ASTM D-3612 is a gas chromatography (GC) method that describes the analysis of hydrogen, oxygen, nitrogen, methane, carbon monoxide, C2-C3 in hydrocarbon-based transformer oil. In this study, two changes were made to the method. The first was substituting a universal Barrier Ionization Discharge (BID) detector in place of a TCD; hydrogen detection levels were lowered from 10ppm to 100ppb. The second change was the addition of propane and butane into the analysis.
Two PLOT columns were placed in series separated by a 4-port stream selection valve that directs the gas components to either the BID or FID. H2, O2, N2, CH4, CO are separated by a molecular sieve column then detected by BID while CO2, C2H2, C2H4, C2H6 and C3H8 are separated by the Carboxen-1006 column then detected by FID. CO2 went through a methanizer and was reduced to CH4 then analyzed by FID.
BID-2010 Plus Principals for Detection
A plasma is generated by applying a high voltage to a quartz dielectric chamber in the presence of helium. Compounds that elute from the GC column are ionized by this He plasma, then, captured with collection electrodes and described as peaks. The photon energy of He is extremely high (17.7 Electron Volt). Therefore, allowing highly sensitive detection of every compound except Ne (Neon) and Helium which is the plasma gas. BID is a near-universal plasma detector.