Engine coolants are an important fluid sometimes neglected in motor vehicles. Some citations in the literature report that a major cause of engine failure behind lubricant failure, is that of the coolant. Nitrite (NO2-) is a common additive to coolant formulations that is used to prevent pitting of the cylinder liner by creating an oxide patina protective layer. The nitrite additive in the fluid is consumed as it is in use however, and as such requires frequent testing to maintain appropriate levels.
Another technique to consider for testing nitrites in aqueous samples is UV/Vis spectroscopy. The UV/Vis technique allows for analysis of nitrite in aqueous samples is easy and offers the advantage of accuracy, speed and automation for high volume testing. This application note describes a method to accurately determine nitrite levels as ppm NO2- in glycol based aqueous engine coolant using the PerkinElmer LAMBDA® 365+ UV/Vis Spectrometer.