Hello . I separate PBMC from blood. Then I use a Yekta Tahzih Azma column kit. I take about two million cells or more to extract RNA. I heat the elution solution and pour about thirty or forty liters into the center of the column. I wash twice. I wash once with ethanol. I have added ethanol to my wash 2 solution, but I still have low RNA concentration and high contamination. What should I do?