Tag Archives: chromatography

Finding the Area for Overlapping Chromatographic Peaks

In a GC analysis the area under the peak is proportional to the amount of analyte injected onto the column. The peak’s area is determined by integration, which usually is handled by the instrument’s computer or by an electronic integrating … Continue reading

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GC-MS

The figure below provides a block diagram of a typical gas chromatography-mass spectrometer (GC–MS) instrument. As illustrated here, a three component mixture enters the GC. When component A elutes from the column, it enters the MS ion source and ionizes to form … Continue reading

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Electron Capture Detector

Shown here is a schematic diagram of electron capture detector (ECD) for gas chromatography. The detector consists of a β-emitter, such as 63Ni. The emitted electrons ionize the mobile phase, which is usually N2, generating a standing current between a … Continue reading

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Flame Ionization Detector

The schematic diagram below shows a flame ionization detector for gas chromatography. The eluent from the column mixes with H2 and is burned in the presence of excess air. Combustion of organic analytes produces a flame containing electrons and organic … Continue reading

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Thermal Conductivity Detector

One of the earliest gas chromatography detectors takes advantage of the mobile phase’s thermal conductivity. As the mobile phase exits the column it passes over a tungsten-rhenium wire filament (see figure below). The filament’s electrical resistance depends on its temperature, … Continue reading

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GC Injectors

Shown here is a schematic diagram of a heated GC injector port for use with packed columns. The needle from the syringe pierces a rubber septum and enters into the top of the column, which is located within a heater … Continue reading

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GC Syringe

Shown here is an example of a syringe for injecting samples into a gas chromatograph. This syringe has a maximum capacity of 10 μL with graduations every 0.1 μL.

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Solid-Phase Microextraction

Solid-phase microextraction (SPME) is an attractive method for isolating an analyte prior to injecting it into a gas chromatograph. In one approach, which is illustrated here, a fused-silica fiber is placed inside a syringe needle. The fiber, which is coated with … Continue reading

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Gas Chromatography Columns

Shown here is an example of a packed column for gas chromatography. This column is made from stainless steel and is 2 m long with an internal diameter of 3.2 mm. The packing material in this column has a particle … Continue reading

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Gas Chromatograph

Photograph showing an example of a typical gas chromatograph with insets showing the heated injection ports—note the symbol indicating that it is hot—and the oven containing the column. This particular instrument is equipped with an autosampler for injecting samples, a … Continue reading

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