Apparatus and methods are provided to obtain RNA-enhanced and protein-enhanced fluid samples which are stable at ambient temperatures. An apparatus includes a filter element made from a fibrous hydrophilic material which preferentially binds and filters cells, DNA-containing macrostructures, mucins and particulates, but does not preferentially bind RNA, RNA-containing macrostructures or proteins. An apparatus may include a sample collector having an absorbent collection pad which also does not preferentially bind RNA, RNA-containing macrostructures or proteins. A method includes obtaining a sample and passing the sample through an RNA-and-protein-preferential filter element to obtain RNA-enhanced and protein-enhanced samples. The method may include use of a RNA-and-protein-preferential absorbent pad material to collect the sample. DNA-rich samples may be obtained by using DNA elution buffer to release the DNA-containing cells and macrostructures after obtaining the RNA-enhanced and protein-enhanced samples.
