六价铬方法验证

1
1.2
mg/L
0.9
0.8
y = 0.7857x - 0.0019
0.7
R2 = 0.9998
0.6 y = 0.7959x + 0.0016
0.5
R2 = 0.9997
0.4
0.3
y = 0.7408x + 0.0039 R2 = 0.9983
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
1.2
mg/L
0.9
0.8
y = 0.7611x - 0.0078
R2 = 0.9995
0.7
0.6
y = 0.7636x + 0.0006
0.5
R2 = 0.9999
0.4
0.3
y = 0.7899x - 0.0014 R2 = 1
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
1.2
mg/L
0.9
0.8
y = 0.7547x + 0.003
Suppose a sample is found to have an absorbance of 0.4 @ 540 nm, the concentration (mg/L) and Error % based on heated digestion would be :
ABS 0.4 0.4 0.4
set 5
Conc. In digest 0.53 mg/L 0.53 mg/L 0.52 mg/L set 6
Conc. In digest 0.52 mg/L 0.52 mg/L 0.50 mg/L
Error % -
0.94% 0.50%
Error % -
-1.47% 0.50%
Error % -
Error % -
1.94% 8.74%
Error % -
11.20% -1.90%
Error %
4.22% -6.90%
ABS 0.4 0.4 0.4
ABS 0.4 0.4 0.4
ABS 0.4 0.4 0.4
set 4 Conc. In digest
0.52 mg/L 0.51 mg/L 0.52 mg/L
ABS 0.4 0.4 0.4
ABS 0.4 0.4 0.4
set 1 Conc. In digest
0.49 mg/L 0.50 mg/L 0.53 mg/L
set 2
Conc. In digest 0.51 mg/L 0.56 mg/L 0.50 mg/L set 3
Conc. In digest 0.52 mg/L 0.54 mg/L 0.48 mg/L
1
1.2
mg/L
0.9
y = 0.767x + 0.0009
0.8
R2 = 0.9999
0.7
0.6 y = 0.7787x - 0.0043
0.5
R2 = 0.9996
0.4
0.3
y = 0.7526x + 0.006 R2 = 0.9992
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
1.2
mg/L
ABS
set 3
ABS
set 4
0.9
0.8
y = 0.7574x + 0.0026
0.7
R2 = 0.9978
0.6 y = 0.8163x + 0.0008
0.5
R2 = 0.9997
0.4
y = 0.7287x + 0.0012
0.3
R2 = 0.9999
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
Study of Hexavalent Chromium Test Method Calibration
Standard+Digestion Solution+Heated digestion+Nitric acid+Diphenylcarbazide+Sulfuric acid Standard+Digestion Solution+Unheated digestion+Nitric acid+Diphenylcarbazide+Sulfuric acid Standard + Reagent Water + Diphenylcarbazide + Sulfuric acid
-0.46% 4.70%
5
Summary
• There was no significant variations observed between the calibration curves prepared with heated digestion, unheated digestion, and no digestion .
2
Study of Hexavalent Chromium Test Method Calibration
Standard+Digestion Solution+Heated digestion+Nitric acid+Diphenylcarbazide+Sulfuric acid Standard+Digestion Solution+Unheated digestion+Nitric acid+Diphenylcarbazide+Sulfuric acid Standard + Reagent Water + Diphenylcarbazide + Sulfuric acid
0.7
R2 = 0.9996
0.6 y = 0.7946x + 0.0018
0.5
R2 = 1
0.4
0.3
y = 0.7606x + 0.0013 R2 = 0.9998
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
1.2
mg/L
4
Study of Hexavalent Chromium Test Method Calibration
• The average of the error % is less than than 5% in 6 sets of the comparison experiments .
6
3
ABS
set 5
ABS
set 6
Study of Hexavalent Chromium Test Method Calibration
Standard+Digestion Solution+Heated digestion+Nitric acid+Diphenylcarbazide+Sulfuric acid Standard+Digestion Solution+Unheated digestion+Nitric acid+Diphenylcarbazide+Sulfuric acid Standard+Reagent Water+Diphenylcarbazide+Sulfuric acid
Study of Hexavalent Chromium Test Method Calibration
Principle: To compensate for the possible slight losses of chromium during alkaline digestion or other operations of the hexavalent chromium alkaline digestion, the chromium calibration standards are treated by the same digestion procedure as the sample. Experiment description: Using the alkaline digestion for hexavalent chromium based on the US EPA 3060A procedure, establish 6 calibration curve sets each with heated digestion, unheated digestion, and no digestion to see the variations between them. Purpose of the experiment: Evaluate the calibration curve impact if the standards undergo heated digestion, unheated digestion, and no digestion.
ABS
set 1
ABS
set 2
0.9Βιβλιοθήκη y = 0.8044x + 0.0033
0.8
R2 = 0.9997
0.7
0.6
0.5 y = 0.7405x + 0.003 R2 = 0.9994
0.4
0.3
y = 0.789x + 0.0034 R2 = 0.9997
0.2
0.1
0
0
0.2
0.4
0.6
0.8