Aug 29, 2013
Learn how to determine the shelf life of volumetric, reagents and buffer laboratory solutions.
Incorrect strength or
concentration of volumetric solutions,
reagents and buffer solutions can alter
the results of analyzed products. Solutions prepared for chemical analysis are
not stable for a longer period.
The
molarities of these solutions may change after a period of time. Shelf life of
the solution depends upon the nature of the compound and the solvent also.
Therefore, it is necessary to validate the stability period of these solutions
individually in which these have to consume. Validation of shelf life is a
mandatory GLP and regulatory
requirement. There are different ways to assign the shelf life of the
solutions; following are the simplest methods for the same.
Volumetric
Solutions:
Prepare the
volumetric solution and allow standing. After 24 hours determine the molarity
of solution in triplicate calculating the mean of the results and continue the
determination at an interval of 3 days for 15 days. Determine the RSD of all 5
values. If RSD of all 5 values remains less than 1.0, shelf life of solution
should be assigned 15 days otherwise RSD shall be calculated with first 4
values and shelf life should be assigned 12 days. It the RSD of first 4 values
remains more than 1.0, RSD shell be calculated with first three values and
shelf life of the solution should be assigned accordingly.
Reagent Solutions:
Reagent Solutions:
Reagents solutions,
those are used in analysis as reactants and molarity is not calculated. These
are validated on their performance. The Performance of these solutions is
checked at an interval of 7 day for 1 month. Evaluate the performance of all 4
tests and assign the life accordingly.
Buffer
Solutions:
Buffers are generally
used for calibration of pH meters.
pH of buffer solutions may change due to chemical degradation. The shelf life
of buffer solutions must not be assigned more than 7 days.
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