Dear Shawyun Khosh,

An abnormal value (high or low) of 260/230 may indicate a problem with a sample or with an extraction procedure. This info may help

1. A low A 260/A230 ratio may be the result of:

• Carbohydrate carryover (often a problem with plants).

• Residual phenol from nucleic acid extraction.

• Residual guanidine (often used in column-based kits).

• Glycogen used for precipitation.

2. A high A260/A230 ratio may be the result of:

• Making a Blank measurement on a dirty pedestal

• Using an inappropriate solution for the blank measurement. The blank solution should be the same pH and of similar ionic strength as the sample solution.

Example: Using water for the Blank measurement for samples dissolved in TE may result in low 260/230 ratios.

Reference:

William W. Wilfinger, Karol Mackey, and Piotr Chomczynski,

Effect of pH and Ionic Strength on the Spectrophotometric

Assessment of Nucleic Acid Purity: BioTechniques 22:474-481

If my answer was helpful please recommend it.

Merry Christmas

The floor of your laminar air flow might also be contaminated or the tips and pipettes could also be the reason behind it.

Give a UV exposure to your work area and then re-extract.

This also could be the reason behind having low concentrations

It may be caused by chaotrophic salts used in the rna binding not being completely removed which can often happen if the purification column is overloaded.

Also if using a nanodrop to quantify they are very sensitive to blanking/zeroing and if the nano is blanked on water but the sample is in TE or has salts absorbing in the UV then very inaccurate and even negative amounts of nucleic acid can be measured.it must be blanked with exactly the same buffer as the rna was eluted in. Try a second wash after binding the rna to the purification column to get rid of salts

Dear Shawyun Khosh,

An abnormal value (high or low) of 260/230 may indicate a problem with a sample or with an extraction procedure. This info may help

1. A low A 260/A230 ratio may be the result of:

• Carbohydrate carryover (often a problem with plants).

• Residual phenol from nucleic acid extraction.

• Residual guanidine (often used in column-based kits).

• Glycogen used for precipitation.

2. A high A260/A230 ratio may be the result of:

• Making a Blank measurement on a dirty pedestal

• Using an inappropriate solution for the blank measurement. The blank solution should be the same pH and of similar ionic strength as the sample solution.

Example: Using water for the Blank measurement for samples dissolved in TE may result in low 260/230 ratios.

Reference:

William W. Wilfinger, Karol Mackey, and Piotr Chomczynski,

Effect of pH and Ionic Strength on the Spectrophotometric

Assessment of Nucleic Acid Purity: BioTechniques 22:474-481

If my answer was helpful please recommend it.

Merry Christmas

It has nothing to do with contamination, it is your extraction method and the matrix. Did you use less material/sample than in previous extractions? And, as Paul said, this is due to the salts in the lysis buffer.

Dear Shawyun Khosh

First thing if your 260/230 reading is low that means the absorption at 230 nm is higher than the absorption at 260 nm, now absorption at 230 nm can be caused by contamination by thiocyanates, phenolate ion and other organic compounds.

I hope this information will help you.

presence of salt is also the reason for the low A260/A230 ratio for RNA. You can purify the RNA with alcohol washes which can also increase your RNA A260/A230 ratio.