Aroclor
Definition
A series of polychlorinated biphenyl (PCB) commercial mixtures manufactured by Monsanto (US) and marketed as electrical insulating fluids. Aroclors are designated by four digits (e.g. Aroclor 1254, 54% chlorine by mass). Their congener-specific GC chromatographic patterns are used to identify the PCB source in contaminated transformer oil.
- Chemical class
- Polychlorinated biphenyls (PCBs)
- Manufacturer
- Monsanto (US)
- Original use
- Electrical insulating fluid
- Naming convention
- Four digits, e.g. 1254 = 54% chlorine by mass
- Forensic use
- Congener GC pattern identifies PCB source
Common questions
Why would an Aroclor identification matter in a fire investigation?+
PCB-containing transformer oil was widely used before bans in many countries, so finding a specific Aroclor's chromatographic signature in fire debris can confirm a transformer failure or leak was involved and help date the equipment, since particular Aroclor formulations were phased out at known points.
How do analysts distinguish one Aroclor mixture from another chromatographically?+
Each Aroclor is a defined blend of PCB congeners with a characteristic relative-abundance pattern on gas chromatography, so comparing the congener peak pattern of a sample against reference Aroclor standards identifies which commercial mixture, and roughly which chlorination level, is present.
Related terms
- C30 17Alpha-Hopane
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- Dissolved Gas Analysis (DGA)
- The analysis of gases dissolved in transformer oil (H2, CH4, C2H4, C2H2, CO, CO2) by ASTM D3612 or IEC 60599 to diagnose...
- GC-IRMS
- Gas chromatography isotope ratio mass spectrometry: compounds separated by GC are combusted (for 13C) or pyrolysed (for 2H) and the isotope ratio...
- GC×GC-TOFMS
- Two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (Leco Pegasus instruments). The first GC column separates by boiling point; a cryogenic modulator...
- Hopane
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- Karl Fischer Titration (KFT)
- Coulometric or volumetric titration using Karl Fischer reagent (iodine / sulphur dioxide / base / methanol) that reacts stoichiometrically with water. Used...
- SAE Viscosity Grade
- The Society of Automotive Engineers (SAE J300) classification of motor oil viscosity: the 'W' number specifies low-temperature cranking viscosity; the trailing number...
- Unresolved Complex Mixture (UCM)
- The broad hump of hundreds of co-eluting cycloalkane and isoalkane compounds in the TIC of heavy petroleum products (diesel, heavy fuel oil,...
- Zinc Dialkyldithiophosphate (ZDTP)
- The primary anti-wear additive in motor oils, contributing zinc, phosphorus, and sulphur to the additive package. The Zn/P ratio and S/P ratio...