determination of halogens with separation by steam distillation

DETERMINATION OF HALOGENS WITH SEPARATION BY STEAM DISTILLATION

Scope

This method covers the separation of the halogens by means of a steam distillation.

Summary of method

A sample aliquot is mixed with a solution containing ferrous ammonium sulfate, sulfamic acid, phosphoric acid and sulfuric acid. The halogens are then steam distilled at a Temperature of 140 ^oC.

Equipment

• Steam Distillation Equipments

• Distilling flask, 200 mL with thermometer well

• Condenser

• Heating Mantle

• Steam Boiler, 500 mL flask

• Potentiometer with ion selective electrode

Reagent

• Absorber Solution (4 M Potassium Hydroxide)-Dissolve 22.4 g KOH pellets in water and dilute to 100 mL.

• Acid Mixture-Mix 0.2 M Ferrous ammonium sulfate 0.5 M sulfamic acid, phosphoric acid 85%, and sulfuric acid (sp gr 1.84) in the ratio of 1+2+5.

• Ferrous Ammonium Sulfate Solution (0.2 M)-Sulfamic Acid (0.5 M) Solution –Dissolve 78.4 g Fe(NH₄)₂(SO₄)₂.6H₂O and 48.6 g NH₂SO₃H in H₂SO₄ (5+95) and dilute to 1 L with H₂SO₄ (5+95).

• Phenolphtalein Solution (10 g/L)-Dissolve 1 g of phenolphthalein in 50 mL of ethanol and add 50 mL of water.

Procedure

• Place a weighed portion of about 15 mL containing approximately 5 g of uranium in the distillation flask.

• Add 25 mL of the acid mixture to the distillation flask.

• Transfer 5 mL of the KOH solution to a 100 mL graduated cylinder and position it under the condenser tip.

• Heat the distillation flask until the thermometer in the well Reaches 140 ^oC.

• Pass steam through from the boiler, and maintain at temperature of 140 ^oC until a volume of 90 mL is collected.

• Add 2 drops of phenolphthalein solution and adjust a pH of the distillate with KOH or HNO₃ to the phenolphthalein end point. Make the volume to 100 mL.

• Repeat the distillation, omitting the uranium sample,to use as the matrix for the fluoride standard curve.

• Reserve the distillate for the fluoride and combined halide determinations.

DETERMINATION OF FLUORIDE BY SPECIFIC ION ELECTRODE

Scope

The method covers the determination of as low as 2 µg F/g U in distillate containing all the halogens.

Summary of method

An aliquote of the distillate reprecenting 1 g of uranium is measured by specific ion electrode and compared to a standard curve prepared by spiking equivalent-size aliquots taken from a blank distillation.

Equipments

• pH meter, expanded scale or potentiometer

• Ion-selective Electrode, fluoride

• Reference Electrode, single junction

Reagents

• Buffer Solution (0.001N)-Dissolve 0.1 g of potassium acetate (KC₂H₃O₂) in water. Add 0.050 mL of acetic acid (sp gr 1.05) and dilute to one L.

• Fluoride Standard Solution A (1 mL=1 mg F)-Dissolve 0.220 g of dried sodium fluoride (NaF) in 25 mL of water and dilute to 100 mL.

• Fluoride Standard Solution B (1 mL = 5 µg F)-Dilute 5 mL of the fluoride standard solution A to 1 L with water.

Procedure

• Pipet a 20 mL aliquot of the sample distillate (representing about 1 g of uranium) into a 25 mL flask and make to volume with the buffer solution.

• Prepare a standard curve by pipetting 20 mL aliquots from the blank distillate into 25 mL flasks and adding F standard solution to make 0, 5, 10, 20 µg F / 25 mL.

• Measure all of the solutions with the fluoride ion selective electrode.

