Determination of Shelf Life of Solutions in Laboratory

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:

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.

Note: Solution should be stored under proper storage conditions otherwise results may alter giving improper shelf life. Validation data should be recorded and maintained for regulatory audits.