Before the New Crown pandemic, many people may have been unfamiliar with viruses and virus testing, but nowadays virus testing can be said to be unknown to everyone. However, not everyone may know about the virus sample preservation solution in the nucleic acid sampling tube. This article focuses on the pH range of the preservation solution.
The pH of virus preservation solution or sample preservation solution is an important basic parameter that provides a suitable pH value for viral nucleic acid samples. Nucleic acids generally dissolve better in a neutral to weakly alkaline environment, and the pH of virus preservation fluid is usually in the range of 6.5-8.5 or something like that. The nucleic acid of the new coronavirus is RNA, which is more likely to free into the aqueous phase than DNA at neutral to weak alkaline, so Tris equilibrium phenol (pH=8.0) separates and purifies the nucleic acid with RNA in the aqueous phase and DNA in the organic phase.
The pH range of virus preservation solution for sampling tubes on the market may vary from house to house, but the difference is small. pH=7 and pH=8 both have lower hydrogen ion (or hydroxide) concentration and the difference is small, but pH is 1 and 2 or 13 and 14, the difference is larger. Also when pH is 8, the hydroxide concentration is small, 0.9 times acid will bring the pH down to 7, but it takes 9 times base to bring the pH up to 9. Therefore the preservation solution needs to be sealed carefully when stored, it may absorb too much acidic CO2 from the air, resulting in lower pH.
When pH is 7, it means that the concentration of hydrogen or hydroxide ions in the system is one part in ten million (pH or pOH value is the negative logarithm of the corresponding ion concentration with a base of 10, and the sum of the two is 14 at 25 degrees). When the pH is 8, the pOH is 6 and the OH- concentration is 10 parts per million. In addition, the pH of neutral water is 7 at 25 degrees and 6 when the temperature rises to 100 degrees. The ultra-pure water used for the preservation solution has a pH slightly below 7, and a weakly basic buffer salt is added to bring the pH above 7.5 to meet the preservation of nucleic acids.
In addition, when virus preservation solution is canned into sampling tubes, the shop environment and sterilization conditions will also affect the pH. Longer bacteria will lower the pH, and higher sterility levels will not result in a change in pH.
In the production of preservation solution, in order to keep the pH of the system stable, the component of buffer salt is added, which has a buffering effect on the change of pH, and there are small changes that will not affect the normal operation.
