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    PH Stability

    Do PH buffers 4,7 and 10 have different shelf life? Why or why not??




    1. tzwilling (Expert Level: Technician) says:

      Ranitidine hydrochloride (RHCl) is a competitive, reversible inhibitor of the action of histamine at the histamine H2-receptors that is used for the treatment of duodenal ulcers. RHCl exhibits pH dependent stability kinetics in aqueous solutions. The purpose of this presentation is to examine the influence of the buffer type, buffer concentration, pH and temperature on the stability and kinetic behavior of RHCl in aqueous solutions. Methods. RHCl solutions were prepared in various citrate and phosphate buffers of pH values ranging from 4.4 to 6.2 at buffer concentrations of 25, 50 and 100 mM. The solutions were stored in sealed glass containers for up to 4 weeks at 25, 40, 50 and 60°C. The rate of loss of RHCl was measured using a stability-indicating reverse-phase HPLC method and kinetic profiles were determined at the various experimental conditions. Results. The relative degradation of RHCl increased as the pH of the buffer solution was reduced. This effect was accelerated with increased temperatures. Increasing buffer concentrations adversely influenced the stability of RHCl, leading to increased degradation at lower pH values. However, the influence of buffer strength on the stability of the drug was substantially reduced as the pH of the buffer solution increased from 4.4 to 6.2. Also, the influence of buffer strength at a given pH increased significantly with an increase in the storage temperature. The extent of degradation of the drug was higher in citrate buffer than that in phosphate buffer at any given buffer strength and pH. The influence of the buffer type on the degradation of the drug was more significant at higher storage temperatures. Conclusions. The stability of Ranitidine HCl in aqueous solutions is influenced not only by the buffer pH and storage temperature but also by the type and strength of the buffer.

    2. bloomingstone (Expert Level: Technician) says:

      They do have different shelf lives because the pH10 buffer shifts pH value more quickly than pH 4 or 7 buffers. Watch your 10 bottles – they are often not really 10.

    3. LeslieSidio (Expert Level: Technician) says:

      The pH 10 buffer has the shortest shelf life compared to the pH 4 and pH 7 buffers because of it’s components. You should buy smaller containers of the pH 10 so you can move through the product lot faster.

    4. lwoodie (Expert Level: Technician) says:

      Yes, the pH 10 buffer has a shorter shelf life. Exposure to air causes the pH to changer quicker than 4 or 7.

    5. H2O man (Expert Level: Water Treatment Operator) says:

      10 does have the shortest shelf life, 4 and 7 are more stabile

    6. horseman44 (Expert Level: Technician) says:

      The 10 pH buffer is the least stable, then the 4 pH buffer, with 7 pH buffer being neutral (not an acid or caustic) will have the longest shelf life. The 10 buffer is a caustic and air will react with the buffer to alter calibration.

    7. Shari (Expert Level: Myth Master) says:

      4 pH buffer and 7 pH buffer have a longer lifespan then the 10 pH buffer which is more acidic/caustic.

    8. slclab2007 (Expert Level: Technician) says:

      My understanding is that the pH 10 buffer is the least stable because it’s the most vulnerable to atmospheric carbon dioxide which tends to decrease that buffer’s alkalinity. Next in line would be the pH 4 buffer, and last but not least the pH 7 buffer as the buffer with the longest shelf life.

    9. jpaulson (Expert Level: Technician) says:

      10 buffer is the least stable and does not have an infinate shelf life and nor should it. The 4 and 7 buffers have shelf life also but they are less likely drift over time than 10 buffer.

    10. itstk (Expert Level: Technician) says:

      I think 4 and 7 have a longer shelf life than 10 but a quantity that will be used in less than a year should be bought so as to keep a fresh solution of each available for calibrations.

    11. kardicat12 (Expert Level: Water Treatment Operator) says:

      4 and 7 have a longer shelf life, but I’ve never had a problem with my bottles of 10 drifting either.

    12. japhillippi (Expert Level: Technician) says:

      10 has a short life plan accordingly.

    13. jjlingo (Expert Level: Technician) says:

      10 is the least stable.

    14. debra669 (Expert Level: Technician) says:

      10 buffers are the most likely to drift.

    15. chatter (Expert Level: Technician) says:

      how can you add to the above comments. I do not know of any.

    16. (Expert Level: Technician) says:

      Buffers with pH of 10 have shorter shelf life once exposed to the atmosphere. They absorb carbon dioxide from air and so the pH starts to drop. Good lab practice to properly stock your inventory to always have what you need but consume enough that none of your products expire and become wasteful.

    17. Kris-10 (Expert Level: Technician) says:

      They have an expiration date and should be discarded when expired.

    18. byrnsie4 (Expert Level: Water Treatment Operator) says:

      All ph buffers have similar times of expiration

    19. pchrcane65 (Expert Level: Technician) says:

      10 is the least

    20. DC081455 (Expert Level: Technician) says:

      Yes they do have different shelf lives.

    21. (Expert Level: Technician) says:

      always follow the expiration date on each buffer

    22. ghassett (Expert Level: Technician) says:

      10 is the most reactionary,will loss its pH value quicker

    23. dmcchristian (Expert Level: Technician) says:

      10 pH buffer will generally have a shorter shelf life because the components are less stable.

    24. dougkimbler (Expert Level: Technician) says:

      in the end, just buy smaller lots of pH10. Don’t worry about rates, worry about (expiration) dates.

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