HIRANUMA APPLICATION DATA

Data No.

Automatic Titrator

G9Apr. 5,
2019

Quantitative determination of lead ion

Metals
1. Abstract

The chelatometric titration is generally used for the determination of lead ion (Pb2+). The pH region thelead ion can be directly titrated is pH 3.5 ~ 10 (stability constant = 17.88). 1 However, it generates Pb(OH) 2
precipitation at alkaline region. When performing titration under alkaline condition, the auxiliary complexing
agent such as ethanolamine, tartaric acid, or citric acid should be added in advance to generate weakchelatometric complex and avoid the generation of lead hydroxide precipitation.
It is titrated at pH around 4 ~ 5 when performing under acidic condition. This report introduces anexample that the lead ion in sample solution adjusted to pH 5 by hexamine solution is determined with using
XO indicator (red purple →yellow).

Pb2+＋Na2EDTA→

Pb-EDTA＋2Na+2. Configuration of instruments and reagents(1) Configuration
Main unit ：Hiranuma Automatic Titrator COM series (Photometric titrator unit type M)
with 530 nm optical filter

Electrode：

Glass - Reference electrode GR-501BZ (for pH confirmation)(2) Reagents
Titrant：0.01 mol/L EDTA standard solution

Buffer solution：5 ~ 10 mL of 20 % hexamine solutionIndicator：0.2 mL of XO indicator (0.1 % solution)

3. Measurement procedure(1) Dispense 1 mL of sample into a 100 mL beaker with volumetric pipette.
(2) Add about 60 mL of DI water.
(3) Add hexamine solution to adjust the pH to 5.
(4) Add 0.2 mL of XO indicator.
(5) Immerse photometric probe into sample solution and titrate with 0.01 mol/L EDTA standard solution.4. Measurement conditions and results
Examples of titration conditions
Cnd. No.
MethodBuret No.
Amp No.
D.UnitS- Timer
C.P. mL
T.Timer
D.P. mLEnd Sens
Over mLMax Vol.

1
B cross
12
T%
15
7
150.1
300
1.5
12sec
mL
sec
mL
mL
mL

Constant No.
SizeBlank
Molarity
FactorK
L
Unit
Formula

1
1 mL
0 mL
0.01 mol/L
1.001
207.2
0g/L

(D-B)*K*F*M/S
Decimal Places
4Auto input parameter

Mode No.
Pre Int
Del K
Del Sens
Int Time
Int Sens
Brt Speed
Pulse

2400053280secmVsecmV

None

Measurement results
Number ofSize

Titrant

Lead ion

Measurement(mL)

Volume (mL)Concentration (g/L)

1

1

9.998

20.737

2

1

9.997

20.735

3

1

9.931

20.598

Statisticcalculation

Avg.

20.69 g/L

SD

0.080 g/L

RSD

0.385 %

Example of titration curve

5. Note(1) Measurement condition
The color of indicator reagent suddenly changes at the endpoint, therefore the minimum increment titration
without “Del K” control allows to get good results. The function “CP mL” can reduce the measurement timeby continuously adding slightly smaller volume of titrant than the titrant consumption required to the endpoint.
The “Method” on condition parameter is set to “B Cross” because the endpoint is defined as the point where
the color change of the indicator is completed.
(2) Interfering ions
There is no interference on the measurement even if alkaline-earth metal or Mg is contained in the sample.
However, please note that Ni2+, Fe3+, Zn2+, Cd2+, and Co2+ ions are also titrated at the same time.
Keywords：Lead ion, Photometric titration, Chelatometric titration
References(1) K. Ueno, “Chelatometry”, 1989, Nankodo, Tokyo.
*Some measurement would not be possible depending on optional configuration of system.