This communication describes a method to detect aluminum in gastric drugs by the naked eye using a microfluidic paper-based analytical device ([mu]PAD). Aluminum ions react with chrome azurol S (CAS) and cetyltrimethylammonium bromide (CTAB) to form a colored complex, which generates a colored band on the [mu]PAD. A printed ruler can be used to measure the length of the colored band on an individual paper channel for the quantification of an aluminum ion. The [mu]PAD system was designed for use in a modern instrumental analysis course taken by students majoring in Food Quality and Safety. This analytical protocol could also be modified to be used as a demonstration or laboratory experiment in a high school chemistry course with some simplifications to the procedures.