Hey Hyun,

I often end up with yellowish pellets when I use higher amounts of liver tissue for RNA extractions. I mostly use the RNA for cDNA synthesis and RT-qPCT and never had an issue. I also measure the RNA with a nanodrop and the ratios are fine.

I don’t dry the pellets until they become completely transparent but just long enough for all ethanol to evaporate. I find it way easier to solve the pellets when they are not completely dry. For me this takes sth like 5 – 10 minutes if ethanol was removed thorough.

Hi Hyun

I suggest you use the protocol in this article

Hello Hyun Jeong Yoon

You may get yellow colored RNA pellet due to the following.

1. If the sample is high in fat content. As a solution, you may centrifuge the sample before chloroform addition and remove the fat layer on the top.

2. For sample with high amounts of blood, some iron or hemoglobin may remain in aqueous phase giving a yellowish color. As a solution, the blood may be prewashed with ice cold sterile PBS before adding TRIzol .

3. Aqueous phase turns yellow upon addition of isopropanol. As a solution, try a fresh bottle of isopropanol.

4. The use of guanidine thiocyanate that has been exposed to light or unfavorable temperature conditions. Guanidine thiocyanate, particularly in the form of aqueous solution, is extremely sensitive to light and temperature. Undesirable redox reactions occur especially in the weakly acidic medium (pH 4.5 to 7.0), whereby elemental sulfur is formed as a decomposition product. This decomposition reaction, which is noticeable gives an intense yellow color. As a solution, store the reagent at temperatures between 2-8°C. At room temperature, the stability of the reagent is significantly reduced. Avoid any prolonged exposure to light.

Hope this helps!

Best.