MQAE, a fluorescent chloride ion indicator, is more sensitive and selective than 36Cl and microelectrode-based methods for chloride measurement in cells. MQAE is quenched via collision with chloride.

Bath-applied to acute brain slices, MQAE provides high-quality labeling of neuronal cells and their processes[1]. MQAE fluorescence is an adequate and comparable method for measuring cAMP-dependent chloride transport in dozens of individual cells[2]. MQAE can be used to measure intracellular chloride concentration in primary cultures of rat aortic smooth muscle cells (VSMC)[3].