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Determination of Antimony in Water by Flame Atomic Absorption Spectrophotometry

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

2,Standard Curve

Standard curve determination data
Sb standard solution concentration (mg/L) 0 2 4 8 16 32 40
Absorbance 0.0004 0.0225 0.0507 0.1052 0.2110 0.4010 0.4919
Standard Curve Regression Equation A=0.012338*C+0.003976
Correlation coefficient 0.999500
flame atomic absorption standard curve

3,Limit of Detection

Detection limit of antimony by flame atomic absorption spectrophotometry with standard curve
Item Determination result
Parallel number 1 2 3 4 5 6 7
Determination results (mg/L) 0.7597 0.7408 0.7260 0.7233 0.6930 0.6873 0.6855
Average (mg/L) 0.7165
Standard deviation S detection limit (mg/L) 0.02875
Detection limit (mg/L) 0.09036
Lower limit of determination (mg/L) 0.3614

4,Precision

Determination Precision of Antimony  by Flame Atomic Absorption Spectrophotometry
No. Standard Solution
  4mg/L 32mg/L 40mg/L
1 4.1197 32.5655 39.3359
2 4.0978 32.6308 39.2721
3 4.0669 32.6282 39.2671
4 4.0604 32.4913 39.3277
5 4.0857 32.4623 39.4758
6 4.0981 32.5884 39.3133
Average 4.0881 32.5611 39.3320
SD 0.02198 0.07037 0.07598
RSD(%) 0.54 0.22 0.19

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%.

6,Precautions

  • 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.
flame atomic absorption spectrophotometry

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