoglobin model system based on dipiperidyltetraphenylporphinatoiron(II) for the spectrophotometric determination of carbon monoxide is reported. At room temperature, oxygen does not bind strongly at the iron centre and does not interfere. Nitric oxide, hydrogen sulphide and carbon dioxide interfere and must be removed before the determination if present in significant amounts. The main disadvantage of this novel method is the low sensitivity (about 300 ppm CO). Possible means of modifying the system to enhance the sensitivity and to further reduce the number of interfering species are discussed.