Calculation

Calculate the F – content as follows

F µg/g = A/B

Where

A = F- found in the sample distillate aliquot, µg

B = uranium represented by the sample distillate aliquot, g

Precision

The limit of error at the 95% confidence level for a single determination is ± 25%

Literature

ASTM-C799, Standard Methods for “Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical analysis of Nuclear-Grade Uranyl Nitrate solution”

Determination of thorium by the arsenazo (III) method (spectrophotometric)

DETERMINATION OF THORIUM BY THE ARSENAZO(III) METHOD (PHOTO-METRIC)

Scope

This method covers the determination of up to 10 µg of thorium ( 2 to 20 µg Th/g U) in uranyl nitrate solution

Summary of method

Thorium is separated from uranium by anion exchange. The thorium-bearing effluent is treated directly with oxalic acid to complex any zirconium and with Arzenazo III to develop the blue thorium-Arsenazo III complex. Measurement is made at 665 nm. The method is nearly specific for thorium.

Reagents

• Anion Exchange Resin Cl – From (50 to 100 Mesh)-Prepare awater slurry of resin and pour it into the column to a height of 4 to 5 cm then rinse the column with 2 or 3 bed-volumes of 8 M HCl.

• Arsenazo (III) Solution o-(8-dihydroxy-3,6 disulfonaphthylene-2,7-bisazo)-bisbenzene-arsonic Acid , disodium Salt), (2 g/L)-Dissolve 0.2 g of Arsenazo (III) in water and add 1mL of sodium carbonat solution (Na₂CO₃, 5 g/L)in the solution. Adjust the volume to 100 mL with distilled water.

• Oxalic Acid (50 g/L)-Dissolve 5 g of oxalic acid (H₂C₂O₄) in distilled water and dilute to 100 mL

• Thorium Standard Solution A ( 1 mL = 100 µg Th)-Dissolve 0.2392 g of thorium nitrate (Th(NO₃)₄.4H₂Oin a 250 mL beaker and fume to dryness three times with 5 mL portions of HCl (sp.gr 1.18) Dissolve the residu with 0.1 M HCl and dilute to 1 L with 0.1 M HCl.

Procedure

• Weigh an aliquot of the solution containing no more than 0.5 g of uranium.

• Evaporate the solution to dryness four times with 10 mL portions of HCl (sp gr 1.18)

• Dissolve the residu in 2 to 3 mL of HCl using heat if necessary

• Dilute the solution to about 10 mL with 8 M HCl and transfer to the treated ion-exchange column.

• Rince the beaker with a minimum quantity of 8 M HCl (about 5 mL), and add the rinse solution to the column.

• Drain the column at a rate of 3 to 4 mL/min into a suitable graduated cylinder

• Discard the first 7 mL of effluent, and collect the remaining effluent in a 50 mL volumetric flask.

• Wash the resin with two 5 mL and two 10 mL portion of 8 M HCl, collect all the effluents in the 50 mL flask

• Add 1 mL of H₂C₂O₄ solution to the flask to complex any zirconium.

• Add 2 mL of a arsenazo (III) solution to the flask, and dilute the solution to volume with distilled water and mix thoroughly

• Measure at 665 nm in 10 cm cells using reagent blank as a reference.

• Prepare the standard curve by carrying 0 to 10 µg through step 2 to step 11.

• Elute the uranium from the column with 10 bed-volumes of 0.1 M HCl at the rate of 3.0 to 3.5 mL/min. Then regenerate as described in step 2 at reagent.

Calculations

Calculate the thorium content as follows

Thorium, µg/g = A/B

Where

A = Thorium found in the sample solution, µg
B = uranium contained in the sample solution, g.

Precision

The limit of error at the 95% confidence level for a single determination is ± 5%.

Literature

ASTM-C799, Standard Methods for “Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical analysis of Nuclear-Grade Uranyl Nitrate solution”

Determination of thorium by the arsenazo (III) method (spectrophotometric)

DETERMINATION OF THORIUM BY THE ARSENAZO(III) METHOD (PHOTO-METRIC)

Scope

This method covers the determination of up to 10 µg of thorium ( 2 to 20 µg Th/g U) in uranyl nitrate solution

Summary of method

Thorium is separated from uranium by anion exchange. The thorium-bearing effluent is treated directly with oxalic acid to complex any zirconium and with Arzenazo III to develop the blue thorium-Arsenazo III complex. Measurement is made at 665 nm. The method is nearly specific for thorium.

