Disclosed herein is a polymeric sampling swab for obtaining samples of an analyte of interest from solid surfaces or from liquid substances. The polymeric material of which the swab is composed is characterized by a high resistance to chemical and mechanical degradation. The sampling swab of the present invention is further characterized by a high internal void volume and a high absorptive capacity for fluids. The swab of the present invention is particularly suited for obtaining samples for use in chemiluminescent assays for, among other analytes of interest, microbial contamination. Also disclosed is a polymeric disc for loading with reagent mixtures suitable for use in bioluminescent assay procedures. The reagent disc of the invention is characterized by high resistance to chemical and mechanical degradation. In addition, the disc has a high void volume and high absorptive capacity.