Methods and systems for verifying the volume of a reagent dispensed into an affinity assay vessel are described. In one embodiment, a method is for verifying the volume of a reagent dispensed into an affinity assay vessel described in which a fluid sample is deposited into a vessel that includes a reaction chamber and a volume determination reference point. The reaction chamber further includes a test strip. According to one embodiment, the dispensed fluid is agitated to promote contact between the fluid and a test strip disposed within the reaction chamber. The relative positions of the volume determination reference point and an edge of the meniscus of the dispensed fluid are then determined such that the meniscus of the dispensed fluid is not penetrated. The volume of the dispensed fluid is determined from these relative positions.