What is the shelf life of organic solvents used for LC-MS? Is there any valid data to substantiate device manufacturers recommendations?

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William Letter

"A Case of Changing Solution pH. Formic Acid Stability in Solution (Methanol)"; https://hplctips.blogspot.com/2019/09/a-case-of-changing-solution-ph-formic.html

A few very general comments on the topic (based on using/teaching/consulting in HPLC over the past 30 years) :

Do not add formic, acetic acid, etc to pure solvents unless you plan on using them within 2-days. Do not purchase pre-mixed versions of the same from vendors (they may change over time which may result in poor quality reproducibility).

Most commonly used PURE organic solvents used for HPLC, such as Methanol (MeOH) and Acetonitrile (ACN), which are filtered and stored according to the manufacturer's recommendations, should be fine to use.

Polymerization of high purity, properly stored ACN is not very common (filtering before use prevents many types of issues later on).

Some types of liquids may decompose or change (i.e. THF is a common example) so precautions must be taken. *Review Supplier documentation.

Additives such as acetic acid, DEA, TEA etc may change over time so should be used from fresh stock solutions.

Best to not "pre-mix" anything that you will not use the same day.

"Mobile Phase Preparation; Part 1, Overlooked HPLC Chromatography Standard Operating Procedures (SOP's)"; https://hplctips.blogspot.com/2018/12/part-1-overlooked-hplc-chromatography.html

Amit Parashar

The shelf life of organic solvents used for LC-MS can vary depending on several factors such as the specific solvent, the storage conditions, and the quality of the solvent. In general, most manufacturers recommend a shelf life of 1-2 years for organic solvents used in LC-MS applications.

There is some data available to support these recommendations, although it can vary depending on the solvent and the specific application. For example, a study published in the Journal of Chromatography A found that the stability of several common LC-MS solvents varied depending on the storage conditions, with some solvents degrading over time and others remaining stable for up to 2 years.

In addition to manufacturer recommendations and published studies, it is important to consider other factors that can affect solvent stability, such as exposure to air, light, and moisture. It is also important to regularly monitor solvent quality and replace any solvents that show signs of degradation or contamination.

Sandro Castronovo

William Letter, thanks for your answer. From your first link: "Briefly, the formic acid content degrades quickly over time and is often found to be only half of what it was initially after just three or four days" -> This is what I am searching for. Do you know any publication that confirms, describes (half-life depending on solvent) and explains this phenomenon?

Amit Parashar, thanks to you as well. "For example, a study published in the Journal of Chromatography A found that the stability of several common LC-MS solvents varied depending on the storage conditions" -> Do you have a link to this publication?