The effect of drying on the homogeneity of DBS.
BACKGROUND
Inhomogeneous sample distribution in DBS is a problem for accurate quantitative analysis of DBS, and has often been explained by chromatographic effects.


RESULTS
We present a model describing formation of inhomogeneous DBS during drying of the spot caused by higher evaporation rates of water at the edge as compared with the center. Color intensity analysis shows that the relative humidity and DBS card position affect the homogeneity of DBS.


CONCLUSIONS
The so-called 'coffee-stain effect' explains the typical distribution pattern of analytes with higher concentrations measured along the edge of DBS as compared with the center. The driving mechanism and potential influencing factors should be considered when addressing the inhomogeneity of DBS in the future.
KTH Royal Institute of Technology, Department for Micro & Nanosystems, Osquldas väg 10, 10044 Stockholm, Sweden.
Gabriel
G
Lenk
KTH Royal Institute of Technology, Department for Micro & Nanosystems, Osquldas väg 10, 10044 Stockholm, Sweden.
Jonas
J
Hansson
Karolinska University Hospital, Department of Clinical Pharmacology, 14186 Stockholm, Sweden.
Olof
O
Beck
KTH Royal Institute of Technology, Department for Micro & Nanosystems, Osquldas väg 10, 10044 Stockholm, Sweden.
Niclas
N
Roxhed
D003116:Color; D059788:Dried Blood Spot Testing / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D006813:Humidity