A stable portable beverage dispensing cooler includes a spring loaded dispensing unit for beverages with freezer packs between the rows of beverages for maintaining the beverages in a chilled environment. In particular, the sampling cannula comprises an open trough-like portion, wherein the trough-like portion comprises at least one wall opening located proximal to the distal end in combination with an interior surface comprising a friction-enhancing surface texture adapted to facilitate sample retention. The media sheet has a leading edge and a trailing edge and the sensors are adapted to identify locations of the leading edge and the trailing edge of the media sheet.