How to use flame atomic absorption spectrophotometry to determinate Antimony?
A typical toxic and harmful heavy metal element, the concentration of antimony in natural water is extremely low, with an average of about 0.2μg/L.Sb is not an essential element of plants, but can be absorbed by plants and crops. Due to the influence of natural processes and human activities, antimony and its compounds are widely distributed in the air, soil, water and other superficial environments, and the environmental pollution of antimony is becoming more and more serious.
The environmental standard is for antimony in water quality, and there are two related standards for the determination of atomic absorption spectrophotometry：flame method and graphite furnace method
This paper focuses on the determination of water quality antimony by flame atomic absorption spectrophotometry
1，Analytical Instrument Conditions
|characteristic wavelength：217.6 nm||Lamp current：8 mA|
|Spectral bandwidth：0.2 nm||Method of background correction：No.|
|Acetylene flow: 2 L/min||Burner height: 10 mm|
|Determination method: standard curve method|
|Standard curve determination data|
|Sb standard solution concentration (mg/L)||0||2||4||8||16||32||40|
|Standard Curve Regression Equation||A=0.012338*C+0.003976|
3,Limit of Detection
|Detection limit of antimony by flame atomic absorption spectrophotometry with standard curve|
|Determination results (mg/L)||0.7597||0.7408||0.7260||0.7233||0.6930||0.6873||0.6855|
|Standard deviation S detection limit (mg/L)||0.02875|
|Detection limit (mg/L)||0.09036|
|Lower limit of determination (mg/L)||0.3614|
|Determination Precision of Antimony by Flame Atomic Absorption Spectrophotometry|
5,Results and Analysis
- The linear correlation coefficient of the standard curve of this test is 0.9995 (The standard requires correlation coefficient ≥ 0.999).
- The detection limit of this method is 0.09mg/L (the standard given detection limit is 0.2mg/L).
- The lower limit of determination is 0.36mg/L (the lower limit of determination given by the standard is 0.8mg/L).
- The recovery rate of sample addition is 97.46%-107.89% (standard requirement is 85%-110%).
- The precision range of the determination under this instrument condition is 0.19%-0.54%.
- There are two sub-sensitive lines 216.8 nm and 217.9 nm near the most sensitive line of antimony at 217.6 nm. When the spectral passband is wide, all three spectral lines enter the measurement system, which not only reduces the sensitivity, but also bends the standard curve downward. ; At the same time, there may be interference from the most sensitive line of lead at 217.0nm, and the spectral passband should be selected as small as possible.
- The concentration of hydrochloric acid, nitric acid and 2% sulfuric acid below 20% does not interfere with the determination of antimony.
- When the mass concentrations of copper, iron, cadmium, nickel and lead are lower than 3500mg/L, 4000mg/L, 1000mg/L, 4000mg/L and 6000mg/L respectively, it will not interfere with the determination of antimony.
- After the acetylene flame is ignited, the flame will absorb the characteristic wavelengths. After the search for the spectral line is successful, the energy of the ignition flame is reduced from 100 to about 60 (the high voltage is 570V when the energy is 100). When the experiment is performed, the energy can be balanced and the energy can be changed back to 100, start the determination.