The life of a C18 column in high-performance liquid chromatography (HPLC) depends on several factors, including the column's quality, how it's stored, and how it's used:

 The life of a C18 column in high-performance liquid chromatography (HPLC) depends on several factors, including the column's quality, how it's stored, and how it's used: 

Quality

Some columns can maintain high efficiency and peak shape for hundreds of hours. 

Storage

Some columns can be stored for 5–10 years without changing. 

Usage

Split peaks, poor peak shape, and other issues can indicate that the column is deteriorating. 

Running conditions

Using a strong injection solvent or working too close to the pKa of the compound can cause split peaks. 

Here are some things to consider when troubleshooting a C18 column:

Peak tailing

This can be caused by a degraded column, contaminated mobile phase, or sample overload. Solutions include reducing the injection volume, flushing the column, or replacing the mobile phase.

Loss of resolution

This can be caused by an inappropriate mobile phase, incorrect pH, or a worn-out column. Solutions include optimizing the mobile phase composition and pH, or replacing the column.

High backpressure

This can be caused by a contaminated column, blocked frit, or flow rate that's too high. Solutions include flushing the column, cleaning or replacing the frit, or reducing the flow rate. 

Cyano HPLC Column, CN Group Analysis Column - Hawach

C18 columns are a popular choice for HPLC because they can analyze a wide variety of compounds. The name C18 comes from the octadecyl chain, which is a chain of 18 carbon atoms that forms the basis of the column's stationary phase