DNA purity for manipulation - (Feb/27/2006 )

i have 4 DNA sample and the purity of the samples are 1.8, 1.9. 1.3 and 1.2

can I use the sample of purity 1.3 and 1.2 in further manipulation????????????

Depends how sensitive your manipulation is. I'd avoid the 1.2 and 1.3 reading (I assume your talking A260/A280) as these sounds like you have protein contamination. The other two are okay. Anything around 1.8 or above means your sample is pretty clean.

hi
for 1.3 and 1.2, i would try first a less dilution (except if OD is >0.1 in both cases) in order to obtain accurater measurements.
If it's done, re do phenol chlo... but for sure results would not be that comparable with 1.9 samples if your exp is a sensitive one...

We need to know what your numbers mean. Fred is answering as though they are A260 readings whereas mine assumes an A260/A280 ratio.

i was talking about DNA purity so the value means A260/A280.

hi
i meant that if the OD of the measures of 280 and 260 are up than 0.1 (and i don't know the values) i can trust them. If these values are less than 0.1, there is a loss of accuracy. For ex : OD 260 = 0,08 and 280 = 0,06 too little a less diluted measure suggested; OD 260 = 0.5 and 280 = 0.4 --> purity problem)

But of course that the ratio should be 1.8... A 1.2 OD is too high
sorry for misexplain me.