Atomic Absorption Spectrophotometer

Atomic Absorption Spectrophotometer (AAS) adopts flame method (air-acetylene flame) to determine the content of common elements in ores and concentrates.

Technical parameters of TAS-990 atomic absorption spectrophotometer

1. Wavelength range: 190 ~ 900nm
2. Spectrum bandwidth: 0.1, 0.2, 0.4, 1.0, 2.0nm five automatic switching
3. Wavelength accuracy: ±0.25nm
4. Wavelength repeatability: 0.15nm
5. Baseline drift: 0.005A/30min
6. Background correction: Deuterium lamp background correction: 1A background can be corrected

Main features of TAS-990 atomic absorption spectrophotometer

1. Structural design of integrated flame atomizer and graphite furnace atomizer, automatic switching of flame and graphite furnace atomizer;
2. The eight-lamp automatic switching turret is used to optimize the working conditions of the hollow cathode lamp in advance;
3. Automatically set the gas flow, select the element analysis combustion ratio;
4. Automatically set flame height and atomizer position, select analysis conditions;
5. Automatic conversion of spectral bandwidth, automatic adjustment of negative high voltage, lamp current, two light balance;
6. Automatic flow setting, automatic ignition, automatic gas protection;
7. When the deuterium lamp is used to buckle the background mode, the semi-transparent semi-mirror device is automatically cut into;
8. Unique graphite furnace design, the use of advanced transverse heating graphite furnace technology, to achieve a uniform temperature of graphite tubes, reduce chemical interference and memory effects, so as to ensure the improvement of atomization efficiency, but also to extend the service life of graphite tubes, to ensure the accuracy of analysis;
9. Pyrolytically coated L ‘VOv platform graphite tube;
10. Perfect safety measures: flame monitor; acetylene leakage alarm; abnormal pressure monitor; Reliable location identification; Graphite furnace protection.

Model and Configuration

In order to adapt to the needs of different applications, the instrument has different configurations and functions: F stands for flame type, G stands for graphite furnace type, and A stands for automatic type

TAS-990F Single flame type
TAS-990G single graphite furnace type
TAS-990FG (Flame type + Graphite furnace type) Manual type
TAS-990AFG (Flame + Graphite furnace) automatic type

 

Basic working principle of atomic absorption spectroscopy analysis

A specific beam of incident light is projected to the measured ground state atomic vapor, and the atomic vapor will absorb the incident light (energy decline), the change of light is reduced, converted into electrical signals, and then converted into numbers.
The hollow cathode lamp is a light source that generates a specific light beam to be absorbed by the element under test, and the atomizer is the source that generates small droplets and generates ground state atomic vapor after the flame is heated. The ground state atomic vapor absorbs light.

 

Atomic absorption analysis method in mining has the advantages

1, high sensitivity, up to 10-4% grade;
2, the selectivity is good, in most cases, the coexistence of elements do not affect atomic absorption analysis;
3, good reproducibility;
4. A wide range of elements are measured.

 

Tips for operation

1. The wavelength must be adjusted accurately, if the wavelength is not correct, it will lead to no results, or the measured result is not the true content of the element being measured
2. The light beam must be aligned with the combustion seam.
3. The beam has a certain distance from the combustion seam, and the height requirements of different elements are inconsistent, generally 5~7mm
4. There are rich and poor flame properties, and different elements require different flame properties. For example, Pb, Bi and Cu, Ag, Fe are different, the front elements use low temperature (rich flame), and the back elements use high temperature (poor flame).
5. The lifting amount of the capillary tube has a certain impact on the measurement, generally requiring 3 ~ 6 mL/min, and the lifting amount can be controlled by adjusting the air pressure and the size of the capillary hole.
6. When the instrument is adjusted, ignite the flame, and the energy emitted by the lamp will decrease for some elements, so the automatic gain can not be clicked again, otherwise it will cause premature damage to the hollow cathode lamp.
7. The solution of the test sample should not have turbidity, fine particles may cause capillary blockage, and more importantly, fine particles will block the beam of the element lamp, making the result high and the analysis result inaccurate.
8, the atomizer must be kept clean, especially after the determination of high content samples, and then the determination of low-grade samples, it is easy to cause errors, should be sprayed after the high-grade samples, it is best to clean the atomization system in time. If the atomization system cannot be cleaned in time, it is also necessary to spray with water containing dilute HNO3 or dilute HCl for 5min, and then spray with water for 5min, and then perform sample determination.
9. Tempering equipment should be installed at the outlet of gas cylinders. When the cylinder gas is running out, the air pressure is extremely low to prevent the tempering from causing an explosion.
10. The element hollow cathode lamp that is not often used should be energized and lit for at least 1 to 2 hours every month to avoid the technical indicators of the element lamp to decline, and even cannot be used.
11. If  you establish a new laboratory,  you can consider adding a GWB-2 Reverse osmosis water purifier to make pure water and ultra-pure water, which can be used to match samples and clean laboratory utensils.

GWB-2 Reverse osmosis water purifier
12. It is recommended that you prepare a stabilized power supply to ensure the stability of the protection equipment.

 

Application Case

flame atomic absorption spectometric method for determin of lithium oxide, sodium oxide, and potassium oxide contents in concentrates of spodumene and lepidolite.

1. Instrument adopted
Atomic absorption spectrophotometer with air-acetylene burner and lithium, sodium, potassium hollow cathode lamp.

2. Sample preparation
2.1, Spodumene concentrate shall pass through a screen with a sieve hole of 0.074MM and lepidolite concentrate shall pass through a screen with a sieve hole of 0.105MM.
2.2. The sample is pre-baked at 105 ° C — 110 ° C for 2h and cooled to room temperature in a dryer.

3. Analytical procedure
3.1, Weigh 0.1 g of sample, accurate to 0.0001 g.
3.2,The sample was placed in a 50mL platinum dish, wet with water, and 3mL sulfuric acid and 1.5mL hydrofluoric acid were added. Heat in sand bath to decompose, steam until thick sulfur trioxide white smoke, remove, cool.
3.3,Add 25mL water to sand bath and heat to dissolve salt completely. Remove and cool to room temperature.
3.4,Transfer solution to 100mL volumetric bottle, dilute with water to scale, mix well.
3.5,The solution was used as the analytical sample for atomic absorption spectrophotometer. At wave length of 670.8nm, 589.0nm, 766.5nm, and the absorbance of lithium oxide, sodium oxide and potassium oxide was determined with air-acetylene poor flame and water zeroed, and the corresponding concentrations of potassium oxide, sodium oxide and potassium oxide were found on the working curve.

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