The basic structure of flame atomic absorption spectrometer

The flame atomic absorption spectrometer mainly includes optical system, monochromator system, photometer, air compression pump, gasoline vaporizer, throttle and spray system, etc. Do users know all these components? Today, I will introduce the basic composition of the flame atomic absorption spectrometer in detail, hoping to help everyone.

1. Optical system

The optical system consists of a focusing reflector, a lens group, a filter plate, a grating, a shutter, and a collimator.

2. Monochromator system

The function of a monochromator is to select light of a certain wavelength that can represent the element to be measured from a light source containing various wavelengths, let it pass, and measure its intensity. The rest of the light is absorbed or prevented from hitting the photocell.

There are complex and simple spectroscopic systems. Complex spectroscopic systems use glass or even quartz prisms and slits to select light, just like ordinary spectrometers. Flame photometers using this monochromator can determine K, Na, Ca, and other elements.

3. Photometer

This part includes photocells (phototubes or photomultiplier tubes), adjustment resistors, amplifiers and galvanometers, which are similar to general photoelectric colorimeters. The commonly used phototubes and even photomultiplier tubes with prisms as the light splitting system are used as conversion elements.

4. Air compression pump

The air compressor pump is composed of a single-phase induction motor and a rotary air compressor pump. In the nail cylinder of the air compressor pump, the rotor is eccentrically installed. Six radial centrifugal vanes are installed in the rotor slot. Due to the centrifugal force, the centrifugal vanes are always close to the cylinder wall. As the rotor rotates in the cylinder, the volume at the air inlet is gradually expanded periodically to inhale gas. At the same time, the volume at the exhaust port is gradually reduced, and the inhaled gas is compressed and discharged into the air storage cylinder. The function of the air storage cylinder is to make the discharged air pressure uniform and constant before entering the throttle. There is an exhaust valve at the outlet of the air storage cylinder, which can open or close the air storage cylinder. There is a pressure gauge at the inlet of the air storage cylinder to observe the exhaust pressure of the compression pump. A glass oil cup is installed above the air inlet of the compression pump. There is a refueling hole on the cup. The spindle oil is added from this hole. There is also a safety valve at the outlet of the compression pump. When the pressure is overloaded, it plays a safety protection role.

5. Gas carburetor

It is a metal cylinder filled with coal gas, with an air intake valve for compressed air and a gas source valve for coal gas. The gasoline inlet is on the side of the metal cylinder, and there is an oil discharge outlet at the bottom, which is controlled by a switch. The residual oil in the barrel can be discharged. The coal gas vaporizer is a relatively important structure of the flame atomic absorption spectrometer.

6. Restrictor

The throttle is composed of a small wooden box as its main body. A barometer is installed on the panel of the wooden box to observe the pressure of compressed air and a glass open pressure gauge is installed to observe the pressure of gasoline vaporization gas. The wave tube of the pressure gauge is filled with colored liquid indicating the pressure, which can be added from the opening of the glass tube and the liquid level can be kept at the "0" scale at all times.

7. Sprayer system

The sprayer is connected to the mist processor, mixer and combustion tube with a rubber tube. The compressed air enters the nozzle of the mist chamber through the throttle, and the sample liquid enters the sample liquid outlet of the mist chamber through the suction tube. Under the action of the air pressure in the nozzle, the mist and gas enter the mist chamber at the same time, and then enter the mixing ball after the mist processor, mix with the gas, reach the combustion nozzle through the combustion tube, and ignite to obtain a flame.