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Analytical Method: Nitroaromates in water

Reagents:
Cat.No. 100103  Amidosulfuric acid for analysis
Cat.No. 106549  Sodium nitrite for analysis
Cat.No. 107815  Tin(II)chloride for analysis
Cat.No. 100317  Hydrochloric acid 37 % for analysis
Cat.No. 108389  Toluene for gas chromatography
Cat.No. 100983  Ethanol for analysis
Cat.No. 106649  Sodium sulfate, anhydrous for analysis
Cat.No. 116754  Water for analysis
Cat.No. 106237  N-(1-Naphthyl) ethylendiamine dihydrochloride
 
Reagent 1:
Dissolve 5 g tin(II)chloride in 95 g hydrochloric acid 37 %.
 
Reagent 2:
Dissolve 40 g sodium nitrite in 60 ml of water for analysis.
 
Reagent 3:
Dissolve 15 g amidosulfuric acid in 85 ml of water for analysis.
 
Reagent 4:
N-(1-naphthyl) ethylendiamine dihydrochloride
 
Measurement range:
1.0 - 10.0 mg/l TNT (reference substance trinitrotoluene) at cell length 50 mm and 550 nm
 
Preparation of aqueous samples:
Extract 1 l sample 5x with 10 ml toluene. Dry the accumulated extracts with anhydrous sodium sulphate for analysis and gently evaporate to dryness in a rotatory evaporator under a weak vacuum. Dissolve the residue in 5.0 ml ethanol for analysis.
 
Preparation of soil sample:
Remove the larger soil particles and dry the rest in a desiccator with a drying agent. Extract 100 g of the finely ground dried soil sample with ethanol in a 50-ml Soxhlet extractor. Evaporate to 5 ml in a rotatory evaporator under weak vacuum.
 
Analysis:
Take 5.0 ml of ethanolic sample, add 2.0 ml of reagent 1 and allow to stand for 10 minutes at room temperature. Place in an ice bath for 5 minutes, add 0.10 ml of reagent 2 and mix. Add 2.0 ml of reagent 3 and shake for
30 seconds. Add 10 mg of reagent 4 and dissolve. Heat the mixture for 2 minutes at 50 °C. Carry out the analysis after a further 13 minutes using a reagent blank.
 
Calculation:
Water:
TNT content in mg/l = analysis value in mg/l TNT
Soil:
TNT content in mg/l = analysis value in mg/l TNT x 10
 
Parameter list for programming the photometer Spectroquant® NOVA 60 und NOVA 400

 

Method number ----
Method-designation TNT
Wavelength 550 nm
Citation TNT
Units mg/l
Resolution 0.1
Zero point (E0) 0.000
Slope (E/C) 0.356
Meas. range begin 1.0
Meas. range end 10.0
Reference cell 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
Result in mg/l
[A sample * 1 / 0.356]
1.000 2.8

 
Parameter list for programming the photometer SQ 118

 

01 Method TNT
02 Cat.No. -------
03 Measuring range 1.0 - 10.0
04 Units mg/l
05 Reaction time 10 15 min
06 Cell 50 mm
07 Wavelength 550 nm
08 Calibration Factor
09 Evaluation Linear
10 Factor 2.81

 
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 * 2.81]
1.000 2.81

 

Materials

     
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