Reagents

• Anion Exchange Resin Cl – From (50 to 100 Mesh)-Prepare awater slurry of resin and pour it into the column to a height of 4 to 5 cm then rinse the column with 2 or 3 bed-volumes of 8 M HCl.

• Arsenazo (III) Solution o-(8-dihydroxy-3,6 disulfonaphthylene-2,7-bisazo)-bisbenzene-arsonic Acid , disodium Salt), (2 g/L)-Dissolve 0.2 g of Arsenazo (III) in water and add 1mL of sodium carbonat solution (Na₂CO₃, 5 g/L)in the solution. Adjust the volume to 100 mL with distilled water.

• Oxalic Acid (50 g/L)-Dissolve 5 g of oxalic acid (H₂C₂O₄) in distilled water and dilute to 100 mL

• Thorium Standard Solution A ( 1 mL = 100 µg Th)-Dissolve 0.2392 g of thorium nitrate (Th(NO₃)₄.4H₂Oin a 250 mL beaker and fume to dryness three times with 5 mL portions of HCl (sp.gr 1.18) Dissolve the residu with 0.1 M HCl and dilute to 1 L with 0.1 M HCl.

Procedure

• Weigh an aliquot of the solution containing no more than 0.5 g of uranium.

• Evaporate the solution to dryness four times with 10 mL portions of HCl (sp gr 1.18)

• Dissolve the residu in 2 to 3 mL of HCl using heat if necessary

• Dilute the solution to about 10 mL with 8 M HCl and transfer to the treated ion-exchange column.

• Rince the beaker with a minimum quantity of 8 M HCl (about 5 mL), and add the rinse solution to the column.

• Drain the column at a rate of 3 to 4 mL/min into a suitable graduated cylinder

• Discard the first 7 mL of effluent, and collect the remaining effluent in a 50 mL volumetric flask.

• Wash the resin with two 5 mL and two 10 mL portion of 8 M HCl, collect all the effluents in the 50 mL flask

• Add 1 mL of H₂C₂O₄ solution to the flask to complex any zirconium.

• Add 2 mL of a arsenazo (III) solution to the flask, and dilute the solution to volume with distilled water and mix thoroughly

• Measure at 665 nm in 10 cm cells using reagent blank as a reference.

• Prepare the standard curve by carrying 0 to 10 µg through step 2 to step 11.

• Elute the uranium from the column with 10 bed-volumes of 0.1 M HCl at the rate of 3.0 to 3.5 mL/min. Then regenerate as described in step 2 at reagent.

Calculations

Calculate the thorium content as follows

Thorium, µg/g = A/B

Where

A = Thorium found in the sample solution, µg
B = uranium contained in the sample solution, g.

Precision

The limit of error at the 95% confidence level for a single determination is ± 5%.

Literature

ASTM-C799, Standard Methods for “Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical analysis of Nuclear-Grade Uranyl Nitrate solution”

Determination of Molybdenum by the Thiocyanate method (spectrophotometric)

DETERMINATION OF MOLYBDENUM BY THE THIOCYANATE METHOD (PHOTOMETRIC)

Scope

This method covers the determination of up to 100 µg ( 5 to 500 µg Mo/g U ) molybdenum in nuclear grade uranyl nitrate solutions.

Summary method

After conversion of the solution to the sulfate by fuming with H2SO4, the molybdenum thiocyanate complexis formed and extracted with 1-hexanol. Spectrophotometric measurement is made on the axtract at 470 nm.

Equipment

Spectrophotometer.

Raegents

• Ammonium Thiocyanate Solution(200 g/L)-Dissolve 20 g of NH4SCN in water and dilute to 100 mL.

• I-Hexanol – Saturate technical grade !-Hexanol with NH4SCN and SnCl2 by shaking in a separatory funnel. Store in a brown bottle.

• Iron Solution (1 mg Fe/mL)-Dissolve 3.6 g of ferric sulfate Fe₂(SO₄)₃ in water and dilute to 1 L.

