▁to ▁form ▁a ▁mixture ▁with ▁a ▁much ▁higher ▁density ▁than ▁water . ▁▁ ▁The ▁hydro ph ob ic ▁lip ids ▁will ▁partition ▁into ▁the ▁lower ▁organ ic ▁phase , ▁and ▁the ▁prote ins ▁will ▁remain ▁at ▁the ▁inter phase ▁between ▁the ▁two ▁phases , ▁while ▁the ▁nucle ic ▁ac ids ▁( as ▁well ▁as ▁other ▁cont amin ants ▁such ▁as ▁sal ts , ▁sug ars , ▁etc .) ▁remain ▁in ▁the ▁upper ▁a que ous ▁phase . ▁The ▁upper ▁a que ous ▁phase ▁can ▁then ▁be ▁pip ett ed ▁off . ▁Care ▁must ▁be ▁taken ▁to ▁avoid ▁pip et ting ▁any ▁of ▁the ▁organ ic ▁phase ▁or ▁material ▁at ▁the ▁interface . ▁This ▁procedure ▁is ▁often ▁performed ▁multiple ▁times ▁to ▁increase ▁the ▁pur ity ▁of ▁the ▁DNA . ▁This ▁procedure ▁yields ▁large ▁double ▁str and ed ▁DNA ▁that ▁can ▁be ▁used ▁in ▁PC R ▁or ▁R FL P . ▁▁ ▁If ▁the ▁mixture ▁is ▁acid ic , ▁DNA ▁will ▁precip itate ▁into ▁the ▁organ ic ▁phase ▁while ▁R NA ▁remains ▁in ▁the ▁a que ous ▁phase . ▁This ▁is ▁because ▁DNA ▁is ▁more ▁readily ▁neutral ized ▁than ▁R NA . ▁ ▁There ▁are ▁some ▁dis adv antages ▁of ▁this ▁technique ▁in ▁for ens ic ▁use . ▁It ▁is ▁time - consum ing ▁and ▁uses ▁ha z ard ous ▁re ag ents . ▁Also , ▁because ▁it ▁is ▁a ▁two - step ▁process ▁involving ▁transfer ▁of ▁re ag ents ▁between ▁tub es , ▁it ▁is ▁at ▁a ▁greater ▁risk ▁of ▁cont am ination .