Plasma Collection Guideline
Plasma should be prepared as soon as possible after collection. Preferably within 3 hours after blood collection.
1. First spin at 1,600xg for 10 minutes in clinical centrifuge.
2. Transfer plasma to a fresh tube and do a second spin at 16,000 xg for 10 minutes.
3. Transfer plasma to a fresh tube for immediate cfDNA purification; or stabilize at room temperature (NeoGeneStar PAC system) or freeze to preserve sample, fresh plasma that is pretreated and stored at room temperature yields best results.
Plasma should be stored at -20 to -80 C.
Important: Thaw plasma at RT, do not warm untreated plasma to greater than 40 C as interfering coagulation may form.
For best result, follow the proteolytic digestion protocol in NeoGeneStar pretreatment kit.
K3EDTA and K2 EDTA (Lavender Top Tubes) Pink Top K3EDTA
EDTA chelate divalent ions which prevents coagulation and has the added advantage of inhibiting DNase. K3EDTA collection tubes has liquid EDTA in solution in glass tube. K2EDTA collection tubes have the EDTA spray dried in plastic tubes. The K3EDTA collection tube is preferred. The plasma should be prepared as soon as possible and preferably within three hours of collection. The plasma samples can be stabilized in NeoGeneStar pretreatment kit - cfDNA is stable at room temperature for up to two weeks. Alternatively the plasma may be frozen or the cfDNA purified immediately.
Streck BCT Tubes (Brown and Black Tiger Tubes)
The Streck BCT is blood collection tube with a preservative and crosslinker that stabilize the nucleated blood cells. Samples are stable for up to two weeks at room temperature. Streck plasma should be proteolytically digested prior to cfDNA purification.
Sodium Citrate - Light Blue Top tubes
cfDNA can be purified from the sodium citrate vacutainer tubes. We recommend processing the plasma and pretreating with the NeoGeneStar pretreatment kit or freezing at -80 C as soon as possible after plasma preparation. Addition of K3EDTA to 12mM can aide in the preservation and stabilization of cfDNA.
Plasma Separation Tubes (Light Green Tubes with Gel)
PST tube contains lithium heparin and gel to prevent coagulation and separate plasma from from the blood cells during the first clinical centrifugation. These tubes are ideal for immediate plasma preparation and stabilization. The plasma from PST tubes can be poured into NeoGeneStar pretreatment and stabilization reagents for room temperature storage and shipping. Alternatively, if minimum genomic contamination is required, the plasma from PST tubes should be subject for a second spin at ~3,000 to 4,000g for 10 minutes and then either frozen or preferably stored in NeoGeneStar pretreatment tubes. Note: These tubes do not have EDTA so sample processing should be done as quickly as possible from the blood draw and/or EDTA should be added to ~12mM as soon as possible.