Some embodiments of the invention provide a system for measurement of at least two hemoglobin species in a patient's blood sample by spectroscopy, and measurement of at least pH of the blood sample by biosensor. The system comprises a disposable cartridge adapted for insertion into a slot of an analyzer, and the results are used to monitor the acid-base status of a patient. A method for monitoring the acid-base status of a patient using the system is also provided.
