Hi,
I'm trying to isolate RNA from cell cultures using the Trizol method. However, all my samples have low 260/280 values (~1.6). Could this be because I used chloroform and isopropanol, which was not molecular biology grade? For RNA isolation, I used samples that were kept in Trizol at -20C for about 2 months.
The most important thing for RNA is that you store your samples at -80, not -20. Fresh is even better. Once you do this, and if you still have a problem, then you should think about other causes such as phenol contamination.
I'd recommend Zymo's Direct-zol™ RNA columns for use with Trizol. No messy phase separation, just quick and clean RNA with excellent ratios. I've not had a sample yet that required a clean up step.
Well in the attached picture you have a 1.87 index if I see it correctly so you do not have anything to worry about. However, as mentioned by Diana, you should keep your samples at -80°C. I have stored some at -20°C but only for a day or so. And for RNA always use DEPC treated water, even to prepare the 75% ethanol for the washing step in trizol procedure.
The role of isopropanol in RNA isolation is to precipitate RNA. RNA is insoluble in alcohols such as isopropanol and ethanol
RNA Isolation with TRIZOL Reagent Problem Possible Cause Suggested Solution Low yield of RNA RNA not solubilized completely. To increase solubilization, pipet RNA pellet repeatedly in SDS or DEPC-treated water. Heat sample at 55°C for 10 to 15 min. Do not allow RNA pellet to dry completely.
An important thing for RNA is to store your samples at -80, not -20.
If the same result persists despite storing at 80, you must ensure the purity of the extraction solutions. Good luck, God willing.
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