Human Cot-1 DNA®-Fluorometric QC is placental DNA predominantly 50 to 300 bp in size and enriched for repetitive DNA sequences, such as the Alu and Kpn family members (1,2). Quantifying Cot-1 DNA® by fluorometry provides more accurate concentration data of higher molecular weight products, making it beneficial to certain genomic-based array experiments, such as array CGH using BAC arrays. Human Cot-1 DNA®-Fluorometric QC suppresses prevalent repetitive elements during hybridization, improving results.