HPLC has emerged as a popular separation science technique over the last few decades and today it enjoys enviable position in several basic research and industrial laboratories across the globe. It is common to come across several dozens of HPLC systems in large laboratories due to their numerous analysis solution capabilities.
It is every chromatographer’s dream that the separations are reproducible in terms of retention times of peaks and their shapes- analysis after analysis. This can be achieved if the columns are properly maintained and other operating conditions are kept constant every time.
The two major cost contributing factors in HPLC analysis are mobile phase solvents and HPLC columns. Investments in mobile phase solvents can be controlled by judicious choice of low flow rates in between analysis runs .The present article focuses on measures on saving expenditure on HPLC columns
HPLC column is undoubtedly a critical component of the HPLC system and deserves proper care for its long trouble-free service life.The cost of HPLC columns can range anywhere between US $ 500 – 1000 depending on the specificity of applications. For limited budget projects frequent column replacements can have serious implications on project viability and overall profitability of laboratories. Reliability on data also suffers seriously when poorly maintained columns are used.
Undesirable and unforeseen experimental failures can be avoided by following the proposed guidelines during handling and storage of HPLC columns.
- Avoid mechanical shocks as these can lead to disturbance of the packed stationary phase beds
- Always maintain the same flow direction as marked by arrow on the column
- Make use of online filters for mobile phases and filter solvents before mixing in required proportions
- Make use of a column oven to maintain constant column temperature
- Change operating flow rates and pressures gradually. Never make abrupt changes.
- Always operate in the recommended pH range
- After using buffers in mobile phases make it a practice to wash column with aqueous – organic mixtures followed by water to remove the solid salt deposits.
- Make use of guard columns to increase useful life of columns
- Column overloading should be avoided by not injecting concentrated samples or making large volume injections
- Always apply the right force for tightening the columns. Use of excessive force can result in damage to the fittings
- After completing the run, program the mobile phase composition to gradually change to the storage solvent
- Fix the end caps of columns if storage is required for long periods
- Never make the mistake of storing columns in the refrigerator or in hot air ovens. This can lead to non-reversible damage to the stationary phase
Even after you have taken the recommended precautions the performance of columns can suffer as columns have finite useful lifetimes. You should be on the lookout for column performance regularly and take effective action on observing degradation of the peak shapes, changes in retention times, poor resolution or appearance of unwanted peaks.