• Ethanol absolute

• Molybdenum Standard Solution (100 µg/mL) –Dissolve 0.184 g of ammonium molibdat (NH₄)₆Mo₇O₂₄.4H₂O in water, add 50 mL of sulfuric acid (1+9) and dilute to 1 L.

• Stannous Chloride Solution (350 g/L)-Heat 350 g of SnCl2.2H2O in 200 mL of HCl (1+1) on a steam bath until dissolution is complete. Filter and dilute to 1 L with freshly boiled water.

• Wash Solution-Mix 50 mL of H2SO4 (1+9), 2 mL of NH4SCN solution and 2 mL of SnCl2

Procedure

• Dilute 10 mL of sample solution to 100 mL in a volumetric flask.

• Pipet 5 mL of this solution into a 100 mL beaker and add 20 mL 0f H2SO4 (1+1) and 1 mL of iron solutions

• Evaporate to fumes of H2SO4, cool and dilute with 25 mL of water. Transfer to a 250 mL separatory funnel with water and dilute to about 100 Ml.

• Add 4 mL of NH₄SCN solution and mix.

• Add 10 mL of SnCl2 solution, mix again and allow to stand about 5 min

• Pipet 10 mL of 1-Hexanol into the funnel and shake for 1.5 min.

• Allow the layers to separate and discard the aqueous Layer.

• Add 40 mL of wash solution and shake for 30 s allow to separate and discard the aqueous layer.

• Transwer the organic layer to a 50 mL graduated flask And dilute to volume with methanol.

• Measure at 470 nm in 2 cm cell using 10 mL 1-Hexanol diluted to 50 mL with methanol as a reference.

• Prapare the standard curve by carrying 0 to 100 µg of molybdenum through step 2 to step 10 in the presence of 200 mg of uranium (4 mL of uranium solution).

Calculation

Calculate the molybdenum content as follows

Molybdenum, µg/g = A/B

Where

A = molybdenum found in the sample solution, µg
B = uranium contained in the sample solution, g

Precision

The limit of error at the 95% confidence level for a single determination is ± 5%

Literature

ASTM-C799, Standard Methods for “Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical analysis of Nuclear-Grade Uranyl Nitrate solution”

Determination of Chromium by the Diphenylcarbazide method (Spectrophotometric)

DETERMINATION OF CHROMIUM BY THE DIPHENYL CARBAZIDE METHOD
(PHOTOMETRIC)

Scope
This method covers the determination of 5 to 120 µg Cr/g U of chromium in nuclear grade uranyl nitrate solutions.

Summary of Method
Chromium is oxidized with ammonium persulfate in the presence of silver nitrate. The hexavalent chromium gives a soluble red-violet complex with diphenylcarbazide. Photometric measurement is made at 540 nm.

Equipments
· pH meter with glass and calomel electrodes
· Spectrophotometer

Reagents
· Ammonium persulfate solution (100 g/L)-Dissolve 10 g of (NH4)2S2O8 in water and dilute to 100 mL. Prepare fresh as needed.
· Chromium, Standard Solution A 1 mL = 200 µg/Cr (VI) – Dissolve 0.565 g of potassium dichromate (K2Cr2O7) in water. Transfer to a 1 L volumetric flask, dilute and mix.
· Chromium, Standard Solution B 1 mL = 10 µg/Cr (VI) – Transfer a 25 mL aliquot of chromium solution A to a 500 mL volumetric flask and dilute to volume.
· Diphenylcarbazide Solution (5g/L) – Dissolve 0,50 g of diphenylcarbazide in 100 mL of acetone. Prepare fresh as needed
· Silver Nitrate Solution (2.5 g/L) – Dissolve 2.5 g of AgNO3 in water and dilute to 1 L.
· Sodium Hydroxide Solution (80 g/L) – Dissolve 80 g of NaOH in water and dilute to 1 L.
· Sulfuric Acid Solution (2 N) – Add 56 mL of H2SO4 to water and dilute to 1 L.
· Uranium Solution (1 mL = 0.05 g U) – Dissolve 10.0 g of uranium metal or 11.8 g of U3O8 in HNO3. Add 25 mL H2SO4 and heat to copious fumes. Cool, transfer to a 200 mL volumetric flask and dilute to volume.

