Heparin is negatively charged, as is RNA and DNA.
Sources of heparin:
(1) A specimen collected into a blood collection tube containing heparin.
(2) Blood withdrawn through a heparinized infusion line.
(3) Bone marrow collected with a heparinized syringe.
(4) Therapeutic infusion of heparin.
Options for removal:
(1) If the target RNA or DNA is contained within intact cells, then the cells can be spun down and washed until the heparin is removed.
(2) Treatment with heparinase, which may increase the cost and which may not always be reliable.
(3) Precipitation of RNA with 8 M lithium chloride (Jung et al, 1997).
(4) Pretreatment with Chelex (Poli et al, 1993)
(5) Pretreatment with Spermine (Davis et al (1986)
(6) Addition of a cation such as Magnesium
(7) Addition of bovine serum albumin (BSA)
(8) Addition of glycerol (1%)
(9) Use of an alternative DNA polymerase (Vent or pfu)
(10) Use of a an alternative buffer system (glycine, pH 8.3, at 25°C)
Sample dilution, which works with many inhibitors, often does not work for heparin because of its potency.
