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volumetric determination of Gold

Method · December 2017

DOI: 10.13140/RG.2.2.30943.36008

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METTLER TOLEDO M297

Factor Determination of Cerium Sulphate vs. Hydroquinone

Titration Excellence Line: The factor of the cerium sulfate solution will be used for the gold determination of
gold alloys and pure gold. See also applications M298 and M299.

Sample Hydroquinone, C6H6O2 Preparation and Procedures

c (1/2 C6H6O2)= 0.05mol/L: 1.5 mL

- Place an empty glass titration beaker on the manual titration stand

- 40 mL HCl 0.1 mol/l will be pumped in automatically
Substance Hydroquinone, C6H6O2 - 1.5 mL hydroquinone will be dispensed
M(C 6H6O2) = 110.11 g/mol, z = 2 - The sample will be titrated with cerium sulfate 0.01 mol/L using a
DM140-SC electrode
Chemicals Hydrochloric acid 0.1 mol/L, Fluka

- Weigh 2.753 g hydroquinone in a glass beaker, transfer it

Titrant Cerium sulfate, c(Ce(SO4) 2) = 0.01 mol/L with deionized water into a 1 L measuring flask
- Add approx. 900 mL deionized water
- Add 10 mL H2SO4 96%
- Fill up to the mark with deionized water

Standard ----
- Pipette 50.0 mL of cerium sulfate 0.1 mol/L (Merck 1.09092.1000)
in a 500 mL volumetric flask
Instruments T50/70/90 - Add approx. 400 mL deionized water
XS205 Balance - Add 10 mL H2SO4 96% and gentle mix it
- Fill up to the mark with deionized water

Accessories Glass beaker, ME-101446

Olivetti JobJet 210 Printer
LabX 2.52
SP250 Pump, ME-51108016
Additional Dosing Unit, ME-51109030
Remarks
Indication DM140-SC
Theoretical consumption

Chemistry C6H6O2 + 2Ce 4+ = C 6H4O2 + 2Ce3+ 2H + - 1 mL hydroquinone, c (1/2 0.05 mol/l) corresponds to a consumption
of 5 mL cerium sulfate, c (0.01 mol/L)

Literature

- Application Brochure Gold and Silver DL67/DL70OES/DL77

Calculation R1 = VENDDi*0.05/(VEQ*c) ME-724613
C1 = 1

H[Cerium sulfate] = Mean [R1]

Results

Waste
Waste Hydroquinone: Evaporate solution, special waste
Cerium: Precipitate with NaOH and filtrate,
disposal
disposal special waste

Author Claudia Schreiner

1
Results

Start time: 22.03.2007

Sample Data Note / ID Sample size

No. 1/6 Hydroquinone 1.5 mL
No. 2/6 Hydroquinone 1.5 mL
No. 3/6 Hydroquinone 1.5 mL
No. 4/6 Hydroquinone 1.5 mL
No. 5/6 Hydroquinone 1.5 mL
No. 6/6 Hydroquinone 1.5 mL

Results Note / ID Rx Result Unit

No. 1/6 Hydroquinone R1= 0.9828 --
No. 2/6 Hydroquinone R1= 0.9822 --
No. 3/6 Hydroquinone R1= 0.9829 --
No. 4/6 Hydroquinone R1= 0.9832 --
No. 5/6 Hydroquinone R1= 0.9833 --
No. 6/6 Hydroquinone R1= 0.9836 --

Statistics
Rx Name n Mean Value Unit s srel[%]
R1 Factor 6 0.9830 -- 0.0005 0.05

Table of measured values Titration curve

2
 Method
Method: M297 Factor cerium sulfate 05.04.2007 Accompanying stating
User: Schreiner Accompanying stating No
Condition
001 Title Condition No
Typ General titration 008 Calculation
Compatible with T50/70/90 Result Factor
ID M297 Result Unit ----
Titel Factor cerium sulfate Formula R1=VENDDi*0.05/(VEQ*c)
Author Mettler Toledo Constant C= 1
Date / Time 05.04.2007 M None
Modified at 05.04.2007 z None
Protect No Decimal places 5
SOP None Result limits No
LabX SOP Record statistics Yes
002 Sample Extra statistical
Number of IDs 1 functions No
ID 1 Hydroquinone Condition No
Entry Type Fixed volume 009 End of sample
Volume [mL] 1.5
Density [g/mL] 1.0 010 Auxiliary Value
Correction factor 1.0 Name Cerium sulfate
Temperature [°C] 25.0 Formula H= Mean[R1]
Entry Arbitrary Limits No
003 Titration stand Condition No
Typ Manual stand
Titration stand Manual stand 1
004 Pump
Auxiliary reagent HCl 0.1 mol/L
Volume [mL] 40
Condition No
005 Dispense
Titrant 1/2 Hydroquinone
Concentration [mol/L] 0.05
Volume [mL] 1.5
Dosing rate [mL/min] 60.0
Condition No
006 Stir
Speed [%] 35
Duration [s] 10
Condition No
007 Titration (EQP)
Titrant
Titrant Cerium sulfate
Concentration [mol/L] 0.01
Sensor
Typ mV
Sensor DM140-SC
Unit mV
Temperature aquisition
Temperature aquisition No
Stir
Speed [%] 35
Predispense
Mode Volume
Volume [mL] 5
Wait time [s] 5
Control
Control User
Titrant addition Dynamic
dE (set value) 8
dV (min) 0.005
dV (max) 0.2
Mode Equlibrium controlled
dE 0.5
dt [s] 2
t(min) [s] 3
t(max) [s] 30
Evaluation and Recognition
Procedure Standard
Threshold 500
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax [mL] 10
At potential No
At Slope No
After numbered
of recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No

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