Procedure
· Transfer 3 to 4 g of sample solution to a 100 mL flask and dilute to volume with water.
· Take a 5 mL aliquot of this dilution for analysis and place in a 150 mL beaker.
· Evaporate on a steam bath to dryness.
· Add 4 mL of 2 N H2SO4 and warm to dissolve the residu.
· Adjust the volume to about 40 mL.
· Adjust the pH with NaOH solution from 0.9 to 1.1 using pH meter.
· Add 4 mL of AgNO3 solution and 4 mL of (NH4)2S2O8 solution and cover.
· Boil gently for 25 min to destroy the excess (NH4)2S2O8 Maintain a minimum volume of 40 mL during heating.
· Cool to room temperature and transfer to a 100 mL volumetric flask.
· Add 2 mL of diphenylcarbazide solution, adjust to volume with water and mix.
· Measure the solution immediately in a 1 cm cell at 540 nm using water as the reference.

Note – The colour of the chromium complex develops almost immediately and starts to fade within a short time. Photometric measurements must be made within5 min after adding the diphenylcarbazide

· Carry a background color blank containing the addition of diphenylcarbazide.
· Carry reagent blank through step 4 up to step 11 at procedure.
· Prepare the standard curve by carrying 0 to 120 µg of Cr through step 3 to step 11 (at procedure) in the presence of 150 mg of uranium ( 3 mL of uranium solution).

Calculation
Calculate the chromium content as follows :

Chromium, µg/g = ( A-B-C)/D

There
A = Chromium found in the sample solution aliquot, µg
B = Chromium equivalent found in the reagent blank, µg
C = Chromium equivalent found in the background color blank, µg
D = Uranium contained in the sample solution aliquot, g

Precision
The limit of error at the 95% confidence level for a single determination is ± 5 %

Literature
ASTM-C799, Standard Methods for “Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical analysis of Nuclear-Grade Uranyl Nitrate solution”

DETERMINATION OF FREE ACID BY OXALATE COMPLEXATION

Scope

This method covers the determination of the free acid content of uranyl nitrate solutions that may contain a ratio of up to 5 moles of acid to 1 mole of uranium.

Summary of method

To a diluted solution of uranyl nitrate, solid, pulverized potassium oxalate is added until apH of about 4.7 is reached. Thesolution is then titrated with standard NaOH solution by the delta pH method to obtain the inflection point.

Equipments

• pH meter, with glass and calomel electrodes, or potentiometer with electrode

• Buret class A, 50 mL.

Reagens

• Nitric Acid (2.0) – Dilute of HNO3 (sp gr 1.42) to 1 L with water. Standardize with sodium hydroxide solution.

• Potassium Oxalate (K₂C₂O₄.H₂O), crystals.

• Sodium Hydroxide Solution (0.3 N) – Dissolve 12.0 g of NaOH in 1 L of water. Standardize with acid potassium phthalate.

Procedure

• Transfer a 5-mL sample aliquot into a 250 mL beaker.

• Add 100 mL of distilled water or such volume that the uranium concentration will be between 7 and 50 g/L.

• Add a spike of sufficient 2.0 N standard HNO3 to make definitely acid if the sample is neutral or acid deficient.

• Add pulverized K2C2O4.H2O slowly and with constant sterring until a pH of 4.7 to 4.9 is reached.

• Immerse the titration beaker in an ice bath. Titration made at room temperature are possible but are less sharp.

• Titrate with 0.3 N NaOH using 0.20 mL increments and determine the inflection point by the delta pH an “analytical” method.

Calculation

Calculate the free acid normality, N, as follows

N = (A x Nb – C x Na) / 5

Where
A = NaOH solution used in the titration, mL
Nb = normality of the NaOH solution,
C = HNO₃ solution used in the spike, mL
Na = normality of HNO₃ solution.

