TABLE 1.

Summary of four dried blood spot (DBS) collection devices selected for initial evaluation

Characteristic	Whatman 903 Protein Saver	HemaSpot HF	HemaSpot SE	TropBio
Device description	Folded card with five half-inch circles printed on filter paper	Self-contained device with wedge-shaped filter paper, built-in desiccant, and a plastic cover	Self-contained device with spiral shape filter paper to separate serum, built-in desiccant, and a plastic cover	Circular card with six protrusions of filter paper, 4 cards packed in 1 sheet
Units (e.g., spots) and whole blood volume per device	5 spots∼375 μl/device∼75 μl/spota	8 wedges∼150 μl/deviceb∼18.7 μl/wedge	Blood components separate out onto four sections in spiral form (whole blood, plasma, serum); no. of punched spots depend on blood component of interest∼150 μl/devicec	6 protrusions∼60 μl/device∼10 μl/protrusion (23)
Collection process	Fill circles independently; potential for blood overlay	Blood flows through a center hole in device to fill all wedges simultaneously; excess blood flows to outer membrane	Blood flows through a center hole in device to spread out through filter paper	Fill protrusions independently; potential for blood overlay
Serum separation	No	No	Yes	No
Integrated collection and storage	No. Card dried >4 h in clean dry space before storage in self-sealing bag with desiccants	Yes. Device shut closed for storage soon after sample collection; built-in desiccantd	Yes. Device shut closed for storage soon after sample collection; built-in desiccantd	No. Card dried >4 h in clean dry space before storage in self-sealing bag with desiccantse
Potential for contamination with other samples	Possible. Spots are covered by a thin flap and require extended drying with flap open	Less likely. Device closed immediately after sample collection	Less likely. Device closed immediately after sample collection	Possible. Spots protrude out from center with no barrier and requires extended drying
Excision device	Punching device cleaned with alcohol between participants	Scissors and forceps for detaching wedges cleaned with alcohol between participants	Punching device cleaned with alcohol between participants	Scissors and forceps for detaching protrusion cleaned with alcohol between participants
Imagef
Strengths	Established card used in studies and many newborn screening programs.	Integrated collection device facilitates ease of collection.	Integrated collection device facilitates ease of collection.	Does not require punching, reduces variability in blood volume per protrusion.
	Existing evidence on comparison between card and serum samples.	Self-contained device and built-in desiccant reduce drying steps and protects from humidity.	Built-in serum separation.	Requires very small blood volume per protrusions which are independently filled.
	Requires small blood volume per spot, independently filled	Devices include barcode for sample identification.	Self-contained device and built-in desiccant reduce drying steps and protects from humidity.
			Devices include barcode for sample identification.
Weaknesses	Requires more extensive drying procedures.	Limited data on sensitivity and stability.	Limited data on sensitivity and stability.	Requires more extensive drying procedures.
	Elevated risk of contamination during drying or punching.	Device to be used within 30 min after opening.	Device to be used within 30 min after opening.	Elevated risk of contamination during drying.
	Potential for variability in volume between punches.	Elevated risk of undersaturation due to larger volume requirement and nonindependence of filling.	Four sections of the device are not clearly defined and concentration in each section dependent on the volume of blood collected.

^aMerck. Whatman protein saver cards 903 protein saver card (US) (package of 100 each; Sigma-Aldrich).

^bLaboratory observed volume required to fully saturate device and all wedges.

^cVolume per spot punched from HemaSpot SE device could not be estimated due to diffusive nature of the serum separation paper (24; also Protein Extraction Methods from HemaSpot HF or SE Devices Standard Curve Preparation).

^dHemaSpot devices may be placed into a self-sealing bag with a desiccant to further prevent exposure to humidity, although this is not required (4).

^eFor this study, TropBio cards were packed in petri plates with desiccants out of an abundance of caution to avoid damage to the protrusion.

^fHemaSpot images from manufacturer’s website (HemaSpot HF; Spot On Sciences [https://www.spotonsciences.com/hemaspot-hf]; HemaSpot SE; Spot On Sciences [https://www.spotonsciences.com/hemaspot-se]).