An FID, or Flame Ionization Detector, is the most common detector paired with gas chromatography instruments for analytical applications. But how does and FID work? An FID uses a flame to ionize organic compounds containing carbon. Following separation of the sample in the GC column, each analyte passes through a flame, fuelled by hydrogen and zero air, which ionises the carbon atoms. Once formed, the ions are collected and measured as they create a current at the detector’s electrodes. The current is produced as the detector collects the charged ions. The current is then converted to an electrical signal in picoamperes (pA) or millivolts (mV). An inert make-up gas is also often used to ensure that additional gas flow is provided to the sample ions as they move through the detector, which can improve analytical results. When using a make-up gas, it is important that the gas used is inert and contains minimal impurities which could interfere with the sample analysis, risking dampening the signal or increasing the baseline. Although helium can be used for make-up gas, nitrogen is often the more cost-effective option, and can be supplied via a nitrogen gas generator. Using a gas generator for GC-FID analysis brings convenience and reliability to the lab. Labs performing analyses such as GC-FID, where multiple gas sources are required saves lab managers and employees the hassle of coordinating gas cylinder orders to ensure the gas supply doesn’t run out mid-analysis. Opting for gas generators for GC-FID can be more cost-effective and is the safest alternative to cylinders, since gas is generated on-demand to meet instrument needs, without storage of large volumes of highly pressurized gas.