Fast, accurate calibration of flow rates used in HPLC flow systems can be compromised if the flow meter is not maintained. While GLP (good laboratory practices) call for annual flow meter recalibration by the manufacturer, improper use of these precision instruments can soon render them inaccurate.
A serious error is introducing in immediate succession two immiscible liquids into the flow meter. Either allow the first liquid to completely evaporate or introduce a third solvent in which the other two are miscible.
Dirty sensing tubes in FlowCal 5000 HPLC flow meters may cause bubbles to become entrapped. This can create falsely high readings. If bubbles are observed, a quick fix is to turn the unit off, wait approximately 2 seconds to allow it to drain, then switch it on. Contaminated tubes will also result in an “Error 4” reading denoting either the flow meter is not draining or the sensing tube is contaminated.
Another good practice is flushing the flow meter with methanol if it is not to be used for a week or more. This prevents algae growth in the tube.
