Flame ionization detector(FID)

Done by:Aya AliMalak Al-GhamdiSupervised by:Dr. Haya Al-Johar

Outline

Introduction

Operating principle of FID

Description of FID

Applications of FID

Advantages of FID

Disadvantages of FID

Sensitivity of FID

Operating principle:Ionization detectors interact with solutes eluted from gas chromatography (GC) columns to produce a current that varies in proportion to the amount of solute present. FID is sensitive to molecules that are ionized in a hydrogen–air flame, including most carbon-containing compounds

The flame ionization detector passes sample and carrier gas from the column through a hydrogen-air flame. The hydrogen-air flame alone creates few ions, but when an organic compound is burned there is an increase in ions produced. A polarizing voltage attracts these ions to a collector located near the flame. The current produced is proportional to the amount of sample being burned. This current is sensed by an electrometer, converted to digital form, and sent to an output device.

Detector performance characteristics (sensitivity, minimum detectable quantity, linearity, and selectivity)FID is A mass flow sensitive detectorthat for organic compounds the intensity of the signal is proportional to the mass flow of carbon.

Applications

FID responds only to substances that

produce charged ions when burned in a

hydrogen/air flame.

does not respond to water, or permanent gases

.

he FID responds only to substances that produce charged ions when burned in a hydrogen/air flame.

Cost: Inexpensive to acquire and operate.

Low maintenance requirements: Apart from cleaning or replacing the FID jet, these detectors require no maintenance.

Rugged construction: FIDs are relatively resistant to misuse.

Linearity and detection ranges: FIDs can measure organic substance concentration at very low and very high levels, having a linear response of 10^6.

Advantages

Disadvantages Flame ionization detectors cannot

detect inorganic substances.

FID flame oxidizes all compounds that pass through it.

destroys sample.

It requires additional Gases and controllers.

For this reason, FIDs tend to be the last in a detector train and also cannot be used for preparatory work.

Sensitivity

The FID exhibits a high sensitivity (10-13g/s),large linear.

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