This is the third in a three-part series on Getting to know your QuickTrace® — The effect of liquid flow.
To catch up on the other blogs in this series click the links below:
- Part one: Getting to Know your QuickTrace®: The Effect of Liquid Flow: Pump Rate
- Part two: Getting to Know Your QuickTrace® - The Effect of Liquid Flow: Importance of Capillary Action
When it comes to pump tubing, Teledyne Leeman Labs recommends not trying to tighten the tension screws to get more flow from worn tubing. Instead, replace all pump tubing as part of general maintenance for the instrument. This minimizes changes between runs, as you don’t need to consistently reset the pump tension to maintain a consistent flow ratio between the sample flow and the stannous chloride. The QuickTrace software helps track the runtime of the tubing and will even alert you to when the tubing is likely reaching its end of life. Please note: this is only accurate when start-up and shut-down procedures are followed consistently.
Most commonly, if tubing was worn but continued to be run by tightening down on the clamps, the next set of tubing can be stretched and wear out more quickly. Overtightening the clamps creates additional friction on the tubing and can lead to consistency issues when running as well. This is a big reason why replacing the tubing as it gets worn is our recommended method at Teledyne, as it will keep runs more consistent through the life of the instrument.
If any changes were made to the tension and the peak profile does not generate a similar response height as before, there usually is an issue with the sample flow rate; the peak still climbing will indicate not enough of the stannous chloride reagent is entering the mix. This is sometimes hard to notice unless the peak height is significantly changed. Problems involving improper tension are more likely to be seen in the consistency of data points rather than by viewing a single run.
If tension is too loose in the middle of a run, the tension arm can be pushed out of place. If tension is removed from either the sample or reagent tubing, the corresponding flow is stopped and the results will all appear blank. On top of receiving no data, you are likely to experience contamination if a flow stops and is unnoticed long enough. This is because the sample and reagent are mixed at the mix tee and oppose one another. However, drain tubing working its way loose will cause pooling in the gas liquid separator (GLS). This will trip the overflow sensor on the GLS mount, leading to the run stopping entirely. When tripped, the sensor will stop the liquid pump flow and the run, but the gas will continue bubbling through the pooled liquid. This can push sample and reagent along the walls of the GLS and require cleaning.
Again, the best practice is to follow the recommended startup and shut-down procedures sent out with the instrument. The pump clamps should not be left on while the machine is not running and during warm-up of the lamp. This can cause excessive fatigue and wear, reducing the life of the tubing and resulting in bad relative standard deviation values on runs. Additionally, rinsing the system by running 10 percent nitric cleaning solution and distilled water through the sample lines helps keep the mix tee and capillary free of any contamination buildup created during previous runs.
Other blogs in this series click the links below:
- Part one: Getting to Know your QuickTrace®: The Effect of Liquid Flow: Pump Rate
- Part two: Getting to Know Your QuickTrace® - The Effect of Liquid Flow: Importance of Capillary Action
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