I've been trying to extract DNA from rat liver tissue using Blood and tissue DNeasy mini kit.
I followed handbook procedure and all of my samples had low 260/230 (
Dear Elena Fauste,
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
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Merry Christmas
I agree with the above ...but the question asks how to solve
1. Try lysing in double the volume of lysis buffer before adding ethanol and applying to column
2. Wash the column twice as suggested but wait 1 min after adding wash buffer before spinning out
3. After adding 2nd wash buffer spin for 2 minutes not 1
4. Then as you already do soin with no buffer to dry before eluting with water or TE
5. If problem with low 260/230 persists, try using lysing half the amount of tissue fopr 10 min on ice and splitting between 2 columns and/or precipitating what is eluted from column with isopropanol and washing with 70% ethanol before spinning and resuspending
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