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Yes, dried blood spots are accepted by the U.S. Postal Service as safe and may be shipped by standard mail if secured within a secondary container before placing inside the mailer. The HemaSpot device is considered the secondary container and renders the blood sample safe and secure after closing.
Typically, we use a mixture of water and a water miscible organic solvent, such as methanol or acetonitrile, to elute analytes from the HemaForm blades. After vortexing or sonicating the blades in 200µL of solvent in deep well plates or conical tubes for 30 to 60 minutes followed by centrifuging at 10,000g for 10 minutes, we are able to draw off 175-180µL of solvent. Usually, this sample may be injected directly onto an HPLC system for mass spec analysis.
With protein or enzymatic assays, we generally use 200µL of a phosphate buffered solution or simply water to elute these components. For enzymatic assays, the enzyme substrate is generally added to the PBS solution and the deep well plate is mixed with heating for as much as 48-hours depending upon the activity of the enzyme. After incubation, the plates may be centrifuged briefly and the liquid decanted and added to an equal volume of cold methanol or acetonitrile to precipitate protein. Again, after centrifuging to pellet protein, the sample is injected onto the HPLC for analysis.
Hematocrit is the volume percentage of red blood cells in blood. Hematocrit (ht or HCT) is also referred to as Packed Cell Volume (PCV) or Erythrocyte Volume Fraction (EVF). Normal HCT levels for adult males is 42-52%. Normal HCT levels for adult females is 36-48%. Hematocrit is measured by centrifuging whole blood in a heparinized capillary tube (to prevent clotting) to separate the plasma from red blood cells. HCT is calculated by measuring the lengths of the layers (PCV length/total length).
Hematocrit has an effect on blood viscosity and may influence the flow and spread of a sample onto DBS filter paper. Spot On Sciences’ HemaForm design reduces the effect of hematocrit by controlling the flow and spread when a sample is applied. (Hematocrit poster data can be supplied)