Apparatus and method for testing blood

A method comprising:

• transferring at least a portion of a fluid sample from a fluid sample collection apparatus to an internal chamber of a barrel via an inlet opening;
• passing the portion of the fluid sample from the internal chamber of the barrel to a colorimetric chamber and a colorimetric assay assembly housed in the colorimetric chamber, the colorimetric chamber being in fluid communication with the internal chamber, and the colorimetric assay assembly having a sample application pad and a colorimetric detection pad, the sample application pad is formed of a prefiltration layer comprising a prefiltration material having a hydrophilic receiving surface and a distal surface, the hydrophilic receiving surface having a first wetting property configured to receive the fluid sample from the internal chamber, and the distal surface having a second wetting property being less hydrophilic than the first wetting property, the sample application pad is further formed of a filtration layer comprising a filtration material in fluid communication with the prefiltration layer, the hydrophilic receiving surface being configured to pass plasma, red blood cells, white blood cells, and free hemoglobin;
• retaining at least red blood cells from the portion of the fluid sample passing into the colorimetric assay assembly in at least one of the filtration layer and the prefiltration layer of the sample application pad;
• indicating, by the colorimetric detection pad of the colorimetric assay assembly, a presence of free hemoglobin in the fluid sample;
• and
• transferring the fluid sample from the internal chamber to a liquid sample analyzer with a sample probe responsive to the indication of the presence of free hemoglobin in the fluid sample being below a predetermined threshold.

An apparatus, comprising:

• a barrel having a first end, a second end opposite the first end, an inner surface defining an internal chamber, and a sidewall extending between the first end and the second end, the sidewall defining at least a portion of a colorimetric chamber in fluid communication with the internal chamber via a passage through the sidewall of the barrel, the colorimetric chamber defined by a portion of the sidewall of the barrel and a cover, the cover comprising a housing having an outside surface, an inside surface, and a compression rib extending from the inside surface away from the outside surface;
• and
• a colorimetric assay assembly housed in the colorimetric chamber configured to visualize free hemoglobin in a fluid sample, the colorimetric assay assembly comprising:
• a sample application pad configured to receive the fluid sample from the internal chamber, wherein the sample application pad is formed of a prefiltration layer of a prefiltration material and a filtration layer of a filtration material, wherein the filtration layer of the sample application pad is porous to plasma and the free hemoglobin and not porous to red blood cells, the compression rib engaging and compressing at least a portion of the prefiltration layer of the sample application pad;
• and
• a colorimetric detection pad in fluidic contact with the filtration layer of the sample application pad, the colorimetric detection pad being configured to visualize a presence of the free hemoglobin.