LC Hints

Like an automobile, HPLC Systems are complex electromechanical devices. All the parts must work perfectly to get good analytical results. And like an automobile, there is much that you can do to prevent problems including preventative maintenance. We suggest that you do the following as standard operating procedure:

1. Use only HPLC or spectro grade solvents

2. Filter and degas solvents. Any method of degassing (boiling, sonication, vacuum filtration, helium sparging) will work if used daily. However, we feel the easiest, simplest, "no brainer" method is to use a degasser on line. See our degasser page for more information.

3. Use a 2 or 5 micron solvent solvent filter in that reservoir. Other filters can also be used throughout your HPLC system. Please contact us for information on solvent filters, inline filters, column filters and guard columns for your LC.

4. If you use buffers, keep the mobile phase moving through the pump continuously. If you are not actually running samples, reduce the flow to the lowest possible flow rate while you are in standby (overnight if necessary). Flush buffer salts out of your pump and leave the pump stored in a solvent mix that will not support bacterial growth. (e.g 10% Methanol in water)

5. If using buffers, wash in back of the pistons if your pump has this feature. (Our Knauer Pumps have this feature)

6. If you store a pump for a length of time (a week or more) flush it with a solvent mix that will not support bacterial growth. (e.g 10% Methanol in

7. Keep a log book on the use of the HPLC System (User, Column, Application, Comments and more)

8. Run a standard from time to time. A good standard can be made from Methyl, Ethyl, Propyl and Butyl Parabens at about 1 mg/ml. Analyze at 254 nm on a 25 cm column using 60% Methanol/40% water on a C18 column. The Parabens are food preservatives and will last a long time.

9. Calculate the Theoretical Plates for one or more peaks of your standard. Do this from time to time, perhaps monthly. Enter this in the log book and keep
a copy of the chromatogram. Columns degrade over time. You need a record of good performance as a benchmark.

10. Check the Energy Level of the Deuterium Lamp from time to time and record it in your log book. Our Knauer Detectors will record the operating hours of the lamp and give an energy reading of the sample and the reference beams. Bay Scientific includes a removable label with replacement lamps. We suggest that the
removable label be placed on the side of the detector to record date of lamp installation. There is no good method of predicting lamp lifetime. Six months to a year of moderate use is reasonable. Please check out Lamp section for FAQ on lamps.

Unlike an automobile, we feel that you can do your own maintenance on an HPLC System. There are advantages to doing your own repairs:

1. Saves Time
2. Saves Money
3. Saves Frustration

Major HPLC suppliers make a profit selling service contracts and replacement parts for HPLC Systems. If you suddenly develop a problem on the HPLC system, you must call for a technician and wait until he or she arrives to fix the problem. Service Fees usually factor in portal-to-portal costs. That means you are paying a technician (probably a non chemist) to travel to your facility as well as to service your Chromatograph.

If you have spare parts in house, it is relatively easy and quick to repair pumps. Our Knauer Pumps are very easy to service. An entire pump head can be replaced in a few minutes. If you have pumps from Waters, Agilent/HP, Shimadzu or other HPLC vendors, check out our spares for pistons, seals and check valves for those vendors from Optimize Technologies. Bay Scientific guarantees complete satisfaction on all replacement parts. They will perform as well or better than the original manufacturer part and usually at a lower cost. Guaranteed!

Save time, save money and avoid frustration waiting and wondering when the service technician will arrive and IF they can diagnose and fix the problem. Most repair techicians are NOT chromatographers.

We recommend that you keep as spares:

1. One set of Seals for your pump
2. Two Check Valve cartridges for a pump
3. Two pistons (if your pump is old)
4. Order a spare lamp if the lamp is a year old

If you find that your pump is going through piston seals quickly, replace your pistons. They may be scratched. Damaged pistons can cause piston seals to wear out quickly. By using Optimize Technologies' check valve cartridges, you can minimize the number of replacement check valves needed in your laboratory. If your system is critical and you cannot be down, then keep a spare lamp in stock as well.

Much more can be written about how to troubleshoot HPLC Systems. It can be difficult to identify the cause of the problem. Bay Scientific with many years of experience in Chromatography can help. We provide free technical advice for all our customers to keep their system functioning well.