Measurement-Procedure-Standardisations.md

@@ -74,19 +74,11 @@ Now the
 | chemiluminescence (internal photolytic converter) | Chemiluminescence is the emission of light (luminescence), as the result of a chemical reaction. Chemiluminescence occurs as a result of the reaction of NO with ozone (NO+O3 --> NO2*+O2). The return to a fundamental electronic state of the excited NO2* molecules is made by luminous radiation in a 600-3000 nm spectrum (NO2* --> NO2 + hv), which can be measured. This method is designed specifically to directly measure NO (and NOx/NO2 indirectly). | Water vapour (above 20 ppmv), 3rd body quenching (CO2, SOx), thermal decomposition of PAN to NO2 within the photolysis cell | |
 | chemiluminescence (internal molybdenum and quartz converters) | Chemiluminescence is the emission of light (luminescence), as the result of a chemical reaction. Chemiluminescence occurs as a result of the reaction of NO with ozone (NO+O3 --> NO2*+O2). The return to a fundamental electronic state of the excited NO2* molecules is made by luminous radiation in a 600-3000 nm spectrum (NO2* --> NO2 + hv), which can be measured. This method is designed specifically to directly measure NO (and NH3/NOx/NO2 indirectly). | Known interferences: Water vapour (above 20 ppmv), 3rd body quenching (CO2, SOx), other NOy species converted to NO by molybdenum converter (PAN, ethyl nitrate, ethyl nitrite, HONO, HNO3, methyl nitrate, n-propyl nitrate, n-butyl nitrate, nitrocresol, NH3), other species undergoing chemiluminescence with O3 (SOx). | |
 | chemiluminescence (internal molybdenum converter and external stainless steel converter) | Chemiluminescence is the emission of light (luminescence), as the result of a chemical reaction. Chemiluminescence occurs as a result of the reaction of NO with ozone (NO+O3 --> NO2*+O2). The return to a fundamental electronic state of the excited NO2* molecules is made by luminous radiation in a 600-3000 nm spectrum (NO2* --> NO2 + hv), which can be measured. This method is designed specifically to directly measure NO (and NH3/NOx/NO2 indirectly). | Water vapour (above 20 ppmv), 3rd body quenching (CO2, SOx), other NOy species converted to NO by molybdenum converter (PAN, ethyl nitrate, ethyl nitrite, HONO, HNO3, methyl nitrate, n-propyl nitrate, n-butyl nitrate, nitrocresol, NH3), other species undergoing chemiluminescence with O3 (SOx). | |
-| sulphur chemiluminescence - gas chromatography | Chemiluminescence is the emission of light (luminescence), as the result of a chemical reaction. Chemiluminescence occurs as a result of the reaction of SO and ozone (SO+O3 --> SO2*+O2).
+| sulphur chemiluminescence - gas chromatography | Chemiluminescence is the emission of light (luminescence), as the result of a chemical reaction. Chemiluminescence occurs as a result of the reaction of SO and ozone (SO+O3 --> SO2*+O2). The return to a fundamental electronic state of the excited SO2* molecules is made by luminous radiation in a specific spectrum (SO2* --> SO2 + hv), which can be measured (by a photomultiplier tube). The concentration of sample total sulphur is directly proportional to the intensity of light emitted. This method can be mixed with gas chromatography (GC) to allow to determination of specific sulphur compounds (i.e. SO2). The gas sample is passed through a GC column before being ultimately measured by the photomultiplier detector. Gas chromatography (GC) is a method used for separating and analysing compounds that can be vaporized without decomposition. A sample solution is injected into a instrument, entering a gas stream which transports the sample (mobile phase) into a separation tube known as the "column". The mobile phase is a carrier gas, usually an inert gas such as helium or an unreactive gas such as nitrogen. Helium remains the most commonly used carrier gas in about 90% of instruments although hydrogen is preferred for improved separations. The column consists of a microscopic layer of liquid or polymer on an inert solid support a microscopic layer of liquid or polymer on an inert solid support (stationary phase), inside a piece of glass or metal tubing, placed inside a piece of glass or metal tubing. Once inside the column, the gaseous compounds being analysed interact with the walls of the column coated with a stationary phase. This causes each compound to elute at a different time, known as the retention time of the compound.  The comparison of retention times is what gives GC its analytical usefulness. If greater separation of compounds is required, multiple distinct columns can be used for this purpose. | | |
+| flame photometric detection (FPD) | Many elements give characteristic emission when burned in flame. Absorption of energy from the flame allows a ground state atom or molecule to reach an excited state. The atom/molecule may return to the ground state through emission of light (luminescence), which can be subsequently measured (by a photomultiplier tube). This process is a chemiluminescent process (where luminescence occurs as the result of a chemical reaction). The concentration of the sample gas is directly proportional to the intensity of light emitted. This method has been applied for the measurement of sulphur containing species (i.e. SO2). For specific measurement of solely SO2, the sample gas must be scrubbed of other sulphur species prior to measurement, and the photomultiplier detector measures emission centred near 394nm. | Other sulphur compounds | |
+| flame ionisation detection (FID) | This method is based on the principle of the generation of an electrical current that is proportional to the rate of ion formation, dependent on the concentrations of species in the sample gas. The method is typically the standard detection method for hydrocarbons, however the method is also sensitive to almost all compounds, mostly combustible ones. There are, however, a few compounds to which the method has very little, if any, sensitivity, including: O2, N2, SO2, NO, N2O, NO2, NH3, CO, CO2, and H2O. | Method is non-specific for different gases in the sample. | |
 
-The return to a fundamental electronic state of the excited SO2* molecules is made by luminous radiation in a specific spectrum (SO2* --> SO2 + hv), which can be measured (by a photomultiplier tube).
 
-The concentration of sample total sulphur is directly proportional to the intensity of light emitted.
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-This method can be mixed with gas chromatography (GC) to allow to determination of specific sulphur compounds (i.e. SO2). The gas sample is passed through a GC column before being ultimately measured by the photomultiplier detector.
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-Gas chromatography (GC) is a method used for separating and analysing compounds that can be vaporized without decomposition. A sample solution is injected into a instrument, entering a gas stream which transports the sample (mobile phase) into a separation tube known as the "column".
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-The mobile phase is a carrier gas, usually an inert gas such as helium or an unreactive gas such as nitrogen. Helium remains the most commonly used carrier gas in about 90% of instruments although hydrogen is preferred for improved separations. The column consists of a microscopic layer of liquid or polymer on an inert solid support a microscopic layer of liquid or polymer on an inert solid support (stationary phase), inside a piece of glass or metal tubing, placed inside a piece of glass or metal tubing.
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-Once inside the column, the gaseous compounds being analysed interact with the walls of the column coated with a stationary phase. This causes each compound to elute at a different time, known as the retention time of the compound.  The comparison of retention times is what gives GC its analytical usefulness. If greater separation of compounds is required, multiple distinct columns can be used for this purpose. | | |