Precision

The limit of error at the 95% confidence level for a single determination is ± 3%

Literature
ASTM-C799, Standard Methods for “Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical analysis of Nuclear-Grade Uranyl Nitrate solution”

MEASUREMENT OF SPECIFIC GRAVITY BY PICNOMETRY

Determination of the specific gravity of a solution of uranyl nitrate

Scope

This method covers the determination of the specific gravity of a solution of uranyl nitrate to ± 0.0004

Summary of method

A known volume of the solution adjusted at a controlled temperature is weighed and compared to the weight of water measured in the same container.

Equipments

• Volumetric Flask, 50-mL, class A

• Water Bath, temperature controlled to ± 0.1 oC at a temperature slightly above

• normal room temperature, and provided with clips for holding volumetric flasks.

Procedure

• Weigh the clean, dry volumetric flask and its stopper to the nearest 0.1 mg

• Fill the volumetric flask with the uranyl nitrate solution to a point close to the volume mark, using a thin stemmed funnel and a glass dropper.

• Place the stoppered volumetric flask in the water bath for 30 min.

• Use a finely drawn glass dropper to adjust the liquid volume to the mark

• Leave the flask in the water bath an additional 10 min to make sure that the bath temperature has been reached.

• Dry and weigh the flask to the nearest 0.1 mg.

• Repeat step 2 up to step 6 using boiled and cooled distilled water instead of the uranyl nitrate solution.

Calculation

Very accurate determinations of specific gravity require that vacuo corrections be made, but if a median correction figure in terms of grams of sample is applied to the solution weights in all cases the resulting error will not exceed 0.05%.

Sp gr = B-A + 0.0007(B-A)
C+A + 0.0010 (C-A)

B = sample plus flask in air, g
A = flask in air, g
C = water plus flask in air,g
0.007 g/g = correction factor applicable for densities of 1.3 to 1.5 and
0.0010 g/g = correction factor for water.

Precision

The limit of error at the 95% level for a singledetermination is ± 0.003%

Literature

ASTM-C799, Standard Methods for “Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical analysis of Nuclear-Grade Uranyl Nitrate solution”

Determination of cyanide ions-Photometric method with pyridine/barbituric acid

Applicability

Thiis method may be applied to absorption solution which contain 0.002 to 0.025 mg of cyanide. Absorption solutions with higher cyanide content may be dilute with sodium hydroxide solutions, c(NaOH) = 0.4 mo;/L. This method is not applicable if oxides or sulfur dioxide reach the absorption vessel during separation of the cyanides. Other interferences include substances that influence the action of the chloramine-T so;ution.

Principle

Reaction of the cyanide ions with the active chlorine of chloramine-T, leading to the formation of cyanogen chloride which reacts with pyridine to form a glutacondialdehyde, which in turn condenses with two molesof barbituric acid to form a red-violet dye.

Reagents

• Sodium hydroxide, solution, c(NaOH) = 0.4 mol/L

• Potassium cyanide, c(KCN) = 10 mg/L of CN - , dissolve 25 mg of potassium cyanide in the sodium hydroxide solution and dilute with the same sodium hydroxide solution to 1000 mL in volumetric flask.

• Chloramine-T (C7H7ClNNaO2S3H2O), solution, dissolve 0.5 g of chloramine-T trihydrate in water in a 50 mL volumetric flask and dilute to the mark.

• Pyridine/barbituric acid, solution, place 3 g of barbituric acid in a 50 mL volumetric flask, wash down the walls of the flask with just enough water to moisten the barbituric acid add 15 mL 0f pyridine and swirl to mix. Add 3 mL of hydrochloric acid solution 1.12 g/mL and dilute to the mark with water.
  

Equipment

• Photometer with cells of optical path length 10 mm.

• Usual laboratory equipment.
  

Procedure

• Transfer the contents of the absorption vessel to a 25 mL volumetric flask. Rinse the absorption vessel three times with approximately 3 mL portions of water, transfer the rinsings to the flask, dilute to the mark with water and mix.

