I got a synthetic DNA sample which i resuspended in 10ul 1X TE buffer. I checked its concentration which came out to be 209 ng/ul but the absorbance is quite poor. Kindly look at the attached photo. How can i remove the impurities?
You could try a minicolumn purification using a PCR/gel purification kit, available from Macherey-Nagel or Qiagen. But don’t expect more than a very poor final yield. The spectrum that you show indicates that most of the absorbance at 260 nm, from which the software calculates the DNA concentration, is due to some non-DNA contamination : DNA would show at least a shoulder at 260 nm.
I agree with Pierre Béguin that most of the 260 signal is probably not from DNA. Since the peak is at 230 it is could be that the absorbance is coming from protein or amino acids but it also could be some aromatic compound or solvent
Since its synthetic DNA can we assume its single stranded (ssDNA) and doesn't have any added protein? If its from a reputable vendor it should be quite pure; did they provide a CofA /spec sheet or concentration/purity numbers? The usual A260/A280 absorbance ratio does not hold for synthetic oligos especially very dilute ones like this appears to be, but there are more sensitive fluorescence based measures from companies like Thermo or Promega. Columns (as mentioned) or alcohol precipitation would allow you to concentrate this sample, MWCO filters could work too, if sized correctly. Good luck!
Thank u everyone for your helpful answers. I have complained the provider.
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