Follow these HPLC maintenance best practices to avoid constant frustrations, interruptions, and unplanned repair services.
Integrating best practices and business processes into your lab can be a linchpin when it comes to growing revenue and increasing profitability. Keeping your entire fleet of lab instruments in working order and out of repair can help keep business flowing at the lab. After all, lost time is lost money — troubleshooting leaks, bubbles, and clogs can eat up a whole day in no time. Let’s dive in and focus on some HPLC maintenance best practices.
Don’t skimp on solvents; keep your mobile phase completely clean and particle-free to avoid expensive HPLC repair needs.
Keeping your mobile phase clean and free of particles is one way to increase the longevity and accuracy of your HPLC. While it might sound good to cut corners on solvents and save money, in the long run, you save money by using HPLC-grade or MS-grade solvents. Contamination in the mobile phase can also cause your columns to wear out at an extraordinary rate. While the columns are engineered to degrade gracefully with each pass, you’ll notice that you can get a lot more out of your columns if you keep your mobile phase clean. In larger labs, this can add up pretty quickly.
Your HPLC pump system will also benefit greatly from a particle-free mobile phase. When particles are present in the mobile phase, they can get under the seals and cause damage/leaks. From there, your pistons will be overworked and worn — requiring a full pump replacement. While they do eventually fail, following this best practice can prolong the life cycle of your HPLC’s pump system. Failing degassers are another sign of contamination in the mobile phase.
Most Lab Managers keep the integrity of the scientific output at the forefront of their minds at all times. Keeping your mobile phase clean and particle-free will also support reproducible results, which is what everyone is looking for. Troubleshooting ghost peaks, increasing backpressure, and baseline drift can easily take a chunk of valuable time and compromise the integrity of your analytical results.
Don’t wait for a problem to arise. Change your pump seals regularly to avoid all-too-common pressure issues.
Speaking of pump seals, they need to be replaced at regular intervals to prolong the life of your pump head. Leaky pump seals will cause inconsistent pressures, which can be hard to diagnose. In many cases, an obstruction has to be removed in order to fix the issue, but many people make the mistake of thinking the column needs to be replaced (when in reality, your columns will likely last longer if you change your pump seals out regularly). When the backpressure steadily increases, it is important to start downstream (at the detector). It is always difficult to know if this is a column issue, or if there are other parts that need attention.
A great way to troubleshoot pressure issues (after ruling out air bubbles) is to remove the column and replace it with what is called a “restriction capillary.” Since this capillary produces SPECIFIC pressure levels, it can help determine the root of the issue. The pressure should not change drastically over a series of sample runs. While a small delta (or “ripple”) can be considered normal, large fluctuations are usually a sign that something is amiss.
By changing out the pump seals and keeping them pliable and fresh, you will find that you are troubleshooting pressure issues less and less. Harsh solvents and PH extremes can be really tough on your pump seals, so pay attention to the types of solvents you are using and check your pump seals for cracks regularly. Your HPLC pump is also an expensive replacement part, so keeping the entire pump system in top working order is certainly an HPLC maintenance best practice.
Change out your PTFE frits every time you change your pump seals to keep your purge valve free from clogs.
Similar to the pump seals, it is much better to stay in front of this (rather than waiting for pressure issues to steal your day away). Your purge valve is a great tool for flushing and priming your HPLC pump system. Inside the purge valve is a small piece of polytetrafluoroethylene, called a PTFE frit. This small piece is meant to protect the rest of the system from particulates, and it needs to be replaced regularly. The PTFE frit is very accessible and easy to switch out, too.
As you run multiple passes with your HPLC, the PTFE frit will get dirty and clogged, which results in a pressure spike. When you purge the system, most of the pressure will be across this frit — so it is very important to keep your eye on this small piece.
If you change out the needle in your autosampler, change out the needle seat as well (and vice versa).
A bad seal between your needle and needle seat can result in ghost peaks. If you ONLY replace the needle seat, the needle will immediately become damaged unless you change out both the needle seat and the needle itself. Additionally, the rotor seals of the injection valve will become worn, which causes sample carryover and inaccurate (irreproducible) results. Do yourself a favor and save yourself a lot of frustration by always changing out both at the same time. This best practice can be noted in your PM process documentation for each instrument.
Don’t wait too long to change out your LC columns.
Using the correct column with the right-sized capillary tubing is very important. For example, too wide can cause leaks and tailing peaks (along with damage to your HPLC). Always make sure you are using the correct column for maximum HPLC efficiency. In addition to that, don’t wait too long to switch your columns out. They are meant to degrade over time, and the column will wear out little-by-little with each sample that is passed through it. When changing out your column, stay clear of over-tightening your column connection fittings, as that will certainly damage the column receiving ports (which will cause leaks and pressure issues). HPLC maintenance is like dominoes. When one thing goes wrong, a domino effect happens downstream and it will cause the need for expensive HPLC repair services or even worse: premature replacement.
These HPLC maintenance best practices are very easy to follow, but don’t hesitate to hire an outside company to run your PM programs.
Sometimes it’s not about the knowledge, it’s about the TIME. If you are leading a lab and you are finding that a lot of your time is being taken up with troubleshooting HPLC issues, you might consider hiring a lab equipment repair company to run your maintenance programs for you. Not only can they save you time by running regularly-scheduled PM (and troubleshooting issues for you), but their job is to help you keep your HPLC running for as long as it will output accurate results. In many cases, they will bring additional, experienced HPLC maintenance best practices into your lab as well!
There is a litany of other best practices that can be listed for your HPLC instrumentation, but these are some of the most basic items at the root cause of most HPLC issues:
- Contamination in the mobile phase
- Skimping on solvents
- Cracked pump seals
- Clogged PTFE frits
- Damaged needles and needle seats
- Column over-use
If you follow the HPLC maintenance best practices listed above, you can expect your LC to output accurate data for years to come.