“…Methods which have used elution techniques (6), microconcentrators (7), syringe-based extraction in combination with freeze-thawing (8), nylon membranes (9), centrifugation-based extraction (10 -12), glass beads (13), pumice stones (14), polyester plug spin inserts (15), elution with filtered pipet tips (16), isotachophoresis (17), etc., have been reported.…”