QIAsymphony DSP Circulating DNA Kit

Human plasma that has been collected in EDTA or citrate blood collection tubes or ccfDNA stabilized blood collection tubes can be used as sample material. In addition, human urine (non-stabilized or stabilized) can also be used.

Serum is not recommended as sample material because it contains a large background of genomic DNA.

It is strongly advised to follow the recommendations for preparing sample material provided in the corresponding Protocol Sheet to ensure reliable results.

Plasma: It is recommended to perform plasma separation immediately after blood collection when using EDTA or citrate as anticoagulant to prevent the release of genomic DNA into the plasma fraction.

Urine: Because circulating cell-free DNA in non-stabilized urine samples is rapidly degraded after sample collection due to high nuclease activity, eluates may contain no DNA or exhibit low DNA concentration. Therefore, it is recommended to stabilize urine samples. Even when using stabilized urine, it is recommended to perform a centrifugation step immediately after stabilization to prevent the release of genomic DNA from cells. Alternatively, non-stabilized urine samples can be processed immediately after collection and centrifugation using ATL-pretreatment and automated DNA extraction as described in the corresponding Protocol Sheet.

Open reagent cartridges can be used for up to 4 weeks without affecting performance. After 4 weeks, circulating cell-free DNA yields are expected to decrease. To ensure the best performance, carefully seal buffer troughs of a partially used reagent cartridge with Reuse Seal Strips when not in use; incomplete sealing of reagent cartridge can reduce the performance.

At least 2.4 ml sample for the 2 ml protocol or 4.5 ml for the 4 ml protocol should be loaded.

Loading smaller volumes increases the risk of “unclear” flagged samples. As described in the corresponding labware list, volumes of 1.4–2.4 ml and 3.5–4.5 ml, respectively, will be processed but flagged “unclear” (“Enable less sample” mode).

Loading volumes less than recommended increases the risk that samples are not transferred (“invalid” flagging). If the sample volume is insufficient, add PBS to the required sample volume before loading the sample.

 When using FIX labware (instrument does not perform liquid-level detection and reporting), load at least 2.1 ml for the 2 ml protocol and at least 4.1 ml for the 4 ml protocol. Because the instrument does not detect sample volumes using FIX labware,  insufficient volumes might result in bubble formation during sample transfer and/or the subsequent binding step. If the sample volume is insufficient, add PBS to the required sample volume before loading the sample.

Sample volumes of 2 ml and 4 ml can be used without affecting the number of preps per kit (i.e., 192 samples per kit).