Research gaps for the development of a cfDNA-based IVD test related to preanalytical factors

Research gaps: lack of standard operating procedures for cfDNA preanalytical steps, especially for urinary samples
    Which is the best extraction kit/method for different sample types?
    How rapidly do samples need to be processed to avoid degradation with and without preservatives?
    Which urine preservative works best to avoid cfDNA degradation?
    How long can plasma samples and urinary samples with preservatives be stored?
    How long can cfDNA extracts be stored at −20°C and −80°C?