Described is a biological sample carrier based on a rigid hydrophilic object fabricated from a non-absorbing inert porous material. A biological fluid sample applied to the surface of the object is absorbed into the pores and constituents of the biological fluid sample remain in the pores after drying. Unlike a disc punched from a conventional dried blood spot (DBS) card, the object is easily handled. In contrast to DBS cards containing glass fiber structures that interact with basic analytes and other DBS card having adsorbing fibers that tend to separate blood constituents as the sample spreads through the fibers, the biological sample carrier is substantially inert to drug analytes.