column bleed

column bleed

[′käl·əm ‚blēd]
(analytical chemistry)
The loss of carrier liquid during gas chromatography due to evaporation into the gas under analysis.
References in periodicals archive ?
It has both the selectivity required to separate the most difficult PAHs, as well as the optimized column dimensions that allow higher molecular weight PAHs to be analyzed without interference from column bleed. As shown in Figure 1, 36 key PAHs are analyzed in just 32 minutes and all priority compounds--including benz [a] anthracene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene, chrysene, triphenylene, cyclopenta[cd]pyrene, and benzo [b], [k], [j], and [a] fluoranthenes--are well resolved allowing accurate integration.
Using purifiers with indicators, and remembering to check them regularly, helps minimize GC column bleed and extend column lifetimes while improving system sensitivity.
Column bleed is the loss of lower molecular weight stationary phase pieces that are either the result of impurities in the starting polymer or the decomposition of the phase at elevated temperatures.
The company claims it uses a proprietary bonding and deactivation procedure that lowers column bleed and reduces activity.
Bowers and Borts argue that the lack of improvement for the QIT when presented with an analyte present in a complex matrix arises because the width of the window for ion admittance to the trap allows matrix or column bleed ions (or both) to enter with the analyte ions.
The columns are compatible with highly aqueous mobile phase and feature low column bleed, high efficiency and rugged packing.
In this instance, the oven must be cooled at a much slower rate to allow dissipation of the column bleed so that 'focused' condensation within the column does not occur.
Thus, the ratio of the number of ions from column bleed or matrix background to the number of ions of the compound of interest stays the same at the time that the total analytical signal is decreased.
If the carrier gas contains even trace amounts of water or oxygen it may damage the GC column stationary phase, resulting in bad peak shape and excessive column bleed. Gas produced on-site can be assured to be pure and without contaminants because most generators, including Proton OnSite's family of hydrogen generators, have built-in, efficient palladium membrane purifiers.
Advantages of fast GC include reduced run times, increased sample throughput, improved signal-to-noise ratio and less column bleed (thinner films).
Reduced column bleed minimizes the risk of contamination of the mass spectrometer while extending the interval between scheduled maintenance.
The low column bleed provides increased detector sensitivity and faster baseline stabilization.