Abstract <p>Extraction of genomic DNA (gDNA) is the critical fore most step in molecular diagnosis. Whole blood samples are one of the key sources used to obtain DNA. The ideal process for gDNA extraction demands high quantities of pure, integral and intact gDNA from the blood sample. Long term stored blood samples may have protein rich content deters many DNA isolation methods causing low quality DNA. Modified conventional methods provide durable improvement in DNA quality with reproducible amplification. Therefore in this study we investigated the integrity, quantity and quality of contaminated versus purified DNA at Absorbance 260/280 and 260/230. Phenol Chloroform Isoamyl alcohol (25 : 24 : 1) combination based method was optimized as conventional method. This method serves as a simple, convenient, easy-to-handle, time-saving, cheap and less laborious way for the extraction of gDNA with a good precision of quality and quantity that could be used for diagnostic purposes. Our results provide a brief comparison between protein contaminated and without protein contaminated DNA. The quality, quantity and integrity of the differentially treated gDNA was subsequently corroborated by 0.8% agarose gel electrophoresis and further evaluated for PCR amplification. The mean DNA yield was 22.75 ng/µL (median 13.2 ± 30.25) and the mean 260/280 absorbance ratio was 1.68 (median 1.70 ± 0.25). These results indicate that this DNA extraction method produces good yield of quality DNA, even from specimens several decades old.PCR tests revealed that there were no inhibiting compounds in the isolated DNA’s final solutions demonstrate the high quality of the separated DNA for further genetic analysis.</p>