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SciCann - The Science of Cannabis

SciCANN which has been working in the Cannabis industry for 15 years. The SciCANN division of Scientific Equipment Source Inc is your source for new and refurbished Cannabis quality control laboratory testing equipment. We supply HPLC, GC, NIR, and more for Potency, terpenes, R&D, Residual solvents, moisture content, pesticide screening, microbiological purity, aflatoxins and more as well as consult on the LP process.

ECD detector, Agilent 6890

The electron capture detector (ECD) cell contains 63Ni, a radioactive isotope emitting high energy electrons (Boparticles).These undergo repeated collisions with carrier gas molecules, producing about 100 secondary electrons for each initial Boparticle.

Further collisions reduce energy of these electrons into the thermal range. These low energy electrons are then captured by suitable sample molecules, thus reducing total electron population within the cell.

Uncaptured electrons are collected periodically by applying short term voltage pulses to cell electrodes. This cell current is measured and compared to a reference current, and the pulse interval is then adjusted to maintain constant cell current.

Therefore, pulse rate (frequency) rises when an electron capturing compound is passing through the cell. The pulse rate is converted to a voltage, linearly related to amount of electron capturing material in the cell.

Thus, the ECD responds to compounds having an affinity for electrons (for example, such halogenated materials as pesticides and related compounds).

General indication of expected sensitivity to different classes of organic compounds.

Chemical Type




Ethers, esters


Aliphatic alcohols, ketones, amines; mono-Cl, mono-F compounds


Mono-Br, di-Cl and di-F compounds


Anhydrides and tri-Cl compounds


Mono-I, di-Br and nitro compounds


Di-I, tri-Br, poly-Cl and poly-F compounds


These are only approximate figures; sensitivity varies widely within each group, depending upon structure of the material. For example, DDT (5 chlorine atoms/molecule) can be measured in the 1 to 10 picogram range.

The ECD is designed for use either with N2 or with 5% CH4 in Ar as carrier gas. A switch selects operation with either carrier gas; the ECD does not operate properly if the switch is incorrectly set. Because of its high sensitivity, the ECD should never be used without traps (moisture, chemical), should be in good condition, and should be installed in the carrier gas supply line. For capillary systems, this must also be done for the makeup gas supply.

An ECD is normally used to detect compounds that are reactive enough to interact with metal columns. Therefore, only ¼” packed glass, or fused silica, or glass capillary columns are recommended with this detector.