How long can I store and reuse reference standard solutions prepared for the Total Organic Carbon system suitability test?
A. Where USP is silent on storage conditions and the stability of prepared reference standard solutions, the implication is that the solutions should be prepared fresh with every use, starting with the solid material provided by USP. Only with suitable stability studies performed over various periods using controlled storage conditions can a user’s storage conditions be justified as suitable. It should be noted that a number of factors can influence the stability of the reference standard solutions used for the system suitability test in the Total Organic Carbon (TOC) test. These include concentration, microbial decomposition, adsorption to the container surface, and the degradative effects facilitated by oxygen, light, and temperature. The development of turbidity, additional color, or performance variability relative to freshly prepared solutions are indicators of instability. If the user wishes to store and re-use these prepared reference standard solutions or solution concentrates,
