If you are setting up LC instrumentation in a new lab, you may find yourself looking for ways to perform Operational Qualification (OQ) tests. The requirements for qualifying a new instrument vary, depending on regulatory needs and SOP requirements, as well as the specific instrumentation. They might involve tests to confirm parameters such as solvent pump flow rate, gradient composition, linearity, reproducibility and wavelength settings (for UV, fluorescence and PDA detectors). For other detectors such as the ELSD or Mass Spec, this may also involve parameters like the measurement of the gas flow rate through the nebulizer, temperature settings and mass tuning.
Here are the products that Restek has to offer:
- LC OQ Gradient Standard (acetone), catalog #30012
- LC OQ Wavelength Accuracy (erbium perchlorate), catalog #31053
- LC OQ Linearity Test Mix Kit (caffeine at 5, 25, 125, 250 and 500 ug/mL), catalog #31805
- LC OQ Standards Kit, catalog #31069, contains catalog numbers 30012 and 31053 shown above, as well as catalog #31068, LC OQ Linearity Kit, containing ethyl paraben and propyl paraben at 5, 10, 15, 20 and 25 ug/mL each. Catalog #31068 is available separately, although not currently shown on our website.
We also have other test solutions that are intended to monitor column performance, not the instrument. You can find the full list of test mixes for LC here. http://www.restek.com/Reference-Standards/Test-Mixes?s=type:lc For mass spectrometry qualification (LCMSMS), test solutions are often sold by the instrument manufacturer, so please contact them in this case.
Some of the above products may also be used for Performance Qualification (PQ) testing, which would be performed more frequently than the OQ test and applied to across the different vendor brands that the analyst may have in the laboratory. This is also sometimes referred to as Performance Validation (PV) and exact requirements are determined by the laboratory. Instrument manufacturers usually provide their own guidelines, at least for OQ testing, which we recommend that you also consider. Here is what we found that the various LC manufacturers suggest:
For gradient composition test in the above, acetone is used as mobile phase B, with UV detection. Please note that acetone is not normally used in mobile phase, due to its high UV absorbance. Agilent suggests using a liquid flowmeter for testing pump performance. We do not sell this type of flowmeter, so instead we suggest using a volumetric flask and stopwatch to manually do this. Mixing chamber performance is usually monitored by the gradient composition test, since it affects this directly.
https://www.waters.com/webassets/cms/library/docs/720000498en.pdf (see pages 349-350)
For the gradient composition test, Waters takes a different approach. They use more typical mobile phases, such as acetonitrile/water, and monitor by injecting a caffeine standard at various mobile phase percentages. Then they plot the retention time versus the ratio of water/organic solvent. Their test for flow rate is more complicated because they are also determining the linearity of various flow rate settings.
It appears that their approach for gradient composition testing is similar to Agilent’s, using acetone. They monitor the flow rate/precision by collecting solvent for a specified period of time, weighing it. This can be done by weight or volume, but I have found volume is much easier.
Shimadzu does not have published procedures for their OQ testing. However, their manuals offer guidance on how their instruments have some automatic functions that assist in these procedures. As an example, please see pages 8-9 of the following manual for the LC2010HT:
Their manual also states that OQ testing can be performed by their representatives at the time of installation (if requested), in addition to the Installation Qualification (IQ) checks. Any subsequent OQ and PQ tests would likely be performed by regular lab personnel.
Here are a couple more links that discuss instrument qualifications in general. As you can see, this is mostly a procedure driven by regulatory requirements:
I hope that the information provided here has been useful. Thank you for reading.