A vial carrier having plural reagent compartments disposed linearly along the length of the carrier. Each compartment is adapted for receiving one of plural reagent vials. The carrier is provided with indicia uniquely identifying it to an automated assay device. Similarly, each compartment of the carrier has associated with it indicia which are at least unique to the particular carrier. Lastly, each vial installable within a carrier compartment has indicia unique to the contents of the vial. A film seal is applied to the vial opening prior to an integrated cap/seal assembly for the purpose of ensuring that the assembly is liquid-tight. The carrier is configured to be disposed on a slide of an inclining tray within an enclosure. Data reflecting which vial is located in which compartment of a given carrier is collected and provided to the automated instrument prior to installation of the carrier into the enclosure. The automated instrument has, associated with the enclosure, an indicia recognition element to identify each installed carrier. In this manner, the instrument has information reflecting that a desired vial is installed in a particular compartment of a carrier which is installed on a particular slide within the enclosure.