I am extracting DNA from cicada exuviae using ethanol precipitation combined with either NaCl 6M or Ammonium acetate. After DNA extraction, my samples have quite low A260/230 ratio such as in the attached picture. I suspect this might be due to left-over salt in my samples, since I dont use kits or phenol/chloroform/isoamyl in DNA extraction protocol. I proceeded on with PCR using 16S primers but received no bands.
Could you advice what potential contaminants could appear in the samples that prohibit PCR? As well as what could I do to improve this ratio? Thank you so much!