IEC TR 62697-3-2018 pdf free.Test methods for quantitative determination of corrosive sulfur compounds in unused and used insulating liquids- Part 3: Test method for quantitative determination of elemental sulfur.
5.3.1co-eluting compounds
Interferences experienced during quantitative determination of elemental sulfur will vary withthe detector used for quantification of elemental sulfur separated with the gaschromatographic column.
5.3.2Electron capture detector (ECD)
An ECD is a very sensitive and selective detector that responds to volatilelsemi-volatilecompounds with high electron affinity. It has gained wide acceptance and use due to its veryhigh sensitivity and selectivity for certain classes of compounds,including halogenatedhydrocarbons,organometallic compounds,nitriles,or nitro compounds,disulfides andelemental sulfur (S;,S-and Sg). Presence of compounds with high affinity for thermalelectrons especially polychlorinated biphenyls (PCBs) in insulating liquids can causeinterference.In such cases an alternate detector should be used.
5.3.3Flame photometric detector (FPD)
The FPD provides a selective signal for sulfur species including DBDS in the form of broadlight emission centred around 393 nm.Emission is separated with an interference filter with a20 nm band pass with peak transmission at 393 nm. The filter is mounted in front of aphotomultiplier that provides electrical signal that is amplified and linearized.Sulfur containingorganic compounds which elute with the same retention time can lead to interference; acolumn with different stationary phase can be used to eliminate or minimize interference.
5.3.4Mass spectrometer (Ms)
An MS is a very sensitive and selective detector that responds to the volatile and semi-volatilecompounds. lt has gained wide acceptance and use due to its very high sensitivity andselectivity for a broad class of compounds.Compounds present in the GC effluent that yieldions at m/z 256 and ions at m/z 218 will cause interference if such compounds elute from theGC column with retention times similar to those of the S and DPDS (IS).
5.3.5Interference from the matrix
The insulating liquid matrix is comprised of hydrocarbons that do not respond well in the ECD,therefore, matrix interference should be low with Gc-ECD.
An FPD response is selective for sulfur through S, emission.Other chemical species whichemit radiation around the 393 nm can cause interference,however,such interference isgenerally low.
lt is possible that certain insulating liquids contain molecules that yield ions at m/z 256 andm/z 218; such molecules can cause interferences with GC-MS.
A balance with a capability for automatic tare,accuracy down to 0,001 g, and a maximumweight range of ≥ 100 g is recommended.IEC TR 62697-3 pdf download.