Ad
related to: gas chromatography sample injection
Search results
Results From The WOW.Com Content Network
Dissolved samples can be introduced directly onto the column via a COC injector, if the conditions are well known; if a solvent matrix has to be vaporized and partially removed, a S/SL injector is used (most common injection technique); gaseous samples (e.g., air cylinders) are usually injected using a gas switching valve system; adsorbed ...
The method uses headspace gas injected into a gas chromatographic column (GC) to determine the original concentration in a water sample. [9] A sample of water is collected in the field in a vial without headspace and capped with a Teflon septum or crimp top to minimize the escape of volatile gases. It is beneficial to store the bottles upside ...
The mass spectrometry process normally requires a very pure sample while gas chromatography using a traditional detector (e.g. Flame ionization detector) cannot differentiate between multiple molecules that happen to take the same amount of time to travel through the column (i.e. have the same retention time), which results in two or more ...
Sample preparation for PI includes first ensuring the sample is in the gas phase. PI ionizes molecules by exciting the sample molecules with photons of light. This method only works if the sample and other components in the gas phase are excited by different wavelengths of light. It is important when preparing the sample, or photon source, that ...
It must be stable and not interfere with the sample components. This mitigates the uncertainty that can occur in preparatory steps such as sample injection. [1] In gas chromatography-mass spectrometry (GC-MS), deuterated compounds with similar structures to the analyte commonly act as effective internal standards. [8]
Analytical thermal desorption originated in the mid-1970s as an adaptation to the injection procedure for GC. Injector liners were packed with a compound able to adsorb organic compounds, used to sample air or gas, and then dropped into the inlet of the GC.
As the sample is carried into the detector by the carrier gas, electron-absorbing analyte molecules capture electrons and thereby reduce the current between the collector anode and a cathode. Over a wide range of concentrations the rate of electron capture is proportional to the analyte concentration.
Analytical gas chromatography A (top) compared with inverse gas chromatography B (bottom). While in gas chromatography a sample containing multiple species is separated into its components on a stationary phase, Inverse gas chromatography uses injection of a single species to probe the characteristics of a stationary phase sample.