Analytical Method: Thiocyanate and Cyanide in wastewater

Reagents:
Cat.No. 103883  Iron nitrate nonahydrate for analysis
Cat.No. 100456  Nitric acid 65 % for analysis
Cat.No. 116754  Water for analysis
Membrane filter 0.45 μm pore diameter
 
Reagent 1:
Dissolve 20 g iron nitrate nonahydrate in 24.5 ml of nitric acid 65 % and make up to mark with water for analysis in a 100-ml volumetric flask.
 
Hints:
Thiocyanate causes interference when cyanide is being determined in water and waste water. This is because it reacts as cyanide and its value is included in the total sum determined. This procedure is not disrupted by 100-fold amounts of cyanide based on thiocyanate. Separate determination of cyanide and thiocyanate allows both components to be determined by differential analysis.
 
Measurement range:
0.05 - 10.00 mg/l SCN at cell length 50 mm and 445/446 nm
0.3 - 50.0 mg/l SCN at cell length 10 mm and 445/446 nm
 
Sample preparation:
The sample solution must be clear; if not, filter through a folded filter membrane filter with 0.45 μm pore diameter.
 
Analysis:
Mix 5.0 ml of sample solution, 0.30 ml of reagent 1. Allow to stand for 10 minutes and measure at 445 nm (at 446 nm in the photometer SQ 118 against water).

 

Parameter list for programming the photometer Spectroquant® NOVA 60 und NOVA 400

 

Method number ---- ----
Method-designation SCN SCN
Wavelength 445 nm 445 nm
Citation SCN SCN
Units mg/l mg/l
Resolution 0.1 0.1
Zero point (E0) 0.000 0.000
Slope (E/C) 0.0617 0.309
Meas. range begin 0.3 0.05
Meas. range end 50.0 10.0
Reference cell 10 mm 50 mm


Calculation when measuring the absorbance value using the above NOVA photometers without programming the method in the memory of the instrument:

 

Measured absorbance
of samples in A
Cell length  10 mm
Result in mg/l
[A sample * 1 / 0.0617]
1.000 16.2

 

Measured absorbance
of samples in A
Cell length  50 mm
Result in mg/l
[A sample * 1 / 0.309]
1.000 3.24

 



Parameter list for programming the photometer SQ 118

 

01 Method SCN
02 Cat.No. -------
03 Measuring range 0.5 - 10.0
04 Units mg/l
05 Reaction time 5 10 min
06 Cell 16 mm round
07 Wavelength 550 nm
08 Calibration Factor
09 Evaluation Linear
10 Factor 3.00


Calculation when measuring the absorbance value using the photometer SQ118 without programming the method in the memory of the instrument:

 

Measured absorbance
of samples in A
Result in mg/l
[A sample * 3.00]
1.000 3.00

 

Materials

     
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