• Transfer by means of a pipette, 10 mL of this solution into second 25 mL volumetric flaskand add whilst mixing , 2 mL of the buffer solution of pH 5.4, 4 ml of the hydrochloric solution 1.12 g/mL and 1 mL of the chloramine-T solution 0.5 g/50 mL Stopper the flask and leave for 5 mnt.

• Add 3 mL of the pyridine/barbituric acid solution, dilute with water to the mark and mix.

• Measure the absorbance at 578 nm in a cell of optical path length 10 mm against a reference liquid. Carry out the measurement 20 mnt after addition of the pyridine/barbituric acid solution.

• Measure the absorbance of the blank test solution similarly.
  

Preparation of standard solutions

Transfer, by means a pipette 2, 5, 20 and 25 mL respectively of the standard potassium cyanide solution into series of four 250 mL volumetric flask. Dilute to the mark with sodium hydroxide solution 0.4 mol/L and mix.

Photometric measurements

Measurement the absorbance of the standard and the blank tes solution with photometer.

Plotting the graph

Plot a graph of absorbance against the cyanide contents, in mg, of the solutions. The relationship between absorbance and concentration is linier. Check the graph from time to time especially if new packages of chemicals are used.

Check the absolute values of the standard solutions by titration with silver nitrate solution.

Expression of result

Total cyanide = (ma-mb) x 1000 / f1 x f2 x Vs = mg/L

ma = is the cyanide content, in mg, of the test solution read from the calibration graph.
mb = is the cyanide content, in mg, of the blank test solution
Vs = Is the volume, in mL, , of the sample
f1 = 0.4, as only 40% of the contents of the absorption vessel are used for the determination
f2 = 0.97as the volume of the sample is increased by addition of preservatives immediately after sampling.

Literature

ISO 6703/1-1984

Determination of cyanide ions-Titrimetric method using an Indicator

Applicability :
This method may be applied to absorption solutions containing more than 0.05 mg of cyanide. The method is not applicable if the absorption solution is coloured or highly turbid.

Principle :
Titration of the contents of the absorption vessel with silver nitrat solution, the silver ions, when in excess, forming a red silver complex with 5-(4-dimethylaminobenzylidine)rhodanine.

Reagents:

• Silver nitrate solution, c(AgNO3) = 0.01 mol/L
• Silver nitrate solution, c(AgNO3) = 0.001 mol/L
• Indicator solution, dissolve 0.02 g of 5- (4-dimethylamino benzylidine) rhodanine in acetone and dilute with acetone to 100 mL.
  

Equipments :

• Usual laboratoty equipment
• Magnetic stirrer, with bar
• Burette, of capacity 10 mL
• Titration vessels, made of glass, of capacity 50 mL.

Procedure:

Transfer the contents of the absorption vessel into a 50 mL beaker. Rinse the vessel three times with approximately 5 mL portions of water and add the rinsings to the beaker, add 0.1 mL of the indicator solution, immerse the tip of the burette containing the silver nitrate solution 0.001 mol/L in the solution, switch on the magnetic stirrer and titrate until the colour changes from yellow to red. Proceed similarly using the blank solution, the volume of the silver nitrate solution used in this blank test is usually 0.08 mL

Expression of result :

Total cyanide = (V1-Vo) x f1 x 1000 / f2 x Vs = mg/L

Vo = Is the Volume of silver nitrate solution required for the blank test., mL
V1 = Is the Volume of silver nitrate solution required for the titration, mL
Vs = Is the volume of the sample, mL
f1 = 0.052 the mass equivalent to 1 mL of 0.001 mol/l siver nitrate solution
f2 = 0.97as the volume of the sample is increased by addition after sampling.

