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GC with Nitrogen Phosphorous Detector (GC-NPD)

Gas Chromatography – Nitrogen Phosphorous Detector or GC-NPD, otherwise known as Thermionic Specific Detector or TSD, is a technique used to analyse nitrogen or phosphorous containing organic compounds and is commonly used in pharmaceutical, food and environmental markets.

Similar to a Flame Ionization Detector, a NPD uses a Hydrogen/Air flame through which the sample is passed. However a NPD uses a rubidium or caesium chloride alkali bead which is heated by a coil, over which the carrier gas mixed with Hydrogen passes. The hot bead emits electrons by thermionic emissions which are collected at the anode and provides the background current. When a component that contains nitrogen or phosphorous exits the column, the partially combusted nitrogen and phosphorous materials are adsorbed on the surface of the bead. This then increases the emission of electrons and the current which is then measured.

As common with other GC techniques, a carrier gas is required with low Water and Oxygen impurities since Water and Oxygen can interact with the stationary phase and cause significant problems such as high baseline noise and column bleed in the output gas chromatogram which both reduces analyser sensitivity and decreases column lifetime.

The NPD is also extremely sensitive to Hydrocarbon impurities in the Hydrogen and Air supply for the flame. Hydrocarbon impurities can cause increased baseline noise and reduce the detector sensitivity.

A make-up gas can be used in GC-NPD at the exit of the column to increase the flow rate into the detector. The routine calibration of the analyser using a calibration mixture is common.

Our range of Experis® ultra high purity gases and patented BIP® technology offer you the optimum gas for your GC-NPD requirements. Don’t forget your choice of cylinder equipment also affects your analytical results. Our range includes high quality cylinder regulators, manifolds, valves and purge systems which will help to optimise the smooth operation and accuracy of your analysis.

The recommended gases and equipment for this application are listed below. Please note that our recommendation is based on common analytical requirements, so you may require a higher purity grade if analysing to lower concentrations or be able to use a lower purity grade if analysing to higher concentrations. If you require any additional advice on the right purity grade for your needs, please contact us.

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Product NameDescription/BenefitsDownloads
Gases

Helium BIP® gas

Helium supplied using our patented BIP® technology contains ultra low levels of Oxygen, Water and Hydrocarbons making it an ideal carrier gas for GC-NPD which is sensitive to hydrocarbons to ensure more accurate analyses.

Helium supplied using our patented BIP® technology contains ultra low levels of Oxygen, Water and Hydrocarbons making it an ideal carrier gas for GC-NPD which is sensitive to hydrocarbons to ensure more accurate analyses.

Hydrogen BIP® gas

Hydrogen supplied using our patented BIP® technology contains ultra low levels of Oxygen, Water and Hydrocarbons making it an ideal carrier and detector gas for GC-NPD which is sensitive to hydrocarbons to ensure more accurate analyses.

Hydrogen supplied using our patented BIP® technology contains ultra low levels of Oxygen, Water and Hydrocarbons making it an ideal carrier and detector gas for GC-NPD which is sensitive to hydrocarbons to ensure more accurate analyses.

Nitrogen BIP® gas

Nitrogen supplied using our patented BIP® technology contains ultra low levels of Oxygen, Water and Hydrocarbons making it an ideal carrier gas for GC-NPD which is sensitive to hydrocarbons to ensure more accurate analyses.

Nitrogen supplied using our patented BIP® technology contains ultra low levels of Oxygen, Water and Hydrocarbons making it an ideal carrier gas for GC-NPD which is sensitive to hydrocarbons to ensure more accurate analyses.

Zero Air

Zero Air with its ultra low Hydrocarbons level is perfect for use as a detector gas in GC-NPD to ensure accurate analyses.

Zero Air with its ultra low Hydrocarbons level is perfect for use as a detector gas in GC-NPD to ensure accurate analyses.

Line Regulators

Essential for reducing the gas pressure in a pipeline, our range of high-quality line regulators are available in either brass or stainless steel, and various flowrate and outlet pressure ranges.

Essential for reducing the gas pressure in a pipeline, our range of high-quality line regulators are available in either brass or stainless steel, and various flowrate and outlet pressure ranges.

Manifolds

Essential for ensuring a batch or continuous supply, our range of high-quality manifolds can connect up to six cylinders, can provide manual or semi-automatic changeover and are available in brass or stainless steel.

Essential for ensuring a batch or continuous supply, our range of high-quality manifolds can connect up to six cylinders, can provide manual or semi-automatic changeover and are available in brass or stainless steel.

Pressure Gauges

Our high-quality, accurate pressure gauges are available in brass, stainless steel or Monel® for a wide variety of pressure ranges.

Our high-quality, accurate pressure gauges are available in brass, stainless steel or Monel® for a wide variety of pressure ranges.

Purge Systems

Purge systems are essential for eliminating impurities in and/or operator exposure to the gas when changing over cylinders. Our high-quality cross-purge, self-purge and T-purge systems are available in a variety of materials for the handling of pure, toxic, corrosive and flammable gases.

Purge systems are essential for eliminating impurities in and/or operator exposure to the gas when changing over cylinders. Our high-quality cross-purge, self-purge and T-purge systems are available in a variety of materials for the handling of pure, toxic, corrosive and flammable gases.

Valves

Our range of high-quality check valves and relief valves are available in brass or stainless steel and a variety of connection sizes for the connection of cylinders to equipment.

Our range of high-quality check valves and relief valves are available in brass or stainless steel and a variety of connection sizes for the connection of cylinders to equipment.

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