14 "p2o5fert – Metrohm 794 Basic Titrino User Manual

Page 184

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6.3. User methods

794 Basic Titrino

180

6.3.14 "P2O5Fert""

Determination of P

2

O

5

in fertilizer.

TIP method with submethods "P2O5-1" and "P2O5-2"

Electrode:

6.0232.100 combined pH glass electrode, at measuring input 1.

additional instrument: 765 Dosimat, connect to 794 Basic Titrino via Remote line.

Titrant:

c(NaOH) = 1.0 mol/L.

Reagents:

c(HCl) = 1.0 mol/L

Sodium oxalate sat.

Sample:

Pipette exactly 10 mL liquid fertilizer into the titration vessel. Add 5 mL

c(HCl) = 1.0 mol/L and dilute with 40 mL dist. water.

Fill the Dosimat with sodium oxalate solution and adjust the dosing vol-

ume to 15 mL.

Sequence: P2O5Fert is startet and the submethod P2O5-1 titrates the sample to the

dihydrogenphosphate and determines the excess of dispensed titrant. An

activating pulse starts the Dosimat dispensing the sodium oxalate solu-

tion. After the waiting time of 30 s P2O5-2 titrates the dihydrogenphos-

phate. P2O5Fert calculates the content of P

2

O

5

.

Reference:

Metrohm Application Bulletin Nr. 240.


P2O5-1
Titration of the first equivalence point of
H

3

PO

4

.















'pa

794 Titrino 01102 794.0010

date 2002-01-03 time 10:01 0

DET pH P2O5-1

parameters

>titration parameters

meas.pt.density 4

min.incr. 10.0 µl

titr.rate max. ml/min

signal drift 50 mV/min

equilibr.time 26 s

start V: OFF

pause 0 s

meas.input: 1

temperature 25.0 °C

>stop conditions

stop V: abs.

stop V 99.99 ml

stop pH OFF

stop EP 1

filling rate max. ml/min

>statistics

status: OFF

>evaluation

EPC 5

EP recognition: all

fix EP1 at pH OFF

pK/HNP: OFF

>preselections

req.ident: OFF

req.smpl size: OFF

activate pulse: OFF

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