Literature :

ISO 6703/1-1984 (E)

Blank Determination of Methanol with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0338.100 double Pt electrode; input Pol

Reagents
HYDRANAL® Composite 5; D0

Sample
20 -30 mL methanol, conditioned to complete dryness
1.000 mL methanol (extraction medium)

Remarks
· Calculations:

Blank=EP1

Blank = blank of methanol (extraction medium)

Blank= 0.0145 mL

EP1 = 0.0145 mL

Water Determination in Paper with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0338.100 double Pt electrode; input Pol

Reagents
HYDRANAL® Composite 5; D0

Sample
20 -30 mL methanol, conditioned to complete dryness
1.000 mL sample solution
extract app. 1.0g of paper (cut in small pieces) in
50 mL methanol (extraction medium)

Remarks
· Calculations:

Water=(EP1-C38)*C39*C01/C00/C02;2;%

smpl size 0.02003 g
EP1 0.2260 ml
Water 5.29 %
Titer 5.0058 mg/ml
Blank 0.0145 ml

Water = content of water in paper in %
C00 = sample size / aliquot (1.0015 g / 50 mL = 0.02003 g/mL)
C01 = factor for % (0.1)
C02 = divisor (1)
C38 = blank value in mL of “Blank_KF“ method (0.0145 mL)
C39 = titer of HYDRANAL® Composite 5

Answer

Water = (0.2260-0.0145) x 5.0058 x 0.1 / 0.02003 / 1 = 5.29%

KF Titer Determination with Sodium Tartrate by Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0338.100 double Pt electrode; input Pol

Reagents
HYDRANAL® Titrant 5; D0

Sample
20 -30 mL HYDRANAL® Solvent, conditioned to complete dryness
app. 200 mg di-Sodium tartrate dihydrate
Water 15.66 ±0.05%

Remarks
· Calculations:

Titer=C00/EP1*C01;4;mg/ml

Titer = titer of HYDRANAL® Titrant 5
C01 = water content * 10 (156,6)

Answer

Titer= 0.2294 / 7.508 x 156.6 = 4.7848 mg/mL

EP1 = 7.508 mL
C00 = 0.2294 g

· Common variables
C39 = MN1
· Mean from 5 determinations.
· Reweigh the sodium tartrate in a weighing boat.
· Adjust the calculation value C01 according to the unit of your sample
weight:
C00 in g C01=156.6
C00 in mg C01=0.1566
· For automatic curve output add in , >report “curve“.

Literature
· Water determination by Karl Fisher titration, G. Wieland, GIT Verlag,
Darmstadt (Germany)
· HYDRANAL®, practical course, Water reagents according to Eugen
Scholz, Riedel de Haën, Seelze (Germany)
· Metrohm Application Bulletin No. 77: KF water determination

Method documentation
'pa
751 GPD Titrino 15215 751.0010
KFT Ipol TarTiter
parameters
>control parameters
EP at U 250 mV
dynamics 100 mV
max.rate max. ml/min
min.volume incr. min. ml
stop crit: drift
stop drift 20 ml/min
>titration parameters
titr.direction: -
pause 1 0 s
start V: OFF
pause 2 0 s
extr.time 0 s
dos.element: internal D0
I(pol) 50 mA
electrode test: OFF
temperature 25.0 °C
time interval 2 s
>stop conditions
stop V: abs.
stop V 99.99 ml
filling rate max. ml/min
>statistics
status: ON
mean n= 5
res.tab: original
>preselections
conditioning: ON
display drift: ON
drift corr: OFF
req.ident: OFF
req.smpl size: value
activate pulse: OFF
------------
'fm
751 GPD Titrino 15215 751.0010
KFT Ipol TarTiter
>calculations
Titer=C00/EP1*C01;4;mg/ml
C00= 0.2294
C01= 156.6
------------
'fr
751 GPD Titrino 15215 751.0010
KFT Ipol TarTiter
smpl size 0.2294 g
EP1 7.508 ml
Titer 4.7848 mg/ml
mean( 5) +/-s s/%
Titer 4.7893 0.00506 mg/ml 0.11
============
'cu
751 GPD Titrino 15215 751.0010
KFT IpolTarTiter
20.0 s/div dV=2.0 ml/div
============
'st
751 GPD Titrino 15215 751.0010
statistics
## Titer
1 4.7936
2 4.7939
3 4.7830
4 4.7910
5 4.7848
mean( 5) +/-s s/%
Titer 4.7893 0.00506 mg/ml 0.11