What should I do if the A260/230 ratio is low?

The absorbance of 260 nm represents the concentration of nucleic acids, the absorbance of 230 nm represents the the salt concentration, if the OD260/OD230<2 indicates that there is salt contamination in the sample, the following methods can be tried to treat the sample during the ethanol elution step:  

1, 75% ethanol, 4 °C, 7500 g/min, centrifugation for 5min;  

2, pour off the ethanol, and then add 75% ethanol, under the same conditions, do the second elution 

3, reverse the direction of the EP tube in the centrifuge again (no longer add ethanol), 7500g/min, 4 °C, centrifuge for 3min, carefully suck off the ethanol with a 200 μl gun (be careful not to touch the RNA at the bottom of the tube), and then open the lid to dry the ethanol that is can be.  

A small 260/230 ratio is salt contamination, which our lab solves by

At the ethanol elution step.

1, 75% ethanol, 4 ℃, 7500 g/min, centrifugation for 5 min.

2, pour off the ethanol, add 75% ethanol again, under the same conditions as above, and do a second elution (note that this time the EP tube is placed in the centrifuge in the opposite direction to the first, so that it can be more fully eluted).

3. Turn the direction of the EP tube in the centrifuge again (no more ethanol added), 7500g/min, 4℃, centrifuge for 3min and then carefully aspirate the ethanol with a 200μl gun (be careful not to aspirate the RNA at the bottom of the tube), and then just open the cap and dry the ethanol.

After doing this, it is much better than washing only once with ethanol, and our proposed RNA measured 260/230 values with nanodrop are around 2.0.