Degassing-Filter Caps and Helium Sparging
The answer to the following reader question about degassing mobile phase solvents was supplied by LCGC's "LC Troubleshooting" columnist John Dolan.
The answer to the following reader question about degassing mobile phase solvents was supplied by LCGC’s “LC Troubleshooting” columnist John Dolan.
Q: Just how good of a job do degasser–filter caps do on degassing HPLC solvent? Where can I find a technique or protocol to degas solvent with helium?
John Dolan: I have not seen data on the effectiveness of the caps, but I suspect that if you use them with a vacuum filtration device, they should be similar to vacuum degassing, which usually is adequate. Helium sparging is simple — just use a sparging frit (a solvent reservoir frit is fine) on the helium line — and bubble a stream of helium (for example, use 5 psi pressure) through the solvent for 4–5 min. Usually this is enough to keep the solvent degassed for a day. In difficult cases, or where any oxygen causes problems (for example, with reductive electrochemical detection), continuous sparging may be necessary. Just turn down the flow to a trickle to keep the solvent degassed. Most popular today are the in-line vacuum degassing systems, which are quite effective, but they might not remove sufficient oxygen for oxygen-sensitive methods.
Best of the Week: Food Analysis, Chemical Migration in Plastic Bottles, STEM Researcher of the Year
December 20th 2024Top articles published this week include the launch of our “From Lab to Table” content series, a Q&A interview about using liquid chromatography–high-resolution mass spectrometry (LC–HRMS) to assess chemical hazards in plastic bottles, and a piece recognizing Brett Paull for being named Tasmanian STEM Researcher of the Year.
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December 19th 2024Testosterone measurements are typically performed using serum or plasma, but this presents several logistical challenges, especially for sample collection, storage, and transport. In a recently published article, Yehudah Gruenstein of the University of Miami explored key insights gained from dried blood spot assay validation for testosterone measurement.
Determination of Pharmaceuticals by Capillary HPLC-MS/MS (Dec 2024)
December 19th 2024This application note demonstrates the use of a compact portable capillary liquid chromatograph, the Axcend Focus LC, coupled to an Agilent Ultivo triple quadrupole mass spectrometer for quantitative analysis of pharmaceutical drugs in model aqueous samples.
